hybridfree/eevblog-posts huggingface dataset:
Tek 2440 repair help needed - Page 1
Forum section: electronics / repair

author: cncjerry
author_rank: Unknown
timestamp: March 16, 2019, 11:36:04 pm
content: I picked up a 2440 cheap with plans to give it to my brother. It starts up, runs diagnostics and they all seem to pass. Then it said to run self cal and ext cal. Self cal runs. When I hit ext cal, it fails without any other errors.I'm going to look for the manual but in the meantime, can someone give me a hint as to what is going on?Thanksjerry

author: cncjerry
author_rank: Unknown
timestamp: March 17, 2019, 12:49:12 am
content: well, I'm progressing. I'm able to exit out of the diagnostics by punching the menu off/extended functions. I hooked onto the calibration signal and hit the auto button and all looks well. Signal should be .4V into 1Meg and it is. As I dial down the horizontal though, it seems to be looping even though the display reads the correct setting. So after 500us, 200us should have fewer waveforms and it has more like it went higher in time opposed to lower. So the display continues like this until I get into the nanoseconds and then it starts to look ok except at 200ns, the square wave looks like a triangle or something.Anyway, this all looks like a calibration issue. I'll start with a new battery and try to get into the EXT calibration. Unless someone thinks this timebase is indicative of some larger problem?Jerry

author: cncjerry
author_rank: Unknown
timestamp: March 17, 2019, 02:40:30 am
content: not trying to look like an idiot, but the issue with the time base is that the calibrator varies with timebase so that was the issue. The calibrator does look funky at 5Mhz though.So anyway, for $50 it looks like an interesting scope. Nothing like my others but will be fine for my brother once I swap out the NVRAMs and battery.Jerry

author: ChuckDarwin
author_rank: Regular Contributor
timestamp: March 18, 2019, 11:15:43 pm
content: If the calibration/config nvram isn't dead yet--assuming you are replacing it--you might want to read it out and copy it to the new nvram to save the extended recalibration step.

author: cncjerry
author_rank: Unknown
timestamp: March 18, 2019, 11:32:01 pm
content: It must be dead because it is asking for external calibration which I'm not afraid of having all that is needed.I can't figure out the lack of battery. There must have been a later change in the schematic as my unit no longer has a battery just a jumper across where the batteries should be.ThanksJerry
Remote Dog Collars - Page 1
Forum section: electronics / repair

author: koolaid2600
author_rank: Newbie
timestamp: March 14, 2019, 04:17:42 am
content: Tring to fix and understand how remote dog collars work! Not much help on the line but repair sites! Learning how things exactly work makes it easy or to fix and understand! Thanx for your time and help if possible.
Manuals needed for Anritsu MS-2626A Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: scopeman
author_rank: Frequent Contributor
timestamp: March 14, 2019, 12:50:15 am
content: Hello group,I am looking for any manuals for the Anritsu MS-2626A 9Khz-6.5GHz Spectrum Analyzer with Tracking Generator. Service manual with schematics highly desirable. Will pay for shipping of for any paper manuals. I would scan them or have them scanned in high resolution and arrange to have the manuals and scanned and returned as soon as practical.Thanks for taking your time to read my note.Sam ReavesW3OHMOwner and Moderator of the LeCroyOwnersGroup, the SencoreOwnersGroup and the LPKFOwnersGroup on groups.io
Anristu MS4624D--Help boot file - Page 1
Forum section: electronics / repair

author: flj
author_rank: Contributor
timestamp: March 13, 2019, 06:44:18 pm
content: Hello,I have a MS4624D that I changed the 2 batteries on the digital board.I tried to copy on floppy but I did a mistake by reformatting the hard drive. Now the VNA can't boot...HELP.The serial number is 024102 with option 2, 5, 8, 10, 11SF and 13.Where can I get a boot file to copy on the floppy and all other app files that I will need.Is there a forum for Anritsu?Thank you for your help...

author: flj
author_rank: Contributor
timestamp: March 13, 2019, 11:07:07 pm
content: I am following the other Anritsu post...I am looking at how to restore the app file....
instek gfg-8219a - Page 1
Forum section: electronics / repair

author: lapiaga
author_rank: Newbie
timestamp: March 13, 2019, 09:14:55 pm
content: Hi to all, I have a nasty issue on instek gfg-8219a. All working but the power amp. four resistor and two bjt gone (and burnt...) any instek user with a schematic or at least with a photo to read the values?https://www.eevblog.com/forum/repair/gw-instek-gfg-8216a-frequency-control/has the same motherboard, but I cannot read the photo!!!!!!!!!!!!!!!
Cleaning and Repairing Battery Corrosion on a PCB - Page 1
Forum section: electronics / repair

author: RukyCon
author_rank: Contributor
timestamp: March 13, 2019, 10:53:09 am
content: Hello, So i'm helping repair a board that has suffered what appears to minor battery corrosion on a battery holder contact and possibly a 16pin chip directly below the said contact.I can't remember what the board number was but it's the motherboard to a Williams pinball machine (or at least it contains the CPU, ROM, and RAM chips).As far as i can tell, the damage seems to be isolated to the terminal and the IC.I'm looking for some input on what i should do as my current plan was to desolder the battery holder, clean off at least half the PCB (so i don't have to remove the ROM and CPU chips), and install a new (external) battery holder.As of right now, the board does, for the most part, work but the battery-backed RAM will randomly lose its memory when the machine is shut off.I'm sorry if the photos are a bit blurry, it was the best i could do at the time and i will try do get better photos in a few days or so.Note: the bubbly thick traces on the bottom side of the board seem to be a factory defect as at least 2 of the 3 boards in the back of the machine seemed to have that issue.

author: PKTKS
author_rank: Super Contributor
timestamp: March 13, 2019, 12:44:55 pm
content: In your local area (US ?) I would not think twice.BRANSON OR solutions after a mild IPA mechanical brush..https://www.all-spec.com/Catalog/Chemicals-Cleaning-Supplies/Ultrasonic-Cleaners-Accessories/Ultrasonic-Cleaner-Solutions/000-955-516-6768Check alsohttps://www.eevblog.com/forum/repair/removing-oxidation-from-plated-through-holes/Paul

author: ArthurDent
author_rank: Super Contributor
timestamp: March 13, 2019, 01:20:06 pm
content: Forget the bubbly look to the traces, that is normal. On alkaline battery crud I have used white vinegar to help neutralize the base while using a brush and tooth picks to get as much under the IC pins as possible. I would carefully remove the battery holder because it will be hard to get rid of any crud under there otherwise. Unless there are any fine traces under the battery holder they are probably o.k. and haven't been ruined. The green resist on the board probably has protected most of the runs.After a good cleaning I have used soap and water then a good rinse to clean the board then totally dry the board for longer than you'd think is necessary before reconnecting it in a circuit. I have used my oven set below 150 degree F to speed the drying as well.Keep in mind this has worked for me but you're on your own deciding whether you want to try this or not. It is important to neutralize the crud to stop any further chemical reaction and remove the conductive runs the crud has formed.
Gigatronics 6062A inside picture wanted - Page 1
Forum section: electronics / repair

author: charlyd
author_rank: Frequent Contributor
timestamp: December 11, 2017, 07:30:04 pm
content: hello today i got my new project in the Gigatronics 6062A it startups, display lights-up with some values on the display so things looks good.. but when i open the unit my eye fell on the emptyU26 chipand the dallas chip...do i miss a chip here is my question.maybe somebody with a Gigatronics 6062A can send a picture from this part from a working generator.

author: SMB784
author_rank: Frequent Contributor
timestamp: December 11, 2017, 07:36:53 pm
content: I would first test to see if the device is working. Hook it up to an oscilloscope and program it to some frequency values less than the bandwidth of your oscilloscope. If they are in line with what the generator says it is putting out, I wouldn't bother messing with anything inside.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: December 11, 2017, 08:37:18 pm
content: 1). Get the manual here:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Fluke2). Read section 4D-11

author: charlyd
author_rank: Frequent Contributor
timestamp: December 11, 2017, 10:22:40 pm
content: hi thanks for pointing me to the manual i only had the gigatronics, now both, you are right. i was just curious it caught my eye.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: December 12, 2017, 09:59:21 am
content: 4D-11 explains what U26 is for and that should make it clear why it is not installed.

author: charlyd
author_rank: Frequent Contributor
timestamp: March 12, 2019, 09:24:36 pm
content: Hello just a question about the dallasChip (location U23)is it a good idea to replace this chip with a new DALLAS 1225AB. because of aging?Does anybody have ever replaced this chip inside a 6062A ?
Component ID help on an Agilent power-supply board - Page 1
Forum section: electronics / repair

author: mark03
author_rank: Frequent Contributor
timestamp: March 12, 2019, 03:58:11 pm
content: I'm trying to work out the schematic of a defective "A50 DC-DC converter" board in an Agilent 4396B. Mostly it's smooth sailing, but there are a couple of SOT-23 parts I can't find referenced in any of the SMD-markings lists returned by google. In the image below (shot through my microscope eyepiece---apologies for the less-than-ideal illumination), I believe the Y27 and Z49, at center-right, are single zener diodes in SOT-23 packages.I can't ID the SOT-23 next to the zener diodes, which may be marked "B3" except that it is a very stylized font so I'm not sure if that's what the marking actually is.I'm also trying to ID the two SOT-23's at the top, marked C3. These are quite common on this board and I think they're transistors of some kind but haven't been able to work out which one.At the left edge, is there anything besides a capacitor that the 221J could be? It's quite a brilliant blue, quite tall, very distinctive. No other capacitors on the board like it. And I'm measuring ~ 8 ohms across it.This section of the board implements the auto shutdown for over-current and fan not rotating conditions. The 74AC00 is wired as a flip flop plus a couple of gates. Another weird thing in this photo, the ferrite inductors at the bottom (there are four of them in total, SO-8 pinout, but only two pins connected) appear to be connected in parallel.The board was designed in Japan in the late 90s, if that helps.
Sony A7R II repair - Page 1
Forum section: electronics / repair

author: D148xZ
author_rank: Newbie
timestamp: March 15, 2019, 09:45:05 am
content: Two days ago I bought a Sony A7R II from the dutch equivalent of ebay knowing it had a broken lcd.The evf still works but I'd like to fix the main screen. The main lcd shows a black screen, the backlight works but the data feed looks like it doesn't. The seller told me that he spilled drinking water over it.I have taken the screen apart and found that the cables seem fine, no corrosion or anything. The lcd driver board looks fine too, no blown capacitors or cracked traces, there was what seemed like a little bit of corrosion on the outside of the board. Now I'm wondering what the issue is, could it be due to the lcd display itself, something inside the camera body or the lcd driver board. Remember, the evf works fine, it displays everything without problems.Here's some images:https://imgur.com/a/AW5FwqmThanks
tds 724 metal cover dont give up tektronix - Page 1
Forum section: electronics / repair

author: Rollin Hand
author_rank: Regular Contributor
timestamp: March 11, 2019, 05:39:45 pm
content: I got this scope non working,Im trying to get the metal blue cover out but onlt moves 21 -2 inches to the back and then becomes very tide,I dont see the cover deformed.Im getting 2 woodworking clamps That i can reverse the tips and do expansion ,This can work ?I can only expand up to 20 30 pounds.I dont want to damage the internals. Thanks

author: picburner
author_rank: Frequent Contributor
timestamp: March 11, 2019, 07:44:33 pm
content: You can find the disassembly instructions in the service manual.It is better to remove the case vertically by gently waving the case itself during the extraction.

author: Rollin Hand
author_rank: Regular Contributor
timestamp: March 11, 2019, 10:37:32 pm
content: I have another tds and that went easy ,vertical ,but this one does not go.if I canot do it with the c clamps expanders I will have to use a dremel to cut the cabinet.
Bench power supply stuck on maximum voltage + current meter stopped working. - Page 1
Forum section: electronics / repair

author: TechX
author_rank: Newbie
timestamp: March 11, 2019, 08:44:21 pm
content: I have a bench power supply where the voltage rotary knob can be moved.But the voltage is stuck on maximum.Additionally, the current meter is stuck on 0.01A.The current can still be adjusted.How can I possibly repair it?

author: wictor
author_rank: Regular Contributor
timestamp: March 11, 2019, 08:48:09 pm
content: Model of power supply?Has it been working or did you get it as non working? Please give more information.
Laptop charging circuit repair - Page 1
Forum section: electronics / repair

author: adamistr0
author_rank: Newbie
timestamp: March 11, 2019, 09:02:20 am
content: Hi, friend gave me HP ProBook 4540s as "not working". It had two blown charger input fets (PU4001 and PU4002 on schematic). I charged the battery and laptop was working fine, so I replaced these fets.Now it works with charger, but when I plug in the battery, laptop starts using it instead of charging. (That resistor next to burnt legs (PR4003) is looking fine, 199k on multimeter)Do you think it blew something inside the charging chip?
HP 8662A PS Inverter Board Question - Page 1
Forum section: electronics / repair

author: lancelotburt
author_rank: Contributor
timestamp: January 22, 2019, 09:42:58 pm
content: I'm going over the power supply boards on my newly arrived HP 8662a SSG and the A7A3 inverter board looks like this. Any cause for concern regarding the cracked black components? The really cracked little one is a ferrite choke. The bigger ones are coil chokes.

author: KE5FX
author_rank: Super Contributor
timestamp: January 22, 2019, 10:51:44 pm
content: I wouldn't be too concerned about the cracked epoxy, but be sure to check the ESR of all electrolytics on that board. Some of them are highly stressed.Also check the screws that hold the various power semiconductors to their heat sinks, very common to find these loosening up over time due to cold flow in the PCB material. It's a good idea to renew the heat sink compound as well, after cleaning the old stuff thoroughly with alcohol.

author: lancelotburt
author_rank: Contributor
timestamp: March 10, 2019, 08:50:54 pm
content: Thanks.Did that. I also ended up replacing the main filter caps, one other electrolytic, and the A3A8 FM SL VCO card, and now it works. Some calibration and I'm set.
where to buy UP1983A QFP - Page 1
Forum section: electronics / repair

author: hercegovac
author_rank: Contributor
timestamp: March 10, 2019, 03:09:21 am
content: Does anyone have speck sheet for UP1983A QFP and where to get replacement from?

author: fzabkar
author_rank: Super Contributor
timestamp: March 10, 2019, 07:39:54 am
content: Is it an NEC part?http://www.bitsavers.org/components/nec/_dataBooks/

author: hercegovac
author_rank: Contributor
timestamp: March 10, 2019, 02:44:42 pm
content: It is not. This is apparently high end buck converter used on some graphics cards
Replacements for BT130 & BT150 in CSA830 and 11801 sampling scopes - Page 1
Forum section: electronics / repair

author: rhb
author_rank: Super Contributor
timestamp: March 09, 2019, 09:37:33 pm
content: Does anyone have a number or source for replacements? I've bought an 11801 with an E5622 error. I don't have it yet, so I can't look inside. I found the NVRAM at Digikey, but I'd like to order the other two batteries at the same time if Digikey has them.

author: dcarr
author_rank: Regular Contributor
timestamp: March 09, 2019, 10:13:41 pm
content: In my notes I found this (11801B):BT130 on A14 I/O board - RTC, 2.7V thresholdBT150 on A18 memory board - 2.7V thresholdLatter two are Lithium Poly-Carbon monoflouride, BR 2/3 APanasonic BR-2/3AE2P or BR-2/3AE2SP

author: rhb
author_rank: Super Contributor
timestamp: March 10, 2019, 01:06:17 am
content: Thanks. Unfortunately, no one has the NVRAM in stock! I don't want to spend $4 shipping $10 of batteries.So this will be a bit tedious. But I bought two SD-22s for $150 and a 1 m extension cable for $100, so with bit of luck and work I'll have a 4 channel 12.5 GHz sampler for under $500. Now if I can just find an SD-24 and a SD-30 or 32 for $1000 total. The cable gives me a shot at fixing a sampling head if one has a simple fault.How should I do the copy of the NVRAM? I was thinking of powering it up for a day or two, shutting down, pulling the chips and copying them as quickly as possible in the hope that the internal batteries are dying, but not so dead that the contents are gone. From the service manual it appears that the 2/3 A lithium cells are backup for the NVRAM batteries.
Harman Kardon AVR 235 receiver repair - Page 1
Forum section: electronics / repair

author: feedback.loop
author_rank: Frequent Contributor
timestamp: December 24, 2017, 12:20:18 am
content: This Harman Kardon AVR 235 receiver had no output. The problem was traced to a shorted ceramic capacitor in the power supply, which resulted in two blown fusible resistors. The process of investigation might be of interest to you.https://youtu.be/JS9_3qPIn6YService manual:http://www.vintageshifi.com/repertoire-pdf/pdf/telecharge.php?pdf=Harman-Kardon-AVR-235-Service-Manual.pdf

author: karyuudo
author_rank: Newbie
timestamp: March 09, 2019, 11:57:09 pm
content: Appreciate the video. This helped me repair my AVR 354 today. I believe these units all have the same faulty issue. In my case, replacing the 2 fuses F110, F111 (2.5A/250V) with 3.15A/250V fixed the issue - even though visibly there appeared nothing wrong with them.
Repair of a Tek 284 - Page 1
Forum section: electronics / repair

author: Zenwizard
author_rank: Regular Contributor
timestamp: March 03, 2019, 10:58:20 pm
content: So it seems I have a sick Tek 284. Attached is the scope captures of an odd transistor failure/ possible bias issue. I think. This is a push pull pulse in to the tunnel diode. The scope shot is Q135 and Q 145.Q135 is the positive drive and is yellow. Q145 is the negative drive and is the pink trace. The fist picture is the base drive signal the second picture is the output of the same transistors at the collector. Then questions now is do I have a partially shorted q135 or is it a biasing issue. The drive signal is slightly high on the base with a little dc. I am just not sure if that will cause this much weirdness?Thanks for the help with a weird one.

author: Zenwizard
author_rank: Regular Contributor
timestamp: March 09, 2019, 12:42:44 am
content: It might be a possible bias issue with the driver transistors some where. The base on the positive rail is reading a little high about 0.6V This might not be allowing the positive side to turn off fully.
Vintage car radio upgrade - Page 1
Forum section: electronics / repair

author: Wimberleytech
author_rank: Super Contributor
timestamp: March 08, 2019, 11:25:35 pm
content: I am studying this company's products in view of upgrading an early 60's era car radio. Most of the companies I have found selling these modules do the retrofit themselves for a $$. I have found no documentation detailing the modules themselves. It appears that at least on some instances, they tap off the tuning cap for the radio and the pots for the audio. They may even use the existing radio LO for tuning...cannot tell for sure.Hoping somebody on my favorite forum has some experience.I could pay to have this done, but what fun is that?? Besides it is not for me but for my brother and if I had to admit to him that his PhD brother paid somebody else to do this job, I would never live it down.http://www.tech-retro.com/Aurora_Design/Home.html
Help identifying a part in Synology NAS - Page 1
Forum section: electronics / repair

author: Desoco
author_rank: Newbie
timestamp: March 07, 2019, 10:02:35 pm
content: I have a Synology DS1010+ that won't power on anymore.So far i have narrowed it down to the power/data extension card for the disc array. When i unplug power to the extension card and remove it from the mainboard the NAS can power on.There is a component i the middle that is blown, but i'm having trouble identifying the part. It's seems to be kemet part.Any help is greatly appreciated.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 07, 2019, 10:12:42 pm
content: your first photo is a tantalum capacitor, when they fail they can short pretty bad or even explodea number 107 : would be a 100 micro farad capacitor, i think its an 6 volts max

author: picburner
author_rank: Frequent Contributor
timestamp: March 07, 2019, 10:16:58 pm
content: Yes 100uF 6V tantalum capacitor, but look at CX3 it seems just fried.

author: CaptCrash
author_rank: Regular Contributor
timestamp: March 07, 2019, 11:58:13 pm
content: Once you have replaced cx3, I would suggest not connecting the disk in slot 3 when you power it up.The backplane is passive, so it’s possible that the disk/ssd is the root cause of the issue.If you power up with the other drives only first that will quickly let you know if the drive is good or bad.

author: wraper
author_rank: Unknown
timestamp: March 08, 2019, 12:14:04 am
content: Quote from: CaptCrash on March 07, 2019, 11:58:13 pmObvious source of fault is tantallum capacitor. They fail short. BTW it's not simply usual tantallum but KO-CAP, LOW ESR conductive polymer tantallum.
Replacement for an Alps tactile switch with a joint stem - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: March 08, 2019, 12:11:56 am
content: I bought some of these and the joint stem fits perfectly on my buttons.But the stem joint makes my buttons run perpendicular to the contacts. I would need the stem to twist 90 degrees so my buttons run parallel to its contacts.Has anyone know about an alternative? I did check ALPS catalog and nothing there.
Boss DB-90 blown component ID - 'ARVR' - Page 1
Forum section: electronics / repair

author: ferrisio
author_rank: Newbie
timestamp: March 07, 2019, 02:42:19 am
content: Hi, can anyone help me ID this part please (or even better does anyone have the schematic)? Is from a Boss DB-90 metronome that someone used the wrong power adaptor with. It's fairly early on in the power section of the board so I'm guessing it's a voltage regulator or similar. Seems to be a SOT23-5, the component reference is IC7, and the unit is dead apart from the 2 LEDs above the display lighting. Since finding this blown IC I haven't troubleshooted much further. Thanks!

author: fzabkar
author_rank: Super Contributor
timestamp: March 07, 2019, 04:05:12 am
content: It might be easier if we could see these components in context. An overall view of the circuit would help.

author: ferrisio
author_rank: Newbie
timestamp: March 07, 2019, 09:56:39 am
content: Hi, thanks for the reply - you're quite right, some more context would be helpful. Unfortunately the component in question is on the other side of the PCB so I'll upload both sides. On the component side pic you can see the +9VDC input via the red/black wires at the very top. The 2 diodes on the daughterboard that has the DC input jack on seem ok so I'm wondering if it has been over-volted as opposed to reverse-polarity'ed. Thanks again!*note ignore the little bit of red insulation on the left hand side of the component side shot - not sure how that got in there!

author: amyk
author_rank: Super Contributor
timestamp: March 07, 2019, 12:51:48 pm
content: XC6114E527MRAOZ6115CIR1112N251ATC1037CECTTrace the schematic and find out what makes most sense.

author: fzabkar
author_rank: Super Contributor
timestamp: March 07, 2019, 11:37:15 pm
content: IC7 looks like a buck converter. Q11 would be the MOSFET chopper, probably incorporating a Schottky flywheel diode (FETKY). I can't identify the MOSFET's markings, though.Edit: Q11 looks like a QS5U27.QS5U27, Rohm, P-ch MOSFET + Schottky diode, -20V, 1.5A, marking U27, SOT23-5:http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/mosfet/qs5u27tr-e.pdfEdit #2: There are no feedback resistors, so the converter (PWM controller) appears to be a fixed output type. If we could identify the other ICs, perhaps they would point to a common IC manufacturer?
APC Plus AIRBORNE PARTICLE COUNTER 942300 repair - Page 1
Forum section: electronics / repair

author: Rollin Hand
author_rank: Regular Contributor
timestamp: March 07, 2019, 05:44:38 pm
content: I have one of this units,it turns on but when i press start counting it give me an error "err pu ", I assume it means error in the pump.The pump makes no noise at any time,and recives no voltage from the pc board,by powering the pump with a external power supply the pump makes noise ,I assume is ok.The unit works with 6 v dc and it has an internal led acid battery wich is bad ,replacing this battery whith 6 v externalyy makes no change still got the error message.Thanks
Measurement & Repair Inverter Solder Machine - Page 1
Forum section: electronics / repair

author: simoncosta86
author_rank: Newbie
timestamp: March 08, 2019, 04:31:51 pm
content: Hello Everyone,I´m from Argentina and i´m electronic engineer. I normally repair power electronics circuit and i´m new in this forum. I want to share same experiences and question about another experiences.I have diferential probes MICSIG DP10013 with attenuator x50 and x500. I have an Agilent DSO3062A osciloscope.Now i have a question about the measurement process in this type of circuits.First of all, i have a question about high frecuency generators, because the TIG solder machines and Plasma Cutting System has a High frecuency arc to start the soldering process. I want to measure it, and i don´t know if my diferential probes are going to blow up.Another question is about the max diferential voltage that i can to apply to my diferential probes, because the datasheet shows 1300 V (using x500) and 130 V (using x50). If i use x500, 1300V/500=2.6 V when my osciloscope can measure up to 300 Vrms. I don´t know why small voltage compare with the max voltage that can measure my osciloscope.Thanks all for your support !!Best regards
sorensen / Xantrex DCS300-3.5 schematic and repair information - Page 1
Forum section: electronics / repair

author: benjalc
author_rank: Newbie
timestamp: March 05, 2019, 12:51:30 pm
content: I have a Sorenson DCS300-3.5M9A supply that powers up OK and works below about 30V, above this it goes into a current limited state with no load attached. The HV lytics, output lytics, and the LV supply lytics are within spec for capacitance, ESR, and leakage. The output of this supply can biased up (with another supply) to 150V (limit of the external supply) without excessive current draw so the fault does not appear to be an internal current draw in the output section. The drive to the transformer looks looks correct.I am looking for a schematic / service information on how to fix this.Thanks in advance,Benja

author: fcb
author_rank: Super Contributor
timestamp: March 05, 2019, 02:30:47 pm
content: I have the manual/schematics etc for a DCS300-3.5EM51PM me.

author: fcb
author_rank: Super Contributor
timestamp: March 05, 2019, 09:35:33 pm
content: Manual sent. Enjoy.

author: benjalc
author_rank: Newbie
timestamp: March 06, 2019, 01:47:22 am
content: Thanks for the manual with schematics. It will be a big help.Benja

author: coromonadalix
author_rank: Super Contributor
timestamp: March 06, 2019, 11:30:57 am
content: Thanks too

author: TheBay
author_rank: Unknown
timestamp: March 06, 2019, 05:53:59 pm
content: Are you using this in standalone config without sense wires etc? You need to make sure you have it configured correctly in the DB25 connector on the rear (J3) double check your plug is wired/jumpered correctly for your usage.Had a DCS30 series come in to work for repair the other day strangely enough, really well made PSU, I needed to do a lot of work to repair it though!
Bridge USB Current limiter - Page 1
Forum section: electronics / repair

author: Jamadir
author_rank: Newbie
timestamp: March 06, 2019, 01:29:11 pm
content: Hello, ive been repairing the right USB board on my laptop. The problem is a AP2301 current limiting power switch (dead). Now ive removed the chip and directly soldert the vout of another usb port to the output pads of the ic and voilla, the USB ports are working again. I already ordered a replacement but its gonna take a few weeks until it arrives. Would it be possible to direktly power the USB port from the 5v rail of the Laptop (Input)? So is it a good idea to just override the protection ic until a replacement arrives?

author: Ian.M
author_rank: Super Contributor
timestamp: March 06, 2019, 01:43:53 pm
content: Not a good idea. Whatever killed the AP2301 could easily kill the 5V supply which would probably take down the whole laptop and be much harder to fix. You also run the risk of burning tracks off the logic board. If you *MUST* bodge it, a 500mA polyfuse to provide short circuit protection would be a good idea.

author: wraper
author_rank: Unknown
timestamp: March 06, 2019, 02:14:37 pm
content: Yeah, without protection any short might damage the motherboard beyond repair. And it won't be simply non functional USB.
BK Precision 1635A - Page 1
Forum section: electronics / repair

author: dardosordi
author_rank: Regular Contributor
timestamp: March 05, 2019, 02:56:43 pm
content: Hi,just wanted to share my success story with this awesome power supply (BK Precision 1635A). I bought one off ebay a few years ago and have been very happy with it. So when I saw an ebay listing for 3 of them I could not resist.On arrival one worked great, the other two had issues on the relays doing the tap switching. 1 of them had a completely busted front panel. After a 2nd plane trip back to my country a 2nd unit got it plastic front panel busted.So I decided to start fixing the electrical parts, and contacted BK Precision asking for the service manual, in less than 1 hour I had it on my inbox. This company is awesome and I would recommend buying from them. Im attaching the service manual since I couldn't find it online.After getting all 3 of them to work (trivial repair only required replacing the relays) I decided to make new front panels. I built those from square tubes using an angular grinder, drill and file.Spray painted and they turned out ok. Had to insulate the potentiometers from the metal front panel (not an issue with the plastic one).After all, the 3 units work great and Im super happy with my 4 power supplies.
Agilent DSO 6000 scope front keypad problems - Page 1
Forum section: electronics / repair

author: super_electron
author_rank: Contributor
timestamp: July 27, 2018, 12:43:23 am
content: I am trying to debug an Agilent DSO 6012A with keypad problem. After the boot up the front panel keyboard is completely unresponsive. The LEDs work just fine on the keypad. I have tried changing the keypad and the keypad ribbon cable from another unit but no change in the keypad behavior. It looks like it might be something on the main board but I don't know where to look.The scope also displays some message about the battery being charged, even though there is no battery present on this unit.Please help.

author: hitecelec
author_rank: Regular Contributor
timestamp: March 05, 2019, 07:43:19 am
content: have one Agilent DSO6034A with same symptoms. Any luck with your unit?
TDS3034B repairs - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: March 02, 2019, 05:56:16 am
content: Hi AllI have 2 nos of TDS3034B. Both had a defective power supplyI managed to repair one of the power supplies ie artesyn NAN40-7615-01. and is working ok.However in the other unit the optocoupler IC A1- TCDT1103G( there ia a triangle logo). that was defective. I ordered a new 782-tcdt1103G from Mouser and replaced the IC . the power supply switches on but gives only 2 V dc. I tried another 782-tcdt1103G still same result.Strangely I pulled out IC A1 - TCDT1103G from the working unit and replaced it in the defective unit. bingo it started working. As someone had posted in this forum tried by replacing CNYF17-03 too still does not work. How do i source the Original opto coupler ICThanks in advanceRegardsAnand

author: hitecelec
author_rank: Regular Contributor
timestamp: March 04, 2019, 06:09:40 am
content: Hi AllI replaced it with an optocoupler TCDT1101G of the same mfr. the power supply worked with the fan load.Yet to assemble and test the unit as a whole. I hope this helps for folks who are having a similar problem with TDS3034bthanksRegardsAnand

author: testpoint1
author_rank: Frequent Contributor
timestamp: March 04, 2019, 11:54:52 am
content: optocoupler is a problem for change, since as the circuit design, the optocoupler has the certain trigger current, but after several years, the old optocoupler type you can not find it, even you can buy same type, but they all dismounted from old PCB, I ever tried to buy same optocoupler six times, each time, the test parameter is different.

author: hitecelec
author_rank: Regular Contributor
timestamp: March 05, 2019, 06:31:47 am
content: thanks
New Version MACKIE THUMP 1300 ..... need schematic ... - Page 1
Forum section: electronics / repair

author: dwivy
author_rank: Newbie
timestamp: March 04, 2019, 08:01:37 pm
content: Got a downed Mackie Thump 1300 powered speaker..... can only find schematics for the older versions ..... this one is revision e02 ..... oh, and thanks.
luke 73 III dc voltage range issues.  - Page 1
Forum section: electronics / repair

author: ddwilson
author_rank: Contributor
timestamp: March 03, 2019, 03:00:17 am
content: The meter works fine except on DC voltage up to about 3v works fine, above that will not read. Like the auto range does not work. Any suggestions where to start?

author: retiredcaps
author_rank: Super Contributor
timestamp: March 03, 2019, 04:50:15 am
content: Service manual athttp://oldradio.tesla.hu/rajzok/muszerek/fluke77multimeter.pdfsuggests U1 or S1 bad. I would check the switch for dirt/debris/damage, etc.

author: ddwilson
author_rank: Contributor
timestamp: March 04, 2019, 03:08:50 am
content: thanks, will take another look at the switch
How to read contents of PCF8570 SRAM - Page 1
Forum section: electronics / repair

author: giosif
author_rank: Frequent Contributor
timestamp: March 03, 2019, 08:38:52 pm
content: Hi all,I am looking to replace the button cell battery that powers a Philips PCF8570 SRAM IC (part of a board from a PM5139 function generator).The battery isn't dead, but don't know how much life it's got left in it, so I would like to put in a new one.However, I would first like to back up the contents of that IC, just in case I end up cutting off power to it.Any ideas how I could achieve that?The trusty TL866 doesn't seem to support the said IC.Thanks!

author: amyk
author_rank: Super Contributor
timestamp: March 04, 2019, 04:08:43 am
content: I briefly looked over theservice manualbut it doesn't appear to mention calibration constants are stored in it. In any case, if it reads the contents upon power-up or entering specific modes, then a logic analyser connected to it should be able to capture the data. There's only 256 bytes, it's not very large.

author: giosif
author_rank: Frequent Contributor
timestamp: March 04, 2019, 06:23:26 pm
content: Thanks for that, but the product is the PM5139, not PM5193!In any case, the idea with the logic analyzer still stands.I guess I was looking for an easier (read "lazy") way.Thanks again!Quote from: amyk on March 04, 2019, 04:08:43 am

author: orbanp
author_rank: Regular Contributor
timestamp: March 04, 2019, 10:04:46 pm
content: Here is the datasheet for the RAM in question:https://www.nxp.com/docs/en/data-sheet/PCF8570.pdfHere is an Arduino sketch for an I2C-scanner:https://playground.arduino.cc/Main/I2cScannerI am sure it would not take much to modify the code to read (and/or program) the content of the RAM.It is also possible that there are other I2C sketches doing similar things, I did not look that hard.Regards, Peter

author: giosif
author_rank: Frequent Contributor
timestamp: March 06, 2019, 07:56:18 pm
content: Thanks, Peter!In the meantime, I read the user and service manuals and I'm pretty sure the SRAM stores only instrument settings, not calibration data.In fact, the calibration is all analog (i.e. adjusting various trimpots).That said, I'd still like to give it a try at reading the contents of the SRAM IC, even if just as an exercise for the next equipment that might store its cal data in a similar IC.Cheers!Quote from: orbanp on March 04, 2019, 10:04:46 pm
Yokogawa TY720 / Kyoritsu KEW1062 Needs repair - Page 1
Forum section: electronics / repair

author: joeqsmith
author_rank: Super Contributor
timestamp: March 02, 2019, 05:35:02 pm
content: I recently tested a Yokogawa TY720 to failure. The only mode that is not functioning is capacitance.The meter is designed using mostly standard parts that are readily available. The upside, the damaged parts may be easy to source. The downside, it would take a fair amount of time to try and trace it out and I have not found a schematic for it.The problem appears to be on the receive side. There is a pulsed waveform when looking at leads of the meter. Manually changing ranges does change the waveform. I suspect the input is on the center resistor an not through the other leg with the second GDT. The second GDT does switch to a high speed clamp when the capacitance mode is selected but it does not appear to go anywhere else.The meter uses an ADS1240 ADC which supports 4 inputs. AIN0&1 route to a couple of 4053 mux's. AIN3 goes to a buffer and it appears AIN2 is shorted to the meter's common lead. This could be a clue.It appears all of the discrete diodes and transistors are fine. The meter has 4 X DG444 quad switches along with the muxs to steer the signals. I can change out an IC much faster than I can trace out the meter and took a change at shotgunning it. No luck.If you have access to the schematic for the meter, it would really save me a lot of time trying to hunt this problem down. If you have a working version of this meters and don't mind checking, I would like to know if pin 13 of the ADC (AIN2) is connected to the common connector. That may give me a starting point.Pictures of the PCB.https://www.eevblog.com/forum/testgear/ty720-kew-1062-handheld-multimeter-inside-high-resolution-images/msg1491871/?topicseen#msg1491871

author: joeqsmith
author_rank: Super Contributor
timestamp: March 02, 2019, 06:05:00 pm
content: From the attached picture, I have replaced all four DG444 quad switches which had no effect.

author: HKJ
author_rank: Super Contributor
timestamp: March 02, 2019, 07:39:41 pm
content: I have the Kyoritsu KEW1062, it looks to be mostly the same (It isnotexactly the same).I have traced out the input section, but not anything more. I supposed you have checked the clamp transistor has not suffered in its breakdown voltage, i.e. the capacity test uses a 1V waveform for testing.I do not really want to desolder the shield again to do more measurements.

author: joeqsmith
author_rank: Super Contributor
timestamp: March 03, 2019, 05:01:13 am
content: No need to reply. I have it sorted out.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 03, 2019, 04:44:40 pm
content: For completeness, what was exactly the issue?You don't want to do what DennerCoder9 did, now do you?https://xkcd.com/979/
Tektronix 2225 ringing issue (normal?) - Page 1
Forum section: electronics / repair

author: jero32
author_rank: Newbie
timestamp: March 01, 2019, 11:22:33 pm
content: Hello, I "repaired" a tek 2225 I got for free. However on the highest amplification range, there seems to be some ringing with the calibration signal hooked up. I was wondering if that was normal?Here's a video of the problem:If not normal, any suggestions on what might be wrong?

author: tggzzz
author_rank: Super Contributor
timestamp: March 02, 2019, 12:13:26 am
content: You are overdriving the amplifiers into non-linear regions, and they take a while to recover from saturation.Tek scopes have a lot of overhead and recover well. Cheap modern digitising scopes are nowhere near as forgiving; ifanypart of the waveform is "off the screen", then be wary of what you see on the screenThe scopes with the best overload recovery are old scopes with sampling bridges in their front end. Except at the sampling instant, the amplifier is not connected to the input, is not being overdriven and so does not need to recover.Summary: you are seeing normal operating behaviour. Congrats for testing and observing and questioning your understanding of the instrument.

author: jero32
author_rank: Newbie
timestamp: March 02, 2019, 12:22:12 am
content: Good to know. I'll have to calibrate it a little better sometime in the future when I have access to better equipment. But it's nice to know I don't have to "fix" anything.Thanks for the help!

author: David Hess
author_rank: Super Contributor
timestamp: March 03, 2019, 01:11:17 pm
content: That looks normal for when the input is overdriven. Note however that the probe calibration signal from the oscilloscope is flat but not necessarily clean on its leading edge.You could use the position control when the signal first shows signs of overload and see if the shape of the leading edge changes with position on the screen which is a sure sign of overload.Check outLinear Technology application note 79for a discussion of oscilloscope overload performance.
Power Supply Driver D2011K - Page 1
Forum section: electronics / repair

author: jaipursky
author_rank: Newbie
timestamp: March 03, 2019, 08:13:45 am
content: Hello Folks,I need little help while I am trying to repair Samsung UN55HU7200FXZA UHD TV.Symptom: No Power, no standby indicator, no other lights of course.Power Supply: BN44-00781AOn the Power Connector, I think stand by voltage 5V should always be present. There is no 5V present. Other supply of 13V will not work when processor initiates it.MOSFET Driver for 5V DC is D2011K. Its datasheet is attached. thinking it could be bad. I get voltages up to this MOSFET chip. but not sure if its getting feedback or not, its OPTO reads 0.9V on low side.This MOSFET Driver is getting 165 V DC from the Bridge Rectifier on HOT Side.I supplied external 5V and Stand by Indicator is works, but Remote and PWR SW still doesn't respond. TV doesn't power on as expected.Spare Power supply board is expensive and I don't want to order it without knowing if the Processing motherboard is good or not. one I find the cause I will get a new supply.No visible signs of burns or faulty components on either boards.High res photos attached. Also attaching similar PWR Supply schematic which shows use of D2011K (for reference)Please advise how would you isolate the issue.Thanks!
Fluke 332D initial power up, paper caps in HV motherboard - Page 1
Forum section: electronics / repair

author: valley001
author_rank: Frequent Contributor
timestamp: March 03, 2019, 05:21:17 am
content: Hello all,I suppose this thread is for hopefully preventing the need for a repair..I have a new to me Fluke 332D voltage standard. I assume it has not been powered on in near 30 years so I was wondering about precautions, my usual practice is to monitor power intake with a watt meter.Upon inspection I noticed three large paper can electrolytic caps in the HV motherboard. My instinct is to replace them before applying power but this is my first real precision type device and do not want to unsettle things that don't need to be unsettled. Replace them anyway?I also notice heat discoloration surrounding some resistor mounting points, possibly normal?I read through the threads here and learned of the shock risk. Checking the outer case to ground with my ohm meter I read 0 ohms.Anything else I should pay attention to before applying power?

author: wictor
author_rank: Regular Contributor
timestamp: March 03, 2019, 05:50:42 am
content: Hi, there is active thread about 3330B, which has similar boards/parts. Please read that first. It did not have problems with those big electrolytics and in my unit those were ok also. However I don't know how long those unit's had been unused.Wictor
Help identify SMD Capacitor - Page 1
Forum section: electronics / repair

author: cryptlabs
author_rank: Contributor
timestamp: March 03, 2019, 03:34:23 am
content: Hello,Can someone tell me what is the voltage rating for this capacitor ?Regards

author: cryptlabs
author_rank: Contributor
timestamp: March 03, 2019, 09:51:13 am
content: Quote from: blueskull on March 03, 2019, 03:57:07 amThanks blueskull, but how did you find out that its 16v, can you find the datasheet ?Regards

author: RES
author_rank: Regular Contributor
timestamp: March 03, 2019, 10:06:04 am
content: http://products.nichicon.co.jp/en/pdf/XJA043/e-ud.pdftrade mark = ?lot no. = Y1capacitance code (microFarad) = 22voltage code (Volt) C = 16series code = CM

author: magic
author_rank: Super Contributor
timestamp: March 03, 2019, 10:17:51 am
content: What a messFirst of all, assuming it's a Nichicon product in the first place, it's CM series so here's the correct datasheethttp://nichicon-us.com/english/products/pdfs/e-cm.pdfAnd, under this assumption, the voltage code is H and therefore 50V.And for all I know, blueskull may be right that C is for voltage and M perhaps 20% tolerance, who knows. That's the joy of abbreviated SMD codes.

author: cryptlabs
author_rank: Contributor
timestamp: March 03, 2019, 10:24:34 am
content: Quote from: magic on March 03, 2019, 10:17:51 amThat's why I'm concerned. I'm thinking that its 50v but it looks little smaller than a 35v that i have.Regards

author: magic
author_rank: Super Contributor
timestamp: March 03, 2019, 10:28:17 am
content: Well, you have the CM datasheet, so go and check if a part like yours exists in this series.If it doesn't, keep searching. If it does, well, at least you have one possible candidate

author: cryptlabs
author_rank: Contributor
timestamp: March 03, 2019, 10:30:05 am
content: Quote from: magic on March 03, 2019, 10:28:17 amIt looks the same in the datasheet.I think that this is the correct info and it might be 50v not 16v.Regards

author: cryptlabs
author_rank: Contributor
timestamp: March 03, 2019, 11:03:16 am
content: Thanks everyone, really appreciated.Regards
newbies: need help reparing a sub psw 1000 kef - Page 1
Forum section: electronics / repair

author: mava70
author_rank: Newbie
timestamp: February 28, 2019, 08:48:02 am
content: hi,I am repairing a sub here's the service manualhttps://www.manualslib.com/manual/788003/Kef-Psw-1000.html?page=2#manualI found the problem within the relais for the pop of the speaker. When powered on the relais start to do a huge sound similar to a 220 attached yo a speaker, I dismounted the relais and it works, pinging with oscilloscope on reofore of the coil of the relais give a 15V but with a small regular peak, I was expecting a Cc about 24V over there, isn't it? Checked +15 and -15 outside the 2 regulators and are ok. Chechek the bridge rectifier after the transformer and I got a cc of 70V and a imput of about 50V ca.Any hint?

author: mava70
author_rank: Newbie
timestamp: March 02, 2019, 12:52:08 pm
content: hi,I did a step: removed the relay, bypass the relay with a cable and the subwoofer works. What can I do? Change relay or change some components around?? thanks Marco

author: mava70
author_rank: Newbie
timestamp: March 02, 2019, 04:16:18 pm
content: reply myself changed relay and cap C52 (C58 on board) 47uf now works