hybridfree/eevblog-posts huggingface dataset:
Anyone in NorCal area who can do repairs on HP 8569B ? - Page 1
Forum section: electronics / repair

author: pfm
author_rank: Regular Contributor
timestamp: March 16, 2018, 10:17:46 pm
content: Is there anyone in the Northern California region who can help with fixing or replacing the resolution bandwidth control/switch rotor on a HP 8569B ? I dont want to ship this unit back and forth but I can drive to drop off/pick up, hence the question about location.Apparently its a common issue with these units where the metal contacts on the plastic rotor fall off. Either the rotor or switch assembly can be swapped out from a donor unit, or anyone who is familiar with this can add the metal contacts back on, although I do not have the metal contacts.Please PM me or reply here.Thanks.
Boonton capacitance model 72bd don't work - Page 1
Forum section: electronics / repair

author: Halide
author_rank: Contributor
timestamp: March 07, 2018, 05:52:59 pm
content: Hi,I have a problem with my boonton capacitance model 72bd. It's show all the time the ~6pf value and i can't set the zero pF. I checked the voltages and all is good. I don't have a service manual and I need a sugestion what I should do next.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 07, 2018, 09:59:03 pm
content: Hi,I expect model 72B to have identical front end.Take a look at the full manual located here:https://www.google.pl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi43NWqmtvZAhVmDZoKHS9XCXQQFggqMAA&url=http%3A%2F%2Fradiosurplus.it%2Fpdf%2FBOONTON%252072B%2520Instruction.pdf&usg=AOvVaw3CE2996BQ1elifkdeJLrWk

author: Halide
author_rank: Contributor
timestamp: March 08, 2018, 09:54:59 am
content: HiThanks for this manual. Did you ever fixed this device and mayby you can prompt which part can be damaged?

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 08, 2018, 10:04:14 am
content: Nope,I'd check :1. supply voltages according to the schematic,2. the signal at A101 input ("analog signal"); then You could determine if the bug is in the analog part or in the digital voltmeter part.3. AFAIK C404 is the differential variable capacitor used to adjust zero reading when the input is open. This capacitor could be damaged or touched by someone.

author: Halide
author_rank: Contributor
timestamp: March 10, 2018, 12:48:53 pm
content: Thanks for fast reply. Currently I am out of my lab and I can't check it. When I come back I immediately chek all this points.

author: korlatos
author_rank: Regular Contributor
timestamp: March 12, 2018, 12:21:21 am
content: Have you turned the Zero control far enough? The Zero control can actually travel beyond the region where you can move it easily. I attached the excerpt from the manual where this is discussed.

author: Halide
author_rank: Contributor
timestamp: March 15, 2018, 10:40:47 pm
content: Today I have a time to look at this capacitance meter. Korlatos you have right, someone turned the Zero control too far. Thanks everyone for help.
Mackie Control Universal LCD Screen problem please help - Page 1
Forum section: electronics / repair

author: trashdinner
author_rank: Newbie
timestamp: March 15, 2018, 08:54:58 pm
content: Hey guys, I have a Mackie Control Universal Midi controller and the last 15 x 2 squares of my LCD screen is acting weird.Sometimes it's blank, sometimes the correct text appears and scrolls to the right after a little while, sometime I see lines going down in the squares ...Here's a link to a video of the screen acting weird and the Schematics:https://www.sendspace.com/file/ck4ehtI would really appreciate your help!Thank you so much!
Help identifiyng smd component "S35E9" ??????? - Page 1
Forum section: electronics / repair

author: Diodo
author_rank: Newbie
timestamp: March 15, 2018, 03:23:26 am
content: Does anyone can help me to identify what type and model of smd component is this in a motherboard of a tablet ONDA V919 AIR, marked as: "S35E9". What is that component? Can be replaced with an equivalent one? Thank you.

author: Samogon
author_rank: Frequent Contributor
timestamp: March 15, 2018, 04:22:26 am
content: My guess MUN5335DW1https://www.digikey.com/products/en?keywords=MUN5335DW1
Pioneer F-28 Tuner Repair (a puzzle for the curious) - Page 1
Forum section: electronics / repair

author: Cliff Matthews
author_rank: Unknown
timestamp: March 18, 2018, 02:31:35 am
content: I'm a fan of some YT repair channels and sometimes toss-in my 2-cents, but I would say few have experienced one like this:After saying he's likely going to give-up on this repair, the show starts at the 10-minute mark.

author: ataradov
author_rank: Super Contributor
timestamp: March 18, 2018, 03:10:25 am
content: Does not look like it would be too difficult to reproduce that glass even if it breaks. It is pretty crude, and any modern printer will print this pattern on a transparency sheet, which can be attached to a piece of glass.It may even be within the capabilities of vinyl cutters.

author: Cliff Matthews
author_rank: Unknown
timestamp: March 21, 2018, 12:50:57 am
content: Here's part 2. This will take some episodes to finish, so unless anything else sets this thing apart, i won't update.

author: KE5FX
author_rank: Super Contributor
timestamp: March 21, 2018, 01:03:20 am
content: Wow, that whole engineering department should have been made to pee in a cup...
Vizio E241-A1 - Page 1
Forum section: electronics / repair

author: neo
author_rank: Super Contributor
timestamp: March 14, 2018, 01:58:00 am
content: I really need help here, please and thank you. Original problem, would not turn on.Screen is fine, worked when i last used it and got a visible confirmation when working on it.I then replaced the power supply board, no change and it acted odd when i plugged in the digital board.Replaced the digital board, and it has made progress. I can now turn it on but the screen doesn't come on and it won't turn off without unplugging it.Power supply is new, the main board is tested and warrantied.Without digital board 5.2V measured as 5.25V and the 16V measured as 15.6VWith digital board 5.2V measured as 5.138V and the 16V measured as 18V

author: Rasz
author_rank: Super Contributor
timestamp: March 14, 2018, 04:50:05 pm
content: Quote from: neo on March 14, 2018, 01:58:00 amis it? who tested it?does it act same with panel not plugged in?

author: neo
author_rank: Super Contributor
timestamp: March 14, 2018, 05:05:55 pm
content: Electroparts, a company who warrantied it.With the panel completely disconnected, that is to say both plugs unplugged, yes it does. Just checked it.

author: Rasz
author_rank: Super Contributor
timestamp: March 15, 2018, 12:29:05 am
content: Well, one of the two is bad, supply or logic board. Its easier to confirm supply and I assume you already did that, Im guessing you got a bad logic board.

author: neo
author_rank: Super Contributor
timestamp: March 15, 2018, 12:48:26 am
content: Quote from: Rasz on March 15, 2018, 12:29:05 amWell i can only confirm the 5V and 16V, no clue what comes out the other pin header and even if i did i can't make it turn on. But given the supply is new and the digital board ain't should i try to return the digital board? Or just give up on the thing?

author: Rasz
author_rank: Super Contributor
timestamp: March 15, 2018, 02:33:09 am
content: no ideathe old supply is dead?

author: neo
author_rank: Super Contributor
timestamp: March 15, 2018, 02:56:45 am
content: Quote from: Rasz on March 15, 2018, 02:33:09 amMaybe, maybe not. It is crusty due to my repair attempts.I think not turning on = death for these things.
Looking for source of Samsung TV service manuals - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: March 11, 2018, 09:29:55 pm
content: Specifically, models LN46C650L1F and B2230HD. Know anyplace where I can download these? Thanks...

author: KhronX
author_rank: Frequent Contributor
timestamp: March 13, 2018, 02:22:23 pm
content: What (sort of) information about those are you looking for?

author: cvanc
author_rank: Frequent Contributor
timestamp: March 13, 2018, 03:49:52 pm
content: The usual... I'd like to find schematics at a minimum, a parts list is always nice, and some test point info (voltages, waveforms, whatever) is icing on the cake. Thanks for anything you can point me to.Quote from: KhronX on March 13, 2018, 02:22:23 pm

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 13, 2018, 06:51:35 pm
content: Whats the problem with the TV ?

author: cvanc
author_rank: Frequent Contributor
timestamp: March 14, 2018, 04:46:06 pm
content: Quote from: lordvader88 on March 13, 2018, 06:51:35 pmI just generally like to have service info for things I own. The B2230HD currently has a backlight problem. Nothing at all wrong with the LN46C650L1F. Thanks.

author: _Wim_
author_rank: Super Contributor
timestamp: March 14, 2018, 08:26:35 pm
content: Quote from: cvanc on March 11, 2018, 09:29:55 pmI think this is what you need:https://elektrotanya.com/samsung_b1930hd_2230hd_2430hd_lpt22ds_lpt19ds_lpt24ds_monitor.pdf/download.htmlhttps://elektrotanya.com/samsung_ln_32a650a1f_ln40a650a1f_ln46a5650a1f_ln52a650a1f_-_ch_gam32mus_40mus_46mus_50mus.pdf/download.html
R9 390 Dead - Page 1
Forum section: electronics / repair

author: bullet321
author_rank: Newbie
timestamp: February 27, 2018, 08:16:22 pm
content: Hello guys!I have a problem with my graphic card. I tried to turned on computer but it only beeps, one long and three short, it is the gpu failure.So i measured with voltmeter and the 270uf 16v capacitors(7 of them) have 12v voltage but the other ones not, 10 of them ( 820uf, 3V). This is what i know so farAnd on 2X8 PIN power supply there is voltage. And i tried other graphic card and it works ok, so other components are ok.Is there any way how to determine faulty component on Gpu board and how?Please i want to make it work if there is some way?Thank youRegards.

author: bullet321
author_rank: Newbie
timestamp: March 03, 2018, 10:06:34 am
content: nobody?

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 03, 2018, 09:58:38 pm
content: IDk, I know it's possible tho if you're lucky to find some problem with the discrete parts. I bet finding useful info on the PCB will be hard too.I have a soundcard that failed 3yrs ago, before I knew much of anything. I need to dig it up and start poking around on it.If u know for sure what pins on the PCIe are supply voltages and respective ground, u could try just applying power to them and the main 12V plugs. And check around the power sections. What other connections might be needed tho for it to 'think' it's powered up normal, who know's.Do u have a MB u could plug it into like on a 'test bench' and not in a case? I bet its near impossible to get the probes in there if its in the case (at least my case)

author: ovnr
author_rank: Frequent Contributor
timestamp: March 03, 2018, 11:22:10 pm
content: Have you tested it in another computer?Anyway:Check the fuses. Between the two black inductors next to the PCI-e power connectors there are four fuses; two white ceramic ones, two others which are red with a big R on them. There's also one next to the PCI-e connector itself.Check the core voltage; the 820µF 3V caps. It should be between 0.7 and 1.5 volts.To be honest: Unless it's something simple like a blown fuse, repair is likely not practical. Incidentally, if you were doing any kind of crypto mining or other long-term high-load stuff, it's your own damn fault.

author: MyHeadHz
author_rank: Regular Contributor
timestamp: March 14, 2018, 02:57:46 pm
content: the r9 390 is basically a re-release of the r9 290x.Hereis a recent thread about a 290x, so it will probably help your case as well. There is a lot of good info there.
Logitech Harmony 650 repair? - Page 1
Forum section: electronics / repair

author: rfengg
author_rank: Regular Contributor
timestamp: March 12, 2018, 11:48:59 pm
content: I have a Logitech Harmony 650 Universal Remote which seems completey dead with no screen at all.I tried all suggestions on the web like taking out the batteries and trying to reset the device.Opened the device and cannot find any broken solder or connections.The PCB is clean as are the battery connections.Any suggestions on how to proceed on this?

author: drussell
author_rank: Super Contributor
timestamp: March 13, 2018, 12:55:14 am
content: Does the battery actually have juice, or have you tried powering the remote from an external supply instead of the battery?

author: cvanc
author_rank: Frequent Contributor
timestamp: March 13, 2018, 01:47:36 am
content: I don't know if it's your goal to fix this yourself or if you just want to "get it fixed". If the latter, I've used this gentleman with great success:https://www.harmonyremoterepair.com/...He does a terrific job (he's even had aftermarket custom LCD touchscreens manufactured for his repair needs!), and his repair reports are a thing of near-military detail and clarity. Highly recommended.

author: rfengg
author_rank: Regular Contributor
timestamp: March 13, 2018, 11:00:30 pm
content: Thanks for your response. Yes, I indeed did try connecting it to my Agilent power supply with alligator clips but the sysmptoms are still the same.Also the battery pack seems to be allright and charges fine.

author: rfengg
author_rank: Regular Contributor
timestamp: March 13, 2018, 11:05:12 pm
content: Quote from: cvanc on March 13, 2018, 01:47:36 amThanks for your response.I wanted to have a go at it myself as I did buy another Harmony when this one conked off.First time opening up a remote like this so I'm a bit clueless on what the issue is.
What did I fry to make all DC voltages and resistance read negaitive ? - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: March 15, 2018, 01:43:14 pm
content: I have a $10 XL830L which is a clone of a DT830xit seems, with ICL7106 and ICL7107 (1 is LCD driver). On mine they are integrated and under a blob.This thing runs off 9V, and I was powering it off a 12V SMPS, into a LM317 to get 9V. (I meant to be using a linear transformer, but wasn't)I was de-soldering a SMD LED with a grounded soldering iron station, and for what ever dumb reason I used the COM DMM tip to get the LED off. I think it was on either 20VDC or buzzer/diode tester. And 5-6 times the LED glowed about as bright as maybe 0.5-1mA would cause. IDK if I also touched the COM tip to the soldering directly.And then later when I went to use it, all voltages are reading negative. With no input, it reads ~-6.7v, or -0.67, or -0.07 as I switch voltage ranges. So a 9V battery reads as -6.7+9=2.3VThe resistance reads as negative as well.Here's the basic schematic for these cloneshttp://indexxit.com/wp-content/uploads/2017/11/cute-using-multimeter-digital-schematic-diagram-masl-simple-circuit-dt830b-pdf-dt9205a-with-lcd-hd-44780-dt9208a-dmm.gifand the ICshttps://www.intersil.com/content/dam/Intersil/documents/icl7/icl7106-07-07s.pdfNo sign of damage at all on the SMD stuff.

author: Chris56000
author_rank: Frequent Contributor
timestamp: March 17, 2018, 08:53:26 pm
content: Hi!I think there's an internal short or low impedance between Analog Common (Pin 32) and V- (Pin 26) within the '7106 IC - this will pull all the I/P high and reference circuitry to approx. - 6.5 to - 6.8V with respect to the Input Low, which the cause the A/D converter to read what you're getting - as the meter's one of those with an epoxy-blob all you can do is bin it I'm afraid - these things can be bought from China for the price of a Morrison's cafe sandwich (with free postage !) on fleabay these days!Chris Williams

author: wraper
author_rank: Unknown
timestamp: March 17, 2018, 09:07:19 pm
content: QuoteThey are both basically the same ADC except 7106 has LCD driver but 7107 LED driver built it. It's impossible to have both in one circuit.
A W Sperry  620C  oscilloscope  vertical  issue   - Page 1
Forum section: electronics / repair

author: Keg
author_rank: Newbie
timestamp: March 12, 2018, 05:20:06 am
content: I recently purchased an A W Sperry 620C oscilloscope . The same as a Hung Chang . I purchased it as working and found there was a problem with the vertical position .When you have the vertical position knobs fully counter clockwise , the trace is still above the center of the screen . When you turn them clockwise the trace goes up and off the screen . This happens with both channels so it must be after the vertical amps . I worry that it might be the crt . Help please .Thanks KennyG

author: amspire
author_rank: Super Contributor
timestamp: March 12, 2018, 05:59:39 am
content: The problem is not the tube.There was a thread about this family of scope along with a manual.https://www.eevblog.com/forum/testgear/my-$50-scope-seems-doa-tenma-72-720/msg271512/#msg271512There are a number of different scopes with different front panels that seem to be the same inside.If you are lucky, it will be a simple adjustment of VR6 as described in the manual.
What blew up? - Page 1
Forum section: electronics / repair

author: iocowboy
author_rank: Newbie
timestamp: March 11, 2018, 09:36:27 pm
content: A friend posted a picture on FB earlier asking what component broke on his DC power supply. The symbol has me thinking resistor but the leads look too long and have me confused. Thought I would bring it to you all and see what you thought.Aditional shots...

author: jheatac
author_rank: Regular Contributor
timestamp: March 11, 2018, 09:38:49 pm
content: Quote from: iocowboy on March 11, 2018, 09:36:27 pmVarister?Sent from my SM-G920V using Tapatalk

author: madires
author_rank: Super Contributor
timestamp: March 11, 2018, 09:47:01 pm
content: Possibly an NTC to limit the inrush current. It would be in series with the fuse. A varistor (MOV) would be between L and N to absorb over voltage peaks.

author: ArthurDent
author_rank: Super Contributor
timestamp: March 11, 2018, 10:00:34 pm
content: As mentioned, a non-linear resistor to limit inrush current. If you are replacing a NTC make sure you check the other parts around it to make sure you don't blow the new part as well.

author: Fraser
author_rank: Super Contributor
timestamp: March 11, 2018, 10:26:04 pm
content: The clue s was n the labelling...... RT1 ....... "Resistor Thermal 1"As others have stated it is likely an NTC varistor.Such parts often fail for a good reason.Fraser
Electrolytic caps again!! - Page 1
Forum section: electronics / repair

author: Dataforensics
author_rank: Unknown
timestamp: March 03, 2018, 03:50:56 pm
content: HI,So my 2011 Electronics Line Infinite Prime alarm panel started playing up last week.Clicking noise from speaker, flashing red board led and pulsing keypad backlight.No difference running from backup or mains, keypad unresponsive and would not arm.Sent tech support email asking for help, such as meaning of board led, no response, not even a 'buy a new one'Anyway it has three electrolytic capacitors so I ordered replacements for all and after fitting all working again.Two made by Hitano and one by CapXon.Physically they look fine, no bulging and all three around 10% low and the worst esr 1.4 Ohms on a 47uF (the CapXon)Not sure I would have failed them on test alone.Now I have a friends NAD C350 amplifier to fix and according to interwebs again common fault is protection circuit electrolytics.At least a schematic is available though, unlike for the alarm panel.Here the two main PSU filter caps (22000uF 63V) have obvious bulges though.Just mentioning.Tony

author: Ray Gianelli
author_rank: Contributor
timestamp: March 09, 2018, 01:06:01 am
content: I've had them measure fine for value and ESR, but are leaky. Had a cassette deck that wouldn't record, there were separate Dolby chips for each channel. Each one had a leaky cap on it. Took me a while to find, since I was looking for something common to both channels, like power supply issues.

author: oventech
author_rank: Contributor
timestamp: March 11, 2018, 02:28:32 am
content: If you need the repair information on the Nad C350.https://www.vintageshifi.com/repertoire-pdf/Nad-2.phpJust download the files you need. SM + SM extra. Have heard about the problems with that part of the unit.
1202X-E The power button does not blink and the oscilloscope does not turn on - Page 1
Forum section: electronics / repair

author: frompmr
author_rank: Newbie
timestamp: March 10, 2018, 11:06:44 pm
content: Hi!I have an oscilloscope one day after purchase. Siglent SDS 1202X-E.Worked during the day and turned off the power button at night.In the morning the button blinks, but when I press it it goes out and the oscilloscope does not turn on. Now it does not blink and the oscilloscope does not turn on.Under the guarantee I can not send. I went through 9 circles of customs hell to transport the oscilloscope to my country. Now I can not even think of sending him back to the seller. Especially since I ripped off the warranty seal, hoping to find the malfunction myself.Tell me where there can be a problem. What are the first steps I should take to find this malfunction.

author: tautech
author_rank: Super Contributor
timestamp: March 10, 2018, 11:21:25 pm
content: Welcome to the forum.Please see this thread where I have Quoted your post so that any problems are easy to find in the Siglent support thread.https://www.eevblog.com/forum/testgear/siglent-technical-support-join-in-eevblog/msg1449111/#msg1449111You should contact Siglent Hamburg for support:SIGLENT TECHNOLOGIES EUROPE GmbHLiebigstrasse 2-20, Gebaeude 14, 22113 Hamburg GermanyTel: +49(0)40-819-95946Fax: +49(0)40-819-95947info-eu@siglent.comwww.siglenteu.comAnd BTW, when emailing them be sure to drop in a link to this thread.
2425+6517=? - Page 1
Forum section: electronics / repair

author: nikonoid
author_rank: Regular Contributor
timestamp: February 28, 2018, 07:46:07 pm
content: What do you do when you have a Keithley 2425 with blown display and Keithley 6517a with blown transformer?You make them "interface":With just a small connection cable they are pin compatible and even most of the buttons on front panel work ok!One thing I really like about Keithley gear is how much they are sharing between different instruments, sometimes produced 20 years apart.What you have learned on one instrument is applicable to others. Many parts are shared and can be interchanged. Beautiful!Beside the VFD, some part on feedback circuit is damaged in 2425. I plan to post the repair here as soon as I have some free time.

author: TiN
author_rank: Super Contributor
timestamp: February 28, 2018, 07:53:32 pm
content: Now you can see why I like Keithley's. Older ones also have rarely custom parts or FPGA magic, so are relatively easy fixable even w/o schematics. We'd like more of photos eventuallyAnd there are a LOT of caps in 2425... As of EM xfrmr, I'll see what I can do for you.

author: Zucca
author_rank: Unknown
timestamp: March 02, 2018, 09:49:53 am
content: Posts like this makes me happy.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 03, 2018, 05:42:47 pm
content: yess an franken meter hope it works for you

author: don.r
author_rank: Frequent Contributor
timestamp: March 03, 2018, 05:46:39 pm
content: I noticed this even on my 80's Keithley gear. The cases are all the same and interchangeable whether they be bench DMM, voltage source, switch frame, etc. The UI is also consistent which is great if you have 5 or 6 pieces of gear.

author: SirAlucard
author_rank: Regular Contributor
timestamp: March 04, 2018, 04:54:27 pm
content: Now you just need to slap a 8942 over the 6517a in a skewed fashion to complete said project.

author: nikonoid
author_rank: Regular Contributor
timestamp: March 10, 2018, 01:47:21 pm
content: Quote from: don.r on March 03, 2018, 05:46:39 pmI totally agree. I think it is all intentional. I know first hand that plastic molds can be very expensive. And custom ASIC is even more so. When you procure components, like VFD display, the quantity you buy in makes a huge difference. Using same part on many instruments helps to bring prices down. Another example is expandability of instruments, like expansion slot that is shared between 2000, 2001, 2002, 2010, 6517. Reusing some of firmware and keeping UI similar also helps.Keithley being in competition with much bigger HP had to do these things to stay competitive on the market.In contrast, if you watch Dave's video #1032 with John Kenny of HP you can hear how different instruments were designed by different people in different locations. He is talking about his role now being to share design elements and components between instruments and engineering groups. HP is now doing things that Keithley HAD TO DO 30 years ago.
[SOLVED] SOT23 351A3 markings cant identify - Page 1
Forum section: electronics / repair

author: Samogon
author_rank: Frequent Contributor
timestamp: March 03, 2018, 06:43:45 am
content: This is fluke 789 process meter failed to power on.i have one good on the board. desoldered it and component tester said that it is mosfet n-ch with zenner between source and draini placed generic mosfet n-channel but without zenner and unit started working, but in off position it shows dashes, it mean not fully off, i suspect it is due to wrong transistor

author: Samogon
author_rank: Frequent Contributor
timestamp: March 03, 2018, 12:32:56 pm
content: Looks like i have found itNDS351AN On semiconductorshttp://www.onsemi.com/PowerSolutions/product.do?id=NDS351AN

author: Armadillo
author_rank: Super Contributor
timestamp: March 03, 2018, 01:04:14 pm
content: Isn't that a typical bodily diode across drain and source. Where is the zener diode you are referring?Will the dashes be the same in the off position?

author: Samogon
author_rank: Frequent Contributor
timestamp: March 03, 2018, 01:10:24 pm
content: Dashes do appear at the off positionAnd maybe i was wrong about zenner, possible it was just diode.I have already soldered it back and itnis under display with wierd snap-in system do not want to remove it. Who knows how much stress it can sustain.Will order transistors on Monday, it is cheaper then fixing dosplay holder

author: Samogon
author_rank: Frequent Contributor
timestamp: March 03, 2018, 04:11:58 pm
content: Correction:Proper device found and it clearly states "Device marking 351A"https://www.fairchildsemi.com/datasheets/ND/NDS351AN.pdf

author: Samogon
author_rank: Frequent Contributor
timestamp: March 10, 2018, 06:01:06 am
content: Installed transistor and dashes have disappeared when meter is off. That was simple repair.
Replacement transistor for a PSB subwoofer - Page 1
Forum section: electronics / repair

author: mjrpainless
author_rank: Contributor
timestamp: March 09, 2018, 02:44:53 am
content: Hey all, hope that someone might be able to point me in the right direction.I have an amplifier board for a subwoofer that I am trying to repair. I have narrowed it down to a bad transistor. But am unable to find a replacement tx.the sub is a PSB Century Subsonic 2i with an Indigo MAIN 600049 REV 7 board. The transistor that is blown is a HARRIS IRF9543.I was able to find a replacement samsung i believe it was, but they are only rated up to -60V (this is from memory so if its wrong I'm sorry)Thanks all

author: Kleinstein
author_rank: Super Contributor
timestamp: March 09, 2018, 09:06:05 am
content: Is this a linear amplifier with a large heat sink, or a class D type with a choke ?The required voltage rating depends on the actual supply used. Especially linear MOSFET amplifiers tend to use higher voltage MOSFETs because of the often better SOA and not because they need the high voltage. So the voltage rating might not matter. However for linear use the SOA does matter and here different manufacturers might differ.If in doubt, there is a 100 V rated IRF9542.

author: Rog520
author_rank: Regular Contributor
timestamp: March 09, 2018, 04:26:34 pm
content: A couple of sources pop up on Google:Newegg, through a third party Chinese seller:https://www.newegg.com/Product/Product.aspx?Item=2A3-0029-09K92HB Electronics, out of California:http://www.hbelects.com/product-6117/IRF9543I have no experience with either one of them. Rochester also has them available, at a steep MOQ.

author: mjrpainless
author_rank: Contributor
timestamp: March 09, 2018, 11:01:43 pm
content: Thanks Rog520, i was able to find the ones on the hdelects.com, but was unable to order from them. It wouldnt let me put anything in the shopping basket.and i didn't seen the ones that were on Newegg. so i made an order, Thanks for the help!
Racal-Dana 5002 / ME-545/G repair - Page 1
Forum section: electronics / repair

author: cprobertson1
author_rank: Frequent Contributor
timestamp: March 07, 2018, 11:54:45 am
content: Good Morning folks!Link to ManualI've just done the first wave of repairs on my Racal-Dana 5002 wideband level meter - themains filter blewand I've since replaced it.The unit now has power-up issues, which I've partially resolved, I'm getting an "Er 01" error showing on screen:QuoteFirstly, the battery is missing (the previous owner must have removed it) - so I've bodged in some wires so I can hook it up to the bench meter for now (I'll add in a lithium button cell holder if I have a spare kicking around somewhere)However, even when supply the specified 3V, the error remains - so proceeding forward to step 3 - "troubleshoot the ram using FO-2-pg4"!So - the question is this! How do I test theseCY7C148RAM ICs to confirm they are working??My first instincts are to:Check the voltage railsLook for data (in and out)(poke with oscilloscope)Check CS/WE pinsDig out the logic probes- But having said that, I've never tested a RAM IC before... RAM assemblies, sure, just usememtest.exe- but never the ICs themselves!Stuff I've done so far (only had an hour last night before I decided to go to bed! I'll have something like six hours to look at it tonight though)Replaced mains filterHooked battery to bench PSU (unit reliably powers up, but still gives error code 01Confirmed voltage rails on board (but not at the RAM ICs

author: cprobertson1
author_rank: Frequent Contributor
timestamp: March 09, 2018, 08:18:16 am
content: Urgh that was a nuisance.Ended up digging out the logic analyser.The data entering the IC was fine, but readback was corrupted - so it either wasn't writing or reading properly - well I suppose it could actually be both.Whatever the problem was, I've replaced it with a modern equivalent and we're up and running!It's even been in spec for the few measurements I've made with it so far; pretty good for a 30-year old bit of free kit!
Issue with wireless loudspeaker MALONE at high volume - Page 1
Forum section: electronics / repair

author: karlis77
author_rank: Newbie
timestamp: March 08, 2018, 08:15:32 am
content: Hi. This is my first thread at this forums so please do not be harsh.I am just a novice in electronics, all my experience is in power supply design and stm32 mcu programming. No audio electronics experience.The problem: Unknown model MALONE wireless loudspeaker randomly drops it volume after few minutes of playing music with highest volume. The volume drop happens randomly, like half of second it plays with no issues and then half of second the volume drops dramatically. This random volume change happens continuously.Loudspeaker was working with no problems until it was used at max volume for like 4 hours. Afterwards these problems started to occur even after some minutes of playing.My thoughts:Time needed for this issue to happen makes me think that it is related to temperature, as temperature rise needs time.When I dissassambled the loudspeaker I noticed that crossover network has high power resistor, which probably dissipates a lot of energy.Right next to it there is a capacitor.I think that this capacitor migh have been permamently damaged from high temperature when loudspeaker was used at max volume for 4 hours.Anyway it seems strange that the random volume drop happens very sharply.So, what do you guys think?Thanks in advance.

author: anachrocomputer
author_rank: Regular Contributor
timestamp: March 08, 2018, 10:14:35 am
content: That NP capacitor has come unglued, possibly due to vibration.Could you please post a detailed photo of the other side of the board? I suspect a bad solder joint somewhere.

author: karlis77
author_rank: Newbie
timestamp: March 08, 2018, 01:44:29 pm
content: Quote from: anachrocomputer on March 08, 2018, 10:14:35 amOhh, I cut the glue to see the parameters of capacitor. I wanted to check if there is something similar available on electronics components distributor websites.

author: drussell
author_rank: Super Contributor
timestamp: March 08, 2018, 02:56:53 pm
content: That is just the crossover board. You need to look at the amplifier.

author: karlis77
author_rank: Newbie
timestamp: March 09, 2018, 08:14:36 am
content: Below you can see images of board which has rectifier, AC/DC and amplifier on it.This is the amplifier usedhttps://4donline.ihs.com/images/VipMasterIC/IC/SGST/SGSTS29620/SGSTS29620-1.pdfMaybe it is some of the amplifier protections that kicks in.I will try to wire it up and do some measurements.
Peavey GPS 1500 Amplifier - Page 1
Forum section: electronics / repair

author: jordanp123
author_rank: Regular Contributor
timestamp: March 08, 2018, 11:09:42 pm
content: Had two bad pots on the front dials, got those replaced and channel B on the amplifier is perfect. Channel A, however is less than so. It almost sounds like clipping in the circuit; as the volume is turned up the sound becomes very distorted, I can bond the two channels and use the input in channel A, but the output on B and everything sounds fine. It has to be something in the amplification circuit, I've tried finding a service manual or a schematic for this unit but no luck. Any body have any previous experience with these units ?

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: March 08, 2018, 11:33:11 pm
content: Hifi manuals seems to have a schematic. You need to sign up though - I do not have an account and did not try to download data from that site, but seems to be free of charge. Maybe sign up with a throw away mail address firsthttp://www.hifi-manuals.com/Peavey-Electronics/GPS-1500/downloads

author: jordanp123
author_rank: Regular Contributor
timestamp: March 08, 2018, 11:40:13 pm
content: Greatly Appreciated !

author: frozenfrogz
author_rank: Frequent Contributor
timestamp: March 09, 2018, 12:00:46 am
content: Good thing is, you have a working channel as reference. That way you could follow the signal path and check for differences. Usually there is some order of failing in amplifier parts. The main suspects are: Bleeding electrolytic caps, then diodes and transistors. Power electronics are also often the first parts to fail due to thermal stress, but since you get output through the power stage, maybe look at the preamp circuit first. Resistors, ceramic caps,... tend to be more robust. Do some thorough visual inspection of the caps first (and burnt parts of course).Good luck hunting that down

author: Ray Gianelli
author_rank: Contributor
timestamp: March 09, 2018, 12:55:40 am
content: I've called Peavey in the past, and they will usually email you a schematic or service manual. Usually either free or a nominal fee.

author: jordanp123
author_rank: Regular Contributor
timestamp: March 09, 2018, 02:19:15 am
content: Got it. Followed the print back, check transistors along the way. This transistor had a small crack in the base lead. Appreciate the help everyone !

author: Ray Gianelli
author_rank: Contributor
timestamp: March 09, 2018, 10:53:09 am
content: Good catch! Pro and guitar/bass amps tend to have problems due to shock and vibration. I can tell you as a former gigging musician that the gear didn't go back into the van at the end of the gig with the same care it went in.
HP 3457a and 3478a fuse holder cap => Bussmann FBI - Page 1
Forum section: electronics / repair

author: tobe930
author_rank: Newbie
timestamp: March 08, 2018, 01:28:44 am
content: FYII got a HP 3478a in without a mains fuse holder cap and could not find any info on a current replacement partfigured out the 3457a used the same fuse holder cap .. not that provide much more infoBut found and got on ebay 'Bussmann FBI, Fuse Holder Cap for ¼” x 1-1/4” Fuses' AND IT WORKS!so I thought I would leave this info for anyone else in a search for replacement for either model

author: bitseeker
author_rank: Super Contributor
timestamp: March 08, 2018, 11:45:03 pm
content: Thanks for the info, Tobe. Welcome to the forum.Here are some additional references:http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/Catalogs/Bus_Ele_FBI_FBM_PC_Board_Mount_Fuse_Holders.pdfhttps://www.mouser.com/ProductDetail/Bussmann-Eaton/BK-FBI?qs=sGAEpiMZZMu5wYkxZVFLt4PTnG%252bkglXRhttps://www.digikey.com/product-detail/en/eaton/BK-FBI/BK-FBI-ND/5420200
MOVED: Symmetry issue with function gen EZ/Goldstar FG-8002 - Page 1
Forum section: electronics / repair

author: rodcastler
author_rank: Regular Contributor
timestamp: March 07, 2018, 11:43:27 am
content: This topic has been moved to Test equipment.https://www.eevblog.com/forum/index.php?topic=104845.0
Washinng Machine software variants? My Hotpoint WMF740P UK R lost its software. - Page 1
Forum section: electronics / repair

author: FrankE
author_rank: Regular Contributor
timestamp: March 07, 2018, 05:21:06 am
content: Anyone familiar which versions of Hotpoint software works with which variants of washing machine or know where I could find out?I'd a power outage when the machine was running unattended.I took the module out and replaced a 220R resistor at the corner which I think is just before a DC area of the board.It illuminates one row of buttons. but nothing will work from the controls.I tested out the sensors and actuators with a dryer board The binary sequence on the LEDs indicate all if fine (dryer fault which I would expect with the machine having no dryer)Now a complete module is expensive about £100 and they are sold without software. Add in a one time usable smard card at 40 and 100 fore a smart card readwer programmer then brand new parts are uneconomical.I've a WMF740 P UK ROn the module is written"Code 21501008302 SW :16.00.13 Bitron code : 30411986"But the dryer module reads the same.I've found boards on ebay but not sure what power modules are interchangeable.
HP 53132A fan replacement - Page 1
Forum section: electronics / repair

author: kj7e
author_rank: Frequent Contributor
timestamp: March 06, 2018, 08:04:42 pm
content: Found some old threads on this subject, rather than resurrecting Ill start a new one. Picked up a 53132A from eBay, included factory installed options 010 and 030 and was a later serial number (for HP branding at least). The eBay photos looked a bit rough, it was not clear if the display was week or if it was just washed out by the flash. The case was re-painted and a bit rough but the price was right IF it was in working order and the OEM options where installed.I lucked out and the display was in very good shape, nice and bright with a blueish tint. The meter cleaned out well but the re-painted case is a bit of an eye sore yet. Found it did indeed included the OEM options 010 and 030 and everything seems to work well, except for a noisy fan. Not just normal fan noise, its rough and sounds like a bearing is failing. Replaced with a Sunon 5.5 CFM 12.8 dbA fan, much better.Sunon replacement fan from Digikey;https://www.digikey.com/product-detail/en/sunon-fans/HA40201V4-000U-999/259-1617-ND/3694184Original fan;Fan replaced;
Need help fast!  identify audio potentiometer  - Page 1
Forum section: electronics / repair

author: godfrey
author_rank: Contributor
timestamp: March 06, 2018, 06:07:58 am
content: Hello everyone,I accidently broke one of the pots in my PSC DV Promix 3 Portable Audio Mixer. I need a replacement immediately, but I have no idea where to go.I believe it's a 20k -- 6 pin, right angle, yellow in color. 1/4 inch(ish) shaft (6mm)? Flat on one side, 0.662 inches in length (17mm). A2 03 is printed on the back. I've tried to be as specific with Google as I can, but I can't seem to locate one.Any ideas?Sincere regards,Phil Godfrey

author: Ray Gianelli
author_rank: Contributor
timestamp: March 06, 2018, 10:56:49 am
content: Have you tried contacting Professional Sound Corporation?If they can't (or won't) help you I'd check Mouser or Digikey.Let us know what happens.

author: DC1MC
author_rank: Super Contributor
timestamp: March 06, 2018, 11:30:29 am
content: Is an ALPS dual potentiometer like this one:https://www.ebay.de/itm/RK12L1210C0R-10kOhm-dual-logarithmic-15A-potentiometer-30mm-Alps/302636867962Fleabay is full of them, just make sure if it's a logarithmic or linear guy and check the value.Cheers,DC1MC

author: godfrey
author_rank: Contributor
timestamp: March 06, 2018, 06:30:56 pm
content: Thank you for the replies. I was in panic mode last night because I know there are some manufacturers that will not sell components. PSC was happy to send me a few along with a schematic. I should have the parts in a couple of days.W00T!(sigh of relief)Thanks,Phil
Toshiba C870 -1EX Motherboard is: PLF/PLR/CSF/CSR DSC MB REV 2.1 - Page 1
Forum section: electronics / repair

author: BlackCore
author_rank: Contributor
timestamp: February 28, 2018, 05:37:37 pm
content: Hi! I have the board from Toshiba C870-1EX, MOBO: PLF/PLR/CSF/CSR DSC MB. (As I have researched it's the same platform that's from Toshiba C850). So Board starts, but there is no Video (there is no external display either). A computer is taking steady 0.9 Amps when ON. The computer was working OK, in the evening they shut it off like always, but the next power on there was no picture on the screen. Measured all voltages present +VDDC_VGA, 1,5VS_VGA, +3VS_VGA,+DPEF_VDD18, VCCORE present, VCCRAM 1,5V, Signals RSMRST# is 3V3, PM_PWRBTN# (DNBSWON) from EC goes LOW on Switch button press, and then HIGH again after release. SUSCLK# is 1,6V (PWM 50 % Duty). LID_SW is 3.3V. I'm still waiting for a programmer to check bios, but if I understand correctly if RSMRST# is present than the bios should be fine? I will try to keep you informed if there is any progress.

author: relax79
author_rank: Contributor
timestamp: March 06, 2018, 04:09:15 pm
content: Hi, sorry for my poor English, I am repairing notebooks since 2003, on this motherboard %98 GPU faulty , there are two types gpu for this platform 216-0810028 HD7650M and 216-0833000 HD7670M . please measure jp8701 (near the pch bridge)against to gnd, if under 5 ohms than gpu really risky but if more than 5 ohms you try reball the gpu but gpus date code on the top starts 12xx means 2012 year xx weeks , 2012 gpus faulty. I am generally put %100 brand new 2015 year 216-0833000 on this mobo. If You search in net a lot of repair forum say same thing about 2012 gpu on this platform. c850 c855 l850 l855 models also use this mobo.
Samsung UN46EH5000 - Page 1
Forum section: electronics / repair

author: tonyh88
author_rank: Regular Contributor
timestamp: March 05, 2018, 01:22:20 am
content: Hi,I've been trying to repair a UN46EH5000 for some time now and I think I need some help.The inital fault was that there was no backlight on the TV. This TV uses LED for backlight. The LED PSU is integrated in the main SMPS and it is a constant current driver based on the SLC1012C IC.The SLC1012C was blown and about half of the LED on the strips were OPEN.I replaced all the LED and ordered a New PSU unit (BN4400667A).OK so now we reach the part were I need help. With the replaced LED and the new PSU unit there is something weird going on. If I only connect the LED strip to the PSU they light up and draw 470mA at 142V as expected from the markings on the PSU so the new PSU constant current driver is doing it's job.If I only connect the main board of the TV to the PSU without connecting the LED strip the TV turns on just fine and I can see everything on the display using a flashlight.The problem is If I connect the LED strip and the main board at the same time the TV PSU keeps power cycling.Since it is a new PSU i'm a bit puzzled. I bought the PSU from an online tv repair parts store. Did they sell me a bad PSU with crappy capacitors causing this power cycling?Should I be checking for anything special? Let me know if you have any ideas. I will post some pictures soon.Thanks

author: tonyh88
author_rank: Regular Contributor
timestamp: March 05, 2018, 02:05:12 am
content: Schematic of a similar model can be found here :https://www.electronica-pt.com/esquema/lcd/bn44-00497a-psu-35975/and attached are some pictures

author: keymaster
author_rank: Regular Contributor
timestamp: March 05, 2018, 02:22:54 pm
content: 470mA is not what is expected . i thing 350mA is the max of the tv leds . in the schematic you provide , its say that the led should drown 250mA.Are you sure that you put the correct leds ?

author: tonyh88
author_rank: Regular Contributor
timestamp: March 06, 2018, 02:56:29 am
content: Yes as I said the shematic is not for the same PSU I have. It is just using some of the same parts and is only a reference.For my PSU 470mA is the correct value. This current is controlled By a pair of resistor in parallel on the sense pin of the SLC1012C. I tried increasing the Resistance value to lower the current since 470mA is pretty high for these LED. Under normal operation 470mA is when the backlight is at 100% and is way too bright.It is a bit of a design flaw on these TV all the LEDS are driven way to hard and the heatsinking is pretty bad.I think I need to investigate the Fault signal on the FAN7340 this might be causing the PSU to power cycle.
Racal 6103 PSU circuit or replacment needed  - Page 1
Forum section: electronics / repair

author: Gordon
author_rank: Newbie
timestamp: March 05, 2018, 01:55:34 pm
content: Hi guys, has anyone got any service info on the Racal 6103 digital test set? I picked up one cheap on Ebay and the PSU has S/C transistors.Alternatively, if anyone has a working one they'd part with I'd be interested.Cheers - Gordon

author: fenugrec
author_rank: Frequent Contributor
timestamp: March 05, 2018, 09:51:54 pm
content: Quote from: Gordon on March 05, 2018, 01:55:34 pmS/C ?
Need Help with a Intenso Scooter - Page 1
Forum section: electronics / repair

author: LinuxMintDude
author_rank: Newbie
timestamp: March 04, 2018, 09:27:19 am
content: Good day there, fellow Forum users.I am having a problem with my Intenso Scooters Headphone output not working, and i have already looked in the datasheet for it as to which pins were to be probed to find out if they have a output. Since i dont have an Oscilloscope, nor small enough tips to probe the pins, i am stranded as to find out if the chip output has died.

author: ebastler
author_rank: Super Contributor
timestamp: March 05, 2018, 09:29:50 pm
content: That's a generic small MP3 player, probably with a 3.5mm headphone jack, right? I think the most probable failure would be a broken solder joint between the PCB and the jack, caused by mechanical stress on the plug. Have you inspected these joints carefully, with a magnifier? Or just try to carefully re-solder them.If it is really the amplifier chip that is broken, would you have a chance to repair it? (Can you desolder and solder these SMD parts? Is it an amplifier chip that is readily available, or some exotic single-chip solution for the whole player?) If the answer is "no", I would not bother beyond checking the output jack and its solder joints.
NEED HELP! Part ID/Replacement Sourcing for TDS 60MHZ (Mono) Scope Repair - Page 1
Forum section: electronics / repair

author: deepreef@150m
author_rank: Newbie
timestamp: March 02, 2018, 07:04:42 pm
content: Came across an old 60 MHz Tek TDS oscilloscope in the bin at work.... Given that I hate to see electronics go to waste I am attempting a repair. I do not have access to schematics on the unit so am having trouble ID'ing the following.Can anyone help?A cap was blown but am unaware of its value, the part # is C633.Also as evident in the photo, one of the chips is fried but I cannot source any information.Does anyone have any pointers, to help me breath life back into this little beauty?Thanks!

author: EEngo
author_rank: Unknown
timestamp: March 04, 2018, 08:51:56 am
content: Hi!that's an SN74TVC3010 from TI(http://www.ti.com/lit/ds/scds088g/scds088g.pdf)The datasheet mentiones the smd-marking TT010Are you sure the chip is blown?ingo.

author: deepreef@150m
author_rank: Newbie
timestamp: March 05, 2018, 02:17:49 am
content: I am afraid so, if I am correct and VCC/Vin is pin 1 then the chip got hot enough to actually fall off, as its not there anymore! Thanks for the find!