hybridfree/eevblog-posts huggingface dataset:
(Fixed) Tek 2445A Small Display problem - Page 1
Forum section: electronics / repair

author: okney1lz
author_rank: Contributor
timestamp: September 08, 2018, 11:53:51 pm
content: Has been sitting for a while, but was working, recapped and power supply gone through then.Now has display, but it's small and centered. See pic.Readouts are too small to use onboard tests.Ideas where to look? Horizontal amp?

author: rf+tech
author_rank: Frequent Contributor
timestamp: September 09, 2018, 02:25:26 am
content: Hi okney1lz,Your photo shows the scope is stuck in "Beam Find" mode. Beam Find reduces gain of both H and V amps. Cycle the switch rapidly and repeatedly, it may intermittently show the proper display. Clean the switch with Deoxit and see if the problem resolves.RF+ Tech

author: okney1lz
author_rank: Contributor
timestamp: September 09, 2018, 09:35:12 am
content: Had tried that, but will give it another try and clean the switch then report back.

author: rf+tech
author_rank: Frequent Contributor
timestamp: September 09, 2018, 03:48:37 pm
content: The real test is to measure the voltage at U600, U800 pin 15 - or - with the power off, measure resistance to ground.Per the attached schematic clip, normal operation depends on U600, U800 pin 15 being held at ground via the normally closed contacts in the Beam Find switch.When the Beam Find switch is depressed (NC contacts open), pin 15 of both U600 and U800 are pulled up to + 5Volts via 10 kOhms.RF+ Tech

author: okney1lz
author_rank: Contributor
timestamp: September 09, 2018, 07:19:04 pm
content: Got it sorted! Thanks for the replies.Traced it out and verified it was the switch, thoroughly cleaned and back up and running.
Repair help for Vizio sound bar power supply - Page 1
Forum section: electronics / repair

author: rynomilner
author_rank: Newbie
timestamp: September 09, 2018, 12:03:25 am
content: My sound bar suddenly quit working entirely (zero signs of life) the other day and now I'm trying to see if I can work out what went wrong.I've narrowed it down to the power supply (MKL90W-02-C1), though I see no obvious places where the magic smoke has escaped and, upon powering the PSU, nothing gets warm to the touch. The rectification and initial smoothing seems to be fine, providing ~174 VDC (I'm in US). The output of the PSU board is supposed to be +24v and +5v. If I manually hook up my benchtop power supply and supply those voltages (supply points indicated in image) the entire thing works fine. So it seems to be somewhere between the "HOT" and "COLD" labeled sides of the board where something goes wrong. I don't measure a single point on the "COLD" side that is either 5v or 24v.My main candidate is the big transformer-looking thing with the yellow plastic peeled off. The label shows MK BCK-32BK. The smaller one next to it is BCK-1609. I think they're from this eLemay companyhttp://www.e-lemay.com/Product1.aspx?fid=1&sid=4I don't understand what a transformer would be doing on an area of the board which is all DC, so maybe it's a filter or something? I don't really know what it is so I don't know how to test it.Any ideas of what I should check?

author: rynomilner
author_rank: Newbie
timestamp: September 09, 2018, 01:35:47 am
content: Solved it! For future reference, the problem was capacitor C21. Didn't look like it was bulging, but replaced it anyway and works like a champ now.
repairing an HP 8530W laptop that does not turn on - Page 1
Forum section: electronics / repair

author: Sky_hawk
author_rank: Contributor
timestamp: September 08, 2018, 12:43:03 pm
content: I have a HP 8530W that does not turn on. someone broke the power-button and in the process a small piece of pcb was ripped right of the PCB.My problem is the +3VL that is coming into the power button circuit is not present.https://github.com/janwilmans/nullptr/issues/1I feel I'm at a loss, can someone help me understand where +3VL is suppose to come from? the link includes all schematics and an excerpt of the piece I think are relevant.My main problem in understanding the tps51120, is it suppose to deliver +3v when EN0=EN1=0 ? Datasheet is linked in also, but it does not explicitly say that it does _or_ does not do this (I think)Greetings,Jan
SONY • "PROTECT" ERROR • - Page 1
Forum section: electronics / repair

author: Pick
author_rank: Newbie
timestamp: September 07, 2018, 04:22:35 am
content: SONYMINI HI-FI COMPONENT SYSTEMMHC-EC909iPUnit normally displays "PROTECT", if speaker wires "cross" or touch one another.After resolving this "wire issue", I simply unplug the unit & then plug it back in.. It then Powers on like normal!However, this time is different.I've unplugged all speaker wires from the back of the unit (and still "PROTECT" error is displaying, when I power on the unit). <--- indicating that this error is not due to speaker wires, like normal.I notice the unit "Clicks", a certain number of times, while powering on (before finally deciding to display "PROTECT"). Does anyone know where I can learn more about this?Perhaps the number of times the unit "clicks", before Powering On, might indicate the problem / help to troubleshoot the error?<-- If so, where might I find such information?Any help is greatly appreciated.Thanks!-PickJosh Pickeraljoshpickeral@verizon.net

author: SL4P
author_rank: Super Contributor
timestamp: September 07, 2018, 07:46:46 am
content: I’d guess the earlier short circuit has taken half or both the output transistors on one or both channels.The protection logic is sensing DC where it shouldn’t be - and let’s you know, so you don’t fry the speaker coils.Good luck.

author: tooki
author_rank: Super Contributor
timestamp: September 07, 2018, 09:51:42 am
content: Service manual came right up on Google:https://elektrotanya.com/sony_hcd-ec709ip_ec909ip_ver-1.0_sm.pdf/download.htmlIf you let Google suggest "Sony MHC-EC919iP Protect mode", you find lots and lots of discussions of the problem. 3 minutes of skimming suggest a few different fixes:1. unplug, wait a bit, plug back in,2. #1, but also spin the fan (by hand or with canned air), or3. replace failed power amp IC

author: radioFlash
author_rank: Regular Contributor
timestamp: September 08, 2018, 02:20:53 am
content: In addition to what has been suggested:Check for physical damage--anything obvious like bulging caps or scorch marks?Try tapping around with a plastic prod of some sort to see if behavior changes in case there's a bad solder joint or connectionCheck the power supply voltages, particularly the standby voltage.I had one Sony receiver that had random relay clicking and resetting due to bad solder joints (the Power supply was soldered to the PCB)I had another Sony receiver clicking on startup and sometimes come up with Protect because the caps for the standby power supply were bad
Atten 8586, is the wiring ok? - Page 1
Forum section: electronics / repair

author: ElectronicSailor
author_rank: Newbie
timestamp: September 07, 2018, 02:05:42 pm
content: I recently started to do some things with my atten 8586 since its performance was quite subpar. Installed a new clone iron with the shorter sleeve without holes, so that original hakko t18 tips fit.The stainless steel heating element was thankfully also a bit longer on the new iron.The heat transfer improved quite a bit:Before 370deg on the station - > 290 on the tip according to my fake hakko solder thermometer.After, 315deg on station - > 295deg on the genuine (more tighter fitting) tip.Next step would be to check the wiring, since I stumbled upon this thread here that talked about some issues with the wiring of 8586 units.https://www.eevblog.com/forum/blog/eevblog-167-atten-858d-hot-air-rework-review/msg101436/#msg101436I'm quite a beginner with all this. Regarding the topic I linked....It seems on my unit the earth is attached to the case. However on the image of the fix that was posted, I see that an additional wire was attached to the transformer. Is this necessary, since the transformer is screwed to the case floor, shouldn't there be sufficient contact with the wire that is attached to the other part of the case. I assume the additional wire was done as a safety measure in case there is no tight contact with the part of the case with the earth wire attached ?What do you guys think ? If you notice anything that seems off or could be hazardous, please let me know. Thank youChinese equip, good value for the money, but most of the time always something to fix....
Nixie tube driver transistor substitute. - Page 1
Forum section: electronics / repair

author: institches
author_rank: Newbie
timestamp: September 06, 2018, 11:15:25 pm
content: I am repairing a 1969 Toshiba nixie tube calculator and have identified a dead power transistor which was the cause of a dead nixie.I'm looking for a replacement / substitute but not having much luck.Does anyone know if there is a modern equivalent available for this transistor?https://datasheetspdf.com/pdf-file/854648/Sanyo/A429/1Or is there another way I could drive the nixie with modern parts? I don't have any schematics for the calculator unfortunately.Thanks in advance.

author: oPossum
author_rank: Super Contributor
timestamp: September 06, 2018, 11:43:41 pm
content: MPSA92 will probably work as a substitute for the 2SA429MPSA42 is it's NPN compliment and is commonly used with nixie tubes.

author: institches
author_rank: Newbie
timestamp: September 07, 2018, 12:15:27 am
content: Thank you very much.

author: wilfred
author_rank: Super Contributor
timestamp: September 07, 2018, 12:23:20 am
content: What about the MPSA43.http://www.mouser.com/ds/2/149/MPSA43-115910.pdf

author: ArthurDent
author_rank: Super Contributor
timestamp: September 07, 2018, 03:24:25 am
content: You don't want the NPN compliment to this PNP high voltage transistor. Check out this list.https://alltransistors.com/crsearch.php?mat=Si&struct=PNP&pc=0.15&ucb=150&uce=150&ueb=5&ic=0.03&tj=75&ft=50&cc=7&hfe=40&caps=TO92&r1=0&r2=0&r1r2=0
Busted Multi-turn Pot on boost converter - Page 1
Forum section: electronics / repair

author: KingPanzerVIII
author_rank: Newbie
timestamp: September 05, 2018, 12:40:07 pm
content: I recently bought a 600w boost converter for use with some fans I needed speed control on. Turns out, one of the multi-turn potentiometers had bent and had a lead torn off the board, and the other one was stuck at an output of 13.84 volts. Is there any danger with replacing these with some of my 2-turn 10K pots?PS. If this is posted in the wrong spot, sorry. I just logged in to ask this.

author: Bratster
author_rank: Frequent Contributor
timestamp: September 06, 2018, 05:18:50 am
content: What's the value of the multi turn pot that's in there?As long as you use one that has the same value there's no problem if it's a different amount of turns, it will just affect how accurate you can set it.and depending on how it is used in the circuit you may even be able to use a slightly different value, but you would actually need to know how it's being used to determine thatSent from my Fi Moto x4 using Tapatalk

author: KingPanzerVIII
author_rank: Newbie
timestamp: September 06, 2018, 10:49:22 am
content: How would i go about reading the value on the Trimpot? There's a whole jumble of numbers and i only have experience with single and dual turn pots.

author: DaJMasta
author_rank: Super Contributor
timestamp: September 06, 2018, 02:44:06 pm
content: Multiturn work the same way, it just takes more turns to go between the maximum and minimum value (if a single turn pot has a wiper on the adjustment shaft, a multiturn effectively has a gear reduction on the shaft and a bigger cog on the wiper), so the pinout and measurement will be consistent with single and dual turn potentiometers. So as long as the center point matches and the taper is correct, a single or dual turn pot will work, but you won't have as fine control as with a multiturn, a single turn pot's finest adjustment (the smallest amount you can move it) is 1/10th of a 10 turn pot's same finest adjustment.

author: Ian.M
author_rank: Super Contributor
timestamp: September 06, 2018, 03:05:57 pm
content: Alternatively, identify the controller or chopper chip and see what its datasheet has to say about the divider network to its feedback pin.Are you sure you need a boost converter? In most cases the fans are rated for the supply rail that feeds them, so without any controller run at full speed. You then *REDUCE* the voltage with a *BUCK* converter, or if there is no tacho feedback, PWM them to reduce the average voltage.
Schlumberger Enertec 2710 EEPROM firmware data wanted - Page 1
Forum section: electronics / repair

author: NortliW
author_rank: Contributor
timestamp: September 10, 2018, 03:43:09 pm
content: Hi all,I'm in need of the data (firmware) of the C2708 EEPROM of my Schlumberger Enertec 2710 120MHz counter. Can anybody make me a copy?Thanks in advance,Bas.
should i attempt to repair this laser driver? - Page 1
Forum section: electronics / repair

author: shant
author_rank: Newbie
timestamp: September 05, 2018, 10:50:21 pm
content: Hi everyone, me and my friend were trying to build a diy laser engraver and we had both 5v and 12v adapters next to each other, as you have guessed we accidentally connected the 12v adapter to the laser and damaged it, the laser still lights up but output is very weak, we're still very new to circuits so i'm guessing that as long as the laser diode turns on then it should work again given i fix the bad component(s)? i wanted to take advice if there's a chance it will work if i replace the melted component?I honestly couldn't identify it using the printed numbers and searching google so if anyone could tell me how to read and search the value of it and if you think it will work by changing that 1 part?Here's a link to the laser:https://www.aliexpress.com/item/1000mW-405nm-Blueviolet-Light-Laser-Head-laser-Engraver-Accessory-Screwdriver-for-CNC-laser-cutter-DIY-Carving/32808493826.html?spm=a2g0s.9042311.0.0.27424c4d9AF4N2Thank you.
yihua 992d+ soldering station hot air problem - Page 1
Forum section: electronics / repair

author: Blisk
author_rank: Regular Contributor
timestamp: August 24, 2018, 01:05:07 pm
content: Today I have noticed that my yihua 992D+ soldering station hot air not working. It start and blow but no hot air.I have a spare gun so I changed it and tested but it is the same no hot air. On screen I get error F-1.Have anyone any idea what can be wrong??

author: Rasz
author_rank: Super Contributor
timestamp: August 25, 2018, 01:12:27 pm
content: start with optocoupler and go from there

author: Blisk
author_rank: Regular Contributor
timestamp: August 30, 2018, 07:53:39 am
content: I have changed optocoupler and transistor and thyristor, but still the same.

author: Rasz
author_rank: Super Contributor
timestamp: August 30, 2018, 03:44:59 pm
content: I didnt mean blindly swap parts, diagnoseis optocoupler getting any signal at all?

author: Fleetz
author_rank: Regular Contributor
timestamp: August 30, 2018, 06:06:31 pm
content: Quote from: Blisk on August 24, 2018, 01:05:07 pmIn your second photo to the left of the blue 102 trimpot there looks like some dodgy soldering. Looks like some solder bridges which may be causing your issue? Either way that needs tidying up.

author: JFJ
author_rank: Regular Contributor
timestamp: August 30, 2018, 06:48:09 pm
content: Quote from: Fleetz on August 30, 2018, 06:06:31 pmThe PCB appears to be peppered with bad solder joints. For example, all four joints around the vertical 1N4007 legend look to be dry:

author: Fleetz
author_rank: Regular Contributor
timestamp: August 30, 2018, 06:54:05 pm
content: Good pick up.There are more what look to be dry joints bottom left of the photo. It’s wonder this ever worked in the first place.

author: Blisk
author_rank: Regular Contributor
timestamp: September 03, 2018, 07:35:15 am
content: Yes this worked more than 2 Years and I have already cleaned that. There should be 0 Ohm resistor but they just shorted that two points.After all testing and trying to repair I will send PCB back to company in china to repair it and they will send it back.

author: m3vuv
author_rank: Super Contributor
timestamp: September 05, 2018, 01:16:48 pm
content: good luck on your solution with china,keep us posted.
Interesting failure mode of color LCD touchscreen - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: September 04, 2018, 11:42:57 pm
content: Hi all-I have a control panel that has a color LCD touchscreen. It more or less works but the displayed image has very low contrast. The backlight is OK and the displayed whites are nice and bright as expected. But the displayed black level is way, way too high, leading to a very washed out, "milky", nearly unreadable image. The image is otherwise intact.I have not seen one fail like this before and wondered if any of you had a thought? Not sure if this is even fixable. I hope so as it's an old product and finding a new display is probably gonna be tough. Thanks.

author: Rasz
author_rank: Super Contributor
timestamp: September 05, 2018, 12:01:05 am
content: bias voltage, dc leak, check tcon for the display, measure voltages, inspect components visually
Tektronix 2440 repair  - Page 1
Forum section: electronics / repair

author: jrabeau@gmail.com
author_rank: Newbie
timestamp: September 03, 2018, 10:45:47 am
content: Hi all,I have a relatively old Tek 2440 oscilloscope that I was given. I switched it on and the display was odd, unfocused, not seeming to respond to any knob turning (I had not signal input). After a few minutes an enormous amount of smoke started to billow out.I put it aside for several weeks with other things to do, but today pulled it out again to see about fixing it. I found the culprits: there are 4 tantalum caps, 2.7uF, I believe 20V. From the digging I did online, they appear to be Vishay, axial and are marked "275" and "8938".The problem is, I can't seem to easily find replacements or alternatives. They also appear to be very expensive! Can anyone give some advice on alternatives?I've attached a snip of the circuit.Thanks for any help!Best, Jim

author: capt bullshot
author_rank: Super Contributor
timestamp: September 03, 2018, 11:01:46 am
content: Some ordinary electrolytics with higher value (10uF ... 22uF ballpark) should work. Maybe with a parallel 100n ceramic. I don't think this is too critical here, since they are "just" power supply decoupling caps, and often were placed into the circuit by the dozen.Anyway, if these four are all toast at the same time, I'd suspect some problem with the supply rails, check them thouroughly. Sometimes tantalums fail for no obvious reason, but not four in a row.

author: Testtech
author_rank: Regular Contributor
timestamp: September 03, 2018, 09:11:57 pm
content: Recap the power supply! Replace ALL the small electrolytic caps on the power supply board. Just do it, don't test them, etc. They are all suspect, and some are definitely bad! I have replaced hundreds of caps on the 24xx digital scopes, the very first thing to be done!When replaced, check the voltages, if good, then see what other problems the scope may have.It is unlikely that the PSU would go out of regulation with a high rail, but it is possible. All test points are on the PSU, or on the side board.

author: jrabeau@gmail.com
author_rank: Newbie
timestamp: September 04, 2018, 09:25:20 am
content: Thanks for the tips. I'll get some re-capping on the PSU. Agree there must be something giving rise to the blown tantallums.
Marshall JCM 800 2203 Guitar Amp - Tube Swap and Re-Biasing - Page 1
Forum section: electronics / repair

author: jcrubin
author_rank: Frequent Contributor
timestamp: June 04, 2018, 12:27:14 pm
content: Chris from Cornerstone joins me again for this Marshall re-biasing video. This is an all original JCM 800 - 2203 that is receiving new tubes all around. Of course, a quick inspection is in order. Measurements of the electrolytic caps show that most of the caps are good, one of the filter caps are about ready to go. As I make incremental adjustments to the bias as the tubes cook, The question is, are the tubes really balanced as the box from mesa advertises.. I'd think not. As a matter of fact, the tube deviation is 6 milliamps from all 4. Good thing I was biasing for the highest current flowing tube.

author: Cyberdragon
author_rank: Super Contributor
timestamp: June 04, 2018, 04:09:41 pm
content: Really? That's some shenanigans! I thought matched tubes were supposed fo be...well...just that.Where did you your new tubes?

author: Ray Gianelli
author_rank: Contributor
timestamp: June 05, 2018, 03:44:32 pm
content: This is a real issue, since Mesa amps have no adjustable bias. They depend on you buying Mesa branded tubes, which are supposed to be matched.

author: jcrubin
author_rank: Frequent Contributor
timestamp: September 03, 2018, 01:24:27 pm
content: When the packaging is shinier than the tube... I get suspicious...

author: Kirkhaan
author_rank: Frequent Contributor
timestamp: September 03, 2018, 06:12:13 pm
content: For lifetime its better that they draw similar currents indeed.But for sound quality, in such a (heavy metal) tube amplifier, I would not bother too much.Guitar players want to hear harmonic distortion!

author: Cyberdragon
author_rank: Super Contributor
timestamp: September 04, 2018, 05:50:03 am
content: Quote from: Kirkhaan on September 03, 2018, 06:12:13 pmNot just the tubes, the whole health of the amp depends on it (component heat). Some amps (as explained and shown by guitarologist) run the tubes so hard that any sudden change in load will blow them right up. Well, guitar players like pyrotechnics and smashing stuff.
SMD cap question in LED driver, pic included.  Cap has no markings? - Page 1
Forum section: electronics / repair

author: TT_Vert
author_rank: Regular Contributor
timestamp: September 05, 2018, 05:38:14 pm
content: I have an inop LED driver for my 3D printer that I'm trying to fix. Looking at it I saw a cap that looked suspicious but I'm not familar w/ the failure mode of these and there are no markings on it. So I have a 2 part question. Looking at the attached pic, is this a typical failure mode or is this just normal for some SMD caps to have the metal around it away from the body of the cap and second, how can one test a cap if you don't have any markings? It is reading 11.8uF but I have no idea if that is within spec or not.Thanks much guys,Dave

author: SeanB
author_rank: Super Contributor
timestamp: September 06, 2018, 02:38:45 pm
content: Probably a 10uF 50v ceramic capacitor, easy enough to get, and no, the end should not be peeling back like that.
8133A Pulse Generator CH1 falling edge glitch - Page 1
Forum section: electronics / repair

author: jhenderson0107
author_rank: Regular Contributor
timestamp: September 03, 2018, 08:28:04 pm
content: No good deed goes unpunished.Recently, I obtained a sampling scope. This has revealed a problem with my pulse generator which was invisible on my 3054T oscilloscope. Specifically, both + and - differential outputs of channel 1 of the 8133A exhibit a glitch on just one edge of each pulse, as depicted in the attachment. The problem remains even if the outputs are inverted via the COMP button. The problem is not mitigated by changing signal amplitude, offset level or phase. The differential outputs on channel 2 on the 8133A behave normally.Has anyone encountered this phenomenon and implemented a fix? I have downloaded the service manual, but hope to benefit from others' experience before diving in.
HP 1710B trace issues - Page 1
Forum section: electronics / repair

author: dwl
author_rank: Newbie
timestamp: September 01, 2018, 07:09:42 pm
content: Got 1710B and it needs repair.Currently it seems that it's not able to focus the beam.Checked all power rails, all are OK.If I remove power to horizontal amp then it's possible to get focused beam.Currently have no idea what to check next.Also if possible would like to have better quality service manual that currently uploaded to Agilent server.

author: dzseki
author_rank: Frequent Contributor
timestamp: September 03, 2018, 07:52:20 am
content: Hi,You can also try the SM for 1715A, 1722A, 1725A as well, these all share basically the same Y output amplifier and the photo quality of the SM differs.As for your problem first check the voltages around the Y amplifier, make sure the work resistors (mounted on a separate ceramic plate) are not open etc.

author: dwl
author_rank: Newbie
timestamp: September 03, 2018, 07:13:05 pm
content: Got some progress updates.Horizontal amplifier had 2 bad transistors after replacing those got nice dot on screen.Cleaning and replacing old caps in sweep sircuit got also sweep working, now I have nice line going cross the screen.Unfortunately vertical amp hybrid is bad so not vertical deflection for now.
Thrift store DVD-RW doesn't open or acknowledge presence of disk - Page 1
Forum section: electronics / repair

author: JonHendry
author_rank: Contributor
timestamp: September 07, 2018, 11:59:13 pm
content: Picked up a Philips DVD-RW drive at a thrift store today. Probably originally part of a Dell PC.Hooked it up to my hackintosh and the OS sees it. But the eject button on the front doesn't do anything, and if I manage to get a disk into it, the drive doesn't seem to acknowledge the disk's presence. In other words, if I put in a blank CD and try to burn a playlist in iTunes, iTunes keeps saying "insert a blank disk".Is this worth trying to repair? Anyone have any suggestions as to how to troubleshoot it?PHILIPS DVD+RW DVD8601:Firmware Revision: KD10Interconnect: ATAPIBurn Support: Yes (Generic Drive Support)Profile Path: NoneCache: 2048 KBReads DVD: YesCD-Write: -R, -RWDVD-Write: -R, -RW, +R, +R DL, +RWWrite Strategies: CD-TAO, CD-SAO, CD-Raw, DVD-DAOMedia: To show the available burn speeds, insert a disc and choose File > Refresh Information

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 08, 2018, 02:15:12 am
content: Worth in the economic sense? A new one goes for as little as $10, so not quite.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 08, 2018, 03:04:01 am
content: Clean the lens. Often overlooked.

author: coromonadalix
author_rank: Super Contributor
timestamp: September 08, 2018, 03:28:01 am
content: An clean up can do, the laser beam is trying to do an focus "ok" check .... it check the cd presence to do its job.Sony had tons of problems in cd players, the suspension lens was made in plastic, over time the lens would simply fall down and make the drive circuit unable to do its job.But for check you need an scope with calibration disk, sometimes it worked fine with an ordinary disk.Since the price of theses unit is very low, toss it away and put an new on instead.

author: james_s
author_rank: Super Contributor
timestamp: September 08, 2018, 05:40:15 pm
content: Is there something special about this particular drive? If not then I would just buy a new one, they are insanely cheap. Before you chuck the dead one though you might pull the laser diode out, many of these are surprisingly powerful. Orders of magnitude more than the standard laser pointers.I won't lecture you on the potential safety issues regarding lasers, there is plenty of info on that online.
1000 W Induction heater - Page 1
Forum section: electronics / repair

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 01, 2018, 08:48:25 pm
content: So I was using my el cheapo induction heater with two 1500W power supplies in series for a total of 41 V DC as the unit works up to 48 V however I did not realize I was drawing 1500 W of power when the unit was only designed for 1000 W and now it just short out my power supplies but I have no idea how to troubleshoot it.Here is the link to the exact unit:https://www.aliexpress.com/item/Low-ZVS-12-48V-20A-1000W-Low-Voltage-Induction-Heating-Board-High-Frequency-Induction-Heating-Machine/32823487345.htmlWhat component could I have fried? I'm guessing the power mosfets?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 02, 2018, 09:04:57 am
content: Your link is not good , it was with your logged account i think

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: September 02, 2018, 09:20:30 am
content: Quote from: coromonadalix on September 02, 2018, 09:04:57 amThanks for the heads up

author: JFJ
author_rank: Regular Contributor
timestamp: September 02, 2018, 09:29:03 am
content: You can view the unit using the product ID number (from the end of the link) as the search parameter:https://www.aliexpress.com/item/Low-ZVS-12-48V-20A-1000W-Low-Voltage-Induction-Heating-Board-High-Frequency-Induction-Heating-Machine/32823487345.html

author: coromonadalix
author_rank: Super Contributor
timestamp: September 02, 2018, 11:25:38 am
content: The output transistors / mosfets may have blown

author: eblc1388
author_rank: Frequent Contributor
timestamp: September 03, 2018, 02:51:06 pm
content: Visit the following webpage for a comprehensive guide for trouble shooting the unit.Pete's 1000 Watt 12 to 48 Volt ZVS Induction Heater Troubleshooting Guide
Fender Deluxe Reverb - Bad tube destroys screen resistor - repair and bias - Page 1
Forum section: electronics / repair

author: jcrubin
author_rank: Frequent Contributor
timestamp: July 30, 2018, 12:15:00 pm
content: The shop amp is back on the bench for repairs after an event during use which was a loud pop followed by red plating of a finals tube. The amp was shut down and the tube replaced but to no avail. There was nothing more to be heard from it.I focus my troubleshooting with a visual inspection in the vicinity of the finals and immediately locate a melted screen resistor. This is not unknown. Sadly, the original tube that did this was not delivered with the amp and I wish it was, because it would have easily identified the mechanical failure in the tube that caused the current through that resistor to flow to ground.The owner gave me all new (NOS) tubes to replace the finals with and match by request so after repairs are made I move the project to a matching and biasing event.This is the first project to use the Hickok 6000!!! A full tube testing event is accomplished with the existing tubes first. We further see that many of the re-label tubes are not what they seem.Just to be safe, voltages are taken to ensure good operation on the B+ before the finals are added.This brings the project to the bias and matching event, noting the B+ improved with the 6V6's added. I dial it back the bias to 35ma for matching per tube. In the end the closest match came to .3ma matchA few hours of testing shows all functions working and everything stable.

author: drussell
author_rank: Super Contributor
timestamp: July 30, 2018, 05:12:13 pm
content: Quote from: jcrubin on July 30, 2018, 12:15:00 pmShorted grid. Quite a common failure in power tubes. Gets heated enough times, something moves enough to touch, you get thermal runaway, red plate, everything bends more and POOF!Especially 8417 tubes... I've had a few go that way, especially the crappy GE-design ones.

author: jcrubin
author_rank: Frequent Contributor
timestamp: September 03, 2018, 01:22:47 pm
content: Some of these Finals used are NOS, and really old NOS, mechanical failures are not out of the question... Ive replaced these resistors a year ago and Im willing to bet they were not the cause
HP8590L YIG output too low -10dbm - Page 1
Forum section: electronics / repair

author: Bjoern
author_rank: Contributor
timestamp: September 02, 2018, 06:06:11 am
content: After much testing I am fairly convinced, that my YIG oscillates but that its output is far too low at about -10dbm.Since matching replacement parts are not easy to find does anybody has an idea of what to do e.g. would it be possible to add an external amplifier or does anybody know any company that repairs such YIG oscillators ?

author: borghese
author_rank: Regular Contributor
timestamp: September 02, 2018, 07:25:20 am
content: What are the symptoms?Can you post a screenshot of the calibration signal with center 500 MHz, span 1000 MHz?

author: Bjoern
author_rank: Contributor
timestamp: September 02, 2018, 10:32:01 am
content: At the moment I have taken out the YIG to measure its output signal with a RF amplitude meter. I have to guess a little bit the exact frequenzy of the YIG but I can see that it changes its output f when I adjust the analyzer f and the highest signal I get out it about -10dbm.I am contemplating to try to amplify this signal by 25 dbm and feed it into the analyzer as a "quick fix" but I found out that so far all the RF amps. I found online require a minimum input of about +15dbm which is exactly the problem.Does anybody have a source or advice on my idea ?

author: borghese
author_rank: Regular Contributor
timestamp: September 02, 2018, 11:55:39 am
content: In the HP8590A the frequency of the first local oscillator varies from 2.05 GHZ to 3.55 GHz with a nominal power signal of 14 dBm
Fluke 89IV components blown off pcb - Page 1
Forum section: electronics / repair

author: mattyelec
author_rank: Newbie
timestamp: August 31, 2018, 10:50:13 pm
content: Hi there,Have just purchased a faulty 89IV, which actually operates normally on basic functions (resistance, voltage AC and voltage DC). After pulling apart, I've noticed a few components have been vaporised off the pcb. I believe these to be a couple of resistors, a bridge rectifier & a diode (compared with my meter and photos online), but am unsure on their specs/values. Can anyone help me out in that department?Also, what is likely to have caused this?Thanks in advance,Matt

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: August 31, 2018, 11:53:09 pm
content: The vaporized bridge rectifier should be a something like DF04S or DF06S and the diode should be something like an S1G rectifier.

author: mattyelec
author_rank: Newbie
timestamp: September 01, 2018, 04:41:05 am
content: Thanks for that! Two down!Any idea on what the resistor values might be? I guess I'm hoping that someone's got either a 87IV or a 89IV that they've had open and could tell me...

author: mattyelec
author_rank: Newbie
timestamp: September 01, 2018, 10:35:15 pm
content: Thanks for that FFR! Any idea on what would have caused this? Perhaps testing a valve with their high voltage?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: September 02, 2018, 08:39:34 am
content: The bridge rectifier is meant to protect the shunt (and ADC) before the HRC blows when measuring currents. Typically the bridge is connected between the AMP and Com inputs in parallel to the shunt(s) and either shortened (two diodes forward/backard) or additional diodes are used to increase the voltage drop. In case of a shortened bridge, there are two diodes in parallel to the shunt resistor, so the voltage drop over the shunt is limited to ~1.2V. Now the DF06S is designed to withstand peaks of 600V and 50A or so for a short time which means that a higher current and/or a higher voltage was applied to it before the HRC blew. Like I guess something like this is supposed to happen if you connect the Com/Amp inputs directly to a voltage supply that can deliver 100A or so.When looking again at the picture above, you can see that the SG1 diode is used to shorten the bridge, i.e. it's connected between the "+" and "-" terminals of the bridge. So there are three diodes between Amp and Com and the total forward voltage is something like 3.3V. And the 10k resistor is obviously connected in parallel to the shunt (between the two "~" terminals of the bridge). Its location indicates that it's related to the protection circuit and its green color makes me think it has some specification beyond its resistance but honestly at this very moment, I'm a bit puzzled what it's meant for exactly.
Fat trace on tek2213 but it's weird - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: September 02, 2018, 04:41:41 pm
content: I have a really odd symptom on Tek2213. Say I have a trace going. Brightness is set at appropriate and usual level. Focus is set to a fine point. If I scan at low speed, it looks all ok. If I speed it up, it gets REALLY FAT, like 4 mm thick trace. At this point, I can re-adjust focus and get a fine point again. If I go even faster, it focuses again. Vertical is set to 1V or so.I've seen traces get dim and fat at high speed but I've never seen a symptom like this.What is this??

author: David Hess
author_rank: Super Contributor
timestamp: September 02, 2018, 07:48:19 pm
content: I think the 2213/2215 have an automatic focus circuit which is suppose to adjust the focus with intensity changes. It may not be working correctly.
HP 54501a How to set XY Mode Oscilloscope? - Page 1
Forum section: electronics / repair

author: Rui Miguel
author_rank: Newbie
timestamp: May 05, 2017, 01:58:07 pm
content: HP 54501a How to set XY Mode Oscilloscope?

author: dbreeze
author_rank: Newbie
timestamp: August 30, 2018, 08:10:41 pm
content: Look under the "waveform math" menu. There you can select 2 inputs to display "vs" each other which should be the equivalent of XY mode.

author: coromonadalix
author_rank: Super Contributor
timestamp: August 31, 2018, 08:34:31 am
content: some user operation manual :https://www.topdogtest.com/inventorypdf/hp_54501a_frontpanelref.pdf
Metcal MX DS-1 Desoldering Gun Parts? - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: August 30, 2018, 03:45:40 pm
content: Members have given great advice on finding parts before...Where would best places be to order Metcal MX DS-1 Desoldering Gun Parts?Seals, Filters Cartridges.Thanks

author: JXL
author_rank: Regular Contributor
timestamp: August 30, 2018, 06:07:59 pm
content: Thermaltronics makes a desoldering gun with compatible (and interchangeable) parts.http://www.thermaltronics.com/m_desolder_gun.phpSearch for their replacement part numbers on the web. They're typically priced lower than the Metcal parts.

author: kc7gr-15
author_rank: Contributor
timestamp: August 30, 2018, 11:05:13 pm
content: I can safely say, from direct (and disappointing) experience that this is true only up to a point. Whereas filters, seals and other minor consumables from Thermaltronics may work well in Metcal systems, I have been very UNimpressed with the "performance" (or lack thereof) of their desoldering tips.I made the mistake of investing in an entire range, originally intended to sub for Metcal's STDC102 thru STDC106 tips. The ones from Thermaltronics were always extremely slow to heat up (on the order of five minutes once removed from the stand). That, and I found they did not maintain temperature as well as the Metcal tips nor did they recover as quickly.I finally got tired of being unable to do efficient desoldering and went back to real Metcal tips (though, in all fairness, I do tend to buy new/old stock tips from Ebay to save a few $$). Haven't had a problem since.So -- Buyer beware! As is often the case, cheaper does not necessarily mean better.

author: Bratster
author_rank: Frequent Contributor
timestamp: August 31, 2018, 03:34:46 am
content: Just keep watching on eBay, that's where I've got the majority of my consumables Etc.Sent from my Fi Moto x4 using Tapatalk
TFT 8,4” fading black/white - power problem - Page 1
Forum section: electronics / repair

author: Gryningsrad
author_rank: Newbie
timestamp: August 31, 2018, 12:31:08 am
content: Have a 8,4” TFT monitor with touchscreen (discarded from work) which is not working. Attaching link to Youtube-clip.https://youtu.be/EssMpw3KcBQThe monitor is fed with 24V from a lab power supply, so there is nothing wrong there. Have visually checked all caps on the graphic card - all seems ok. The ribbon cable connecting the graphic card with the actual screen has dried out at both ends (this screen has been used for 10 year in a engine room onboard a passenger ferry, so HOT!) but I’ve managed to isolate them so there is no short circuit.The things that the screen acts like in the YouTub-clip EVERYTIME I turn on the power. For a short time the screen works (displays ”No signal”) but then dies...Is this a power problem or something with the TFT-display itself? Any input before I get into soldering off the caps och power supplys on the graphics card?
Help me identify this pushbutton switch? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: August 30, 2018, 02:23:51 am
content: Photos attached. It's from a handheld remote control. Thanks in advance for any assistance you can offer - there's like a million of these to sort through.Switch body is approx 11.8mm square and 3mm thickButton is approx 7mm diameter & 5.5mm tallPC pin spacing is approx 5mmSPST push-to-close (ah, if only these would close! They're crap, totally intermittent)

author: floobydust
author_rank: Super Contributor
timestamp: August 30, 2018, 05:02:21 am
content: The original "parent" is theOmron B3Fseries tactile switch. The chinese have copied them and made it a generic with many different plungers built-in, instead of Omron's approach which requires additional buttons.There are two (base) sizes, 6x6mm and 12x12mm. Plungers come in 0.5mm increments.I think you have a 12x12mm, H=5.5mm plunger (or 6mm), through-hole part.Search fleabay or ali for 12x12 tactile and you will find them.

author: Nusa
author_rank: Super Contributor
timestamp: August 30, 2018, 05:17:07 am
content: Note that the specified height usually includes both base and button, but not the pins. So the size you want is probably 12x12x8.5 or 12x12x9. Measure your existing switch as a whole...eliminates rounding errors on separate measurements at least.

author: cvanc
author_rank: Frequent Contributor
timestamp: August 30, 2018, 12:53:26 pm
content: Thanks, with the right search terms I'm finding lots of them. Much appreciated.
Fluke 45, optocoupler replacement - Page 1
Forum section: electronics / repair

author: vidi
author_rank: Contributor
timestamp: August 29, 2018, 08:22:49 pm
content: Hi folks,I'm trying to repair Fluke 45 for a friend and one of the issues is that optocoupler U3 is half dead (stops optocoupling at temperature 30 C). I wonder if anyone here did a replacement and if - what component has been used instead, since I'm not able to find any specs. What I know about the old one: it is phototransistor optocoupler with forward threshold voltage 1.06V.Thanks.BTW, it seems to be the cause of ERROR 8 (Analog Measurement Processor A1U1 dead) and ERROR 9 (Measurement self-check failed).

author: coromonadalix
author_rank: Super Contributor
timestamp: August 29, 2018, 11:59:31 pm
content: If i search IL11 optocoupler, as i see it on an teardown photos :https://www.flickr.com/photos/eevblog/with/21129692555/Google gives : Siemens IL9 IL10 IL11 serieshttp://pdf.icpdf.com/PdfOld/icpdf_datasheet_1/IL9_datasheet_19792/325327/IL9_datasheet.pdfSeems to be a perfect fit ...
IS it broken? - Page 1
Forum section: electronics / repair

author: Zenwizard
author_rank: Regular Contributor
timestamp: August 28, 2018, 11:21:55 pm
content: The attached is the output wave form from a Tektronix type 106. I have checked out the power supply section and all seem to be with in spec. My question is about the massive over and undershoot pulse at the end of the waveform. The power supply voltages all are good and the fast rise pulses look flawless. Is there a fault in the high amplitude side that I need to look at and repair?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 28, 2018, 11:55:07 pm
content: How are you connecting the generator to the scope?The Rigol has 1 meg impedance inputs and the generator has 50 ohm outputs. And the 106 has those GenRad connectors.Can you go ahead and zoom in to one waveform's spike so we can see its detail shape?

author: Zenwizard
author_rank: Regular Contributor
timestamp: August 29, 2018, 12:13:12 am
content: Scope connection is through a 16 inch tektronix 50 Ohm bnc cable the to get the BNC on the front of the 106 I am using GR to BNC adapters 50 ohms. I have checked the adaptor on the fast rise output and they are clean. There is also a Rigol 50 Ohm BNC through terminator right on the front of the scope input. I should also mention triggering is on the rising edge and this is the falling edge where the noise is.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 29, 2018, 01:03:08 am
content: Well, the hookup sounds good enough and that waveform definitely isn't an inductive ringdown caused by stray hookup inductance.And it definitely isn't getting its advertised falltime.Have you swapped tubes around, or tried banging on them (gently!) with a wooden tapper?How do the capacitors look?

author: Zenwizard
author_rank: Regular Contributor
timestamp: August 29, 2018, 01:46:34 am
content: I did tap the tubes lightly. they did cause some jumpyness with the scope though something interesting happened. The symmetry or oscillator is not stable. It is jittery, here is the negative edge of the square wave triggered on the negative going edge it is a lot more stable. I am starting to suspect some weirdness in the symmetry circuit. I am starting the think the symmetry circuit is fluttering.

author: Zenwizard
author_rank: Regular Contributor
timestamp: August 29, 2018, 01:54:44 am
content: But adjusting the symmetry control does not effect the waveform.
Cheap MastechMS8229 failing. Need pointers - Page 1
Forum section: electronics / repair

author: Moriambar
author_rank: Unknown
timestamp: August 28, 2018, 04:35:15 pm
content: Hey, I'm a total beginner here, but really hyped from Dave's videos…Recently my "trusty" cheap Mastech kinda failed: from time to time the Ohm (≥100k) and DCV measure (≤5V) are not correct. Especially the ohms are displayed showing a fricking high 30 M or thereabouts slowly climbing down (I never had the patience to let it settle, since it takes more than 1 minute).Measuring its resistance from another (way cheaper) multimeter, shows around 600k (should be 10M), while the mastech cannot measure the other DMM resistance (altough well within its range).Since the EEVBlog Brymen is on its way, I thought it would be quite nice to try and repair the old mastech and keep it around as a backup, not-so-reliable-but-already-paid-for meter. Also I find this "project" kinda instructive…Do you have any pointers on what to check, please? I tried (perhaps you'll laugh at me, IDK) the fuses and the batteries (of course) but everything seems fine.Thanks

author: SeanB
author_rank: Super Contributor
timestamp: August 28, 2018, 04:40:45 pm
content: Probably first clean the PCB around the input, and also clean the PCB switch contacts as well, along with the area around the main chip. Use some pure alcohol, Isoprpoyl or even methanol or ethanol, and a small stiff plastic bristle brush, and dry with clean paper towel and allow to dry. Otherwise the input protection diodes are leaky, and need to be replaced.

author: Moriambar
author_rank: Unknown
timestamp: August 28, 2018, 04:41:56 pm
content: Quote from: SeanB on August 28, 2018, 04:40:45 pmThanks, tomorrow I'll check the diodes and try the cleaning with isopropyl alcohol.

author: JFJ
author_rank: Regular Contributor
timestamp: August 29, 2018, 11:19:29 am
content: Quote from: Moriambar on August 28, 2018, 04:35:15 pmWere you measuring the resistance 'in circuit'? If so, then be aware that other components on the PCB could affect your reading. For example, a capacitor on the board, still holding some charge, might account for the 30MΩ reading that slowly decays away. A common way to avoid this problem is to unsolder and lift one end of the resistor under test, so that its resistance can be checked in isolation.

author: Moriambar
author_rank: Unknown
timestamp: August 29, 2018, 11:28:19 am
content: Quote from: JFJ on August 29, 2018, 11:19:29 amNope.My other (ok totally rubbish) meter was measuring the "correct" value, ie 300k or whatever. But anyway all of this was done out of the circuit (I was actually trying to pair up precise resistor values), and the reading was off.Anyway I plan to check it out tonight, now that my BM235 has arrived.Thanks for the advice, if you have any other pointers, please do tell!