hybridfree/eevblog-posts huggingface dataset:
Need to identify small round plastic switch - Page 1
Forum section: electronics / repair

author: vjekobalas
author_rank: Regular Contributor
timestamp: January 28, 2022, 07:22:16 pm
content: There are two of these switches on a MedContour ultrasoundhead (machine made in Italy) - would appreciate if someonecould give me some direction as to who makes them/whereI could buy them as one of them seems to be going out of business- much less spring to it than the other (guess due to constant useand oily environment).The switch is all plastic, between the pins isa hole (I initially thought of pneumatics)Underneath the switch we can see the letters PAon one side of the pins and a symbol on the other side of thepins.It was glued to the plastic hand piece I guess I can siliconeit when putting it back or should I use some type of glue(ultrasound hand piece is plastic) ?

author: free_electron
author_rank: Super Contributor
timestamp: January 28, 2022, 07:25:33 pm
content: that S logo could be shaffner.

author: inse
author_rank: Super Contributor
timestamp: January 28, 2022, 07:26:17 pm
content: Schurter!
Need to locate ultrasound transducers - Page 1
Forum section: electronics / repair

author: vjekobalas
author_rank: Regular Contributor
timestamp: February 25, 2022, 09:47:42 am
content: Does anyone know the producer of the ultrasound transducers on the attached photos -they are in the head piece of a beauty salon machine ?The following is written on the two transducers:Transducer A on outside metal part MED TU. 0552 TITransducer B on outside metal part MED TU. 0536 TIWriting on both PCBsiCS 130LETEB9096ROHS 2716

author: Marco
author_rank: Super Contributor
timestamp: February 25, 2022, 02:27:37 pm
content: The metal cage is unlikely to be part of the transducer from its manufacturer, get the bare piezo disc out and examine that?

author: vjekobalas
author_rank: Regular Contributor
timestamp: February 25, 2022, 06:42:58 pm
content: The transducers still work i.e. won't be able to disassemble them - was hoping toidentify source so that I can purchase and have handy before replacement is needed.Doesn't the writing on the metal part tell you anything ?

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 26, 2022, 01:11:25 am
content: know nothing on that, but can't help to ask why the maker should differs to that of main unit's

author: vjekobalas
author_rank: Regular Contributor
timestamp: February 26, 2022, 07:29:25 am
content: Quote from: abdulbadii on February 26, 2022, 01:11:25 amSorry, don't quite understand the question.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: February 26, 2022, 08:03:13 am
content: Should the producer be different to the larger / main unit's producer brand, which's usually not, but just the one name so simpler is to get that main unit brand ?then google it

author: vjekobalas
author_rank: Regular Contributor
timestamp: February 26, 2022, 08:11:42 am
content: As I said, the unit is working / I won't be pulling it apart now - was wondering whethersomeone can point me to the producer based on the writing on the units.

author: vjekobalas
author_rank: Regular Contributor
timestamp: February 26, 2022, 08:34:52 am
content: Quote from: Marco on February 25, 2022, 02:27:37 pmHaven't had any experience with these components or their associated circuits before - is there anything special to be taken care ofwhen removing/inserting the transducers ?
Need Transistor Recommendation for  Conar 212 Transistorized VOM  - Page 1
Forum section: electronics / repair

author: BrandonD
author_rank: Newbie
timestamp: December 29, 2020, 09:35:19 pm
content: This is a great meter when it works. The transistors are for the meter circuit of the Conar 212 TVOM designed in the 1970s.I need an accurate recommendation for low power N-channel JFET’s, that are available to buy. I have the manual but it does not specify.The meter was working before. 9 volts hit it (my goof), not an overloaded test mistake. I came to the conclusion that it is a transistor because now when I turn it on, the needle hits the right pin and stays there,regardlessof settings.The movement is 200 microamps, and the numbers are linear on the dial (except for ohms), so I assume the transistors need to be linear in the range used.On the transistors it says TS20 and has a Motorola “M”.Circuit diagram follows.Please don’t guess if you are not expert!Please do tell us why you made the recommendation you did.Thank you,Brandon

author: bob91343
author_rank: Super Contributor
timestamp: December 29, 2020, 09:54:10 pm
content: Try J112. They are cheap and pretty good, used by HP and others. I don't think it's a critical component, especially if you replace both of them.

author: fzabkar
author_rank: Super Contributor
timestamp: December 29, 2020, 10:17:18 pm
content: Here are Motorola's old databooks:https://mirrorservice.org/sites/www.bitsavers.org/components/motorola/_dataBooks/Edit:You can see what FETs were used in other VOMs:https://elektrotanya.com/showresult?what=vom&kategoria=All&kat2=All

author: BrandonD
author_rank: Newbie
timestamp: December 30, 2020, 05:29:55 am
content: Thanks for the good advice so fast!Looks like I can resurrect it.Brandon

author: octillion
author_rank: Contributor
timestamp: December 30, 2020, 06:24:51 am
content: If one of the JFETs is bad, you can replace it with a JFET with an IDSS of a few mA (like the J112 suggested above). Both transistors are just source followers. They should be similar just for the purposes of temperature compensation (as the temperature changes, you'll have to twiddle the "zero" pot less if temperature characteristics are similar). In the DC and Ohms settings, Q1 drives the meter, while Q2 is statically biased. In the AC setting, Q1 buffers the AC signal, which gets converted to a negative DC voltage in the doubler above, and applied to the gate of Q2, and Q2 "drives" the meter (it conducts less, and its source resistor is really doing the driving).You may want to check the JFETs before replacing, just to confirm one of them is the problem. If either the 6.8 kOhm source resistor of Q1, or the 51 kOhm resistor above Q2 were open, you would have the same symptom.
Need Warranty service for Juntek PSG9080 - Unable to get Juntek to respond  - Page 1
Forum section: electronics / repair

author: hdskullfire2
author_rank: Newbie
timestamp: January 20, 2023, 01:39:59 am
content: I have a new Juntek PSG9080 that is only a few months old. Everything had been working fine until suddenly Channel #1 output stopped working entirely. I looked around inside but can't find anything obvious, it'll need to see the service dept for warranty or replacement. Bought from AliExpress. (FYI, It's not a clone) Took nearly a month to come direct from overseas.Anyone know why Juntek is not getting back to my emails or contact requests from their main page?Steve NordahlNazareth, Pa. USA

author: R-1125F
author_rank: Regular Contributor
timestamp: January 20, 2023, 03:03:44 am
content: Could be are off for Chinese New Year.
need wiring diagram for hakko 851-2 - Page 1
Forum section: electronics / repair

author: jparker708
author_rank: Newbie
timestamp: October 25, 2023, 06:16:18 pm
content: I have a hakko 851-2 that I can not figure out how to reconnect or find any documentation on how to wire the air pump and the heat gun back up. I have contacted hakko they said the schematic and wiring diagram are proprietary. So if anyone has this unit can send me a picture or a guide on how to reconnect so greatly appreciated!!

author: Swake
author_rank: Frequent Contributor
timestamp: October 29, 2023, 11:17:57 pm
content: The board seems to have some markings:https://hakkousa.com/b1218.htmlIn the last seconds of this video it is somewhat visible. It is not much but maybe just enough to help.
Needed NVSRAM Dump of TDS640 or/and TDS600 field adjust software [SOLVED] - Page 1
Forum section: electronics / repair

author: madao
author_rank: Frequent Contributor
timestamp: November 06, 2019, 05:56:39 pm
content: Hello people.I have repaired TDS640,of course capacitor plague.But NVSRAM is corrupt und i am needed dump of functional TDS640.Do exist TDS600 field adjust software?Thanks.Matt

author: madao
author_rank: Frequent Contributor
timestamp: November 09, 2019, 08:04:07 am
content: I have getting NVSRAM Dump of TDS640.Greetingsmatt

author: rf+tech
author_rank: Frequent Contributor
timestamp: November 12, 2019, 02:52:57 am
content: Hello madaeo,Attached below is TDS600A.ADJ Field Adjustment Software. To add support for TDS640 (plain, no letter) to TDS600A.ADJ after installation:Open directory TDS600A.ADJEdit DUTLIST. There are three entries, TDS620A, TDS640A and TDS644AAdd TDS640 below the last entry, save and close file DUTLIST.It is necessary to make a copy of file Tds640a.con, and name the copy Tds640.conAlso, make a copy of file Tds640a.idx, and name the copy Tds640.idxIt is not necessary to edit either file copy. With these steps, I have successfully calibrated a TDS640 on the first attempt.RF+ Tech

author: madao
author_rank: Frequent Contributor
timestamp: November 12, 2019, 04:38:48 am
content: Great ! Thanks.It is really simpel !RegardsMatt
Needed schematic for pH meter Elwro N5170 - Page 1
Forum section: electronics / repair

author: bborisov567
author_rank: Regular Contributor
timestamp: March 20, 2024, 08:09:59 pm
content: Hello, i am repairing this old ph meter. Unfortunately when powered up only the minus sign lights up. All power supply voltages look good. But i need a schematic or service manual to further continue repairing. Even a user manual still would be helpful. Thank you in advance!

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2024, 03:28:54 pm
content: A PH meter is a realtively simple instrument. Not really that much inside: a very low bias input amplifier and than scaling (can be temperature dependent - thus the pot and maybe exter PT100 input) for a mV meter.The line of - signs could be indicating overflow for the ADC part.Even without schematics one could likely check the input amplifer / buffer part.It may be normal that the meter reads an overflow with an open input. For a test one should try with a short across the input and than get 0 mV and ~ PH7.

author: doktor pyta
author_rank: Frequent Contributor
timestamp: March 21, 2024, 05:55:24 pm
content: Hi,not much but still better than nothing.It is a part of a manual of a similar model.

author: bborisov567
author_rank: Regular Contributor
timestamp: March 22, 2024, 11:39:16 am
content: I have tried shorting the input and supplying 200-300 mv but there is no change. Thank you very much for the pictures! This is the model with the nixie tubes, right? I believe the schematic could be very similar. Could you scan the whole manual (you can use one of the smartphone scanning apps like Camscanner, no need for high quality), especially if there is a schematic. Also does somebody recognize the multi pin connector on the back? It looks like something similar to GPIB but it is definitelly not.

author: bborisov567
author_rank: Regular Contributor
timestamp: March 26, 2024, 09:36:16 am
content: It turned out that the schematic regarding the digital circuitry inside this Elwro is the same as Meratronic V640 .Regarding the problem - the display reading came after i replace C502 (68p) which is responsible for the clock of the D triggegrs.Also I had to change all 4 7-segment displays because of dead segments. I put some Kingbright SA56-11EWA - exact pin to pin replacement. Now everything is functional. Also had the same problem with a Meratronik RLC meter E317. So it seems that all CQVP31 led displays are failing after all these years.
Needed schematic/service manual for Metravolt 10D - Page 1
Forum section: electronics / repair

author: bborisov567
author_rank: Regular Contributor
timestamp: December 29, 2022, 10:05:37 am
content: Hello, i am trying to repair this multimeter but navigating without schematic is really hard. I really would appreciate if someone share service manual or schematic. The 12D model is similar. Nothing comes up on Google search
needing a sanity check!! - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: December 05, 2020, 07:12:02 pm
content: Hi all,im not sure where to post this but here goes anyway,ive just brought an avometer model8 mk11,it seems fine on most ranges'but' on the ohms divide by 100 range it seems to multiply ie a 100 ohm reads 10k and the same resistor on the multiply x 100 range like 0 ohm,are they supposed to be like this?,its like it works opposit to what i expect,am i going barmy??.

author: mikerj
author_rank: Super Contributor
timestamp: December 05, 2020, 07:50:53 pm
content: Sounds perfectly normal. On the ÷100 range you divide the reading by 100 (10k/100 = 100Ohms). On the x100 you multiply the reading by 100 i.e. your 100R resistor probably read close to 1ohm, so multiply by 100, though this clearly isn't a suitable range for low resistances.

author: m3vuv
author_rank: Super Contributor
timestamp: December 05, 2020, 08:06:28 pm
content: cheers it makes sense now,was having a blonde moment lol.
Needing a source for a FP6717 buck/boost converter - Page 1
Forum section: electronics / repair

author: davesnothere
author_rank: Newbie
timestamp: October 02, 2022, 08:57:27 pm
content: I've got a small piece of portable test equipment that recently failed and will no longer run off it's battery, runs fine when connected to the charger.After removing the battery and tested it I found that the battery is fine and there is a dead short on the connection that the battery makes to the circuit board.Upon further isolating of the components I found that the 8 pin voltage 'regulator' had a short to ground (.2 ohms) on its input pin.This 'regulator' (buck/boost converter) is a Fitipower FP6717, I have attempted a search to find an online source for either sample quantities or small quantity orders (I only need one) but so far have come up with no results.Anyone know where I could find a small quantity source for the Fitipower FP6717?TIA for any helpers

author: thm_w
author_rank: Super Contributor
timestamp: October 03, 2022, 10:55:43 pm
content: There are some on aliexpress for $1.50 each.This is a common style of boost converter (battery voltage to 5V). So you can also likely find a similar part with the same pinout, or, buy a prebuilt module and jumper it onto the board in place of the original circuit.
Needing help identifying mystery connector - Mezzanine type? - Page 1
Forum section: electronics / repair

author: SlyTom
author_rank: Newbie
timestamp: July 26, 2022, 02:59:01 pm
content: I'm needing to replace this connector but I haven't been able to find anything similar.I've tried google lens as well as manually trawling through a number of sites (mouser, Digi-Key, etc.).10 pin, 2 rows, blade type, surface mount.It's from a piece of equipment made by GE Healthcare, so possibly proprietary but unlikely.Any ideas?

author: jwet
author_rank: Frequent Contributor
timestamp: July 26, 2022, 04:28:33 pm
content: You don't give dimensions so I can't give you a P/N but go back to Mouser and look at SAMTEC board to board/mezzanine connectors. They make every conceivable config in my experience- they're also good with samples.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 26, 2022, 06:01:42 pm
content: I didn't see any mezzanine type connectors in Samtec that would work. Assuming that's a 1.27mm pitch part.These do not appear to be blade type. Sure they are blades?https://www.digikey.com/en/products/detail/samtec-inc/CLP-105-02-L-D-P-TR/6561513

author: SlyTom
author_rank: Newbie
timestamp: July 26, 2022, 08:54:08 pm
content: Unfortunately I couldn't see this connector type from samtec either.I can track down specific part numbers based on the size later, but I just need to start with the family it belongs to.Connectors aren't something I need to buy often, so let me know if there is other specific information I could provide that would help.I think 1.27mm is correct.Pretty sure it's blade type. I've attached a photo of the male end.

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 26, 2022, 11:27:39 pm
content: Ok, the photo of that flex cable connector looks amazingly similar to ones we have used here at work. Tomorrow I will try to find the information for you!

author: SlyTom
author_rank: Newbie
timestamp: July 27, 2022, 12:07:42 am
content: Found it!Part # P10-010SLT-A-G made by 3M. (Actually a 1mm pitch).Went obsolete in 2009, which is bizarre considering this piece of medical equipment was purchased less than 3yrs ago!My customer might just have to fork out for a new PCBA..Thanks for the help legends!

author: SoundTech-LG
author_rank: Frequent Contributor
timestamp: July 27, 2022, 12:18:23 am
content: This co. claims to have over 8000 in stock, but no pricing, only RFQs.https://www.heisener.com/Finder?pn=P10-010SLT-A-G&type=partnumber

author: gnuarm
author_rank: Super Contributor
timestamp: July 27, 2022, 05:17:41 am
content: Quote from: SlyTom on July 27, 2022, 12:07:42 amIf 3M obsoleted the part, it might be made by an Asian outfit. I've seen many similar connectors made by different companies, which may or may not be compatible.How did you determine it was 3M? By pictures? That may not be good enough. There are lots of very similar looking parts that are not actually compatible. Even "standard" 0.1" connectors are not actually standard enough to be assured to work with the competitors mating connector.
Negative output in my oscilloscope - Page 1
Forum section: electronics / repair

author: AirScooter
author_rank: Contributor
timestamp: April 30, 2021, 01:12:54 pm
content: I use a LeCroy 9400 oscilloscope. It has 4 separate power supplies. + and - 5volts and + and - 15volts.The power supplies that output -5volts and -15volts have quit.I assume the output of these voltages is related electronically. Could someone explain to me how the two power sources are related and what I might try to get them going again,Thank You,AirScooter

author: ledtester
author_rank: Super Contributor
timestamp: April 30, 2021, 02:45:42 pm
content: You can find schematics and an upside-down service manual on archive.org - search for "lecroy 9400":https://archive.org/search.php?query=lecroy%209400I'd first look at the service manual -- it is very complete in describing how the scope works.Maybe start on page 185 for details on the power supplies.Another resource to investigate is the Lecroy Owners group on groups.io (formally a Yahoo mailing list).

author: AirScooter
author_rank: Contributor
timestamp: April 30, 2021, 09:50:04 pm
content: Thank you for your helpful reply.AirScooter

author: james_s
author_rank: Super Contributor
timestamp: April 30, 2021, 11:18:08 pm
content: Is this the one that has essentially the same power supply as the Tek TDS400 series? The one with the 4 separate magnetic amplifier regulator channels and the vertical daughter board on the output end that has a the regulator control circuitry?
Nelsonic Pac-Man game watch faint sound repair - Page 1
Forum section: electronics / repair

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 12:42:40 am
content: Hi all, wondering if anyone can give me some tips on this one. I’ve managed to get this old 80’s PacMan watch working after cleaning up corrosion on the battery terminals but the sound is so faint I have to smash the watch up against my ear to hear it. There’s what looks to be two tiny FETS, a tiny capacitor, and what looks to be a variable capacitor on the board and the traces go to the springs that touch against the piezo speaker element. I thought maybe it was the cap and maybe adjusting the tiny pot/variable cap would be the culprit but Adjusting the variable pot made no difference. I tried putting a ceramic cap in place of the fixed cap and that did nothing. It wouldn’t even power up. I’ve attached a pic of the pcb. If anyone had any ideas please let me know. Thanks.

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 08:44:53 am
content: Well I have since learned from this site:https://www.explainthatstuff.com/quartzclockwatch.htmlthat what I thought was a tiny capacitor is actually the quartz oscillator. I did make small adjustments to that pot thinking it would effect the sound volume but what I might have done is alter the rate of the oscillator maybe?? Not sure. So far not is keeping correct time still so I am not sure what that pot is for.As far as further troubleshooting the low sound problem, I am now thinking maybe it is those FETs but not sure what type they are or anything. Or maybe its that round choke/coil looking thing.

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 09:11:07 am
content: Wow I can't believe I just fixed it!I took it back apart and re-flowed the solder on the tiny FETS and that choke/coil and bam perfect sound, loud and clear!

author: Bashstreet
author_rank: Frequent Contributor
timestamp: December 22, 2018, 12:46:01 pm
content: Quote from: sideburn on December 22, 2018, 09:11:07 amAnother dicky connection sorted

author: coromonadalix
author_rank: Super Contributor
timestamp: December 22, 2018, 02:29:34 pm
content: Be sure to clean the pcb properly

author: sideburn
author_rank: Regular Contributor
timestamp: December 22, 2018, 02:44:03 pm
content: Yeah, now I really believe in the “bake it in the oven” fix trick.

author: chuckyab
author_rank: Newbie
timestamp: January 16, 2021, 12:47:03 am
content: Hi, I have a first edition pac man nelsonic. Nothing happens when I put in a new battery. Is there a page with instructions on how to get this back to working? A website, or youtube video? Thanks for the help
neoden 4 24v power supply problem - Page 1
Forum section: electronics / repair

author: ronmetrix
author_rank: Newbie
timestamp: February 01, 2018, 05:12:18 am
content: hi guys<Just new in this forum. I want to seek advise on what to do with our neoden 4 pnp. We first encounter vacuum problem and then head xy ordinate. We first reboot but same error occur with xy ordinate then check power supply we found out that theres no 24v coming out from the signal cable of the head.

author: JanL
author_rank: Contributor
timestamp: January 03, 2019, 12:18:14 pm
content: Hi Ron,did you get your problem soplved? My power supply has some problems of it's own and I would like to open the NEODEN4. Can you give me some advice?Thanx - Jan

author: Tonny-NeoDen
author_rank: Contributor
timestamp: November 18, 2019, 08:24:13 am
content: Hi All,If have any problems in using,feel free contact to our technical support person:service@neodentech.com or support@neodentech.com.
neon in regular bulb holder hack - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: August 21, 2023, 11:12:09 pm
content: If you get some nice miniature panel inicator lights that have say 20V tiny bulbs in them, you can replace them with a neon using this neat trick.1) remove bulb2) smash glass and clean out inside3) cut into the section of the taper area of the bulb top so it is compliant (6 incisions around the flare from the top glassless end), like a collet4) melt the solder on the end and stuff in a neon with 1 lead bent up while solder is molten. Gently force it so it goes in there and pushes apart the cut you made int he flare bit of the light bulb.5) fold the lead over and solder it down6) check to see if it fits in the indicator.I had a neon that was just a bit too tall to splice into a regular bayonet bulb body and close the lid. But if you cut into the top of the flare of the bulb with say 3mm deep incisions, it expands enough to accomodate the neon bulb.YOu might find old incandescent light bulb indicator holders are well built, threaded panel mount, have grounding safety, good terminals.. compared to neon indicator that are some snap fit bull shit.If you break OLD HP neons (common) that have ridiculous snap fit crap, you can use this hack (but don't forget the resistor).I guess you can do a LED too, easily.I was getting SERIOUSLY pissed off by this repair, I bought a bunch of incorrect sized shit, and some how light bulb indicators.. but now I can stuff a NE-2 or whatever into the broken bulb and it fits and its real small too. 3/8 hole and its only 7/8 inch long from top of light diffuser to end of solder terminals.There is a fair bit of space between the lgiht bulb body and the ground, anyway this should be neutral. No harm in putting some epoxy around the base of the bulb either to stiffen up the assembly (apply with syringe after bulb is soldered into holder).I swear they have everything from weak snap fit plastic tubes to fucking acrylic PCB turret terminal plates with bulbs clipped to them. its so much better with a proper holder that threads in. Those HP front panel are INFURIATING>!1
Nest Camera - USB-C capacitors? - Page 1
Forum section: electronics / repair

author: southport
author_rank: Newbie
timestamp: July 15, 2021, 04:16:42 pm
content: I have a Nest IQ Outdoor camera  that got some water in it. The damage is limited to a small board that contains the USB-C connector (on the back) and a couple caps and resistors, so I'm trying to repair it. I don't have much experience with USB-C... My question is about the caps. I haven't found any app notes about capacitors with USB-C (just the pull-up/down resistors). Are they just filtering caps? Any harm in removing them completely? Any recommended values if I should leave them in? Google has scrubbed it from their site, but it's this model:https://www.homedepot.com/p/Google-Nest-Cam-IQ-Outdoor-Full-HD-Wired-Smart-Home-Security-Camera-NC4100US/303009233

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: July 15, 2021, 06:37:03 pm
content: My best bet would be filtering capacitors for the DC supply from the USB, does the camera get its power from the USB-C?

author: southport
author_rank: Newbie
timestamp: July 15, 2021, 07:09:27 pm
content: Yeah, camera is powered by USB-C. No data connection at all.

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: July 16, 2021, 04:14:19 pm
content: Can you tell if any of those capacitors are shorted? Those MLCCs often fail that way in rough conditions.

author: janoc
author_rank: Super Contributor
timestamp: July 16, 2021, 06:42:16 pm
content: Quote from: Alex_Baker on July 16, 2021, 04:14:19 pmEhm, given the state of those two caps in the photo, I would say they certainly got some "rough" conditions. One is broken in half and the other one has the bluish copper corrosion growing on it.Both need to be replaced, IMO. Also the connector at the bottom seems to be damaged (the right-most pin is gonski).Given the amount of water traces there, that board will likely have significant corrosion on it, likely damaged/broken tracks.

author: Alex_Baker
author_rank: Frequent Contributor
timestamp: July 16, 2021, 08:40:33 pm
content: yeah that's what I'm thinking, the whole camera probably isn't getting any power because of electrolysis corrosion on the caps and connectors.

author: southport
author_rank: Newbie
timestamp: July 17, 2021, 04:56:24 pm
content: Quote from: Alex_Baker on July 16, 2021, 04:14:19 pmThe cap on the left is shorted, so that's definitely a problem. The right one fell off when I tried to probe it.Quote from: janoc on July 16, 2021, 06:42:16 pmWhat's a reasonable value? 1uF?Good call on the tracks - I'll test them. I was able to get the connector back together.

author: janoc
author_rank: Super Contributor
timestamp: July 18, 2021, 05:41:58 pm
content: Quote from: southport on July 17, 2021, 04:56:24 pm100n-10u would be probably a good guess. If it is across the power rails it is only a filter/decoupling cap so the value is unlikely to be very critical.
Nest Thermostat - Page 1
Forum section: electronics / repair

author: tonyh88
author_rank: Regular Contributor
timestamp: October 16, 2022, 12:42:46 am
content: Hello,I'm trying to repair a Nest thermostat at the moment mostly for fun. This is the newer version released in 2020 which is called simply "Nest Thermostat" no to be confused with the several other similar Nest thermostat naming scheme.... thanks google...At first glance when inserting batteries the unit is completely dead. Nothing on the screen. I then powered it via a power supply with 3V and it was getting current limited at 0.5A. Using a thermal camera I discovered that U35 was getting super hot. I removed it and now the thermostat draws still around 200mA.The circuit is really quite complex for such a simple device and uses crazy small package all over the place. So without any schematic It's alot of guessing.Anyone got a similar unit and would be willing to get some of the expected test points value on a working unit? There is about 90 testpoints on that thingOne thing I know is I do have a steady 3.3V rail so there is a boost converter doing it's job somewhereAnother thing that doesn't help is that a bunch of the IC I can't find any info on. I know some are most likely regulators for different voltage rails but so far apart from the 3v3 rail I have'nt found any other standard voltage railsAnyway I'll leave some pictures of the main board for the curious as it is quite interesting design.If you have already worked on these or know where I could get a schematic/service manual it would certainly help.I already checked all the fuses and did a visual inspection and probed pretty much every testpoints.I'll probably need to reverse engineer the whole thing to get it working

author: tonyh88
author_rank: Regular Contributor
timestamp: October 16, 2022, 01:11:49 am
content: More pictures
Netatmo thermostat power supply - Page 1
Forum section: electronics / repair

author: yo3gts
author_rank: Newbie
timestamp: August 29, 2023, 05:26:53 pm
content: Hello, I have a power supply from Netatmo thermostat and I found the driver burnt and I don't know what integrated it is, it says .1UAFThe final transistor is 13003 and it is ok, the capacitors are ok, only the 3.9R resistance is burnt.I have the request, maybe someone knows what SMPS with 6 pins is.Thank you
Netgear router clicking and dead - Page 1
Forum section: electronics / repair

author: kosta
author_rank: Newbie
timestamp: March 14, 2021, 07:17:13 pm
content: Hi, my Netgear WNDR4500 worked fine until I had it off for about 2 weeks. When I plugged it back in it didn't work anymore, there isn't even any lights flickering.I changed the power supply, so that's not the problem.Inside the router there is a regular clicking sound with about 1.3Hz. I believe it is coming from the round green component (I believe a self resetting fuse). I encircled it pink.This part also gets really hot after 20s - I could smell something making me worried before opening. Can't see any damage, the big capacitors seem ok and hold some charge tested with a multimeter. Also the 2 flat fuses X250F right behind the power switch have continuity.Any ideas what happened? I'm mostly curious and more than fixing it I'd like to know what is wrong and happened - so even "destructive" experiments would be ok.

author: Monkeh
author_rank: Super Contributor
timestamp: March 14, 2021, 07:19:27 pm
content: Dead short on the input or output of one of the buck regulators. Maybe internal to the regulator.

author: kosta
author_rank: Newbie
timestamp: March 14, 2021, 08:09:55 pm
content: I didn't know that was a "possible" failure mode for those regulators. Like the MP1484EN on this board. They can just short internally? By age or overheating or what? That would explain a spectacular failure of a self built DC-DC converter that worked fine for 3 years and suddenly burnt up.So I could desolder the Nr. 2 pin (input) on all 3 MP1484ENs and power it back up, if it works push down one pin at a time and see if the fuse reacts? Or could I actually measure with just a multimeter without soldering?

author: Monkeh
author_rank: Super Contributor
timestamp: March 14, 2021, 08:42:45 pm
content: Heat or overvoltage, especially the latter. Hotplugging the cable's a great way to blow up poorly designed switchers.It's very likely if there's a short you can pick it up with an ohmmeter. You can also just see if any of them get hot. Other culprits include ceramic caps, the SoC, RAM, flash, or any other IC on the board. But the power stage is a good place to start.
Network cable tester fault seeking help - Page 1
Forum section: electronics / repair

author: daisizhou
author_rank: Super Contributor
timestamp: January 02, 2025, 04:21:31 am
content: Network cable tester "Smart Mouse" NF-168，Fault in wiring function.Upon inspection of the motherboard, it was discovered that one U4 chip was damaged.Unfortunately, the model has been erased. Does anyone know what type of chip this is?

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: January 03, 2025, 07:23:53 pm
content: Probably this is just a button, connected to a binary counter, connected to a BCD-to-n decoder. 74LS145 or equivalent.

author: wraper
author_rank: Unknown
timestamp: January 03, 2025, 07:29:15 pm
content: To me it looks like a drop of rosin flux, not damage. You didn't say what's an exact issue but 455kHz ceramic resonator present on PCB is quite fragile and often fails when device is dropped.
Neutrik A1 screen - Page 1
Forum section: electronics / repair

author: misonic
author_rank: Newbie
timestamp: March 14, 2025, 09:21:48 am
content: HiI have an Neutrik A1 which needs a replacement screen. Can anybody confirm that the Chinese made DMF682A displays on Aliexpress work as a replacement for the Optrex DMF682A in the A1? Has anybody actually replaced their A1 screen with an Aliexpress DMF682A? If so, aside from soldering in the ribbon cable, are are they fully 'plug in and play' i.e work 100% the same, don´t need any additional modifications etc.. I´m not too bothered if the quality is not as good as the Optrex.P.s Before anybody refers me to the Neutrik A1 display thread already on this forum, i have already seen it and posted my question there but no reply.cheersMike
New 500 Watt Variable Transformer Made in China - Page 1
Forum section: electronics / repair

author: jdragoset
author_rank: Frequent Contributor
timestamp: May 09, 2021, 11:58:58 pm
content: Got the following: (500W AC Voltage Regulator Variac Variable Auto Transformer 110V Metered 130V) from Ebay and found the following errors:Neutral (brown wire) incoming wired through on/off switch and fuse, connected to 120 volt transformer input but wired to neutral outlet terminal.Hot (blue wire) incoming wire directly to transformer common input.Transformer variable output wired to hot outlet terminal.Besides the obvious hazard of all output terminals becoming hot when switched off or fuse blown, voltage between ground and neutral outlet terminals will vary depending on transformer setting and load.Be aware of and correct these problems if using this transformer to power your instrument for testing purposes.

author: TheMG
author_rank: Frequent Contributor
timestamp: May 10, 2021, 03:25:25 am
content: By EU standards brown is hot, blue is neutral. So I guess they just got the neutral and hot mixed up on the north-american plug and receptacle?

author: CaptDon
author_rank: Super Contributor
timestamp: May 10, 2021, 03:12:19 pm
content: Brown is the hot wire here in the states also with blue being neutral!!!

author: jdragoset
author_rank: Frequent Contributor
timestamp: May 10, 2021, 05:58:38 pm
content: Checking cords we import from the UK, brown is hot.This cord, when plugged into a standard outlet, the blue wire is hot with a Klein NCVT-1 (non-contact tester).Does make one wonder about the number of appliance/replacement cords that are wired incorrectly.

author: james_s
author_rank: Super Contributor
timestamp: May 10, 2021, 06:34:16 pm
content: Brown is hot and blue is neutral in every UK/Euro coded power cord I've seen. Sounds like they just got the plug on wrong on that one, assuming the receptacle you have it plugged into is wired correctly. Other than that this sounds correct. Do check the receptacle, I have found them wired backwards in a number of instances.

author: jdragoset
author_rank: Frequent Contributor
timestamp: May 10, 2021, 06:45:26 pm
content: Receptacle is correct, brass screw/black wire/narrow slot hot, nickel screw/white wire/wide slot neutral
New Crystals Peltier cooler and heater - Gift gone to pot? - Page 1
Forum section: electronics / repair

author: armandine2
author_rank: Frequent Contributor
timestamp: June 04, 2025, 11:48:52 am
content: Not such a good gift - a family member's cool box gifted Christmas present soon packed up.Looks like overheating (possibly shorting out?) at the "splodgy" soldering on one of the switchesSMPS is okay - fan spins.Will clean burnt area on pcb and check - I assume (still to check) the yellow wires are for an overtemp cutout?

author: Ian.M
author_rank: Super Contributor
timestamp: June 04, 2025, 04:27:27 pm
content: The lower switch selects mains (actually DC from the SMPS) or 12V power. The upper switch is a polarity reversing switch (DPDT crossover) to select heating or cooling. Long ago, I had a similar unit which I modified to auto-switch from mains to 12V, by adding a mains coil SPDT relay witH 10A DC rated contacts to swap from ext 12V to the SMPS output when it operated. That would free up a suitable switch to replace the top burnt one, then blank off the lower switch hole. Otherwise you'll need to find a 10A DC rated DPDT slide switch with the same pin spacing and shape . . . .It does look like the yellow wires are in series with one side of the crossover switch so as you suspect are almost certainly a thermal fuse or trip. With the switch removed, check continuty.I think the PCB substrate is likely to be badly charred, so you may have to do some serious grinding back of damage and board repair with/ fibre reinforced epoxy or similar, before re-making the tracks with copper foil or heavy solid copper wire.Is there any chance the giver can provide a copy of the receipt, (possibly with the price obscured) so a claim can be pursued under UK consumer law, as some of the soldering looks poor enough to be "not fit for purpose"?

author: armandine2
author_rank: Frequent Contributor
timestamp: June 04, 2025, 05:28:16 pm
content: yes badly charred - hadn't fully seen the cause from the effect

author: Ian.M
author_rank: Super Contributor
timestamp: June 04, 2025, 08:06:28 pm
content: That's clear evidence the polarity reversing switch got far far too hot. I doubt it was from the solder joints as the heat would not have transferred to the frame of the switch so easily, and one would expect the track side damage to be more extensive than the top side damage. I suspect the switch itself overheated, possibly due to loose contacts. Assuming this was purchased in the UK or EU, please consider reporting this to the appropriate authorities as it is clearly a fire hazard. Also, if reporting it, don't dismantle the switch unless asked to do so!It may be a bit to far gone to repair safely short of cutting of and re-mounting the LED end of the board and replacing the switches with good quality ones and point-to-point wiring their terminals.

author: armandine2
author_rank: Frequent Contributor
timestamp: June 05, 2025, 06:41:37 am
content: ...the switch has been dismantled.I agree that the product, at least as supplied, was clearly dangerous.
New poster here..Pic of Key for Lab Volt 187 Variac Classroom Autotransformer? - Page 1
Forum section: electronics / repair

author: itsme_Bernie
author_rank: Newbie
timestamp: March 29, 2022, 05:14:40 pm
content: Hello All About Circuit FolksIf I am asking a question answered before, I apologize, and I would appreciate the name of the thread or link so you don't have to go through explaining again.I am sure I could "hack" it, but I have a small machine shop and can fabricate a key if it is simple enough, which I suspect. If I can leave it original I can keep to hacking my other belongings ha hah.I cannot find a pic of the key anywhere. Do any of you happen to have a key like it, and possibly post a pic? Do you know how thick it is? Other dimensions?Or do you happen to have a pic or know where I could find a pic?Thank you so much for your helpBernardLab Volt Model 187 Variac Buck Eng Classroom Power Station 120V Autotransformer

author: AndrewNorman
author_rank: Contributor
timestamp: March 29, 2022, 08:37:31 pm
content: That might not be a key but a switch with a missing toggle bit.I found an old pdf with a picture of a similar LabVolt 187 AP supply that might help.-Andrew

author: jpanhalt
author_rank: Super Contributor
timestamp: March 29, 2022, 09:09:54 pm
content: Good idea, but it appears to be a key. Here's a picture of a newer model with the same keyed switch.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 29, 2022, 09:32:24 pm
content: A little searching showed nothing LabVolt specific, but that "keyed" switch is not like a real keyed switch with a coded key, but more like the safety keyed switch used by Craftsman and Jet (and others) for their saws. They are generic keys with no code, except when removed, the switch is locked off. Here's a picture of the Jet version. Craftsman's is similar.
New resistor bigger than old  - Page 1
Forum section: electronics / repair

author: .....
author_rank: Contributor
timestamp: November 05, 2019, 08:08:01 pm
content: Hi thanks for looking.i am currently trouble shooting a power supply and the -12v rail is only measuring around -2v.i was looking at the board for anything obviously broken, i saw that a resistor was exploded so that i could not read the colour bands.i looked at the schematic and it says 10r for the restore so i orders some 10 ohm restistors from eBay, they have arrived but they are significantly bigger.i measured them with my multi meter and they are 11 ohms.is there a problem with them bring bigger.here are the resistors i bought:https://www.ebay.co.uk/itm/0-1-100ohm-Various-Value-Resistors-In-1W-2W-Power-5-Pack-of-5/231188853221?ssPageName=STRK%3AMEBIDX%3AIT&var=530403143436&_trksid=p2057872.m2749.l2649thanks for any helpJAck

author: DaJMasta
author_rank: Super Contributor
timestamp: November 05, 2019, 09:03:39 pm
content: Resistors rated for higher power will be larger to be able to dissipate the heat, the ones you bought are suitable replacements so long as they fit in the space. The original probably wasn't a 2W rated resistor.That said, resistors are straightforward parts that don't often fail on their own - there's a good chance that replacing the resistor isn't the only thing that needs doing.

author: .....
author_rank: Contributor
timestamp: November 05, 2019, 09:43:43 pm
content: Thanks for the replygood to know the resitors i bought will work.im working my way back through the -12v rail and the resitor is the first broken part ive foundthanksjack
new vacuum tube boxes - Page 1
Forum section: electronics / repair

author: graybeard
author_rank: Frequent Contributor
timestamp: March 05, 2022, 08:08:31 am
content: My Tektronix 575 died a week ago and I am testing the tubes. I found a few very weak ones that need replacement. However when I look at my stock of tubes they are a disorganized mess. I need to get some boxes to store them better and make a spreadsheet as I box them.Where is the best place to buy new boxes for vacuum tubes?ThanksChris

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 05, 2022, 11:13:13 am
content: Places like Uline will have small boxes that are not a perfect fit for your tubes, and will happily make custom sized boxes. Prices and minimum orders are discouraging.I make my own from cereal boxes. When really motivated I print the outsides, usually by printing the desired material on white paper and gluing that onto the cardboard with spray adhesive.It is a bit tedious, but in a weekend you could have a tub of tubes boxed.

author: Ian.M
author_rank: Super Contributor
timestamp: March 05, 2022, 11:47:05 am
content: Thin card can easily be laser cut. If you've got access to a laser cutter, and use roll-on permanent glue tape and a wooden block jig for each size for assembly, you could easily make all the boxes you need in a couple of hours, including inserts to cradle the base of non-straight sided tubes.

author: TimFox
author_rank: Super Contributor
timestamp: March 05, 2022, 04:31:38 pm
content: Antique Electronic Supply has white tube boxes.https://www.tubesandmore.com/products/tube_accessories

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 05, 2022, 04:44:36 pm
content: I would be looking for larger boxes with dividers, especially for the smaller tubes.

author: graybeard
author_rank: Frequent Contributor
timestamp: March 05, 2022, 06:09:39 pm
content: I found thesevacuum tube boxes at Tube Depot. They seem to be the best source I can find. However I am still open to suggestions.
New Wave Research Laser Controller repair - Page 1
Forum section: electronics / repair

author: magnetchief
author_rank: Contributor
timestamp: March 29, 2022, 05:32:53 pm
content: Hi I have an old New Wave Research Laser that we use for trimming HTSC coils.Model is LCS-1, build date Sept 1992.Has been working well for many years.Unfortunately today, it died. there was a clicking noise from the control box and a very distinct electrical overheating smell from the box.Decided to remove the cover and look for anything obvious.There is a large sized capacitor, label in the photo.I have a question, the label states '50 MFD' Is this 'Mill farads? it actually measures 53 micro farads.Thanks is advance.

author: DaJMasta
author_rank: Super Contributor
timestamp: March 29, 2022, 06:00:50 pm
content: MFD is an old fashioned way of writing microfarads, seems like your cap is still in good shape.

author: magnetchief
author_rank: Contributor
timestamp: March 29, 2022, 06:42:11 pm
content: Many thanks,The investigation goes on.

author: magnetchief
author_rank: Contributor
timestamp: April 05, 2022, 01:31:34 pm
content: To close,Disassembled the various boards and found this beauty.Hard to decipher the value from the burnt colors, but it was the same value as the unburnt resistor.The damaged one had desoldered from the board, board was also damaged.Took a replacement 2w resistor and soldered it at alternate contact points.Laser now works correctly but I'm concerned as to why this overheated in the first place.Will have to watch it closely.

author: thm_w
author_rank: Super Contributor
timestamp: April 05, 2022, 11:15:10 pm
content: The sprague cap beside it is ok?Could just be a bad design and replacing with a higher power resistor would be low risk.But you won't know without measuring power consumption in use.

author: coppercone2
author_rank: Super Contributor
timestamp: April 05, 2022, 11:20:35 pm
content: I am curious why you use a laser to trim coils. Are they tiny or very precise? (just want to learn about what a HTSC coil is, is it a micro coil of some sort?). Are you trimming superconducting materials with a laser, or the conductor?

author: magnetchief
author_rank: Contributor
timestamp: April 06, 2022, 12:52:21 am
content: I did actually remove the cap and test it.Along with the relay. They both looked fine.As for the resistor. I will see how it holds up.If needed reevaluate and possibly use a larger size.

author: magnetchief
author_rank: Contributor
timestamp: April 06, 2022, 12:55:10 am
content: Coils are tiny.20 microns wide. Racetracks of YBCO on a sapphire substrate.Cooled to 20kResonance frequency of the coils is modified by trimming small sections to change the frequency.Attached is a pdf put together by a coworker. Explains in more detail than you would probably need.Enjoy.