hybridfree/eevblog-posts huggingface dataset:
Video: Repair of Kenwood TH-F6A handy-talkie radio's Push-to-Talk switch - Page 1
Forum section: electronics / repair

author: w2aew
author_rank: Super Contributor
timestamp: June 20, 2016, 04:04:54 am
content: Video showing the repair of the PTT on a compact handheld amateur radio transceiver.

author: bitseeker
author_rank: Super Contributor
timestamp: June 20, 2016, 04:48:36 am
content: Nice one. I was a bit worried about those traces. Good thing they were still mostly intact and there was extra in the correct orientation to bridge more solder onto.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: June 20, 2016, 11:21:16 am
content: Nice repair Alan. Could have been a disaster.

author: The_Penguin
author_rank: Regular Contributor
timestamp: June 20, 2016, 08:36:16 pm
content: Nicely done. Thanks for recording and sharing!
APC Smart UPS SUA1500I - Page 1
Forum section: electronics / repair

author: raresvintea
author_rank: Contributor
timestamp: June 18, 2016, 07:11:26 pm
content: Hello. I need some help to repair a SUA1500I, wicth i've burned because i was soldering battery terminals with the soldering iron connected on the mains, while ups was pluged and was on.I've found that all the FETs are shorted and i've removed them, gate resistors burned and HIP4082I exploded. Also on the back side of the board one trace was burned. The HIP ic i understand that is the driver for the fets.How can i test ic361-0015A, because the trace burned is on the other side of the board. What i mean, i want to take all the precautions when i put new transistors and new ic, will not be damaged. Also i've found one 1ohm(1R0) resistor open.I can't see other components damaged like varistors etc. All the 22uF caps where repalce before the damage because their ESR was way to highPlease give me any idee what to test.

author: Anora
author_rank: Newbie
timestamp: June 21, 2016, 11:12:16 am
content: if a trace burned as in completely gone you may need to bodge it

author: raresvintea
author_rank: Contributor
timestamp: June 21, 2016, 11:14:02 am
content: I've repaired with an insulated wire. I don't have any diagram, i don't know what to measure
Emphaser EA 475 BASH - Page 1
Forum section: electronics / repair

author: huhu
author_rank: Newbie
timestamp: June 19, 2016, 07:52:10 am
content: hello to all,i am looking the servisemanual from Emphaser EA 475 BASH.Thanks.

author: tautech
author_rank: Super Contributor
timestamp: June 19, 2016, 07:59:43 am
content: This one?http://www.acr.ch/uploads/media/EA1500_2140_475_BASH_DE_UK.pdf

author: huhu
author_rank: Newbie
timestamp: June 19, 2016, 06:27:01 pm
content: Thanks,yes it is, but i am looking for the servicemanual.best regards
FSFR2100 SMPS Repair - Page 1
Forum section: electronics / repair

author: dundee
author_rank: Regular Contributor
timestamp: June 17, 2016, 09:05:40 pm
content: Hi Guys!Im trying to repair a SMPS based on a FSFR2100.Datasheet:http://www.promelec.ru/pdf/FSFR2100.pdfIt is part of my Audio-System (no schematics available).Actual Situation:-Standby Voltages OKI get 25V at the output without load. It should be 32V. If i connect a load the voltage goes down to 20V (if i draw 700mA).Any ideas, what could be the problem?Pictures Tomorrow...

author: tautech
author_rank: Super Contributor
timestamp: June 18, 2016, 01:27:32 am
content: How are you measuring voltages, a DMM I'd guess but have you checked for excessive ripple, the frequency of which may exceed the capabilities of your DMM.So blindly going forward, check secondary side caps, diodes and possibly the feedback opto.

author: wraper
author_rank: Unknown
timestamp: June 18, 2016, 01:35:46 am
content: IMO either electrolytic capacitors on the secondary side are dead or something wrong in the feedback loop.

author: dundee
author_rank: Regular Contributor
timestamp: June 18, 2016, 10:31:16 pm
content: I changed all primary and secondary electrolytic caps.I measured 1Vpp Ripple at the 320V behind the rectifier.I'm wondering about that. I changed the two 330uf/200V caps against new ones.Could they be the problem?Here can see the supply in original condition:
THS720A inverter board component identification required - Page 1
Forum section: electronics / repair

author: R_G_B_
author_rank: Frequent Contributor
timestamp: June 17, 2016, 08:58:36 pm
content: Hi,Can somebody tell me what this component is? see attached file it has an effect on how the THS720 increases contrast.It should have a value around 5 ohms D.C resistance using the Peak atlas ESR. But this one reads 27 ohms and effects the contrast e.g 75% contrast setting and you can see whats on the screen.thanksR_G_B

author: dundee
author_rank: Regular Contributor
timestamp: June 17, 2016, 09:08:41 pm
content: I think it's a 0,10uf / 63V (Tantal?)Capacitor.

author: R_G_B_
author_rank: Frequent Contributor
timestamp: June 17, 2016, 09:09:44 pm
content: Yes its a capacitor I found the manufacture wima I just need to source the component.ThanksR_G_B

author: SeanB
author_rank: Super Contributor
timestamp: June 18, 2016, 07:33:27 pm
content: Looks like a polyester film capacitor. If you cannot get a SMD version use a 100n 100V leaded part there as a test.

author: HighVoltage
author_rank: Super Contributor
timestamp: June 18, 2016, 07:43:01 pm
content: Yes, that is a Made in Germany polyester film capacitor,You can get it herehttp://www.ebay.de/itm/151954925497
Help finding a LCD screen for a Blood Pressure Monitor - Page 1
Forum section: electronics / repair

author: Ponzaro
author_rank: Newbie
timestamp: June 15, 2016, 11:17:42 pm
content: HiI have a blood pressure monitor (Avita BPM645 -http://www.avita.com.tw/BPM64en.html) that has the LCD broken and doesn't work. The problem is that I can't find the replacement LCD, because there aren't model or serial number on the screen that can help identifying the partI attach two screenshot of the front and the rear of the screenThe only text is the letters and numbers that are on the rear. If aren't readable well here they are:EDC5558C1 060208060123-0198 BP64-2I've tried to search those codes in Google but didn't find anythingIf anyone can help in identifying this component and find where to buy online would be great, thank you

author: TheMG
author_rank: Frequent Contributor
timestamp: June 16, 2016, 12:26:32 am
content: That's a purpose-specific LCD, manufactured for that specific product, and not a standard LCD display.Unfortunately, unless you can find another unit to salvage one from or obtain a replacement from the manufacturer, you're probably out of luck.

author: Ponzaro
author_rank: Newbie
timestamp: June 16, 2016, 07:44:46 am
content: Understood, thanks for the reply

author: wagon
author_rank: Frequent Contributor
timestamp: June 16, 2016, 11:36:04 pm
content: Have you tried the manufacturer of the machine? I've had some success doing that in the past with other things.

author: Ponzaro
author_rank: Newbie
timestamp: June 17, 2016, 07:14:52 am
content: Quote from: wagon on June 16, 2016, 11:36:04 pmSure, I tried but the answer was totally useless
portable dvd player no sound when playing a dvd - Page 1
Forum section: electronics / repair

author: sony mavica
author_rank: Frequent Contributor
timestamp: June 17, 2016, 04:56:39 am
content: hey guys so over a year ago there was a shop up the road from me having a 1 day sale and they had portable dvd players 8" for $29 so i decided to get up early and buy one so i got one took it home put a dvd in it to watch and it played fine but i got no sound so i thought the speakers where broken it had av in so i hooked my ps3 up to it and it worked fine and had soundso i was not too bothered as i could use it to play my ps3 i put it away it the box till i had a tided my desk up and had room to set it up but its been over a year now and i have just got around to setting up the dvd playernow im asking would anybody know what could cause the problem of the dvd player no playing audio from the dvd?

author: poot36
author_rank: Frequent Contributor
timestamp: June 17, 2016, 05:57:38 am
content: So you get sound from the internal speakers when using it as a monitor (ie AV in) but no sound when the dvd is playing? If so it could be the AV input output switching circuit or the audio DAC for the DVD side of the player. What tools do you have to fix this? I would recommend a oscilloscope and potentialy a SMD hot air rework tool.

author: edy
author_rank: Super Contributor
timestamp: June 17, 2016, 06:08:44 am
content: It could be even simpler than that. If the audio jack let's you hear sound, but the internal speakers don't work, maybe they just have a loose wire to them? Vibration or shock may have jiggled a wire loose. Or if the speakers are mounted to the flip-lid, moving the lid open and closed may have tugged a wire loose. Or if some liquid may have spilled on the DVD and got on the speaker?Anyways, I'd open it up and check the wiring to the internal speakers and see if it is just a bad solder joint or broken wire.NOTE: I bought a brand new out-of-the-box DashCAM and the image on the LCD looked all messed up, wrong color, straight from the factory. At first I thought it was a software error, chip, etc.... Turns out it was a loose flat-flex that connected the LCD to the display board. I just opened the little connector, pushed the flatflex more snuggly and deeply into it, and then closed the connector tab and it works fine now! No solder required. It was just a simple physical connection that caused a completely messed up display, straight from the factory.
Oscillating fan - Page 1
Forum section: electronics / repair

author: metrologist
author_rank: Super Contributor
timestamp: June 16, 2016, 08:01:32 pm
content: It's summer and I discovered my fan does not work. It's the oscillating kind with 4 buttons on the base (O123) and the fan (head) swivels. It acts like it's not plugged in.I opened the base first and measured 120VAC on the power cord input at the switch block. I noticed that when I select one of the fan speeds, a metal piece pokes out a tiny bit from the switch case, right where the 1 of the three wires go from the motor into the switch . On each of these wires, I measure 120VAC when that speed is selected. I think the switch is working, but I was kind of expecting to read a different voltage for each speed setting.The three wires plus neutral go into the motor, and there appears to be a large square capacitor also wired into the motor. I'd need to take the motor out and its housing apart to see anything more. Is there something I might be missing before I proceed? I was going to measure the cap, but it is sealed in epoxy with the wires coming out. I might poke through the insulation though. I need to look at it again, maybe it's not even a cap.

author: uncle_bob
author_rank: Unknown
timestamp: June 16, 2016, 08:04:52 pm
content: HiThe switch isn't going to change voltage levels. It simply supplies power to a different winding of the motor depending on it's setting.Bob

author: metrologist
author_rank: Super Contributor
timestamp: June 16, 2016, 08:06:01 pm
content: OK. This might be too easy then.http://www.instructables.com/id/FAN-repair/?ALLSTEPS

author: Gyro
author_rank: Super Contributor
timestamp: June 16, 2016, 08:11:39 pm
content: Certainly a possibility. If it is the thermal fuse then be very careful if you try to solder in a new one, they'reverytemperature sensitive (for obvious reasons). Use a heavy pair of pliers as a heat shunt, or better still crimp, as the original probably is.

author: uncle_bob
author_rank: Unknown
timestamp: June 16, 2016, 08:15:40 pm
content: HiKeep in mind that the fuse is generally dual purpose. It has a current rating and profile that relates to the way the motor operates. It has a temperature rating that relates to the insulation used in the motor. You want to be sure you get both parameters right.Bob
Another TV Repair... Apparently sound intermittent - Page 1
Forum section: electronics / repair

author: edy
author_rank: Super Contributor
timestamp: June 14, 2016, 12:05:34 am
content: Hi folks,I have a colleague who is going to bring me his 52" TV in the next few weeks that he was going to dump by the curb. Apparently, the image works fine but it has problems with sound. He says the sound cuts off and then doesn't work. Sometimes by restarting the TV he gets sound back.I don't know much more about it at this point, but I wanted to see if anyone else has any clues as to what may be going on. As soon as I get the TV, I'll provide more information. My suspicion is there is an amp driving the speakers or a separate power line supplying it from the power supply, and maybe some capacitor on there has failed.I'm going to check visually first for any obvious blown caps, then see if I can still hear sound from the audio output jacks/ports. If it is only the speakers, I can at least trace it to the speaker drivers. Otherwise if all sound fails it could be something with the audio DACs. Will be interesting to see what is going on, what brand of TV it is and how old it is.

author: tautech
author_rank: Super Contributor
timestamp: June 14, 2016, 12:14:36 am
content: Possibly caps but the first thing that comes to mind is reseating any audio connectors....really, itcouldbe that easy/simple.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: June 14, 2016, 05:40:01 am
content: Loose/dry solder connections...?

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 16, 2016, 02:56:16 pm
content: Or audio menu set to "SAP" or "Second Audio Program". In this case there may be sound on some channels, possibly a different language or no sound on others.
9Mom resistance reference. - Page 1
Forum section: electronics / repair

author: Samogon
author_rank: Frequent Contributor
timestamp: June 15, 2016, 02:10:07 am
content: Hello,Recently i have scored two Agilent 34401A DMMs (and absolutely love them), one was sold for part or repair with description that 10MoM range has significant error.I have tested it and was not able to find any diviations from other 34401A measurments.But i have tested it on 1/4w 5% carbon resistors. Reading were consistent among both 34401A anb my trusted Fluke 289.Anyway i found that input resistors of oscilloscope are very precise on my Agilent DSO5054A there are two 0.4993 MoM in series. Then i concluded that probes have to have equal or better precision 9MoM resistor in them, and it looks like it is true. I have measured two Agilent N2890A probes and they show pretty close resistance of 9.029 and 9.000 MoM.Can we say that there is high tolerance resisters used in scope probes?Asking it that i was not able to find any at least 0.1% tolerance resistors of MoM range.Anybody knows what types of resistors used in high quality probes? And can we rely on those to test DMMs?

author: Vgkid
author_rank: Super Contributor
timestamp: June 15, 2016, 05:47:45 am
content: The scope probe resistors could be Caddock's(might be to expensive, they could use multiple smaller resistors). Instead of a 9.0Meg resistor, use a 10M resistor. For a precise one a Caddock USF will work.

author: Samogon
author_rank: Frequent Contributor
timestamp: June 15, 2016, 07:48:40 am
content: Yeah, 20M .01% $41 on digikey

author: Vgkid
author_rank: Super Contributor
timestamp: June 15, 2016, 05:26:38 pm
content: 10Meg is what you need. A 0.01% should be about$ 20.00. You don't need to buy the 20Meg unless you plan on putting two in parallel. A 20Meg resistor will kick you into the 100M range, which that ranges accuracy gets measured in percent.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: June 15, 2016, 08:11:30 pm
content: Quote from: Samogon on June 15, 2016, 02:10:07 amSo, there's your 10Meg reference

author: Samogon
author_rank: Frequent Contributor
timestamp: June 15, 2016, 08:30:21 pm
content: Quote from: RobK_NL on June 15, 2016, 08:11:30 pmYou mean DMMs voltage input resistance is 10Megs? It measures 11Megs

author: Vgkid
author_rank: Super Contributor
timestamp: June 15, 2016, 09:07:08 pm
content: That would work as a comparasion between 2 similiar meters. The 34401A is 12.000,000 counts, so the 11M would be at the top of the scale. Wouldn't rely on it for precision, as you are dealing with the leakages associated with its input protection circuitry.

author: Samogon
author_rank: Frequent Contributor
timestamp: June 15, 2016, 09:20:47 pm
content: Agree, and good to have to similar (better tree) DMMs comparison gives confidence in readings. It is unlikely that two meters would give exactly same level and sign of deviation.Convinced to order caddock 10Meg
New DC power supply WEP-305D fan not working(does not spinning) - Page 1
Forum section: electronics / repair

author: air_chair256
author_rank: Newbie
timestamp: June 14, 2016, 06:27:32 am
content: Thanks.....

author: mikerj
author_rank: Super Contributor
timestamp: June 14, 2016, 02:41:08 pm
content: I'm guessing you are measuring from each wire to the case, and you are just seeing the result of leakage currents. This is pretty meaningless.Looks like the fan is controlled by a temperature switch, so how do you know it doesn't work i.e. did you get the heatsink hot enough to make sure it turns on? Have you tried shorting out the temperature switch to see if the fans powers up?

author: GEuser
author_rank: Frequent Contributor
timestamp: June 15, 2016, 03:56:11 am
content: I seriously suggest that you stop poking around where-ever you like especially around the Mains plug and sockets , death can be Quick and sometimes it might take some time .In the evaluations you made , did it not seem strange that written on the Fan isDC24V and a warning pop up and wonder why there was 110V and not only that but writtenDC, so why is the multi-meter on AC .Keep going with this style and we will be reading about you in the Newspaper on watching about you on the TV , "Newbie Dies with only 3 Posts"
Tips How Search for Samsung UN32EH4003 Service Manual? - Page 1
Forum section: electronics / repair

author: KenO
author_rank: Newbie
timestamp: June 09, 2016, 04:05:57 pm
content: Hi,I am trying to find the Samsung UN32EH4003 Service Manual.Googled using "Samsung UN32EH4003 Service Manual" and got 8 results but none go to the Samsung UN32EH4003 Service Manual?Am thinking I am doing something wrong and would appreciate any suggestions!!!ThanksKen

author: joao2004
author_rank: Contributor
timestamp: June 14, 2016, 02:59:06 pm
content: http://elektrotanya.com/samsung_ue32eh4000_training_manual.rar/download.html
Help me repair Hakko Fx-888D - Page 1
Forum section: electronics / repair

author: chihaxinh
author_rank: Regular Contributor
timestamp: June 28, 2016, 08:02:04 am
content: Hi everybodyI have 2 solder station Hakko Fx888.One have reset when power on , Led 7 seg display profile 250'C - 888 - and restart loop againOne have not display, resistor 120R to hot, and i checking board have SOT-89 regulartor with marking 9C113 ( i searching on internet dont found any information , and i thing it's 5V regulartor like 7805 - Provide 5V VCC digital for MCU ).I thing regulartor shot make resistor 120R to hotHear it's link about board picture.http://runawaybrainz.blogspot.ca/2013/03/hakko-fx-888d-solder-station-hi-res.htmlMany thank so much !
Stahwerk TIG welder power supply weird problems - Page 1
Forum section: electronics / repair

author: Hagis2k
author_rank: Regular Contributor
timestamp: June 20, 2016, 06:03:05 pm
content: I am trying to help a friend to troubleshoot a non starting Stahlwek (china made) WIG200pIt was working last summer but my friend stored it out on his porch but it has both windows androof, i nailed it down so far yet that the powersupply does not start up (in the schematic) Q101gets fed thru C103 and D107? shall this give the gate a positive voltage pulse around 8-9V on thegate on the mosfet? It was dead until my friend touched the gate of the mosfet Q101 with his multimeterDoes this circuit make sense to anyone else?Am i wrong with that the 8.2V zener shall get some voltage thru these: C103/D107/R210 ?Can't find anything else C103 is measured at 9.9nF ERS 18ohm all electrolytes seems okhe even checked the diodes in the circuit (1n4148)Something is wrong i say lol!

author: Andy Watson
author_rank: Super Contributor
timestamp: June 20, 2016, 07:06:51 pm
content: Looks like it is missing power to start-up the oscillator. Check the path C103 - R210 - R209. Make a thorough visual inspection of the solder joints on that path - including the gate of the mosfet.

author: Hagis2k
author_rank: Regular Contributor
timestamp: June 20, 2016, 07:36:03 pm
content: Yeah my point of view too, i measured C103 it is ok then i shall check the 510k resistor too thanks for your input then atleast we where thinking the same
AOC F22+ repair, fragmented white screen repair - Page 1
Forum section: electronics / repair

author: hobo2566
author_rank: Contributor
timestamp: June 12, 2016, 09:41:14 pm
content: Hello,I have seen many white screen failure, but this one bugs me.The image is fragmented from top right in grid and you can clearly see a grid, on each grid part there is date and time stamp and "screen 1" to "screen 8" marks. (Took the best picture i could)Before i start further, is it repairable?Never bothered fixing this kind of defects before, but this one got me interested in trying to repair panel.Nothing is visibly burnt or damaged, voltages on LCD PCB seem fine. Could changing NT7168FG-10014 chip do the thing? Because writings on it are faded, so i suspect it got burned from overheating(just a guess).Thanks!
Denon UD-M31 - Page 1
Forum section: electronics / repair

author: rahandford
author_rank: Regular Contributor
timestamp: June 13, 2016, 06:47:04 am
content: Calling all CD repair experts!This is my first in depth CD repair and I have the following questions:I have the above unit, that won't play CD's. I have replaced the laser mech and still have the same fault.The CD will 'twitch' but not run up to speed.Using service mode I am monitoring the output from pin 62 IC802 and it never seems to go low (thus powering the laser).Clock, data, CS and all Vcc lines are correct and the chip is being told to turn on from the processor.I have also checked the operation of TR806.Has anyone had experience of these IC's failing or is there another possible cause?Please let me know if I have missed anything!Regards,Rupert

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 13, 2016, 04:24:44 pm
content: Most new laser pickups have a "solder short" between two adjacent pads for static protection, which must be cleared before the new pickup will work.

author: rahandford
author_rank: Regular Contributor
timestamp: June 13, 2016, 05:03:09 pm
content: Hi, Yes I did remove the short on the pickup. Problem seems (to me) to be transistor never gets turned on as output from chip does not go low.
male sma connector repair - Page 1
Forum section: electronics / repair

author: NortliW
author_rank: Contributor
timestamp: June 11, 2016, 10:47:15 am
content: Hi all,anyone an idea how to repair a male sma connector, the screw part is missing and now I want to add one from a piece of rigid coax but I can't get it off. Tricks welcome.TNX,B.

author: NortliW
author_rank: Contributor
timestamp: June 12, 2016, 08:57:17 am
content: it is actually a 3.5mm connector..........Mavin sells these as 2.92mm on Ebay but $40 just for a connector all together is too much for me.

author: Neganur
author_rank: Unknown
timestamp: June 12, 2016, 09:04:11 am
content: if you're repairing a 3.5mm SMA you're risking to destroy anything you connect it to.Don't do it and swallow the price for a used branded one if you absolutely have to.

author: NortliW
author_rank: Contributor
timestamp: June 12, 2016, 09:58:16 am
content: Done it, it has become an Omni Spectra 201-1 screw part, same dimentions as the Wiltron head. With new spring it works fine.
Problem - Network Analyser HP8713B - Page 1
Forum section: electronics / repair

author: omega12
author_rank: Contributor
timestamp: April 17, 2016, 10:02:20 pm
content: Hello,my Network Analyser HP8713B has problems. You can see on the picture that it has problems. I connected a 50Ohm through cable. Need some ideas to repair it. Don´t have extension boardsbut maybe someone can help me. Sorry for my bad english.Thanks, RegardsFranz

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 18, 2016, 01:09:12 am
content: Hi,I have an HP8714C which should be similar. Here are a couple of tests to get you started. The idea is to measure the amplitude of the RF source.First I set the Sweep to CW and the Freq to 10 MHz:I then set the level to -20dBm:I can measure the output on a Spectrum analyzer, set for a centre frequency of 10MHz and 5 MHz SPAN:Or measured on a scope. The scope input has been set to 50 Ohms:I get 61mV p-p. (It should be 63.6mV)Try this test to see if the source is working.Regards,Jay_Diddy_B

author: omega12
author_rank: Contributor
timestamp: April 18, 2016, 06:08:24 pm
content: Hello Jay_Diddy_B,thanks for your answer. I made the test and it´s look like the source is ok. See the pic please. CW is at -10 dbm by 10 MHz. I don´t know if its normaly but something sweeps slightly at CW from left to the right but i think this is normaly. If i chose sweep 5 MHz than i can see a beautifull sweep on the spectrum analyser. Hm, next step?Thanks, Franz

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 18, 2016, 06:28:24 pm
content: Franz,The next step is to go to the Keysight website and download the Service Manual. Here is the link:http://literature.cdn.keysight.com/litweb/pdf/08713-90005.pdf?id=828971Section 5 of the manual describes the test software that is built into the analyzer.Work through this section and see if the analyzer gives any error codes.Regards,Jay_Diddy_B

author: omega12
author_rank: Contributor
timestamp: April 21, 2016, 07:57:54 pm
content: Hello,so, i found the problem. The detector diodes are toasted and i wanna also replace the protection diodes. It´s not easy to find original replaces but i hope someone have a good ideaI need 4 x detector diodes HP part number 1900-0293. This are Schottky signal diodes SMT.I also need 4 x protection diodes HP part number 1900-0273. This are Pin Diodes.Hm, not an easy job.Regards, Franz

author: omega12
author_rank: Contributor
timestamp: June 12, 2016, 07:01:15 pm
content: Hello,i found the problem. It was U1 on the A4 Board. After replacing U1 the analyzer is working very fine.Regards,Franz
TS-430S LSB audio distorted. - Page 1
Forum section: electronics / repair

author: maxbarjr
author_rank: Newbie
timestamp: June 12, 2016, 04:24:52 am
content: I have a TS-430S transceiver with transmit audio problem on LSB. USB is fine. The report I got from other station says my audio pitch is high and distorted compared to USB which I got is good audio report. Tried to calibrate using WWV and I can't make the sound similar or even almost similar. Reference oscillator is measuring 36Mhz. I only have MFJ Antenna Analyzer that I use to check freq. and a Fluke DMM and other basic tools.Appreciate any help.Max

author: cncjerry
author_rank: Unknown
timestamp: June 12, 2016, 05:14:11 am
content: How is the receive? Are you implying that listening to WWV sounds distorted? Sounds like your carrier oscillator or BFO is off frequency. Could be a crystal. Some radios have two separate oscillators that feed a mixer and depending on the sideband selected the oscillator gets dc power. So something in the switching can be off powering the wrong oscillator?

author: maxbarjr
author_rank: Newbie
timestamp: June 12, 2016, 08:09:00 am
content: Hi cncjerry. Thank you for your reply. The receive is fine. Except that when I calibrate to WWV, I can not match the sound switching back and forth on LSB and USB no matter what adjustment I do. When receiving SSB transmission on LSB or USB, the sound is fine except for a little off frequency on both that I have to use the RIT to get the correct pitch.Hmm..I hope that explains it.
Trimble Thunderbolt GPSDO - Page 1
Forum section: electronics / repair

author: TheSteve
author_rank: Unknown
timestamp: June 12, 2016, 03:51:25 am
content: A friend of mine dropped off a Trimble Thunderbolt GPSDO that stopped working. The OCXO still heats heats up, all voltages/supplies look good. I can see activity on the data and address lines of the firmware memory(29F400) however the data sure looks ugly. You can see edges galore on every single data line, they aren't from a probe grounding issue.I have attached a pic, the yellow trace is an address line, the blue is a data line. I really can't imagine something working with such noise on the data lines.Thoughts?

author: edpalmer42
author_rank: Super Contributor
timestamp: June 12, 2016, 06:06:34 am
content: What do you mean by "stopped working"? Stopped talking, off frequency on one or both outputs, all of the above?Ed

author: TheSteve
author_rank: Unknown
timestamp: June 12, 2016, 06:17:54 am
content: Quote from: edpalmer42 on June 12, 2016, 06:06:34 amAll of the above. There is no serial communication and the OCXO is not controlled.
Problem power supply - Page 1
Forum section: electronics / repair

author: BrianBro
author_rank: Newbie
timestamp: June 11, 2016, 12:56:14 pm
content: Hi, I have a Pyramid 12 volt power supply that when I put a load on it the power drops to around 5 volts. Does anyone know what component or components might be bad?

author: rolycat
author_rank: Super Contributor
timestamp: June 11, 2016, 01:20:10 pm
content: Insufficient data.What model of power supply?What sort of load?Have you tried other loads?How much current is drawn when the load is applied?Have you opened the supply to see if there are any obvious faults?Incidentally, power is not measured in volts.

author: BrianBro
author_rank: Newbie
timestamp: June 11, 2016, 01:48:01 pm
content: The model is Pyramid PS-26KX and it doesn't take much current for it to drop. About an amp. Everything inside looks good. Nothing burnt

author: rolycat
author_rank: Super Contributor
timestamp: June 11, 2016, 04:45:31 pm
content: A good start would be to check the electrolytic capacitors, as these are a frequent source of PSU problems. Look for bulging tops and/or leaking electrolyte. If you have a multimeter you could also check the output ripple using the AC volts setting.Also check for unusually hot ICs, resistors etc.

author: BrianBro
author_rank: Newbie
timestamp: June 11, 2016, 10:15:38 pm
content: Ok thanks, I'll see if I can find anything
Identify component. - Page 1
Forum section: electronics / repair

author: pappkopp
author_rank: Contributor
timestamp: June 10, 2016, 08:42:11 pm
content: Hello, i need some help identifying this part. I belive its a MOV(its part of a Loop Calibrator) But i cant find anything about it.It measures 8? The logo looks like Ms stacked..

author: madires
author_rank: Super Contributor
timestamp: June 10, 2016, 08:51:44 pm
content: Polyfuse, 600V, 150mA.
any repair men in trinidad  - Page 1
Forum section: electronics / repair

author: Sparky_Freak
author_rank: Contributor
timestamp: June 10, 2016, 03:04:15 am
content: good day i have been a hobbyist for a while now and i was wondering if their were any repair me on the eevblog i am thinking about starting my own business and was wondering if u have any tips and where to gt parts
Help identifying this IC - Page 1
Forum section: electronics / repair

author: papabol_24
author_rank: Contributor
timestamp: June 03, 2016, 10:00:24 am
content: Hello, i cant find this on the net (Google search) so maybe someone here knows this chip, thank you..M3003 -16PIF77315800R-uEM87-49C

author: wraper
author_rank: Unknown
timestamp: June 03, 2016, 10:15:43 am
content: Seems to be M3003-16PI Manufacturer:EM MICRO. Don't know what it is but is can be bought on ebay.

author: papabol_24
author_rank: Contributor
timestamp: June 03, 2016, 11:29:34 am
content: Thanksil try searching for em micro....

author: bitwelder
author_rank: Super Contributor
timestamp: June 04, 2016, 12:06:15 pm
content: It seems to be a low power RTC:http://images.ihscontent.net/vipimages/VipMasterIC/IC/EMMM/EMMMD001/EMMMD001-4-11.pdf

author: coppice
author_rank: Super Contributor
timestamp: June 04, 2016, 12:12:01 pm
content: Quote from: bitwelder on June 04, 2016, 12:06:15 pmLower power? Its says 5uA. That's HUGE for an RTC.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 04, 2016, 12:17:29 pm
content: Quote from: coppice on June 04, 2016, 12:12:01 pmWell, perhaps not 20 years ago. Compare with a 1993 NSCDP8573A.

author: coppice
author_rank: Super Contributor
timestamp: June 04, 2016, 12:34:33 pm
content: Quote from: rsjsouza on June 04, 2016, 12:17:29 pmIn the mid 90s the going rate for I2C RTC chip battery consumption was below 1uA.

author: papabol_24
author_rank: Contributor
timestamp: June 04, 2016, 08:31:55 pm
content: Thank you Thank you guys

author: Jasper
author_rank: Contributor
timestamp: June 10, 2016, 12:07:37 am
content: That silkscreen looks more like early 80s to me than early 90s...

author: wraper
author_rank: Unknown
timestamp: June 10, 2016, 01:38:09 am
content: There is CD74HCT04 IC made by RCA which does not exist since 1986. That 3 digit date code looks like that IC was made in 1981
Datron 4950: Additional Service Handbook (with schematics) available? - Page 1
Forum section: electronics / repair

author: Zermalmer
author_rank: Regular Contributor
timestamp: June 07, 2016, 07:26:55 pm
content: Hi,I find the usermanual for the 4950.This manual includes also a lot of calibration procedures and diagrams, but no circuits aso.Does exist some kind of Service Handbook or is the usermanual the only available information source?A collegue of me (unfortunatly he is in holidays) searched for it, because he have problems with one range (and I can't remember what the exact problem is).Best regardsAndreas

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: June 09, 2016, 05:40:09 am
content: I have not seen the insides of a 4950 but I have been inside(briefly) my 4920 and also a few 1281's. I would bet that they may have used most of the technology from the 1281 and perhaps some of the 4920.I uploaded the 4920 manuals a few years ago to ko4bb and they are probably on xDevs.Please get pictures and I am sure TiN will host them. My 1281's had self-test errors and were cured by replacing the caps in the digital and dc board assemblies so I would begin by measuring them.It would also be worth measuring the internal lithium battery. All of mine were 10+ years old.

author: Zermalmer
author_rank: Regular Contributor
timestamp: June 09, 2016, 03:42:03 pm
content: I try to catch pictures, but at first my collegue must allow me to touch his baby

author: TiN
author_rank: Super Contributor
timestamp: June 09, 2016, 04:35:33 pm
content: Just keep him/her distracted in other room and you will be fine, taking the beast apart.Sorry, couldn't resist. 4950 is rare beast, and surely many volt-nuts would love to see machinery guts.
Thunderstormed Routerboard Mikrotik RB2011UiAS-2HnD-IN - Page 1
Forum section: electronics / repair

author: frenky
author_rank: Unknown
timestamp: June 09, 2016, 09:06:36 am
content: My friend asked me to take a look at router that died during thunderstorm.Model is RB2011UiAS-2HnD-IN also known as RouterBOARD 2011:http://routerboard.com/RB2011UiAS-2HnD-INHigh resolution img of PCB:http://img.routerboard.com/mimg/677_hi_res.pngBurned components:Mosfet on the left is completly shorted to all pins. Two bridge rectifiers have vent holes. This is what I have found so far.Does anybody know why there are bridge rectifiers inside router?I wasn't able to find service manual or schematic for this board.Tnx.

author: chris_leyson
author_rank: Super Contributor
timestamp: June 09, 2016, 09:15:34 am
content: The bridge rectifiers will be for power over ethernet.

author: frenky
author_rank: Unknown
timestamp: June 09, 2016, 09:24:14 am
content: Tnx.It weird that this bridge rectifiers have holes in them but I tested all the diodes inside and could not find anything wrong with it.

author: lukaq
author_rank: Regular Contributor
timestamp: June 12, 2016, 09:43:20 am
content: wonder how did it die. Hope you can tell us that

author: Monkeh
author_rank: Super Contributor
timestamp: June 12, 2016, 09:59:03 am
content: Quote from: lukaq on June 12, 2016, 09:43:20 amIt got a few million volts shoved down its throat?

author: SeanB
author_rank: Super Contributor
timestamp: June 12, 2016, 11:38:38 am
content: U903 is likely cooked as well, as it was driving the dead MOSFET. The bridge rectifier will be open circuit on at least one diode, if it let out smoke, or will break down at over a few volts. If you are lucky the secondary switchers U902 and U1 are not dead as well, if so then both U100 and U400 will be blown, and not easy to replace.

author: frenky
author_rank: Unknown
timestamp: June 12, 2016, 08:28:12 pm
content: I think I've solved the case but sadly the patient is dead...Voltage spike first fried the modem. Then it travelled trough POE port into router.There it fried tiny 85ohm resistor between sockets and magnetics.Then it fried both bridge rectifiers and from there the mosfet and both buck converters. (And a few capacitors...)And from there both main ICs.I noticed that both power rails are shorted so I applied 3V 2A to each rail and used thermal camera to find (and remove) all shorted components.But sadly short circuit on 3.3V rail is still there and the only components heating up are ICs... So no luck I guess...On this 3.3V rail I also increased the current to 3A but voltage only went up to 2V.
BGA reflow to fix GPU - Page 1
Forum section: electronics / repair

author: microbug
author_rank: Frequent Contributor
timestamp: June 08, 2016, 08:35:04 pm
content: I've bought a couple of cheap dead GPUs from eBay to try to repair. I have an Atten 858D heat gun, a Brymen BM257 multimeter with a thermocouple and some cheap chinese flux paste (tested it for continuity and it's non-conductive). Just wanted to check if there's anything I should know before I attempt this. My plan is as follows:Cut an appropriately-sized square from a piece of aluminium foil to shield the rest of the PCB.Apply flux paste around the outside of the GPU chip.Set fan speed to low and gradually heat the GPU up to 220 celsius (using thermocouple to check temperature).Hold at 220 celsius for 15 secondsAllow to cool for 30 minutes.If anything falls off I can resolder with my Hakko FX-888D.Am I missing anything? I'm planning to set the temperature with the thermocouple on the chip rather than the 858D's slightly dodgy temperature setting (thermocouple said it was 250 degrees when it was 220 on the display).Also, should I get a cheap IR thermometer instead of the thermocouple or will it do?Thanks in advance

author: wraper
author_rank: Unknown
timestamp: June 09, 2016, 01:05:51 am
content: once again someone clueless tries to do this kind of BS. First of all those chips themselves are faulty not soldering. By heating them, you can revive them for some short time but this is not permanent fix. Secondly good luck melting solder balls under such big BGA whith such hot air station. Probably you will heat up the thermocouple by blowing hot air on it, but not solder underneath of the chip.

author: crispy_tofu
author_rank: Super Contributor
timestamp: June 09, 2016, 01:07:24 am
content: Obligatory link to a Louis Rossmann video:

author: microbug
author_rank: Frequent Contributor
timestamp: June 09, 2016, 06:54:16 am
content: Watched the video. That sucks, guess I'll flip the gpus as broken.
Can I put this board in ultrasonic cleaner? - Page 1
Forum section: electronics / repair

author: olewales
author_rank: Regular Contributor
timestamp: June 08, 2016, 10:32:05 pm
content: Hello!I've recently aquired and attempted repair of gopro-like sports camera that was used in not-so-waterproof case and thus was water damaged. It has white residue all over the main PCB but one place suffered the most. Unfortunately it is located right next to the sensor on a little flex. Here is where I could really use your expertise: I am planning to get small ultrasonic cleaner for situations like this but I am not sure if I should even use it here. Wouldn't it damage image sensor? It is capped with glass window and would probably survive rinsing it with water but I am not sure about cavitation in ultrasonic bath. Any experiences with this? What is your procedure in restoring electronics flooded with water?I am attaching some closeup photos of the board in question. As you can see corrosion of the two SMD components is quite severe and possibly even broke the leads completely but it MIGHT be recoverable with some modwire.As a side question: any idea what QUW and QUX smd codes might stand for? I am guessing they are some sort of power components (transistors or linear regulators) but I've had no luck googling so far.Of course, the "curse" strikes again. Minutes after sending this post I found this:http://www.mouser.com/ds/2/405/tlv702-558090.pdfAll help appreciated!
Tektronix 2235A Ch 1 No Reading Below 1 Volt  - Page 1
Forum section: electronics / repair

author: gmcjetpilot
author_rank: Newbie
timestamp: May 30, 2016, 02:05:55 am
content: This should be easy for you experts. Blew to dust off my trusty Tek and it's all working except channel 1, setting 0.5 volts or less, either DC or test signal zip, nothing, some noise. Otherwise works fine 1 volt up. Channel 2 fine. Thanks

author: tautech
author_rank: Super Contributor
timestamp: May 30, 2016, 04:18:52 am
content: Welcome to the forum.This thread should've been in the Repair board:https://www.eevblog.com/forum/repair/If you use the Report, you can ask a Moderator to shift it there.It is not uncommon for the front end of a scope to behurtwith an overvoltage event and maybe the V/div attenuators have been damaged.You'll need a Service manual and there's several manual repositories linked in the sticky threads in the Repair board that you can download from.Here's one to get you started:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdfCome back to us and link the manual you're using so we're all on the same page.

author: David Hess
author_rank: Super Contributor
timestamp: June 07, 2016, 10:02:05 pm
content: The 2235 service manual is almost as good for this.As far as the repair, the x100 high impedance attenuator is switched in at 1V/div and above so the problem is with bypass switch 2 or 3; the switch contacts need to be cleaned or maybe the leaf springs need to be bent a little. Gaining access will require removing the A2 attenuator board which is accessible from the top of the oscilloscope.Clean the switch contacts by wetting some card stock or clay free paper like vellum in alcohol and drawing it through them while they are closed. Do not use anything abrasive to clean them as it will remove the gold plating.
Cross for OB2358AP? - Page 1
Forum section: electronics / repair

author: dietz
author_rank: Newbie
timestamp: June 07, 2016, 01:58:13 am
content: Hi everyone, long time lurker finally posting!Over the weekend my audio receiver let a bit of the magic smoke out, which turned out to be the offline PWM power switch on the SMPS board. I've identified it as OB2358AP, but I was wondering if anyone is familiar with a drop-in replacement from a reputable brand. I'd prefer not to put another wun-hung-low chip back in if possible, but it looks like that may be the only choice I have.Cheers!

author: Tomorokoshi
author_rank: Super Contributor
timestamp: June 07, 2016, 04:14:25 am
content: No crosses, but it seems to be active. No suppliers.Seems to be available from the manufacturer here:http://www.on-bright.com/cn/english/contact.htmhttp://www.on-bright.com/cn/english/products/products_OB235X.htmA PDF datasheet doesn't seem to be available.What made it blow out?

author: dietz
author_rank: Newbie
timestamp: June 07, 2016, 05:16:12 am
content: Thanks. The manufacturer of the receiver offered to sell me a few, but I was kind of hoping to be able to put bit better part in to prevent this down the road.As for what happened, not a clue. Powered it up, big pop, the smell of n-type in the air... After I get my hands on a few more of these I'll be able to see what kind of damage (hopefully nothing) the amplifier stage took, but everything looked OK...

author: Tomorokoshi
author_rank: Super Contributor
timestamp: June 07, 2016, 11:48:24 am
content: Perhaps throw a MOV in before the bridge. Also check the DC capacitor in case it shorted.
Datron 1271 firmware bug - Page 1
Forum section: electronics / repair

author: Mickle T.
author_rank: Frequent Contributor
timestamp: May 18, 2016, 07:07:00 am
content: I have an old Datron 1271 DMM in excellent condition. But one day I found a strange bug in the DMM's firmware: the full scale (display range) is limited to 199 990 000, but not the standard 199 999 999. DMM is 1992 year of manufacture and have no any sign of repair. Full selftest is passed. S/W ISS 02.10.Can anyone help with a more fresh ROM dump?

author: TiN
author_rank: Super Contributor
timestamp: May 19, 2016, 05:03:43 am
content: Ain't firmwares from 1271 and 1281 compatible? I'd try flashing 1281 just to see if that's true.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: May 19, 2016, 05:11:09 am
content: They are totally incompatible

author: dacman
author_rank: Frequent Contributor
timestamp: May 20, 2016, 06:43:05 pm
content: The Fluke 8508A does the same thing. It's in the specifications (although not in the extended specifications). I would assume it is not really a bug on the 1271.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: May 20, 2016, 06:45:34 pm
content: Well, it's time to dig in the 1271 f/w code

author: dacman
author_rank: Frequent Contributor
timestamp: May 20, 2016, 06:58:03 pm
content: Datron may have done that so that it does not need to check how many digits are selected for display.

author: quarks
author_rank: Frequent Contributor
timestamp: June 07, 2016, 08:19:00 am
content: unfortunately I missed this, but I think it is as designed and not a bug.I can check my 1271 and 8508, when I am back in my lab.edit: as expected both (1271 and 8508) show the same 199.990.000 digits and then switch the rangeexactly what is in the 8508A user manual (see att. screenshot)and makes perfect sense for 5digit resolution
Floating HP 6113A still measures voltage between positive terminal and GND - Page 1
Forum section: electronics / repair

author: Tim T
author_rank: Contributor
timestamp: June 07, 2016, 01:53:07 am
content: I picked up a HP 6113A power supply with known problems in order to learn a bit about trouble shooting. A new 3000 uF electrolytic cap did a lot to improve power output beyond the 10 watts it was previously capable of putting out ( half of what was expected), and to clean up a 120 Hz spike measured off the output terminals.All was looking pretty good until I removed the strap across the rear GND and negative terminals in order to float the power supply, and I am now measuring negative voltage across the positive terminal and GND. It starts out as only a few mV but gets to -0.5 V ( and continues to go more negative) after about 5 minutes of warm up.I have three other vintage power supplies that can be floated ( two HP 6216As and a Power Designs 2020B) and don't see this behavior on any of them.This Keysight article talks of placing resistors and/or capacitors between the output terminals and ground in order to deal with stray ESD and RFIhttp://powersupply.blogs.keysight.com/2014/11/why-do-i-measure-voltage-to-earth.htmland from what I can tell such resistors/capacitors are lacking in the 6113A, so on the surface this doesn't appear to apply.So my question boils down to might there be another problem to solve in this 6113A or is this normal behavior and if so why?Thanks,tim
Jitter in a simple circuit - Page 1
Forum section: electronics / repair

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: June 05, 2016, 08:06:43 pm
content: Hi, all, I am repairing a simple micro controller circuit that has a few 12 volt relays, a step down transformer, a smd voltage regulator, a bridge rectifier using 4 diodes a smoothing capacitor and some passives. The circuit does not function at all and after testing voltages I get a stable 5 volts out from the voltage regulator to the pic. The problem is: the voltages in the circuit jump a few milli volts. When I looked at it using a DSO it seemed to be jittering on an off. I think it is the micro controller causing the problem but before I give up I want an opinion. Any assistance would be appreciated.