hybridfree/eevblog-posts huggingface dataset:
Lithium battery corrosion on PCB, will this keep eating away the board? - Page 1
Forum section: electronics / repair

author: smiba
author_rank: Contributor
timestamp: September 01, 2020, 10:33:56 pm
content: Hey everyone,I've taken it on myself to fix another Macintosh SE/30 with the most horrendous battery damage. The battery holder rotted itself off the board and even ate away a part of the shield.Now, let it be said I'm not unknown to repairing devices like these and I'm progressing nicely:Some pads have rotted off, no big issues I'll just run some wires..... But wait, those vias look pretty bad too.Oops, most vias around the RTC area are absolutely rotted through!!This makes it really challenging as this is a 4 layer board, a lot of these vias come and go and I have no way to know what they carry. (Also in this area is the System ROM, RAM memory and Video Rom.... so eh, probably important)This means I'll need to check pretty much half of the motherboard for continuity. An absolute pain in the ass, but also relaxing once you're going and cross off all lines on the schematic one by one.Now to cut to the chase,if I leave these vias untreated will they keep on rotting away further and further? The battery is removed and the surface is cleaned off (for the most part).How do I stop these vias from worsening over time? I want to make sure I'm not spending 50 hours of my time on this, only to have 10 new open circuits the next year.

author: rvalente
author_rank: Frequent Contributor
timestamp: September 01, 2020, 10:41:37 pm
content: I never had myself a good experiences cleaning battery leakage. Although you wash with detergent, scrub with isopropanol, try to neutralize it with some weak base/acid, after some time it always come back, even in the simpler parts like bat contacts. With boards I believe the battery electrolyte gets in the boards fiber (fiberglass has a tendency of absorbing moisture, why not electrolytes).I would scrub it over and over again, water and detergent

author: smiba
author_rank: Contributor
timestamp: September 01, 2020, 11:10:18 pm
content: Might just be a bit over my head with this one then, it had more then 10 years to slowly rot away.Like I say, doing all the work is not much of a problem... but if in the end it will still die I may have to prematurely pull it off life support before it takes up more hours
Lithium battery laptop revive - Page 1
Forum section: electronics / repair

author: robint
author_rank: Regular Contributor
timestamp: October 17, 2023, 01:13:51 am
content: Hi AllI hope this is in the right categoryI just want to give something back here ( as EEVblog has really helped me) with my recent success reviving a laptop (Acer Aspire One) Netbook. A trusty 20 years old little friend still going strong on Win XP rev 3 and indispensable from the days when you had control over your life.I hadnt used it for perhaps a year or more and powered it up and saw that the battery pack wasnt charging. I saw it was difficult to source a replacement cos the form factor was one of many different shapes and sizes.That was when makers deliberately made 100's of different forms so you would have to probably buy a new laptop when your lion batteries wore out (they even put count down chips to disable your pack after ca 600 cycles - just like ink cartridges had - till EU outlawed the practice cos of the mountain of industrial waste this practice produced - same applies to laptop. If you do your YT homework its surprising easy to repair a lion battery pack. YMMVSo I did and at no cost, revived a pack that had discharged below the lock out level ca 2.5v imposed by the BMS cct.I prised open the casing and found 2 oo 6 cells down to 1.9v. All the BS on the web will tell you to send them to a recycle depotRubbishI followed the advice to charge the two cells at 1mAdirectly across the cells. The ocV came up to 2.5v, then I up the charge to 30mA to ocV 3.2V as per the other 4 cells deemed ok. Reassembled the pack roughly and put it back into the laptop and plugged in the psu block. Started up Win and the battery app said 20% remaining but was charging. 2hrs later, I had full charge 100%. So I shut down/restart and removed the psu and left it running 30 mins. I have my m/c set to power save so the screen powered off after 5 mins. but on refresh I had only used ca 5% of available capacity. WHAT A RESULTI should say that I rarely used my m/c on battery and only expected the battery to perform as a UPS, so generally very little deep cycle use (good for battery life).So that saved me £30 for some dodgy? alt replacement pack.I herewith post some links to YT vids and others that may help someone else with an old cherished laptop.https://www.nature.com/articles/srep30248I strongly recommend bigclivedotcom as a source of genuine info (not the usual waste of time BS vids and comments by armchair puff adders and worse infomercials pushing their brand and expensive products etc.https://www.youtube.com/@bigclivedotcom/search?query=lithium%20batteriesBCDC has been going over 10 years and has ca 700vids of personal experience and workbench tear downs - amazing wealth of knowledge packed in his site - and he is not sponsored or selling anythingI daresay many EEVblog members will already know of this invaluable source of (sometimes weird) topics - well he does live on the IoMHope this helpsRobin
Little help tuning up an old CRT TV?  - Page 1
Forum section: electronics / repair

author: BrokenYugo
author_rank: Super Contributor
timestamp: May 26, 2022, 07:29:37 pm
content: What do "Sub brightness" and "AGC adjust" do exactly? Set in question is a Gold Star GCT1954MN, chassis NC-4JA, service data unavailable for free best I can tell. Goal is to to give the thing a quick realignment for a friend to get the most out of the tired tube until he finds a nicer CRT TV for CRT TV things. This thing is old enough it's mostly pots to set it up. I have a basic understanding of how to go through with the service mode line and whatnot setting up the bias, drive, and screen controls, know not to mess with the tuned circuits, etc. but I am not sure where those two fall in to the procedure, or if I should even touch them.

author: mclute0
author_rank: Regular Contributor
timestamp: May 26, 2022, 08:57:28 pm
content: Sub brightness = coarse brightness control, brightness would be fine controlAGC adjust = Automatic Gain Control for RF signal, normally not touchy. Does not change picture quality only signal.always use plastic tweeker to be safe, even if the adjuster can be finger turned.https://crtdatabase.com/faq/crt-color-adjustment

author: strawberry
author_rank: Super Contributor
timestamp: May 27, 2022, 04:48:59 am
content: should be closehttps://elektrotanya.com/goldstar_gct2505_cn26b46_chassis_nc44a.pdf/download.htmlcould adjust Screen to get up brightness

author: BrokenYugo
author_rank: Super Contributor
timestamp: May 27, 2022, 05:55:21 am
content: That does indeed look close enough, pretty concise explanations of what you're looking for with the two controls.
LM317/LM337 Bipolar Power Supply Not Regulating (Mackie HUI) - Page 1
Forum section: electronics / repair

author: Maniac303
author_rank: Newbie
timestamp: May 10, 2022, 10:11:51 pm
content: Greetings folks. I have _two_ Mackie HUIs with PSUs that are not regulating on the +/- 15 VDC rails. They are based on LM317 and LM337. I have found and changed a few bad caps (changed all electrolytics regardless), refreshed diodes in bridge, checked all diodes, all resistors etc., replaced the LM317 and LM337 and tested with supplied transformer (providing ~37VAC, once rectified and split this gives ~24VDC per side). The PSU does not regulate, even when loaded with 220 Ohm 5W resistors, what goes in comes out the other side. Regulators were tested in simple breadboard circuit prior to install!I am seeking hints. Also trying to understand the purpose of R15 and R16, 30 Ohm power resistors bridging each input and output. These were not in the breadboard test circuit.Attaching a simplified schematic derived from the one in the service manual.Thanks in advance for any advice!

author: edavid
author_rank: Super Contributor
timestamp: May 10, 2022, 10:22:38 pm
content: The shunt resistors reduce the power dissipation in the regulators.The downside is that the regulators won't work until there's a 9V drop across those resistors (load resistance must be < 50 ohms).

author: Maniac303
author_rank: Newbie
timestamp: May 10, 2022, 10:56:21 pm
content: I may actually understand this....24V-15V = 9V drop before the regulator kicks in?9V across 30 Ohms is 0.3 A current to get the 9 V drop.15 V @ 0.3A occurs when load is 15V/0.3A = 50 Ohms?So I have been banging my head against the wall when the circuit was working properly once I recapped and refreshed the diodes (diode drops were wonky). I was simply testing with a load that was too low to get the regulators to kick in.Thank you so much for your reply. FWIIW, the circuit regulates fine with one leg of the shunt pulled on my test jig.

author: David_AVD
author_rank: Super Contributor
timestamp: May 11, 2022, 01:29:26 am
content: Wow, that circuit seems like it could cause all sorts of mayhem !
LM378N Alternative - Page 1
Forum section: electronics / repair

author: thunderfm
author_rank: Newbie
timestamp: October 18, 2020, 12:29:35 pm
content: Hi,I'm restoring a Dynamix 3000 mixing console and I'm struggling to find a replacement IC for the LM378N in the monitor section. Does anyone know of a suitable alternative?Datasheet is here:https://www.datasheetarchive.com/pdf/download.php?id=69482863dca77b29d6ebbd5cfec86dd9ed701c&type=O&term=LM378NThanks!

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 18, 2020, 09:53:24 pm
content: Hi!Little diode and Nikko Electronics both list small stocks of this device, however if the L.T. supply is less than 22V you can get away with the much more readily available LM380!Chris WilliamsPS!I don't have the power supply schematic – apparently that never got leaked out of Dynamix's emporium, however, since two ±15V regulator i.c.'s are shown on the monitor board circuit diagram, I would think it's nothing more than a dual–voltage unregulated linear type (transformer, bridge rectifier plus two smoothing electrolytic capacitors) fed from a transformer of something like 18–0–18V at 1.5A!

author: thunderfm
author_rank: Newbie
timestamp: October 20, 2020, 10:24:03 am
content: Thanks Chris!You're right, the PSU is very simple and outputs +-18V. I've already recapped and repaired the PSU.I'll look into the LM380.Thanks for your help!

author: rayj306
author_rank: Newbie
timestamp: October 22, 2020, 01:22:44 am
content: Holy Canoli,I cant believe this was posted 3 days ago. I am in the process of restoring a Dynamic 3000 as well.Ray

author: thunderfm
author_rank: Newbie
timestamp: November 19, 2020, 12:25:49 pm
content: Regarding the LM380, do you know how one would re-map the pins? I've looked at the datasheets and I'm confused as to what the Output, Bias, and Feedback pins of the LM378 would be mapped to on the LM380?Thanks,

author: ijchan223
author_rank: Contributor
timestamp: November 20, 2020, 06:36:54 am
content: https://www.ti.com/amplifier-circuit/op-amps/audio/overview.htmlthe 380 seems like a fairly bad choice to me.to change the pinout you will have to make an adapter board but most likely you will have to change the components that set the gain of the amp and what not.

author: fzabkar
author_rank: Super Contributor
timestamp: November 21, 2020, 10:15:45 pm
content: The NTE804 is an equivalent (identical?) part.https://www.nteinc.com/search.phphttps://www.nteinc.com/specs/800to899/pdf/nte804.pdfSeveral suppliers have stock:http://dilp.netcomponents.com/cgi-bin/nteinc.asp?partnumber1=NTE804If you can believe this ...https://instrumentalparts.com/ic-ic-lm378n/

author: thunderfm
author_rank: Newbie
timestamp: November 26, 2020, 03:11:36 pm
content: Thanks, that does look like a good equivalent. I can't seem to find any stockists in the UK sadly, but I'll keep searching!
LM3886 bridge mode... calling all gurus of Gainclone - Page 1
Forum section: electronics / repair

author: peteb2
author_rank: Regular Contributor
timestamp: April 16, 2020, 01:47:46 pm
content: I have a DynAudio active speaker with a simple internal amp pcb consisting of wired two LM3886s in bridge that feeds the main speaker & a third single LM3886 for tweeter. The fault is random. Powering on randomly results in full on motor-boating oscillation for the main driver speaker. It’s extremely high volume and has seriously given a few folks a fright more than once. Checking data sheets and reading design references it looks as though there are a few suggested parts not included!The unit is not old, maybe 18months. The problem has always happened & yes warranty would have been a better route.So far I’ve replaced the entire set of ‘one-hung-low’ no name brand electrolytics but the very random oscillation issue continues to suddenly happen at power on in a very random fashion.At the bench I pulled the bridge rectifier and have a substituting external laboratory bench supply set at the usual 40VDC which is normally supplied by the onboard supply. I’ve been ‘scoping the + & - terminals of the LM3886s wired in bridge. I’ve a 1kHz ref tone at the input and a 4ohm dummy load (driver disconnected).For multiple power-ons via the bench psu, the amplifier comes up perfectly with a clean sine wave 1KHz... and draws just over 1A but if I give it a large grouping of on - offs say 30 seconds apart there’s a sudden single failure as there’s obvious low freq motorboating oscillating then slowly the 1KHz appears both + & - feeds seriously cropped on the upper half of the tone signal cycle. It takes a good minute to finally settle back into a proper clean sine wave with no clipping on the upper peaks & multiple power cycles things are fine until oops a random bad one happens.I’ve never dabbled with the Gainclone chipset (so hence my call to any gurus) but what’s happening? Is it possible like the lousy no-name brand electrolytics hints that the LM3886s are fakes that are not working correctly? I have some genuine spare devices but to swap them is a really huge process on account of the layout. Any experiences of similar trouble or ideas of what to do appreciated.. TIA

author: peteb2
author_rank: Regular Contributor
timestamp: April 17, 2020, 09:45:26 am
content: Solved the problem... replaced the two LM3886's set up in bridge mode, no more random cases of motor-boating oscillating upon switch-on even after 50 attempts so i hope its ok now. With 400Hz signal applied the scope traces for output + and - come up perfectly together every time even during a very quick power up, off and on...

author: SilverSolder
author_rank: Super Contributor
timestamp: April 17, 2020, 01:25:54 pm
content: Interesting failure mode... I guess there aren't that many parts to swap, one advantage of a chip amp!
Load switches - Page 1
Forum section: electronics / repair

author: fzabkar
author_rank: Super Contributor
timestamp: February 10, 2022, 06:19:07 pm
content: Could someone please identify these load switches ?They are functionally and electrically identical to the following:SiP32462DB-T2-GE1, Vishay Siliconix, 50 mOhm, Slew Rate Controlled Load Switch, Vin = 1.2V - 5.5V, 1.2A, marking AH, WCSP4:https://www.vishay.com/docs/67754/sip32461.pdfSiP32458, SiP32459, Vishay Siliconix, 20 mOhm, Slew Rate Controlled Load Switch, Vin = 1.5V - 5.5V, 3A, marking AA or AB, WCSP6:https://www.vishay.com/docs/63999/sip32458.pdfMore information in this thread:https://forum.hddguru.com/viewtopic.php?f=10&t=39872I also need help to ID this component:I'm guessing that it is an electronic fuse or another load switch. "CK" is the part code.This appears to be the ballout:Code:+3.3V in O O output+3.3V in O O output+3.3V in O O ground

author: fzabkar
author_rank: Super Contributor
timestamp: December 28, 2022, 06:04:18 pm
content: I found this part which has a "CK" branding and compatible pinout, but it seems wrong because it is atypical for an SSD. The marking style seemssimilarto other Analog Devices packages, but I haven't found an image of this particular chip.ADP1196ACBZ, Analog Devices, Logic Controlled High-Side or Low-Side Load Switch, 5V, 3A, 0V - 5.5Vin, marking CK, WLCSP-6:https://www.analog.com/media/en/technical-documentation/data-sheets/adp1196.pdfI haven't found anything on the "794DKI" part, but TI's TPS22954 load switch has a "ZDKI" marking, and "PDKI" is a power MUX (TPS2103) ...
SMD Part Identification for Logitech ConferenceCam CC3000e repair - Page 1
Forum section: electronics / repair

author: 0xPIT
author_rank: Regular Contributor
timestamp: March 20, 2020, 02:03:50 pm
content: Hi,so, I got this Logitech for free with a mechanical defect that I could repair thanks to PTFE glue that cost 40€.In course of the repair, I've added a Mini-USB to the camera module to use it stand alone, which worked fine.Never used the cam at all, but due to current circumstances I fetched the device from the basement to use for remote work, and it no longer works.Now, there seems to be a power issue. When I plug in the camera, there is high current draw, switching off the base unit.I look for help to identify the power supply SMD controller with the marking "B3GnSK" – see photo.Any hints greatly appreciated!Thanks,pit

author: 0xPIT
author_rank: Regular Contributor
timestamp: March 21, 2020, 02:59:18 pm
content: Traced the schematics to a DaveCAD...

author: benj38
author_rank: Frequent Contributor
timestamp: March 22, 2020, 05:39:45 pm
content: I am sorry I can't exactly identify the IC, but if you do not mind me asking, are you sure you need to?I mean, this looks like a simple micro-power buck converter controller with integrated diode(s). The roles of all but one pin in your diagram should be(clockwise, starting top-left in your diagram): boost, ground, feedback, ? (maybe to set the switching frequency??), input voltage, switching output.I would simply measure the output voltage without the camera plugged in, and if it falls when you plug it in, try to connect a lab power supply (preferably with current limit capability) as the power source instead of this converter, and see what happens.Identifying these SMD chips is more luck than anything else, so I usually do that as a last resort, not as the first step.

author: fzabkar
author_rank: Super Contributor
timestamp: March 22, 2020, 08:39:26 pm
content: I would also measure the voltage at the feedback pin, if the IC is working correctly. Otherwise measure the feedback resistors and calculate the required feedback voltage for the expected Vout.

author: 0xPIT
author_rank: Regular Contributor
timestamp: April 08, 2020, 02:56:22 pm
content: So, I've removed the IC and it's supporting circuit and bodged one of those 4$ mini buck converter from eb*y --> Works again
Logitech Harmony 900 repair? - Page 1
Forum section: electronics / repair

author: rfengg
author_rank: Regular Contributor
timestamp: May 27, 2019, 09:33:06 am
content: Our Logitech Harmony 900 has completely died on us........the battery is perfectly fine and holds charge well.The screen is completely blank and does not respond to any button inputs.On opening the unit, I can't see any obvious signs of damage, so am at a loss on how to proceed?Is there any way I can get a schematic for this?The main processor is a BGA and I don't have the tools to do anything on it.TIA.

author: eKretz
author_rank: Frequent Contributor
timestamp: May 28, 2019, 02:25:42 am
content: Got a scope? Is it getting any signals to the lcd screen? IIRC I read somewhere that they're notorious for failing. Someone was making aftermarket replacements for a while.

author: cvanc
author_rank: Frequent Contributor
timestamp: May 28, 2019, 02:48:08 am
content: https://www.harmonyremoterepair.com/#/He fixed 2 Harmony Ones for me many years ago (including one that needed a new LCD display); they are still working great. Highly recommended (if you want to outsource the fix, that is).
Logitech Unifying Receiver (solved) - Page 1
Forum section: electronics / repair

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: April 19, 2023, 12:25:30 pm
content: I was having connection problems between my mouse and this receiver. The connection was intermittent. A look under the micro scope revealed the problem. A 0201 C13 in the antenna matching network has run off. Since this is what I assume to be a tuned matching circuit, any ole coupling cap will probably not be optimal. I have another receiver, but really don't want to snap the top off to see what the cap value might be. The dongle operates at 2.4GHz feeding a trace antenna. Any thoughts on what a range of values might be?

author: Gribo
author_rank: Frequent Contributor
timestamp: April 19, 2023, 01:02:00 pm
content: What's the part number on the transceiver? In the past, Logitech used TI's CC25xx parts.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: April 19, 2023, 02:56:03 pm
content: Quote from: Gribo on April 19, 2023, 01:02:00 pmIt's NRFD24LU1P. I added another pic. Also found a data sheet and it looks like I'll need a 1.2pF cap in 0201.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: April 19, 2023, 08:21:28 pm
content: I scraped some solder mask off the trace and scabbed in an 0603. Works perfectly.
Logitech Z-5500 Power Supply to Control Unit Repair help wanted - Page 1
Forum section: electronics / repair

author: Sci666
author_rank: Newbie
timestamp: June 25, 2020, 07:34:47 am
content: Hi there,i have a problem.i have a Logitech Z-5500 Sound System with a small defekt.this defect causes a higer voltage on the power line to the control pod unit.normally on this line is 8Volts ! i have 13-14 volt on this line and if the control pod is off about 15voltsit seems that the pod can handle this higer voltage but this causes more problems like overheating and failing/gone LED lightsi attached a schematic i found in another forum.i swapped out already the voltage regulator, the capacitor and the bridge rectifier but all of this has no effect. the problem remails exactly like before. (this circuit board is in the subwoofer)the Pod unit is okay, i have another Z5500 and if i take the other pod its the same problem, if i take the other subwoofer everything is fine.so what can cause the higher voltag ein this "small" circuit ? i have no idea.please help me

author: TheMG
author_rank: Frequent Contributor
timestamp: June 25, 2020, 01:34:32 pm
content: Have you checked the two resistors connected to the ADJ pin of the LM217? A faulty resistor or broken solder connection there would cause the regulator to output the incorrect voltage.From the voltage you are measuring, it sure seems like the unregulated voltage minis dropout voltage. In other words, the regulator is attempting to output a voltage higher than the unregulated input would allow. This is why I would suspect something with those resistors, since they set the output voltage of thee regulator. LM217 is an adjustable regulator.

author: Sci666
author_rank: Newbie
timestamp: June 25, 2020, 01:38:14 pm
content: good hint !i will check this and post again
Logitech Z333 2.1 Speakers - Page 1
Forum section: electronics / repair

author: thyaguster
author_rank: Newbie
timestamp: April 17, 2021, 10:50:33 pm
content: Hi there, need some help fixing these Logitech Z333 2.1 Speakers.They stopped outputting any sound suddenly, tested with 3.5mm jack and with RCA cable.If I connect headphones to the 3.5mm socket in the volume control PCB while playing an audio book - I can hear it very faintly, can't make out any words, but I can hear the narrator speaking. It does this whether I have the speakers on or off.The PSU always had a buzzing sound, to the point I could clearly notice a difference in pitch when I turned my speakers on or off.Since they stopped working I can still perceive a difference, but I have memory of it being much more noticeable. The amp board gets 17v from the PSU, the value doesn't change with on or off.I've tested with a 19v laptop adapter and got the same results.Tried to jump wire VOL_RIN to VOL_ROUT and VOL_LIN to VOL_LOUT to exclude the volume control PCB and it's cable but also got the same results.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: April 18, 2021, 01:57:48 am
content: I've tested with a 19v laptop adapter and got the same results.Never do this, extra 2V is high enough to make chips damage.Give marked working voltage to chips.You make faulty area larger, otherwise.Now you need to check ALL chips if they are working or getting hot.If chips get damaged, Vcc shorts to ground always as well as hot.How to troubleshoot, see photosDownload 1KHz wave file and input to the speaker via smart phone.Then follow copper foils to see where signals gothat are inputs where it may be pre-amp or filtering caps.Oscilloscope will be a great help when troubleshooting audio equipment.If you have it, use it without any hesitation.If chips are OK, check their peripheral SMD components.I will leave police station and meet Ada Wong again tonight .
Logitech Z906 - Page 1
Forum section: electronics / repair

author: elektro_Jarda
author_rank: Newbie
timestamp: August 21, 2021, 12:30:29 pm
content: Please, give me an advice. The Logitech Z906 began to fluctuate in audio output on a regular basis. The fault is in the switching power supply, which has the designation 94V-0 E 322995, but I did not find the diagram anywhere. Only the 45 V output voltage pulses. The 12 V and 5 V output is OK, verified by an oscilloscope. Thank you for your help or ,if you can find it, for the schematic. I apologize for my bad English.
Logitech Z906 Amp testing - Page 1
Forum section: electronics / repair

author: jormy299
author_rank: Newbie
timestamp: January 30, 2022, 08:42:18 pm
content: Hi all;Bought the set a few weeks ago and the thing was working intermitently, and eventually stopped working.Looked inside and came out to the conclusion the PSU was at fault. (Transformer was making weird sounds and no voltage coming out to the amp)Found some info on here about guys replacing with an alternative power supplies, which I did.I have a 400w chinese power supply set at 40V connected to the +HV leadsAnd then 3 buck converters to make the 12v, 5v, and 3,3v (first pin of small connector)All negative connected together, and connected to GND pins, and second pin of small connector (the 3,3v one)Everything is connected, console works perfectly (which it did not before) but I still have no sound comin out of any speakers, even using the speaker test mode.Are there any test points I should check on the amp board to go further into my troubleshooting ?I truly hoped this was gonna fix my issue, and I have a feeling I'm real close to success.... but there's something I am missing apparentlyTIA

author: jormy299
author_rank: Newbie
timestamp: January 31, 2022, 01:59:35 pm
content: I can provide pictures of the amp itself if that may help....
Repair | Logitech Z906 Burnt Component C86 - Page 1
Forum section: electronics / repair

author: egolgeli
author_rank: Newbie
timestamp: March 05, 2024, 10:32:58 pm
content: Hi,In an early morning, I went to my room and felt the known burnt circuit board smell. Seconds after, I found my Z906 dead. It never turns on since that moment. When plugged to AC, there is a clicking sound but nothing appears on the controller unit. Power button is totally unresponsive.I checked the board and found a large burnt mark around the component C86. While cleaning, burnt component (C86) dropped. Also, components on the other side of the board, C49, R72 might be affected as well, but there is no visual damage there.Anyone encountered such/same? Any known or suggested way to fix this? Is it possible to buy the power unit somewhere?Thanks,

author: MathWizard
author_rank: Super Contributor
timestamp: March 06, 2024, 01:02:51 am
content: IDK the Z906 but it looks like the secondary side of a SwitchModePowerSupply-SMPS, those 2 big thing's would be 2, dual diodes. They don't really look burned, but they need testing.Assuming the problem started and ended about there on the secondary side rectifier's, and no chips got damaged, then yeah it should be pretty fixable with common parts.Like for instance, if one of the caps on the secondary side failed and shorts say the 5 or 12V to the local GND, there will be sensing circuits and chips that will see this problem of low voltage, and quickly tell the primary side chips to shut down. If the diodes failed as a short/low-resistance, then some over-current or over-voltage sensing should shut down the PSU.If you have a DMM, and a soldering iron, and flux, I'd remove the brunt parts, and check those diodes, and see what the output resistance measured then. It still can be pretty low on some SMPS's, like on a computer PSU, it might measure 100ohms from 12V to GND, on the Z906 it's probably higher.I haven't fixed that many SMPS, but usually the damage was pretty limited, and the protection circuits did their job and reset or shut down the PSU.The clicking you keep hearing is probably the PSU resetting over and over as it senses the problem, and resets. With any luck the primary side was fine and still is fine, but you never know, read or ask about some safety questions if you're not sure.
Logitech z906 buzzing output - Page 1
Forum section: electronics / repair

author: hpibmx
author_rank: Regular Contributor
timestamp: July 01, 2021, 05:02:35 am
content: Hi,I've got this Logitech Z906 with no sound at all, but when it's touched by my finger i can hear it's being detected and amplified!after changing input first time I had sound for 2 or 3 second then it was gone. (which was not clear or loud though)what I've done,- new 3.5 audio jack with different devices,- tried different inputs- tried resting by holding input button for 7 sec- tried 3 or all 5 speaker connectedthank you for advance.

author: Rasz
author_rank: Super Contributor
timestamp: July 01, 2021, 10:20:17 am
content: I think we had a few threads about those with blown power supplies
Logitech Z906 power button - Page 1
Forum section: electronics / repair

author: mikle65
author_rank: Newbie
timestamp: February 16, 2020, 11:19:26 am
content: hi everyone!i have a logitech z906 where the power button is acting up, i have to play and push it several times sometimes 10-15 before it turns on, push it harder or push on the edges of the button etc. i thought i will open the controller unit and clean with IPA and apply contact spray, but it is not designed to open and i'm afraid of breaking it, same thing with the remote control where the volume down button have to be pushed so hard to work, but also will break if i pry it open. Has anyone done open these units before? or any other tips or hints about the issue?EDIT:ok i managed to do it, you have to be kind of brave with it pop it of and then i also found this video:to remove the pcb you have to gently pry off the volume button and there is a nut around the potentiometer what is fingerthight +4 screws on the back.so i think it will need a new micro switch as nothing obvious found . will try to clean it first and see what happens.EDIT2: it seems to be working now.i also removed the pcb from the remote control for the volume - issue. these are not really microswitches but there is a sticky clear tape layer holding round metal bits touching the pcb "button" part, i lifted the clear tape at the problematic button and cleaned under with IPA. the battery connections are also a bit rusty, cleaned them and coated with wd40, the issue seems to be sorted.
Logitech Z906 Power Supply oscillating - Page 1
Forum section: electronics / repair

author: katriik
author_rank: Newbie
timestamp: August 20, 2020, 01:35:41 am
content: Hello everyone,I'm having some issues with my Z906.It started with the 3 input leds on a few years ago.Left the system stored for many months until I decided to take a look and tried to follow a YT comment recommending to replace R79 and R80 with 5.6R 2W resistors.The system came back to life and was working well until today.I thought the resistors were at fault again, but this time, after replacing them, the system came back to life, but the sound amplitude is heavily oscillating at around 3 Hz.It makes any sound being played to "FEel lIKE it IS beINg dISTorTED".Whenever I place my ear close to the PSU, I can hear a clicking sound that also coincide with the 3 Hz oscillation, and when measuring the 5, 12 and 40 V outputs, none of them are stable and they keep oscillating. The clicking sound becomes more apparent when the system is turned on.I have the feeling that something is not maintaining the PSU output constant, and I can't tell if it is from the controlling side, or from the output.The clicking noise is definitively coming around the transformer in the middle, I just can't tell if it is from the 120 V being modulated or if it is from a relay (assuming that the RL components are relays).Any assistance is appreciated.

author: StraidTheRock
author_rank: Newbie
timestamp: September 20, 2020, 06:16:10 pm
content: Hi there. I had the three LEDs issue earlier this week, and have tried a few things to resolve it.The resistors R79 and R80 seem fine, checking them with a multimeter reads 5.8 Ohms each.I connected the speakers on a different wall socket, that seemed to make little difference.If powering up the speakers while all 5 satellites are connected, the three LED issue comes back.If powered up without any satellites, the system starts normally. Connecting the speakers after the system is switched on results in the oscillating behaviour you described.My subwoofer doesn't make any discernible sound, and I can also hear the ticking noise from the electronics.Have you had any luck?
Long shot, anyone have an eMMC image file for Formlabs V2 SLA printer - Page 1
Forum section: electronics / repair

author: Psi
author_rank: Super Contributor
timestamp: January 28, 2023, 06:58:02 am
content: Long shot, does anyone have an eMMC image file for a Formlabs V2 SLA printer.We fixed a fault on a Formlabs V2 printer PCB but it has been power cycled so often during boot-up (due to the original fault) that the eMMC has become corrupt and Linux can no longer boot up far enough to be controlable for a FW upgrade to repair the OS.I can see from the console port that linux starts booting but it cannot mount one of the eMMC partitions.I'm investigating removing and dumping the eMMC chip to a file so I can maybe mount it in desktop Linux and fix the FS but it would help if anyone has a copy of what it's supposed to be, or maybe a doner board I can buy to pull the eMMC chip off.Thanks.

author: Psi
author_rank: Super Contributor
timestamp: January 31, 2023, 04:36:47 am
content: Nevermind, no longer needed.The issue turned out to be bad BGA ball on eMMC chip preventing booting rather than corrupt image.
Longwei power supply mod: TPR3005-2D - Page 1
Forum section: electronics / repair

author: asterix2344
author_rank: Newbie
timestamp: March 08, 2024, 03:30:03 pm
content: Greetings to everyone, my LONGWEI power supply mod: TPR 3005-2D has broken down, I don't have the wiring diagram. The fault is that the left section does not work on the front the DC LED is on, the voltage can be adjusted but the amperage does not work. The right section works perfectly. Can someone kindly help me?

author: Jwillis
author_rank: Super Contributor
timestamp: March 09, 2024, 01:33:01 am
content: Linear? Based on the HY3005 linear supply. Mastech or Volteq. There are many re-brands.https://elektrotanya.com/mastech_hy-3005f-3_matrix_mps-3500l_2x30v,5a_psu_sch.pdf/download.htmlThe front pots fail and can cause problems.Edit for better link

author: asterix2344
author_rank: Newbie
timestamp: March 09, 2024, 12:18:13 pm
content: Jwillis thanks for replying. Can you explain to me what the: The front pots , are you perhaps referring to the final power circuits?

author: Jwillis
author_rank: Super Contributor
timestamp: March 09, 2024, 10:02:44 pm
content: Quote from: asterix2344 on March 09, 2024, 12:18:13 pmWhat can happen is the wiper of the Current limit adjustment pot fails. The potentiometer (W10) is a voltage divider for the non inverting input of 741 op amp 2N2. That input needs 0V to 12V to adjust the current limit to output. If that input remains 0V because of a failed wiper on current adjustment pot, then you get no current to the output.I pointed to the potentiometer as a cause because it's common for mechanical devices to fail first.

author: asterix2344
author_rank: Newbie
timestamp: March 10, 2024, 11:16:28 am
content: I solved the problem in the following way: since the two control boards are identical, I disassembled the operational amplifier that controls the ic:N2 current of the board that doesn't work, with that of the section that works, and I found the culprit. Now the instrument has started working perfectly again. Thanks for your help, regards.P.s. sorry for my bad English, I use a translator.
Looking for 2SK 364 FET equivalent - Page 1
Forum section: electronics / repair

author: Audiorepair
author_rank: Frequent Contributor
timestamp: June 19, 2023, 10:35:55 am
content: Can't seem to find much available to replace these 2SK364 JFETs.They are used as audio switcher/mutes in an ADA guitar pre-amp/effects unit.Not sue why these things are unobtanium.Cheers.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 19, 2023, 11:12:37 am
content: For switch use I would suggest J113 or PN4393 as a TO92 version. If there is headroom in the voltage and low R_on is important that the J112 / PN4392 could be more suitable.There are many obsolete JFETs, especially in the older THT case. There are just no longer used that much with more OP-amps and switching with CMOS chips.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: June 19, 2023, 01:22:34 pm
content: Quote from: Kleinstein on June 19, 2023, 11:12:37 amAh, thanks for that, J113 seems to have done the trick.
Looking for 6532 Rockwell RIOT chips - Page 1
Forum section: electronics / repair

author: jrr
author_rank: Newbie
timestamp: February 14, 2023, 09:29:00 pm
content: Having trouble finding these chips other than China and most of those are fakes. Sorting them takes a bit of time even with my 6532 tester. Hard to tell if the working ones are actual 6532s or renumbered copies made by someone else...Anyone have a stash of 6532s that they are interested in selling?Alternatively, does anyone know the part number of the Russian or other copy of this chip? Is there a listing of Russian clones somewhere?Thanks!

author: daveho
author_rank: Newbie
timestamp: February 16, 2023, 11:31:25 pm
content: Unicornelectronics.com has them (although I don't know specifically if they have Rockwell ones). I've ordered stuff from them before, and never had any issues.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 17, 2023, 07:51:45 am
content: I should still have a few 6532 - though likely the Mostek version, as they are from an Comodore board. Still oversees shipping sounds excessive.

author: Jeremie
author_rank: Newbie
timestamp: February 17, 2023, 03:45:25 pm
content: I can try to find it
Looking for a 12 pin SMD/TH USB C connector - Page 1
Forum section: electronics / repair

author: DaJMasta
author_rank: Super Contributor
timestamp: July 10, 2020, 06:26:38 am
content: I've got a Rode AI-1 USB interface with a damaged USB-C connector. Seems like it would be a fairly straightforward fix, but the connector only has one row of contacts - just 12 surface mount pads out the back and four through hole mounting tabs. I've found 24 pin (double row SMD or SMD + TH), and even a 6 pin legacy part, but this at least appears to use more than 6 pins.Any ideas what a suitable replacement would be? Went through a few pages of connectors on digikey and mouser and didn't see something that looked like it would line up with all the holes correctly.

author: Renate
author_rank: Super Contributor
timestamp: July 11, 2020, 12:22:01 am
content: Is it one of these? USB4110 made by GCThttps://www.eevblog.com/forum/projects/usb-type-c-(usb2-0)-wiring/msg3116086/#msg3116086

author: DaJMasta
author_rank: Super Contributor
timestamp: July 11, 2020, 05:55:08 am
content: That looks like a match! Mine has through hole mounting tabs so I ordered the ‎USB4105 instead, but it's even got those double wide pins on the side.Interesting, it didn't show as a USB-C connector because without the extra contacts it didn't meet the 3.0 or 3.1 specification - I wonder if there was a separate connector type for physical mating parameters rather than electrical parameters.

author: DaJMasta
author_rank: Super Contributor
timestamp: July 16, 2020, 04:53:13 am
content: The USB4105s arrived from Digikey and I'm happy to report they're a perfect fit. They look like a slightly pricier version of the original - gold plated contacts and a bit of metalwork on the back whereas the original was just plastic - but they fit the same. A bit annoying for a connector fix, though, as the PCB layout designer didn't include thermal relieves on the through hole anchor points, so it needed a fair bit of heat just to get all the way in there.
Looking for a 3.3V LDO regulator with different pinout - Page 1
Forum section: electronics / repair

author: maxmad
author_rank: Contributor
timestamp: August 06, 2023, 05:19:55 pm
content: hello,I am looking for a SOT-23-5 or SOT-25 3.3V LDO regulator.The original one has been blown and there are no marks except for a 3V3.Every similar LDO I have searched has no identical pinout.The majority have Pin 1 as Input and Pin 5 as Output. Those two pins are connected at the PCB so such a pinout is not acceptable.Looking for an LDO with a pinout like this:Pins 1-5 ---> Vin - Enable (Shorted)Pin 2 -----> GroundPin 3 -----> Capacitor to groundPin 4 -----> VoutRight now I dont want to make any modification to use another LDO.So i am looking for the right one.

author: fzabkar
author_rank: Super Contributor
timestamp: August 06, 2023, 05:41:22 pm
content: https://toshiba.semicon-storage.com/info/TAR5S50U_datasheet_en_20220801.pdf?did=764&prodName=TAR5S50Uhttps://uploadcdn.oneyac.com/attachments/files/brand_pdf/toshiba/00/5F/TAR5S33TE85LF.pdfhttp://markingcodes.com/search/c/3v3

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 06, 2023, 06:54:07 pm
content: NJM2888F

author: maxmad
author_rank: Contributor
timestamp: August 06, 2023, 08:03:17 pm
content: TAR5S33 seems exactly the same!RT9193-33 more mA but wrong pinout...NJM2888F is also good!Thanks all!

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 07, 2023, 03:05:03 am
content: Oops, sorry, my copy & paste failed, the RT chip was from a previous search... I actually meant NJM2888F.
Looking for a complete service manual for a Fluke 7260A (Frequancy counter) - Page 1
Forum section: electronics / repair

author: Zenwizard
author_rank: Regular Contributor
timestamp: June 28, 2024, 02:32:06 am
content: There are a few service manuals on line but they are not complete units. I need the schematic sections. On my unit it is counting periods but not frequancy. It is also only counting with an external reference. I have confirmed that the internal time base is not running so I will need to get that up and running as well.Zen

author: coromonadalix
author_rank: Super Contributor
timestamp: June 28, 2024, 07:48:10 am
content: some refers to the 7261a who seems almost identicalmanual no schemhttps://bama.edebris.com/download/fluke/7261a/fluke%207261a%20ops%20&%20maint%20manual.pdfand some say read this one to find some infos 7250a model ?https://archive.org/details/manualsonline-id-55894522-6352-4260-bffd-32a5bfb7d6f9

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: June 29, 2024, 02:23:52 am
content: The 7260A uses a 10MHz clock, the 7261A uses a 100MHz.I have a manual on the 7261A.Jeff

author: Riccardo_Tommasin
author_rank: Contributor
timestamp: August 28, 2024, 10:00:34 am
content: If you need it i have a complete printed copy of the 7260a manual. I can email you the schematic part.
Looking for a fluke 87 case front - Page 1
Forum section: electronics / repair

author: panamaszr12
author_rank: Newbie
timestamp: December 15, 2019, 07:17:19 pm
content: I just picked up a fluke 87V and the previous owner used brake Kleen on it and now most of the painted lettering is gone. The tester it’s self works perfect. I’m just wondering if anyone out there has a parts case front they want to sell?I did find a new one on eBay but $50 sounds a bit ridiculous to me. Any thoughts greatly appreciated.

author: rvalente
author_rank: Frequent Contributor
timestamp: December 16, 2019, 11:58:00 am
content: A few years ago I got a 28 in worst condition than yours. Called fluke service and the price for a new case was not worth what I paid in the instrument itself.Keep looking at ebay, probably the auctions.Since the 87 is pretty much indestructible it is also not a part donor.I know you want the instrument in mint conditions but, you may laser engrave the case instead of replacing it.

author: Flukejunkie
author_rank: Newbie
timestamp: February 17, 2020, 02:06:54 am
content: I have a like-new Fluke 87V case front if your still looking for one.

author: panamaszr12
author_rank: Newbie
timestamp: February 17, 2020, 02:29:20 am
content: Thank you for the reply. I had to purchase one on eBay already, but thank you for thinking of me. I do appreciate it. I bet if you put it on eBay you can sell it.

author: MarcX
author_rank: Contributor
timestamp: February 20, 2020, 10:12:37 pm
content: The printing on some Fluke multimeter is very weak. I‘ve cleaned a Fluke 115 at work with water and a melamine sponge and the printing also started to disappear

author: notMyScreenName
author_rank: Newbie
timestamp: September 30, 2020, 09:22:55 pm
content: Quote from: Flukejunkie on February 17, 2020, 02:06:54 amDo you still have that?
Looking for a good PLCC puller - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: February 08, 2021, 07:17:27 pm
content: I just replaced EEPROM chips on HP53132A. These are PLCC32 type.My cheapo chip extractor didn't quite get claws under the chips so I ended up prying them out of socket. (which is not a good thing) I also didn't like the fact the design of the puller requires me to put stress on PCB, because I have to PULL the puller up.This is what I have:https://www.amazon.com/gp/product/B08J7DBZZ1/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1Would anyone recommend me one that's likely to work (smaller claw) and I can pull a lever to pull the chip up?Like these but for PLCC?https://www.amazon.com/Jonard-EX-2-Extraction-Tool-24-40/dp/B006C3Y8IY/ref=sr_1_15?dchild=1&keywords=PLCC+puller&qid=1612811699&sr=8-15

author: wraper
author_rank: Unknown
timestamp: February 08, 2021, 07:23:57 pm
content: Quote from: tkamiya on February 08, 2021, 07:17:27 pmNobody besides you can see your order history. I have cheap PLCC extractor which I made working significantly better by grinding area above hooks to make hooks a bit longer and angle flatter.

author: tkamiya
author_rank: Super Contributor
timestamp: February 08, 2021, 07:36:44 pm
content: Fixed link in OP. Thanks!

author: wraper
author_rank: Unknown
timestamp: February 08, 2021, 07:48:28 pm
content: Quote from: tkamiya on February 08, 2021, 07:36:44 pmI have the same. As I said, you can make it work better by grinding it a bit.

author: m k
author_rank: Super Contributor
timestamp: February 10, 2021, 08:48:50 pm
content: I still have few of those cheapos, they were giveaways once.I've grinded and filed them depending the situation.One socket model had so narrow air cap that it was unbelievable.Back in the day a friend liked to use simple long hook nosed pliers.Not exactly popular, says google.
looking for a NAD PP4 preamplifier schematic and component identification - Page 1
Forum section: electronics / repair

author: max-bit
author_rank: Frequent Contributor
timestamp: August 08, 2024, 09:43:26 am
content: I am looking for a NAD PP4 preamplifier schematic (service manual) and component identification11TI PSZQ i 9BTI PTJQ

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 08, 2024, 09:51:29 am
content: PSZQ = TPS7A3001PTJQ = TPS7A4901

author: ftg
author_rank: Frequent Contributor
timestamp: August 08, 2024, 09:53:40 am
content: PTJQ = TPS7A4901Texas Instruments now has an official part marking lookup tool:https://www.ti.com/packaging/docs/partlookup.tsp

author: max-bit
author_rank: Frequent Contributor
timestamp: August 08, 2024, 10:17:18 am
content: Thanks !