hybridfree/eevblog-posts huggingface dataset:
Noco GB70 Jump starter Repair - Page 1
Forum section: electronics / repair

author: dta116
author_rank: Newbie
timestamp: March 05, 2025, 11:01:18 pm
content: I have a Noco GB70 jump starter that will charge fine but when I press the power button it will come on bvut if I release the button it will go off. Seems like a relay is not latching. I can here the relay engage but also here it release. Can't seem to track down the culprit without a schematic.Any Help out there?Maybe someone actually repairs these units?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: March 06, 2025, 02:39:44 pm
content: Good Morning Dta116, There are several videos related to the GB70, here's one:https://youtu.be/jWpZhPNmNVYIf it doesn't work, open 'er up and do some probing with your DMM, but be aware of highamperage and do your probing safely. Make notes of your findings and come back with some specific questions. If you find that suspected relay, you may have to remove it from the circuit for a proper test. Let us know your findings, and good luck.

author: mikerj
author_rank: Super Contributor
timestamp: March 06, 2025, 03:51:33 pm
content: I have repaired a few of these, it quite common for resistors to burn up on the PCB, for diodes to go short circuit and for the tactile switches to fail. The NOCO battery chargers are also unreliable, and some are virtually unrepairable due to being internally potted so I strongly recommend NOT purchasing NOCO products, just look at the number of broken ones being sold on eBay etc.
NOH-3 nightivision sight repair help - Page 1
Forum section: electronics / repair

author: schwirrwarr
author_rank: Newbie
timestamp: July 29, 2020, 08:32:16 pm
content: i will later add pics.ok, so some time ago i saw this sich nightvision scope for sale, for only 40$! i bought it, put 2 aa batteries in it and startet it up...slowly a green image was forming, but then i hear a loud pop, the image goes instantly dark and it starts up again, makes a popping sound and so on..then i decidet to take it apart, and see what the problem was. i opened it, mad the room dark, pressed the button, whilst wearing rubber gloves and a big arc flies from the transformer to the tube housing!!next step was to take the thing completely dissasemble the scope, because the reticle also wouldnt show up.i didnt find any plans or even drawings of this scope online, so it was quite a hastle to dissasemble it, but i had done it and i now had access to all the components of the scope, which was nice , but confusing, because this was my first time dissamsembling something like this.first i screwed the led that lights up the reticle out and viola, it was working fine when i connected a battery to it, but it didnt work when i was poweering the scope up, so something in the circutry was broken.it was the variable resistor!i ordered it and soldered it on to the cables, but the led still youldnt light up, so i looked at the resistors and it seems that some resistors were faulty, so i ordered them today and they will arrive in some days i hope.back to the tube..the tube in this scope was a ekran v8 ep33 :https://www.google.com/url?sa=i&url=https%3A%2F%2Fpicclick.co.uk%2FPhotocathode-Image-intensifier-tube-V-8-EP33-night-vision-293286073012.html&psig=AOvVaw2BJE3K3bJwHORLhplmVWg3&ust=1596140533442000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCNDkv_qk8-oCFQAAAAAdAAAAABBBthis tube was connected to a little but powerfull high voltage transformer, which , when powered up outside of the scope and with nothing to release the arc on, was making static noise, like when you switch an old crt off.i think i just have to insulate the trandformer a bit more and i would then be abe to use it completely normal.what do you think??the tube also has one small black spot, u think i should replace it?sorry for possible spelling mistakes, my english isnt so good.
Noise figure meter Magnetic AB 117a / schematic - Page 1
Forum section: electronics / repair

author: loulou31
author_rank: Contributor
timestamp: April 10, 2024, 07:41:26 pm
content: HiI have bought a old noise figure meter model 117A from Magnetic AB. Magnetic AB IS a company based in Sweeden and was designing specific instruments.This instruments is in trouble and started to repair it without any schematic or synoptic. I have found the problem on the AGC signal processiing. When I force the AGC voltage between 0 to 4V to the RF module there is dôme amplification and signal détection. Without any signal or with signal the AGC is always -5v and there is no any gain.I started to draw the diagram of the board in charge of AGC but seems not obvious to understand.If I could have schematic or principle of opération of instrument that will help.RegardsJean-Louis
Noisy cassette tape recorder, even without tape (Sony TCM-200DV) - Page 1
Forum section: electronics / repair

author: squarna
author_rank: Newbie
timestamp: January 30, 2020, 01:40:55 pm
content: I recently bought this thing for cheap, and I'm ready to split it open and solder if necessary.It makes a lot of noise even without a tape in it. And even when an external speaker is connected.Video:https://streamable.com/kehx1Any ideas?Thanks in advance!
Noisy Channels - Page 1
Forum section: electronics / repair

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: January 27, 2022, 02:46:04 pm
content: I just acquired a Tek 784D functioning perfectly except for noise that appears to be uniformly about 1.0mV p-p on all four channels. I looked through the performance checks and specs and have not seen a figure for expected quiescent noise. However, I also have a 584D (converted to 784D) and the channel noise is essentially zero. Pardon the photo colors. The shutter system isn't very compatible with photography.Of course schematics for this are non-existent; at least I haven't found them. I'm suspecting power supply noise, but wanted to see if anyone here has tackled this before.

author: David Hess
author_rank: Super Contributor
timestamp: January 27, 2022, 11:47:10 pm
content: Let's do the math:1 millivolt peak-to-peak is roughly 170 microvolts RMS. Noise bandwidth of 1 GHz is roughly 1.6 GHz. So noise density is 170uV/Sqrt(1.6 GHz) yielding 4.3 nanovolts/SqrtHz which does not seem high to me.When you made the comparison between the 784D and 584D, were they both configured for 50 ohm inputs or high impedance inputs? They should have very different noise levels.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: January 28, 2022, 02:33:35 am
content: I did the comparison with all channels on both machines 50 ohms, then 1 MOhm, both of those with DC, AC, grnd coupling with results identical on all configurations. In all cases the inputs were open. I've done factory reset and SPC a couple times and it did alleviate some minor offsets, but the noise remained.You're right it doesn't seem high and I can live with it. I Just thought it was odd that this otherwise very well cared for scope has this anomaly. Of the dozens of used instruments I've purchased off EBay this is by far in the best physical condition and asking price was too good to pass up.Also, the noise is not common. It's completely random across all four channels, so I'm thinking it may not be bleeding through from a common source.
Noisy Coil (inductor) - Page 1
Forum section: electronics / repair

author: hpibmx
author_rank: Regular Contributor
timestamp: November 12, 2021, 04:28:55 am
content: Hi,I’ve come across few motherboards iPad and a laptop.Right after power on I can hear very small noise sound, found out when coil windings get lose they start making noise when current passing through them.So my question is how can I spot one? I’ve more than 20 in the iPad motherboard. Is there anyway I can find out which is making this noise?Thank you in advance.

author: amyk
author_rank: Super Contributor
timestamp: November 12, 2021, 04:46:58 am
content: Stethoscope. You can make a usable one out of a rolled sheet of paper.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: November 12, 2021, 06:06:20 am
content: By touching them. The noisy one will get a bit quiet, once you put your finger on them. I guess if they are making enough audible noise, then they are big enough to touch them one by one.

author: jonpaul
author_rank: Super Contributor
timestamp: November 12, 2021, 07:34:53 am
content: Poor SMPS stability and subcycle oscillation.Due to sloppy Chinese designj
Noisy / failing output inductors in a SMPS  - Page 1
Forum section: electronics / repair

author: Andersounds
author_rank: Newbie
timestamp: April 26, 2019, 08:22:51 pm
content: Hi,Thought someone might find this fault interesting.I inadvertently overheated the inductors on the +/- 18v rails of a basic SMPS and they failed, the outputs went very noisy, sounded like white noise with some jittery square content..Didn't expect these green blob inductors to fail from heat, the bigger ones are 150uH and the small one is 20uH, so if you see similar inductors on a really noisy supply try swapping them out, as just measuring them didn't show up the fault.Background info long version:Was doing a routine recap on an 80's switch mode power supply, I have done this refurb many times before zero issues, this time however I used hot air to loosen up the old hot glue / gunk that was holding the capacitors in place, powered it up and there was excessive noise on the output of the audio circuit, put it to one side and moved on to another one, same thing happened, after swapping various parts and getting nowhere I took out the inductors and measured them all looked good, eventally got some known good ones and swapped them out, then circuit was quiet again Wasn't a component I would have suspected.PS thanks to EEVBLOG members for helping me with my last post, got me on the right track for the repair, so I'll share any findings I make here to contribute.
Noisy linear regulation on Agilent 33220A - Page 1
Forum section: electronics / repair

author: mower
author_rank: Contributor
timestamp: July 18, 2023, 02:58:01 am
content: Hello,I am repairing a dumpster find Agilent 33220A. The symptoms are that the output has a negative DC offset. I have probed around and noticed that the isolated -15V is noisy, measuring 0.3V on my DMM. it is also closer to -16V DC. Is this a failed linear regulator? The noise of the input is a lot lower, both by measuring it with my DMM and observing the signal on my oscilloscope.

author: mower
author_rank: Contributor
timestamp: July 18, 2023, 03:06:20 am
content: I just probed around some more and discovered that the noise is only present when the output is turned on. Thing is, the configured setup is to only output 0.00 VDC, no AC signal. When the output is turned on the -15V rail drops from -15.9V to -16.4Vdc which I imagine is way out of spec. Could the linear regulator be the culprit? How else can I narrow down the issue.

author: alm
author_rank: Super Contributor
timestamp: July 18, 2023, 06:35:20 am
content: Have you looked at the input and output to the linear regulator with a scope? I'd suspect dried up electrolytic caps that have lost most of their capacitance so the regulator is dropping out of regulation under any load due to excessive input ripple. Second guess would be an open rectifier diode causing a 50/60 Hz rectified signal instead of 100/120 Hz.

author: floobydust
author_rank: Super Contributor
timestamp: July 18, 2023, 06:57:35 pm
content: Download the service manual, check the capacitors associated with the -15V regulator like C1338, 1339, 1340. Or else the regulator IC is damaged.some bad tantalum caps herehttps://www.eevblog.com/forum/repair/agilent-33220a-teardown-and-quick-repair/

author: Vovk_Z
author_rank: Super Contributor
timestamp: July 20, 2023, 07:22:58 am
content: Often it is enough to make DC measurements of input and output voltages of a regulator. You don't really nead an oscilloscope but havin it makes picture possibly more clear.

author: mower
author_rank: Contributor
timestamp: July 26, 2023, 12:54:21 am
content: I have a IR covid thermometer and I measured the temp of the regulator, and it isHOTI got peaks of 140 degrees Fahrenheit. On a good unit it doesn't get nearly that high. I'm still not sure what it is wrong, is something sucking up a huge amount of current on the -15V line? The input of the regulator is only about -17V or so, on a good unit it's always a clean -20V. If something else is drawing all that current then something else should also be getting mad hot, no?

author: mower
author_rank: Contributor
timestamp: July 27, 2023, 01:22:35 am
content: update i removed a 0 ohm resistor that disconnected the output of the regulator. It was still getting hot so it guess the part is toasted? Imma replace it and see if that fixes it.
Noob Question About Macbook Pro 820-3787-A Board Repair - Page 1
Forum section: electronics / repair

author: per4manz
author_rank: Newbie
timestamp: March 09, 2019, 05:18:38 pm
content: I am working on a Macbook Pro board (820-3787-A for A1398) and see "XW7700" AND "XW7701" listed on the boardview near the backlight driver (U7701). Boardview & schematic indicates pin 1 is "GND_LCDBKLT_SGND" and pin 2 is simply ground. However, I do not see anything on the board, not even pads.I am very new to working on boards, but I am pretty sure that nothing is supposed to be there (and there isn't), but am certainly looking to learn more and understand exactly what that is or isn't.I can share screenshots of the area in question, but unfortunately cannot share actual images.Thanks.

author: per4manz
author_rank: Newbie
timestamp: March 10, 2019, 02:54:49 pm
content: I found the answer elsewhere. XW on Mac schematics simply indicate a PCB trace or wire. Figured I would post that here in case someone else is searching for the same information later.

author: ljcarballo
author_rank: Contributor
timestamp: December 01, 2019, 12:30:21 pm
content: I would be very grateful if you could publish it to see if I am able to see where the 5v power supplies go
Nooelec HDSDR Smart front end - Page 1
Forum section: electronics / repair

author: antenna
author_rank: Frequent Contributor
timestamp: November 16, 2021, 12:21:52 am
content: I recently forgot my sdr connected to a nearby antenna that had about 1kw to it and it seems the front end of my sdr is now dead. I can hear my HT on it, but none of the nearby stations come in, not even the weather. I assume that the transistor right at the RF connector is the culprit. I tried to identify the junctions, but only get a .7v drop across one set of pins. I want to try replacing this transistor, but I have no idea what it is. It is labeled "WAT 85". Does anyone have a clue what transistor that is or if I am even looking in the right area?Thanks!

author: TheMG
author_rank: Frequent Contributor
timestamp: November 16, 2021, 12:44:09 am
content: ESD protection diode not a transistor.https://www.nexperia.com/products/automotive-qualified-products-aec-q100-q101/automotive-esd-protection-and-tvs/automotive-esd-protection/PESD24VU1UT.htmlIf it's shorted from the RF input to ground, then it would be the culprit. If not, the R820T chip is likely damaged.

author: antenna
author_rank: Frequent Contributor
timestamp: November 16, 2021, 01:52:14 am
content: There does not appear to be a short to ground at the ESD device. I see the 820 is discontinued. I saw a site that said the 860 is a direct drop in but I cannot find either for sale.
not a repair as such but here goes - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: January 21, 2021, 02:44:39 pm
content: Hi all,i have a kenwood dso,the rtc battery was flat when i got it,i changed that but still the clock wouldnt keep time,after some poking about i changed the xtal+associated caps around the rtc,the original rtc battery was soldered on to the pcb,i fitted a holder for a lithium 3v cell (the original battery was twice the size),it had no markings!,i assume 5 or 6v,the replacement works but only lasts a few months,could i replace it with a 18650 cell in a holder and tap off a 5v supply for a tp 4056 charger modual,or is that asking for trouble,there is just about room inside to do this,what do you think?,cheers Paul.m3vuv

author: CJay
author_rank: Super Contributor
timestamp: January 21, 2021, 03:19:15 pm
content: What markings were on the original cell?I don't think constantly charging a cell is a great idea.

author: m3vuv
author_rank: Super Contributor
timestamp: January 21, 2021, 03:22:05 pm
content: there wasnt any,just yellow shrink wrap,looked to be like 2x cr2032 cells stuck together by the look of it.

author: CJay
author_rank: Super Contributor
timestamp: January 21, 2021, 03:34:22 pm
content: From your description it could have been anything, NiCd, NiMh, lithium, manganese dioxide, it could have been 1.2V, 2.4V, 3V or more than 6V, difficult to tell what it was definitively, I assume you've disposed of it?Edit (and yeah, you did say there weren't any markings)What's the model number of the 'scope?

author: m3vuv
author_rank: Super Contributor
timestamp: January 21, 2021, 03:49:34 pm
content: its a kenwood DCS-8200

author: CJay
author_rank: Super Contributor
timestamp: January 21, 2021, 04:21:47 pm
content: Oh wow,there's nothing out there on the net.Are you able to take some pictures of the board which show the chip markings better, the ones you've taken before aren't readable?

author: aqibi2000
author_rank: Regular Contributor
timestamp: January 21, 2021, 08:34:51 pm
content: https://www.eevblog.com/forum/repair/kenwood-dso-wont-keep-its-time/Boom

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 22, 2021, 09:48:29 pm
content: Quote from: m3vuv on January 21, 2021, 03:49:34 pmAfter all, you talked about this earlier and the problem was solved...

author: m3vuv
author_rank: Super Contributor
timestamp: January 25, 2021, 07:57:14 am
content: was it?,if so for who??

author: m3vuv
author_rank: Super Contributor
timestamp: January 25, 2021, 08:25:05 pm
content: admittedly,the issue was solved ish but only short term,thats why im asking about this,seems logical to use an 18650 with a tp 4052 charger ic,that was the whole point of the post.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 27, 2021, 09:38:19 am
content: Quote from: m3vuv on January 25, 2021, 07:57:14 amhttps://www.eevblog.com/forum/repair/kenwood-dso-wont-keep-its-time/
not electronics but kinda related : squeegee for vacuum cleaner - Page 1
Forum section: electronics / repair

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 11, 2019, 01:16:59 am
content: There is a small rubber or plastic squeegee in my Dirt Devil spinning carpet brush thingy.The squeegee has dried out and bits went missing. Now it no longer has proper suction since I guess that squeegee creates a curtain to sweep crap forward back into the brush.Without the squeegee stuff is thrown clear out back the roller brush, I can feel them on my feet!I created a kind of replacement out of a silicone channel I got on eBay but it's not perfect and constantly pops out.I've searched a bit and can't find anything close to the original part. Dirt Devil themselves don't stock it.Maybe a small solder paste squeegee looks similar? Any thoughts?The rest of the cleaner still works, seems like a shame to lose functionality over something so simple.

author: MarkF
author_rank: Super Contributor
timestamp: June 11, 2019, 01:35:12 am
content: It looks like a car windshield wiper blade.Maybe you can find something close and shave it down to fit?

author: babysitter
author_rank: Frequent Contributor
timestamp: June 11, 2019, 05:37:34 am
content: Animals detected!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 14, 2019, 12:05:47 am
content: I found a kind of industrial rubber band that is 15mm wide. Folded in half it fits snuggly in the rail.Seems to work for now but it snaps out on carpet. Too much drag. Now I'll bet the unintended consequence will be that it will drag debris on hardwood floors thus causing scratches.I have to find the exact dimensions so it juuuuuuuuuust touches the floor.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 22, 2019, 04:08:21 am
content: I ended up buying an exercise rubber band on eBay.https://www.ebay.ca/itm/Resistance-Elastic-Training-Rubber-Band-Stretch-Exercise-Fitness-for-Yoga-Pilate/323699844767?ssPageName=STRK%3AMEBIDX%3AIT&var=512695072915&_trksid=p2057872.m2749.l2649The universe is weird because I walked by a gym yesterday and saw exactly that rubber band on the sidewalk, so I took it....Now my power brush works and the squeegee no longer pops out even though it gets a bit pulled out of alignment.Why Dirt Devil doesn't supply this stupid part is a mystery.
NOVOTRON ND31/32 servo converters issue - Page 1
Forum section: electronics / repair

author: Z. Khalid
author_rank: Contributor
timestamp: August 01, 2024, 08:02:51 pm
content: Hi all,Do any of you guys have experience with ND31/ND32 servo converter modules troubleshooting?Concerning the “AC1” error message, I searched the Internet for but couldn’t find what it means.Is the cause of this error a software or hardware related fault?
Noyes M600 OTDR - Page 1
Forum section: electronics / repair

author: Bics
author_rank: Newbie
timestamp: April 11, 2020, 09:00:40 pm
content: G'day, all!I recently picked up a Noyes M600 OTDR from the Ebays; someone in Pennsylvania clearing out a storage locker. This device was built in 2002 and appears to have been last used in 2007. After some poking and prodding, I was able to get the device to boot but as soon as the OTDR application launches I get a "Floating Point Error: Divide by Zero. Abnormal Termination" message, and the machine immediately shuts off. I was able to download the firmware from the AFL (Noyes) website, but the upgrade procedure requires the use of a 3.5" floppy, which isn't something I have laying around the house. While I work on tracking down a floppy disk and a working drive, I thought I'd ask to see if there are any AFL/Noyes fibre guys that may have seen this error before.Many thanks!
NPN's with floating Collectors?? - Page 1
Forum section: electronics / repair

author: Rjc987
author_rank: Contributor
timestamp: June 25, 2024, 06:16:03 pm
content: Hi guys,I'm working on a Granville Phillips 342/343 mini-ion vacuum gauge (343004) that uses a triode or Bayard Alpert style ion gauge to sense vacuum (basically a vacuum tube with a hot filament anode at 24v and a grid cathode at 180v and a collector that uses a few opamps to detect ions resulting from electrons smashing into gas molecules in the tube with current directly proportional to pressure. All the voltage trails are measuring with inspect, the filament comes on as it should, but the current from the collector Isn't getting to where it needs to go, the output signal stays high and the gauge shut the filament off thinking it's over pressure. In the process of troubleshooting, I came across a part of the circuit where the collector enters and it is something I've never seen before:2 NPN transistors with their bases connected together but not to anything else, one connected to the gauge Collector, then to the other emitter through a spark gap and a resistor, and both collectors floating and not connected to anything at all!I've quadruple checked that they are indeed floating and not connected to anything, it's a simple two layer board so I can see right through it but I've double checked with the multimeter as well as made sure I have the pin correct and they are. Here's a quick schematic I drew of that section of the circuit as well as a close-up of the front and back of the board.What is going on here? I've never seen something like that any ideas why they would do something like this?

author: oPossum
author_rank: Super Contributor
timestamp: June 25, 2024, 06:36:16 pm
content: Base-emitter reverse breakdown is providing overvoltage protection. Lower leakage than some other methods. Sometimes used in multimeters.

author: SeanB
author_rank: Super Contributor
timestamp: June 25, 2024, 09:05:04 pm
content: Yes base emitter voltage is typically going to break down around 5-10V, and till then the buried junction makes a very low leakage current diode. Avery fast diode as well, and with a current rating equal to that of the transistor, and the response is about equal to the transition frequency, and also has a low capacitance as well.
NRVD service manual  needed - Page 1
Forum section: electronics / repair

author: Jarek
author_rank: Regular Contributor
timestamp: December 27, 2022, 12:53:49 am
content: Hello .I need the NRVD service manual and any information about calibration after replacing the battery.Best regards

author: coromonadalix
author_rank: Super Contributor
timestamp: December 27, 2022, 01:57:16 am
content: Could you explain more NRVD means nothing for some people

author: Jarek
author_rank: Regular Contributor
timestamp: December 27, 2022, 02:08:41 am
content: Of course I can .This is Rohde & Schwarz Dual-Channel RF Power Meter ̧https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/NRVD_en.pdf

author: coromonadalix
author_rank: Super Contributor
timestamp: December 27, 2022, 02:23:23 am
content: http://manuals.repeater-builder.com/te-files/R&S/R&S%20NRVD%20Operating.pdfyou surely have this ??

author: Jarek
author_rank: Regular Contributor
timestamp: December 27, 2022, 01:16:25 pm
content: Thank you .Yes, I have this manual. I am looking for a service manual.Regards

author: Jarek
author_rank: Regular Contributor
timestamp: February 02, 2023, 12:12:39 pm
content: HiDoes anyone have a program for calibrating NRVD - CAL_D.BAS ?

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: February 03, 2023, 08:26:00 pm
content: Hi Jarek,I had the same problem with an NRVS (NRVS = 1/2 NRVD).Battery empty = calibration lost.Several R&S subsidaries no longer support these TE, so it's difficult to get them calibrated.IMO, finding the cal soft won't be that easy, but of course, it's worth to give it a try.You probably will have to send your unit to a cal service. Perhaps try to get in touch withthose guys, to see if they can help you. They also have subsidaries in Austria and Hungary. Here's some information onthe setup and workflowthey use.As you can see in the attached picture, my unit (last cal about 12 years ago) was off the ±1200 ppm spec for most of the AC ranges.After calbration, the worst case error is now ±70 ppm. So I would say it was worth doing it. For my private use, it will suit me for the next ten years.

author: Jarek
author_rank: Regular Contributor
timestamp: February 04, 2023, 03:13:16 pm
content: HiThe cost of calibration in R&S is about 400 Euro + shipping.You can buy a calibrated used one for that amount.I will try to do it myself, I already have some information on how to do it.Regards
NTC identification - Page 1
Forum section: electronics / repair

author: laban93
author_rank: Contributor
timestamp: April 20, 2022, 12:29:26 pm
content: Hey!At work our UPS transformer module died, and as there are no replacement parts for it, i had a look myself. I found the pcb inside to be faulty as it had a blown NTC. Its inline after the rectifier and fuse for the control circuits wich monitors current and temperature. The issue is that the number is gone, only 632 is visible. I have a sck 055 NTC for replacement if that is possible? As i understand, the NTC is there mostly for IEC compliance anyway?

author: TheMG
author_rank: Frequent Contributor
timestamp: April 20, 2022, 02:54:59 pm
content: The exact value isn't too critical, it's there to reduce the inrush current on power-up. As long as it is rated for a sufficiently high steady-state current for the application but don't go too crazy big either.I would also check that the circuitry downstream of the NTC doesn't have any obvious shorts before powering up.

author: fzabkar
author_rank: Super Contributor
timestamp: April 20, 2022, 06:57:03 pm
content: Could "632" be a YWW date code?

author: PKTKS
author_rank: Super Contributor
timestamp: April 21, 2022, 07:57:58 am
content: Up to 2kva NTC 5D 25 should fit...https://a.aliexpress.com/_mLaGwAKPaul
NTP7402 and NTP7414 datasheet is supported - Page 1
Forum section: electronics / repair

author: kastell123
author_rank: Contributor
timestamp: June 01, 2020, 11:36:26 am
content: NTP7402 and NTP7414 datasheet is supported ?Please help.Thanks

author: fzabkar
author_rank: Super Contributor
timestamp: June 01, 2020, 11:19:32 pm
content: I was able to find nothing other than that they are manufactured by Neofidelity.Could the TDA7402 be a match for the NTP7402?http://pdf.datasheetcatalog.com/datasheet/SGSThomsonMicroelectronics/mXuzruz.pdfIf so, then maybe there exists a TDA7414?
Nubert Nu-Pro 100 active speaker not working - Page 1
Forum section: electronics / repair

author: Michaelaudio
author_rank: Regular Contributor
timestamp: August 13, 2023, 06:37:33 pm
content: Ive got my Hands on a defective active shelf speaker, which will turn on, Display working, but no Sound comes out. So besides a ADC, there is a DSP (D2- 92633 LR) and a class D (digital in) amp Chip ( TAS5352a).So besides a defective 12v Buck converter, which was for powering the amp Chip Up, i have a unchanged Signal coming out of all 4 Outputs of the dsp. Its just a rectangle signa, that doesnt Change at all when signal gets fed into the speaker. The Input signal is changing, jittering when i play music, so thats fine till this Point. And even when the amp chip is powered up, i cant hear any noise coming out of the speaker, which may be the cause of the unchaning Input Signal of the amp Chip?Idk If im Missing something, or if the dsp is just broken (what i dont think) so maybe someone has an idea what to look at next.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 13, 2023, 07:00:53 pm
content: The TAS5352a takes a PWM input so you should see a jittering mark/space ratio there when input audio is applied. If not, then both the ADC and the DSP are suspects. Scope the analogue input pin of the ADC. The DSP datasheet is athttps://www.renesas.com/eu/en/document/dst/d2-926xx-d2-3s-audio-soc-datasheet?r=502821. Not clear from what you wrote if there is separate ADC or using the D2- 92633 LR for that.

author: Michaelaudio
author_rank: Regular Contributor
timestamp: August 13, 2023, 07:10:27 pm
content: Yea thats the point, the Input, or Output Signal of the DSP doesnt Change at all when i play music, the Output of the DAC is just fine.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 13, 2023, 09:41:48 pm
content: Quote from: Michaelaudio on August 13, 2023, 07:10:27 pmI don't understand how the Input to the DSP does not change but "the Output of the DAC is just fine". (I assume you meant to type ADC.)Be aware that the DSP chip is configured via I2C input which I assume is coming from a micro.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: August 13, 2023, 10:18:05 pm
content: Quote from: Michaelaudio on August 13, 2023, 06:37:33 pmWell that rings some alarm bells.How do you get to a situation where there is a defective buck converter AND a defective DSP?Some information missing here I suspect.

author: Michaelaudio
author_rank: Regular Contributor
timestamp: August 14, 2023, 06:21:33 am
content: Sorry i missed a Word, i mean the Input of the amp (or Output of the dsp)@Audiorepair Well all i know is what i wrote, im not sure if the dsp isnt working, i just cant get a right Signal Out of itEdit: idk why, but i turned it on and now it Runs, will let it run for a few hours, but seems to Work now
nuc6i7kyk heat sink - Page 1
Forum section: electronics / repair

author: stafil
author_rank: Regular Contributor
timestamp: May 08, 2020, 06:09:47 pm
content: This is more of a mechanical question rather than electronics.I have a nuc6i7kyk that is ridiculously noisy, so I thought I exchange the fan for a better one, but I didn't find a good quality fan that is compatible. So my next "bright" idea was to remove it from it's original case, and build a custom case, with an off-the-self heatsink and fan combo.But it seems the holes for mounting the heatsink are not standard. They have 3 holes according to their STEP file arranged in what it looks like a equilateral triangle.The BGA socket (named BGA_1440P_1102x1654_N in the step file) has dimensions 28mm x 42mm.I searched around and couldn't find a heatsink that would fit the dimension of the holes or the BGA or the mounting holes.I got a couple of quotes from online CNC's and a custom made heatsink seems a bit expensive (100's of $$).I was wondering if anyone has any alternative ideas/suggestions.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 09, 2020, 02:52:39 am
content: Its a damn laptop fanI noticed some people had or have problems with the fan ... i dont know for the noise, my guess would be clean the fan ( you surely did it? ) and sometimes theses fan can be dismantled, maybe add teflon oil drop on the sleeve ?Unless you go the hard route and hack it to be a fully passive cooling ? you have thermal pads going from 0.5 mm to 2 mm thick, and maybe use some old xeon server / full copper heat sink ...something like thishttps://www.ebay.com/itm/Pure-Copper-Heatsink-Heat-Sink-Radiator-Cooling-Fin-for-LED-IC-Power-Amplifier/143442605549?https://www.ebay.com/itm/Intel-Xeon-Copper-Heatsink-2U-D36871-001-FJJ-Xeon-5000-Series-LGA771/233578263219?With some drilling, tapping and add 3 adjusted in height sleeves / spacers you could have a totally silent pc ? not as compact ?The originals fan are sold pretty high priced up to 65$ usd ?
Nvidia 1080TI component replacement - Page 1
Forum section: electronics / repair

author: karek
author_rank: Newbie
timestamp: February 25, 2021, 08:09:07 pm
content: I have an nvidia 1080TI that is missing a couple of the tiny components that are mounted around the main die. Any idea what these are and what their ratings are so i can find new ones and solder on? I am sure these need to be replaced as i have found one of them loose and floating around. This is an ASUS Geforce GTX 1080ti

author: wraper
author_rank: Unknown
timestamp: February 26, 2021, 12:30:59 am
content: Do you have experience with soldering tiny SMD? If not, try running it as is. If it works fine, just leave it as is. It will probably work just fine and certainly won't damage anything further. Soldering there without experience may cause more harm than good. As those are just decoupling capacitors, there are others connected to the same power rail in parallel.

author: karek
author_rank: Newbie
timestamp: February 26, 2021, 05:28:58 am
content: Info about the card,Before taking it apart I installed and tested it. The pc would boot up, I would enter password for win10 64, desktop loads and then 30 secs later pc reboots. Fan runs, card LED light up, 6+8 gpu power connectors light up blue. Figured I would check the thermal paste so I opened it and the paste was all over the die and out over the capacitors, there is still small amounts of paste caked around the edges of the caps. Thanks for the info on the caps being in parallel sounds like they are overkill. Any thoughts on the pc rebooting after loading the desktop? The pc currently runs 2 gtx 670 in SLI and drivers are up to date, pc runs fine with the 670's but no luck with the 1080ti

author: wraper
author_rank: Unknown
timestamp: February 26, 2021, 10:33:38 am
content: Wasn't it conductive silver paste by chance? Missing capacitors could be the issue of course but I doubt that. The problem with them is that they are located very close to silicon die. So you can easily damage it, especially when soldering without microscope and fine soldering iron. Another problem is that substrate has high thermal mass, so it will be hard to solder without preheater underneath. What is history of this card, did you buy it broken?QuoteDoes it crash with blue screen or what?

author: perieanuo
author_rank: Frequent Contributor
timestamp: February 26, 2021, 01:33:36 pm
content: usually there you gor 0.1uF or 10nF caps, nothing more complicated, vcard must work without themfor beginner it's not easy to resolder them, but not impossible eitherdo a good visual check on tha pcb

author: karek
author_rank: Newbie
timestamp: February 26, 2021, 05:56:37 pm
content: Thank you for the information. I believe it is old thermal paste that is around each capacity, is it ok to leave it?
Nvidia GTX 780 PCB component ID - Page 1
Forum section: electronics / repair

author: hadses
author_rank: Newbie
timestamp: June 09, 2020, 11:31:31 pm
content: Hello everyone!I'd like to ask for help with identification of component marked as U502, its probably pcie controller vrm, but need correct name of the chip.Thanks you for any help

author: amyk
author_rank: Super Contributor
timestamp: June 10, 2020, 12:04:33 am
content: Surely U502 is a component designator, not the marking on the part itself?

author: M0HZH
author_rank: Regular Contributor
timestamp: June 10, 2020, 12:47:59 am
content: U502 - PCI-e controller supply, RT8071AZQW.
nvidia Quadro K1200 VRM - Page 1
Forum section: electronics / repair

author: super_postie
author_rank: Newbie
timestamp: August 16, 2020, 02:11:11 pm
content: HiWhat I believe is the VRM for my quadro card failed a little while ago. Magic smoke and everythingLooks like U501 is cooked, as well as one of the N channel mosfets in the top right of the card.I am going to attempt to fix it by replacing U501 and the mosfet but unfortunately the U501 chip is so toasted I can't make out the part numberIs there anyone out there with a genuine nvidia Quadro K1200 that can tell me what U501 is?Thanks

author: super_postie
author_rank: Newbie
timestamp: September 01, 2020, 04:32:44 am
content: Looks like it is an ANPEC APW8722 5v to 12v single buck voltage mode PWM controller
Nvidia shield pro 2019 - Page 1
Forum section: electronics / repair

author: j.a.mcguire
author_rank: Contributor
timestamp: November 05, 2023, 06:29:06 pm
content: Hi there,My shield pro 2019 suddenly developed an HDMI issue whereby it will only display at 720p and the audio output is limited to PCM.I dismantled the device hoping to be able to test the HDMI traces, and expecting to see an HDMI chip of some sort close to the HDMI port but the traces appear to be hidden I think due to it being a multi-layer board and the only chips in the vicinity are a INA3221 voltage shunt (which I am not sure what would be used for or if it relates to HDMI) and a realtek B111H5 HD audio chip. Everything else seems to be covered by EMF shields which are soldered to the board.Does anyone know if there's a schematic somewhere which identifies where everything is, or can anyone help me identify where the HDMI related chips are on this board?All of the information I have found so far online seems to relate to older versions of the shield. Thank you.
Nylex digital weather station - no outside temperature or humidity - Page 1
Forum section: electronics / repair

author: Saronni
author_rank: Contributor
timestamp: April 24, 2025, 07:27:25 am
content: Our trusty weather station started reporting outside temperature and humidity as "--" although wind speed and direction seemed ok.The temperature and humidity sensor lives inside this louvered part of the weather station.Opening the outside unit started to reveal interesting bits.Brute force and ignorance eventually extracted this sensor which I guess cannot be sealed off completely from the external environment. Ours had become home to a lot of fine and sticky spider web-ish substances. Cleaning it off revealed it was labelled "SHT3X-01".DuckDuckGo suggested the module may have been aSensirionsensor with I2C interface and it looked like the module was communicating over I2C but perhaps the sensing elements themselves had been affected by the goo although the interface to the brain box was still working.AliExpress offered to send me a module that had similar text to the original.Some modifications were required to the new module's physical dimensions to allow it to fit into the old module's base plate and into the weather station housing.... and the surprising result was that it appears to be working again!

author: CapLeaker
author_rank: Regular Contributor
timestamp: April 24, 2025, 07:11:27 pm
content: Funny. I just done the same repair on the “AcuRite 5 in 1 temperature sensor replacement repair” weather station subbing the original SHT21 to a HTU21D sourced at AliExpress over at badcaps. However you gotta be careful with the specs of the sensors. Some say they have a wider voltage range and clunk out @ 2.9 or 3V but go up to 5V.

author: Saronni
author_rank: Contributor
timestamp: April 25, 2025, 01:44:03 am
content: Interesting you mention voltage range. My AliExpress module had 2.4V-2.5V silk screened onto the back. CheckingSensirion's websitethough suggested their sensors could be powered from 2.4 to 5.5V.

author: CapLeaker
author_rank: Regular Contributor
timestamp: April 25, 2025, 10:39:56 am
content: Well I know, because I went looking for a SHT21 sub for my station and found a some different replacement (can’t remember) which said it is an original replacement with a wider voltage range. Sounds good? Nope.The original SHT21 goes from min 2.1v to max 3.6VThat replacement I looked at had a low voltage cut off at 2.9 or 3v but went up to 5V.I ended up replacing the SHT21 with an HTU21D. Identical specs, different manufacturer. Works like a charm.
O2r crashed after doing a reset - Page 1
Forum section: electronics / repair

author: DigiMix
author_rank: Newbie
timestamp: July 23, 2024, 06:44:49 pm
content: I have two O2r digital mixers, and did a reset on #2 by turning it off, then holding down the left curser and turning it back on. Rather than reset, it did nothing, and the only evidence of life was on the screen with the O2r display. Previous to this, I had done a recalibration of the faders by turning the mixer off, then turning back on with the Enter button held down. I think it was this action that caused the mixer to go to la la land. Is there another procedure to try before making a boat anchor out of this mixer?Today I unplugged the mixer and removed the backup battery, then turned it back on. It lit up; then I turned it off and unplugged it again; replaced the battery and then plugged it back in and turned it on. Now I'm back in happy land.
Objet Eden 330 3D printer embedded PC not POST'ing - Page 1
Forum section: electronics / repair

author: prototonic
author_rank: Newbie
timestamp: February 26, 2021, 04:38:24 am
content: I thought I would post something here since I've enjoyed EEVblog videos and content for a while, and there doesn't appear to be any information about this fault on the net.So, long story short, I acquired an Objet Eden 330 3D printer right around the time my home town of Melbourne went into Covid19 lockdown, around April or May 2020. So, it sat there doing nothing for a long time.First time I powered it on, a few months ago, I heard a pop and smelled the magic smoke, to my thorough disappointment. First check of the 3D printer power supply seemed OK. Inside there is an embedded PC and this was dead.The embedded PC that runs the machine features an IEI PCI-6S2 backplane with ISA and PCI slots. There is an ACS Electronics SB214PC4-F Multi-Axis Motion Control Card on the ISA bus, an Objet PCI card with Spartan FPGA, and the host PC motherboard is an Advantech SBC-81612VE with 1GHz Pentium 3 and VIA chipset, this connects to the backplane via PCI and ISA.Anyway, back to troubleshooting - I replaced the power supply, got lights on motherboard, CPU fan spinning up, but no POST. Clear CMOS, no help. Bought some PC133 SDRAM to swap with the old stick, still nothing. Double check all jumpers, visual inspection of motherboard to see if anything's obviously broken, no help.The backplane has LEDs for all voltage rails. Noticed the -5V LED isn't illuminated. Replacement power supply I bought is of course modern and doesn't have -5V rail. Was pretty skeptical that this would prevent POST but as luck would have it a mate had a spare old PSU with -5V output that I could borrow. Put it in, no change!Pulled out the other two cards connected to the back plane to see if it would help. Nada. Disconnected CD-ROM, nothing. Getting pretty despondent at this point, leaving a few days between attempts to alleviate the butthurt.A few days ago I inspected the motherboard a bit more closely, and noticed a little bit of leaked capacitor goop jammed in the tiny space between the offending cap and the CPU fan header, see attachments. On closer inspection of the four 1000uF 10V caps in this area, another one was bulging at the bottom. After replacing these, it boots! I'm yet to put it back into the printer chassis and reconnect everything, that's coming up.In retrospect, this probably would have been a lot easier to find if I'd pulled everything out and checked voltages, but just didn't really have the time to allocate to it!
Obsolete output pair 2SA1302 & 2SC3281: Any hope of finding some real ones? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: August 15, 2019, 10:26:51 pm
content: Do we know of a trustworthy source for some of these or are those days long gone? Thanks.

author: edavid
author_rank: Super Contributor
timestamp: August 15, 2019, 10:49:15 pm
content: MJL1302A/MJL3281A are still in production from On Semi - buy them from your favorite distributor and they'll be fine.https://www.findchips.com/search/mjl1302ahttps://www.findchips.com/search/mjl3281a

author: mzacharias
author_rank: Frequent Contributor
timestamp: August 15, 2019, 11:42:24 pm
content: The modern replacements, specified by Toshiba, the manufacturer, are:2SA1943 and 2SC5200
Obtaining schematics legitimately these days ? - Page 1
Forum section: electronics / repair

author: lordvader88
author_rank: Frequent Contributor
timestamp: July 25, 2019, 11:33:57 pm
content: What brand name consumer electronics could an average consumer even buy a schematic for ? When did companies making stuff like radio's, TV's, VCRs, computers, EE equipment, , stop selling/including schematics, or anything useful to a repair-person(or robot) for that matter ?

author: tggzzz
author_rank: Super Contributor
timestamp: July 25, 2019, 11:55:54 pm
content: You're currently on post 930, so that's only 70 more to go.

author: fzabkar
author_rank: Super Contributor
timestamp: July 25, 2019, 11:59:09 pm
content: Grrr, now you've got me started.I still remember the days when a circuit diagram was stuffed inside the back of every TV set. Today there is no excuse for a circuit diagram or service manual not to be made available as a PDF via a free public download.

author: tggzzz
author_rank: Super Contributor
timestamp: July 26, 2019, 12:14:42 am
content: Quote from: fzabkar on July 25, 2019, 11:59:09 pmI suspect that was the OP's principal objective

author: texaspyro
author_rank: Super Contributor
timestamp: July 26, 2019, 02:05:14 am
content: I have a small GE microwave oven that I bought around 15 years ago. The button than operates the door latch broke. When I opened it up there was large foldout sheet service manual in an envelope taped to the inside.

author: lordvader88
author_rank: Frequent Contributor
timestamp: July 26, 2019, 03:05:58 am
content: So what does Tektronix and the like do these days ? I guess let the machine do a self-test and give you a service department.