hybridfree/eevblog-posts huggingface dataset:
Uni-T UT61D diode id? - Page 1
Forum section: electronics / repair

author: frodef
author_rank: Newbie
timestamp: August 19, 2023, 01:42:17 pm
content: My somewhat trusty UT61D dmm has become rather unreliable (ohm-mode spurious beeping and/or no contact, "works again" if I turn it on and off, etc). Looking at the PCB I see a cracked diode, one of a pair, on the front side near the probe plugs. I want to replace the diode(s), but with what? The PCB silkscreen is labeled D6, and both SMDs are labeled "65" above "6i" in relatively big, clear lettering. Somehow I'm unable to identify either the diode itself of find a schematic.Any ideas what to replace one or both of these diodes with?The diode pair is clearly visible here, center stage between the circular multi-switch and banana receptacles:

author: wasedadoc
author_rank: Super Contributor
timestamp: August 19, 2023, 02:12:12 pm
content: Can you post a close-up photo of the diodes so we can see the markings?Those are probably protection diodes. If so, removing them should eliminate any spurious operation*. If it does not you probably still have a problem slsewhere.* Not recommended to continue using the meter until faulty diodes are replaced.

author: gamalot
author_rank: Super Contributor
timestamp: August 19, 2023, 02:17:48 pm
content: https://pdf1.alldatasheet.com/datasheet-pdf/view/394658/EIC/STU656I.html

author: frodef
author_rank: Newbie
timestamp: August 19, 2023, 02:22:09 pm
content: Thanks for the info. Here's a photo:

author: frodef
author_rank: Newbie
timestamp: August 19, 2023, 02:25:06 pm
content: Thank you!

author: frodef
author_rank: Newbie
timestamp: August 19, 2023, 03:16:46 pm
content: Not so easily sourced, that STU656i ...

author: fzabkar
author_rank: Super Contributor
timestamp: August 19, 2023, 05:15:16 pm
content: I would think that any 6V TVS diode would be a suitable replacement.

author: floobydust
author_rank: Super Contributor
timestamp: August 19, 2023, 05:17:08 pm
content: STU656I is a 600W SMB TVS diode, 6.45-7.14V at 10mA. Oddball manufacturer. Other 61E's schematic use two 1N5342B (6V8 5W) in series protecting the low current shunt.For a substitute I would consider SMBJ5.0A or SMBJ6.0AIf your diode cracked open circuit, it might have allowed the overload to get further and damage a shunt or other parts.

author: oskimac
author_rank: Contributor
timestamp: February 27, 2024, 04:11:17 pm
content: My ut61b started acting strangely in the ohms reading, never stabilizing. So I opened it and the first thing I found was a very strong burning smell. Then I found the same two diodes broken. I just removed them and everything was fine (except the ESD and surge protection!). I was reading amps and forgot the settings and started measuring volts...that was the problem.
Uni-t UT61E autorange problem? - Page 1
Forum section: electronics / repair

author: thanosbi
author_rank: Newbie
timestamp: December 02, 2024, 09:41:09 pm
content: Hello everyone,After a few years of use i noticed my 61e doesn't autorange in DC if the polarity is reversed,it just displays -OL. If i select manually the range displays the value correctly. I have already changed the battery and cleaned the selector switch pads.The calibration is spot on. I also noticed that AC amperes gives around 0.056A without being connected. Does anyone faced something similar?. Where should i begin looking? Thanks.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 03, 2024, 03:00:54 am
content: ut 61e schematics

author: thanosbi
author_rank: Newbie
timestamp: December 03, 2024, 07:35:34 am
content: Thank you! i already have this

author: thanosbi
author_rank: Newbie
timestamp: December 03, 2024, 08:12:40 am
content: Update. I think i fix it looks ok so far.C36 tantalum was dead.The readings suggested something like a diode issue,hard to imagine that this tantalum transformed into one! Replaced both decoupling caps around the LDO with 22uf smd electr.Abnormal readings fixed by changing c33,which after removing revealed electrolyte? leakDont trust capacitors especially tantalums.Basicaly these multimeters seems to be made with awful quality parts!
UNI-T UT71D - Page 1
Forum section: electronics / repair

author: meel
author_rank: Newbie
timestamp: November 13, 2021, 10:41:11 am
content: Hi,I have had this multimeter for many years, it worked very well.Recently, while measuring DC voltage, I heard a beep, so I turned off the multimeter.After turning it on again, it turned out that the measurement in the DC range cannot be made, the display shows nothing, the other ranges work normally.Check the motherboard, but I didn't notice anything,I measured the current consumption from the battery in the n damaged DC range, it is several times greater than in the other ranges.Maybe someone had a similar damage and could help me fix it.Thanks!

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: November 13, 2021, 11:52:05 am
content: edit:Mine is the 71B model, it doesn't have the selector like yours.Review:https://www.eevblog.com/forum/testgear/uni-t-ut71d-review/And this should then be the 71D schematic, follow the DC voltage path, some component on that line will be burned.

author: meel
author_rank: Newbie
timestamp: November 13, 2021, 01:33:37 pm
content: The measurement can only be made on AC voltage.

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: November 13, 2021, 02:20:11 pm
content: I corrected my previous post

author: tunk
author_rank: Super Contributor
timestamp: November 13, 2021, 02:27:04 pm
content: Just a guess - bad rotary contacts?

author: meel
author_rank: Newbie
timestamp: November 13, 2021, 03:41:37 pm
content: I checked the rotary switch is ok.

author: meel
author_rank: Newbie
timestamp: November 28, 2021, 08:15:27 pm
content: Most likely, the M430F149 chip is damaged.
Uni-T UT804, FI2804MT calibration procedure - Page 1
Forum section: electronics / repair

author: Lajt
author_rank: Newbie
timestamp: November 09, 2019, 09:11:43 pm
content: Hi to everyone,Some time ago I bought a bench multimeter: Française d'Instrumentation FI2804MTSeems to be re branded Uni-T UT804 inside and out.I searched all the internet but could not find calibration instructions.Sent e-mails to: Française d'Instrumentation and Uni-T but they never replied.I even tried to cal it as UT71E since inside it is almost same as UT71D and Volcraft VC940 but it didn't work.Does anybody here knows what is the cal procedure for this instrument?Thank you

author: Lajt
author_rank: Newbie
timestamp: November 14, 2019, 08:40:09 pm
content: Just for the info if anyone else will need it.I managed to find a working e-mail address and got a positive response from Uni-t support team.E-mail can be found on this link at the bottom of the page:https://www.uni-trend.com.cn/index.php?m=content&c=index&a=lists&catid=18

author: uspeakers
author_rank: Newbie
timestamp: May 12, 2021, 07:01:56 pm
content: Hi LajtI also found my UT804 not calibrated properly.The link you send takes me to a page displaying chines text.Can you post the actual calibration procedures please.Cheers
UNI-T UTD2042C DSO Screen not working - Page 1
Forum section: electronics / repair

author: Synthron
author_rank: Newbie
timestamp: April 08, 2021, 09:31:49 am
content: Hey everyone,I currently have trouble with my UNI-T DSO. I used it a few days ago now and during operation, the screen turned completely white. Reboot didn't help.On reboot, the DSO still makes all boot-up procedures, you can hear the relais clicking. The buttons also respond (judged by color-change and expected relais-clicking sound), so I'm confident that only the screen is affected and the rest is still operational.I took it apart and did my basic troubleshooting-step of reseating the LCD cable, also cleaning the inside from dust. Nothing changed, still white screen.LCD cable does not look broken and doesn't have a kink or sharp bend in it. I can't confirm data transfer since my oscilloscope currently does not have a working screen...Has anyone an idea where and how I can look for a fault? I have a DMM available at hand for troubleshooting, nothing more...And no, I can't send it to the supplier for repair. I got the DSO a few years ago second-hand with the warranty seal already broken.Best regardsSynthron

author: Synthron
author_rank: Newbie
timestamp: May 19, 2021, 01:26:27 pm
content: soo... I tried searching for other faults, but without another oscilloscope, debugging might become hard...has anyone else any suggestions what I could try to fix it?
UNI - T UTD2102CEX  firmware upgrade problem - Page 1
Forum section: electronics / repair

author: Hazorius
author_rank: Newbie
timestamp: October 08, 2022, 09:18:54 pm
content: I try to connect my oscilloscope to a computer but it doesn't properly connect with UNI-T software even after installing the drivers and etc.Does anyone have newest firmware as a file so I could try to update from memorystick?I've contacted UNI - T support orcourse they don't answer.

author: RES
author_rank: Regular Contributor
timestamp: October 11, 2022, 01:01:51 pm
content: Do you run Linux? Then try this:https://github.com/mandl/ut2XXXThis program is useful with UNI-T digital storage oscilloscopes UT2XXX or UT3XXX. It's intended to be a replace for original software, which doesn't work under Linux.

author: Hazorius
author_rank: Newbie
timestamp: October 12, 2022, 06:58:27 pm
content: Hello, thanks for reply!I've seen this page. I was thinking about sending email to this person maybe he has firmware extracted. But couldn't find any info.It's a shame UNI - T has next to 0 support.
UNI-T UTi120S repeating recalibration issue - Page 1
Forum section: electronics / repair

author: Peter78
author_rank: Newbie
timestamp: October 13, 2024, 02:37:49 pm
content: Hello all!I have a problem with UNI-T thermal camera. Immediately after turning on or calibration readings are correct, then temperature slowly dropping to wrong values, then we have automatic calibration and this loop repeats endlessly. To illustrate the problem I've created video:

author: Bryn
author_rank: Regular Contributor
timestamp: October 13, 2024, 03:04:10 pm
content: First of all, according to the thumbnail of the video, I see that the battery level is quite low, so maybe charging that up might do the trick. If not, try turning it off then on again or else reset it to factory settings.

author: Peter78
author_rank: Newbie
timestamp: October 18, 2024, 12:13:17 am
content: Unfortunately all of those steps already failed. Factory reset is not changing anything, same for battery level.
Uniden CR-2021 - Page 1
Forum section: electronics / repair

author: Terry Bites
author_rank: Super Contributor
timestamp: October 05, 2022, 08:34:18 am
content: Dodgy cap I expect.My nice CR-2021 is silent for a couple of minuites after turn on for bursting back to life with normal function.Switch off- back on exactly the same thing. Same delay every time.The trouble is, I can't track it down. Does anyone have an idea where this cap is and/or a schematic.

author: fixy88
author_rank: Contributor
timestamp: October 05, 2022, 08:41:38 am
content: Google suggests it's very similar to the RS DX400. There appears to be a schematic for that available herehttps://www.radiomuseum.org/r/radio_shac_realistic_dx_400_dx400.html

author: Terry Bites
author_rank: Super Contributor
timestamp: October 06, 2022, 07:48:39 pm
content: Google lies!Its not the same inspite of the rumours.

author: fixy88
author_rank: Contributor
timestamp: October 06, 2022, 10:06:53 pm
content: Try heating different areas with a heatgun or hairdryer and see if anything changes.
Unidentified switching regulator from Netgear LB2120 - Page 1
Forum section: electronics / repair

author: octillion
author_rank: Contributor
timestamp: March 22, 2020, 02:24:15 pm
content: I inadvertently reversed the input voltage on a Netgear LB2120 LTE modem, killing the switching regulator. I've been unsuccessful identifying a replacement. The 8-pin part has "IAQAH" laser etched on top. I'm not sure exactly what SMD package it is, the package itself is about 2.8 x 1.4 mm with a lead spacing of about 0.65 mm, no exposed pad on the bottom. See attached image for removed crispy part next to the power circuitry (laser etching was much more legible before desoldering).The desired output seems to be 5 volts, as I manually injected power to the modem to get it functioning. An LED lit at 3.3 volts, but it was otherwise non-operational; 5 volts works.Pinout is as follows:Pin 1) 22 nF capacitor to GND (C88)Pin 2) V_in (supplied with 12 V 1 Amp SMPS wall adapter)Pin 3) OUT (to 3.3 uH inductor; I find no external diode, so likely internal)Pin 4) GNDPin 5) RC back to pin 3 (20 Ohm R82, 0.1 uF C91)Pin 6) Enable (100 kOhm pull-up to V_in, external latching push-button shorts this to GND for "off" state)Pin 7) 0.1 uF capacitor to GND (C90)PinFeedback. R77 (5.6 kOhm) to R80 and R78/C89. R80 (10 kOhm) to GND. R78 (>=13.8 kOhm) to R76 (10 Ohm). R76 to via which somehow finds it's way to the output voltage.Thanks for any help here.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 22, 2020, 03:01:28 pm
content: MP2235SGJ

author: octillion
author_rank: Contributor
timestamp: March 22, 2020, 03:06:41 pm
content: We've got a winner, thanks PA0PBZ!
Unifi G4 Doorbell Repair - Page 1
Forum section: electronics / repair

author: bdttre666
author_rank: Newbie
timestamp: July 09, 2025, 02:05:12 am
content: G4 doorbells (non pro version) have a common issue where the power supply dies leavening them either only able to power off of usb or not at all. mine does not show any signs of life at all.i am tracking my repair process here for others, though i do not guarantee that i will finish the project. i hope someone is interested, if not it is here for mesteps i have taken.1. power over usbResult no lights2. check the internal batteriesResult, looks good 3.8v3. measure current over usbResult, all the power >1A, not good4. thermal imaging with usb power of just the power supply board.Result, U28 marked 15TBD1 or maybe 15TBDI gets hot instantly. a clue!I would like to know what this part is but i can't find a datasheet.5. take a guess that it is a regulator. measure the caps around it looking for shortsResult, shorts found on 5 caps and an ic U26 (MP2617 3A Switching Charger)6. desolder U26Result, unlucky7. desolder U28Result, unlucky8. thermal imaging of just the power supply board while applying power with a limit of 1V 1A to the trace that looked like the U26 regulator output without U26 or u28 installed.Result, cap next to U26 lights up8. remove cap and check for short on the power railResult, No more short

author: Swake
author_rank: Frequent Contributor
timestamp: July 09, 2025, 07:46:32 am
content: caps.... when you see a short in a supply like this it is frequently a cap issue.The chip might be an LDO indeed. The marking 15T seems to be used frequently in relation to LDOs.
Unilab Oscilloscope 032.601 showing no trace - Page 1
Forum section: electronics / repair

author: MontyTheGreat10
author_rank: Newbie
timestamp: June 07, 2021, 07:16:19 am
content: A few days ago I picked up a vintage CRT oscilloscope at a car boot sale. It is quite a simple model, but I was going to use it with synths and stuff. When I turned it on, though the power LED turned on and the transformer started humming, there was no trace on the screen, however I adjusted the controls. Later, I had a poke around inside, and found out that all of the potentiometers were working on the front panel, and that there were no broken traces on the board. I also confirmed that the heater on the CRT glowed when the power was turned on, showing that the CRT was probably working. My guess is that the focussing circuitry is broken, and I would be very grateful with any help people can give me on this matter. I have included a schematic.https://elektrotanya.com/unilab_032.601_educational_oscilloscope_d7-200gn_sch.pdf/download.html#dl

author: MontyTheGreat10
author_rank: Newbie
timestamp: June 08, 2021, 08:38:38 am
content: bump2

author: MontyTheGreat10
author_rank: Newbie
timestamp: June 09, 2021, 03:22:46 pm
content: Reply for a poor broken oscilloscope?

author: ambrosia heart
author_rank: Regular Contributor
timestamp: June 10, 2021, 12:32:59 am
content: " I also confirmed that the heater on the CRT glowed when the power was turned on,." thermoionic emission OK.Accelerating grid voltage must be checked.Check ALL circled components. Caps, diodes and opampsreplace. Components are not expensive compairing labourcost.See photos.

author: MontyTheGreat10
author_rank: Newbie
timestamp: June 10, 2021, 10:04:39 am
content: Thank you! I will start with checking all power supply voltages, then I will look at the control grid and anodes with the oscilloscope in XY mode, to see if I can get a dot to appear. I will then check the time base circuits, and will follow your advice if it doesn't work properly.

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 10, 2021, 11:37:33 am
content: If you can't get a dot, keep in mind IC 4 is an optical isolator that appears to control blanking.Fortunately the CRT voltages are not terribly high (+- 500VDC) to use a DVM for testing., standard hands off testing for safety.

author: MontyTheGreat10
author_rank: Newbie
timestamp: July 09, 2021, 11:31:40 am
content: I may actually just try unplugging the control grid of the tube, and if it comes on in full brightness mode, I will know that the control grid circuit is stuck, causing the tube to appear off. If that doesn't make a difference, I will know that it is probably one or both of the anodes, and will test their voltages.

author: JFJ
author_rank: Regular Contributor
timestamp: August 03, 2021, 09:51:51 pm
content: Have you tried adjusting R46, the Set Blank variable resistor? It can usually compensate for the aging opto-isolator in the CRT blanking circuit.

author: MontyTheGreat10
author_rank: Newbie
timestamp: August 04, 2021, 05:11:53 pm
content: I think I may try that, before unplugging the control grid, so thank you for saying!
Unique dead Samsung S7 scenario. Traditional advice doesn't apply. - Page 1
Forum section: electronics / repair

author: Sirgeorge
author_rank: Contributor
timestamp: October 24, 2020, 05:52:34 pm
content: I'll make it punchy for you: I've got an S7 that doesn't turn on. No notification lights, no sound, soft and hard reset key combos don't work, wireless charging is detecting that it's charging something, wired charging doesn't detect a device. IMMACULATE condition prior to this critical failure. What's happening and is there any use going through the process of popping the back off?

author: Sirgeorge
author_rank: Contributor
timestamp: October 26, 2020, 12:47:08 pm
content: So I've done some further research and figured that, most likely, a component failed on the logic board and, less likely, a cable came undone. I'll update with info after I've pealed the back off.

author: Jane
author_rank: Frequent Contributor
timestamp: October 26, 2020, 08:36:27 pm
content: First you can connect S7 to a laboratory power supply and check current consumption ( preferably withanalogueampermeter)when power button ON and OFF.
UniT UT139C is broken - Page 1
Forum section: electronics / repair

author: l0v4szl
author_rank: Newbie
timestamp: February 05, 2023, 03:18:12 pm
content: Hello!I would like to ask for help in repairing my multimeter.I bought UniT UT139C, barely a year old, based on the tests here, it seemed to be the best value for money for my hobby purposes.I didn't expect it to break a month beyond the warranty period.I am attaching the video of the error, it produces this without test leads.https://1drv.ms/v/s!AuJYF5zxa_GLgcRUpdgGy6yYdsRmEA?e=1uAR2QI changed the battery, cleaned the contacts under the control dial with alcohol, nothing changed.Any idea how I can fix it?Thanks!

author: m k
author_rank: Super Contributor
timestamp: February 08, 2023, 05:44:23 pm
content: Since same reading is flipping sides it's not really intermittent.Maybe checking cold solders first is the way.
Universal LED TV board - LED driver low voltage - Page 1
Forum section: electronics / repair

author: gojunnyo
author_rank: Contributor
timestamp: April 10, 2020, 09:13:12 am
content: The TV Backlight has 4 strips with 9 LEDS all connected in series. My rough estimation ( 9 * 4 * 3.3 = 118.2VDC) assuming the LED consumes 3.3V, so I expected the LED driver to output such voltage but in turns out to output 52 volts on standby and 57 volts when the tv is turned on. I can't find the schematic online, but the board has a model no. of TP.V56.PB801Any tips on where to start is much appreciated! I need to be enlightened by your experiences.

author: Haenk
author_rank: Super Contributor
timestamp: April 10, 2020, 09:55:39 am
content: https://www.kazmielecom.com/2019/03/20/tp-v56-pb801-software-free-download.htmlThe voltage stated matches your measurements, so that board is probably OK.

author: gojunnyo
author_rank: Contributor
timestamp: April 10, 2020, 11:22:43 am
content: Quote from: Haenk on April 10, 2020, 09:55:39 amInteresting, the strips are connected in series, and hooked each strip on my bench power supply, It is surely bright at around 27 volts, unless I modify the whole strip connection into series-parallel

author: shakalnokturn
author_rank: Super Contributor
timestamp: April 10, 2020, 12:45:57 pm
content: I don't have that much experience with TV LED string supplies, in theory a LED supply should be current regulated.Of course the maximum voltage the LED supply can deliver is one limitation.Maybe you can get away with 2 series 2 parallel wiring although the string voltage will be close to the maximum that the supply will deliver.If you try 4 parallel strings and the supply will accept to run at that voltage the next problem is getting enough current to each string to achieve sufficient brightness. Maybe you have some adjustment for that.In any case when paralleling strings the minimum would be to add a little series resistance on each branch to the effect of Vf imbalances.
Universal NiMh charger repair (Philips TEA1400) - Page 1
Forum section: electronics / repair

author: reflowman
author_rank: Contributor
timestamp: October 18, 2019, 03:07:07 pm
content: I've tentatively repaired a mid 90's Philips shaver with (essentially) this universal charger circuit (from a Philips app note):The input resistor (marked "33E") had burnt out and one of two series 3/4 AA NiMh cells (LOAD) was dead.It's charging happily (but slowly) again now from a bench supply at 20Vdc 40mA.I'm a bit wary of plugging in 240Vac though.That 33E input resistor's colour coding had burnt off. I'd guess it's black, yellow, grey. The black could be toasted brown. The yellow is pretty definitely yellow and the "grey" band has virtually disappeared and could be anything. At any rate it's not a 33R resistor - more like 14R (toasted brown, yellow, very toasted black). It's the size of a 1/4W thru hole but cement coated - I'm guessing 1/2 or 1W.I don't think the value is critical to circuit operation (one schematic for the TEA1400 omits it entirely) but is more to limit instantaneous current through C 2.2uF and a very slowblo fuse for failing batteries. I've replaced it for now with 3x100R // 1/4W.Rough calcs for R = 33R:@20Vdc with new cells the charge current is 40mA quiescent; guess ~100ma max. so max 4W total. max dissip. 33R =~ 330mW. Instantaneous current at switch on = 20/33 = 600mA.@240Vac 17mA (assumes same 4W total), dissip. 33R ~ 10mWMax. instantaneous current at switch on = 240*1.414/33 = 10A yikes! No wonder it was a cement type. A lot of thermal shock there.I can't find a repair manual for the actual shaver, nor a comprehensive spec sheet for the TEA1400 to check what value/dissipation is needed.What value and dissipation would you think reasonable as a permanent fix?

author: martfoxy
author_rank: Regular Contributor
timestamp: February 22, 2021, 12:32:46 pm
content: Have you still got this shaver?
Unknown (to me) CFL inverter part - Page 1
Forum section: electronics / repair

author: mondrota
author_rank: Newbie
timestamp: July 05, 2019, 07:35:39 pm
content: Hi allSorry if this sounds silly but would anyone be able to tell me what this part is (attached)?It's from a cfl driver board, quite clearly toasted and caused the backlight to flicker.I'd like to get it going again but I have no idea what this part is. I think it was marked as a capacitor on the pcb. I tried putting a random one in but no joyThanks in advance!

author: Chriss
author_rank: Frequent Contributor
timestamp: July 05, 2019, 07:59:59 pm
content: I assume it is a 0.01uF non polarized cap.For sure it is a cap but I can't see clearly the marking for the value.Sent from my SM-J500F using Tapatalk

author: mondrota
author_rank: Newbie
timestamp: July 05, 2019, 08:08:13 pm
content: Wow nice one,Can I replace it with one of these:https://www.ebay.co.uk/itm/100V-2A-Polyester-Film-Capacitors-Green-Radial-Leads-Non-Polarized/192807036718?hash=item2ce431e72e:m:mPpu2llFhEeuP9tVX51daXAThanks for prompt reply!

author: Chriss
author_rank: Frequent Contributor
timestamp: July 06, 2019, 07:04:52 am
content: Can you pls post a picture about the circuit where your cap is?Sent from my SM-J500F using Tapatalk

author: mondrota
author_rank: Newbie
timestamp: July 06, 2019, 09:52:48 am
content: Here it is!

author: shakalnokturn
author_rank: Super Contributor
timestamp: July 08, 2019, 12:21:53 am
content: I'd bet on a Kemet 100nF 100V MKT for the original part.Then you'll want to be checking the small green fuse, transistors (quick no-shorts) and thermal fuse.
Unknown circuit found in a cheap battery charger - Page 1
Forum section: electronics / repair

author: Alimash
author_rank: Newbie
timestamp: May 13, 2025, 06:16:49 am
content: HiI reversed engineered the attached circuit from a cheap battery charger for my old grandpa( I just want to make him happy)I don't know what it is, what does it do or how it works.I didn't draw everything just the part i don't understand.The name of the circuit for me to google it and understand it will be great.cheers

author: xavier60
author_rank: Super Contributor
timestamp: May 13, 2025, 09:55:52 am
content: Search "single ended forward converter". Looks very similar to single ended flyback converter, main difference being the way the transformer secondary is rectified, the forward converter having an inductor at the rectifier.The core reset winding doesn't look right. I would expect an independent winding from the top of C5 to HVDC ground.

author: Alimash
author_rank: Newbie
timestamp: May 13, 2025, 02:56:59 pm
content: Actually, I mistakenly uploaded the wrong file, here is the right one.

author: MathWizard
author_rank: Super Contributor
timestamp: May 14, 2025, 09:09:00 pm
content: So is the output side on the left and those MOSFETs are doing synchronous rectification ? But they use BJT's on the power side with the TL494 ?Hmm but a 450V cap is on the left.

author: jwet
author_rank: Frequent Contributor
timestamp: May 16, 2025, 01:51:32 pm
content: If you search google a little more- you'll find the schematic. This is a common chinese design.I found it at this location but it wants me to sign in.https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.scribd.com%2Fdocument%2F722084337%2F20amp-12v-3-phase-smart-battery-charger-schematic&psig=AOvVaw3juz0WSqMDm6zsyP2Tqn6V&ust=1747488942052000&source=images&cd=vfe&opi=89978449&ved=0CBcQjhxqFwoTCKjKxN-NqI0DFQAAAAAdAAAAABAEIn your circuit- A TL497 is driving a FET gate driver transformer shown in your schematic. The two FET's are driving a larger transformer down stream, not shown. There are high voltages on all all those parts- be careful. Common failure modes are the big cap (look for bulging or leakage- DISCHARGE THEM FIRST). Another common failure is the FET's. Its basically an off line switcher with some charger stuff thrown around it.If this is just to spend time with your Grandpa then carry on but be careful. If he needs it and you have a few bucks, buy him a new one- they're about $75 max. You could easily spend this much buying parts and some tools with shipping, etc. Our disposable world.

author: Alimash
author_rank: Newbie
timestamp: May 17, 2025, 09:30:03 am
content: Thanks manAt first I thought the two FET's in series are used for power factor correction.Now it's clear.I found it strange for a cheap charger to have PFC includedI will upload the schematic for others to make use of it.
unknown component - Page 1
Forum section: electronics / repair

author: moose
author_rank: Contributor
timestamp: January 27, 2023, 11:50:50 am
content: HiCan anyone please help me identify the component or even the type of component.It has 6 pins.pins 1/2/5/6 are shorted together.This component is in a Black & Decker 18V battery charger.There are 3 of these components on the PCB.thanks in advance

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 27, 2023, 01:01:51 pm
content: A bit of a guess, considering resistor and 4 pins shorted together I'd say probably MOS transistor.On photo 4 grouped pins as Drain, top-left Source, top-right Gate.Knowing encapsulation type would help in finding exact reference.

author: moose
author_rank: Contributor
timestamp: January 27, 2023, 01:18:48 pm
content: my apologies, but what do you mean by "knowing encapsulation type"??

author: gamalot
author_rank: Super Contributor
timestamp: January 27, 2023, 01:22:46 pm
content: Quote from: moose on January 27, 2023, 01:18:48 pm"knowing package type" I guess.---For me, a picture that can see the components around the unknown chip would be more helpful.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 27, 2023, 01:29:09 pm
content: Maybehttp://www.stansontech.com/download/Trench%20MosFet/STP3481_v1.pdf

author: moose
author_rank: Contributor
timestamp: January 27, 2023, 01:43:03 pm
content: in that case it is SOT23-6.....(i just measured it 3.0 x 2.75)the resistor (300K) seems to be some type of 'bypass' to pins 3/4.But your link DOES make a lot of sense as the Drains connect to another 814 at the Source pin.

author: moose
author_rank: Contributor
timestamp: January 27, 2023, 02:21:26 pm
content: and following on from that suggestion this device seems to fit completely!!https://4donline.ihs.com/images/VipMasterIC/IC/TWSC/TWSC-S-A0003171389/TWSC-S-A0003171389-1.pdf?hkey=6D3A4C79FDBF58556ACFDE234799DDF0TSM3481...30V P-Channel MOSFET by taiwan semiconductor...they show the marking as "81YML" where Y = year, M = month, L = lotthank you everyone!!!
[Solved] Unknown component SOT23-6 marking HXYY  - Page 1
Forum section: electronics / repair

author: cozza
author_rank: Regular Contributor
timestamp: May 10, 2024, 02:41:15 am
content: Hello, I've got a defective part on a board and am having trouble identifying it to replace it.It's monitoring the current sense output of a BTS50085A smart fet through a resistive divider, and it's output is being used to control the enable pin of the BTS50085 (likely an overcurrent protection circuit) via a small mosfet.The board is from a lithium ion battery bank with 24V and 48V outputs intended for camera power supply. I've searched every code lookup table I can think of and drawn a blank so far.The pinouts are1) output - control the gate of a transistor to enable / disable the smart FET switch2) ground3)4) input from resistive divider on current sense output from BTS500855)6) positive supplyThere are two identical 24V output switch stages and I have found that the faulty side has broken down internally in the IC, pulling the current sense input down to 0V.Thanks for any assistance.

author: amyk
author_rank: Super Contributor
timestamp: May 10, 2024, 03:25:51 am
content: MCP65R46T-1202E/CHY

author: cozza
author_rank: Regular Contributor
timestamp: May 10, 2024, 03:53:45 am
content: Thank you amyk! This certainly looks to be a very likely candidate, how did you track this down?Thanks for your fast reply

author: fzabkar
author_rank: Super Contributor
timestamp: May 10, 2024, 04:45:06 am
content: http://markingcodes.com/search/c/hxhttp://markingcodes.com/search/c/HXxx
Unknown componenti, help identifying  - Page 1
Forum section: electronics / repair

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: March 19, 2023, 09:25:36 am
content: Hi,I am repairing an old switching PSU and I found an unknown component, can you help me identifing it?Any help will be appreciated.

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: March 19, 2023, 09:57:29 am
content: other photos

author: wraper
author_rank: Unknown
timestamp: March 19, 2023, 10:02:46 am
content: It's some custom module.

author: NiaDebesis
author_rank: Frequent Contributor
timestamp: March 19, 2023, 10:23:53 am
content: So if its broken I am screwd

author: wraper
author_rank: Unknown
timestamp: March 19, 2023, 10:27:28 am
content: Well, likely it can be taken apart and repaired but it will be very troublesome as it's most likely potted.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: March 19, 2023, 08:04:54 pm
content: Possibly a resistor network??

author: wraper
author_rank: Unknown
timestamp: March 19, 2023, 08:05:30 pm
content: Quote from: Wallace Gasiewicz on March 19, 2023, 08:04:54 pmno chance.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 19, 2023, 09:32:16 pm
content: Looks like a hybrid IC, how old is the device?The good news is that it looks like a casual switching power supply, judging by all the surrounding transformers and the optocouplers. Maybe the whole thing can be replaced with a generic SMPS with the same output voltage. Try to look at the silkscreen, or try to get a service manual in order to find the outputted voltages and their max currents.

author: R-1125F
author_rank: Regular Contributor
timestamp: March 19, 2023, 10:09:30 pm
content: What type of equipment is it? Manufacturer and model number?

author: gamalot
author_rank: Super Contributor
timestamp: March 19, 2023, 10:26:42 pm
content: Maybe a single in-line relay, or resistor networks.---Well, I looked again and I noticed that the OP said it's a SMPS, but couldn't find any IC on the board, not even a BJT or MOSFET, so it's most likely a thick film IC module.

author: wraper
author_rank: Unknown
timestamp: March 19, 2023, 11:10:56 pm
content: IMHO it's just a potted circuit on regular FR-4. Maybe a hybrid on ceramic substrate, but I don't think so. Those usually have a hard coating and no enclosure.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: March 20, 2023, 12:36:12 am
content: Imho really demands reverse engineer to have its vicinity schematicis in primary or secondary part ?
unknown DC-DC chip of SI-9110 differential probe - Page 1
Forum section: electronics / repair

author: teatime
author_rank: Contributor
timestamp: April 19, 2024, 09:00:43 am
content: Hello all,Right now I have a defective SI-9110 differential probe,Input 6Vdc,the problem is no -12V, +12V is normal.I checked the waveform of Pin15, the PWM of +12v as attachement.But Pin 10 no any waveform.If using external -12v instead, this differential probe works properly.So the only problem is the DC-DC chip.But the factory erase all chip mark.I have draw the schematic of this part,please see the attachement.The length of this chip is 1cm.The bottom marked"NBK" and have a "Philippines" mark.I hope some one can tell me the model of this chip.Maybe this chip also used on other type differential probe.Thanks & Best regards

author: BennoG
author_rank: Frequent Contributor
timestamp: April 19, 2024, 11:02:44 am
content: I don't see any feedback divider, so this chip is specifically designed to generate +12V and -12V.But I can not find that kind of boost converter controller.Benno

author: coromonadalix
author_rank: Super Contributor
timestamp: April 19, 2024, 02:46:19 pm
content: but feedback pins are 9 and 16 for the ic ??if the schematic is ok ?

author: BreakingOhmsLaw
author_rank: Frequent Contributor
timestamp: April 19, 2024, 02:49:00 pm
content: https://www.analog.com/media/en/technical-documentation/data-sheets/max743.pdfor a clone of that part.

author: fzabkar
author_rank: Super Contributor
timestamp: April 19, 2024, 04:18:40 pm
content: https://ae01.alicdn.com/kf/Sf508e8f9f731407b89c61c5a37d4a0d3K/1pcs-lot-100-New-original-MAX743CWE-MAX743EWE-MAX743-SOP16.jpghttps://ae01.alicdn.com/kf/Hf6e06e2bed7e4a59936f710dc9221ce24/100-Original-New-In-Stock-MAX743CWE-MAX743EWE-MAX743-SOP16.jpg

author: asis
author_rank: Frequent Contributor
timestamp: April 19, 2024, 07:43:33 pm
content: Hi,Here is part of the diagram of the working product.

author: teatime
author_rank: Contributor
timestamp: April 20, 2024, 01:05:16 am
content: After compare with the datesheet, MAX743 is the right chip.Thanks alot for your great help!

author: teatime
author_rank: Contributor
timestamp: April 20, 2024, 01:08:06 am
content: After remove the chip, then I draw this schematic, it's right.The chip MAX743 is the chip I needed.
Unknown dual channel 5V/12V current limit switch - Page 1
Forum section: electronics / repair

author: fzabkar
author_rank: Super Contributor
timestamp: July 16, 2021, 09:27:25 pm
content: This PCB ...https://ae01.alicdn.com/kf/Hd2161dd55b72428e93a18cf6c1d1b5848/WD-hard-drive-WD20EZAZ-PCB-2060-810011-001-REV-P1-P2-unlock-PCB-board-Decrypt-PCB.jpg... has a dual channel 5V/12V current limit switch at the SATA power connector, marking "6512".I suspect that it is electrically and functionally compatible with the following part.MP5094, Monolithic Power, dual channel 5V/12V current limit switch, marking AYUy, TSOT23-8:https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP5094/document_id/4894/I'd like to add the mystery part to my database. Can anyone help me to identify it?Edit:Here is another compatible part.STEF512GR, STMicroelectronics, Dual electronic fuse for 5V (3A) and 12V (4A) rails, marking H512, TSOT23-8L:https://www.st.com/resource/en/datasheet/stef512gr.pdf
Unknown faulty component's power supply - Page 1
Forum section: electronics / repair

author: t4rmo
author_rank: Contributor
timestamp: December 27, 2021, 11:31:22 pm
content: Hi there,I'm trying to repair a tv's power supply, i think that the faulty component is the U100.I found the datasheet and there is no information about this component ,any idea what component could replace it?

author: bob91343
author_rank: Super Contributor
timestamp: December 28, 2021, 12:18:11 am
content: Is it in the parts list?

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 28, 2021, 12:21:57 am
content: try data mining / googling "+driver 8 pin ic for smps adapter"e.g.https://www.datasheetarchive.com/8%20pin%20smps%20power%20control%20ic-datasheet.html

author: RayRay
author_rank: Frequent Contributor
timestamp: December 28, 2021, 12:24:42 am
content: No information on the component itself? Not specified in the service manual (often times, the components themselves are not specified in the schematics, but as a parts list somewhere underneath it). Also, what makes you believe it's that one particular component? Commonly, capacitors/diodes/mosfets are the issue on such boards. Also, are you aware you can lookup the board number on ebay/aliexpress and find a full-on replacement? Might be less time consuming than repairing the existing, and sometimes, those boards are sold at very affordable prices.

author: strawberry
author_rank: Super Contributor
timestamp: December 28, 2021, 01:31:19 am
content: low side gate driver

author: timenutgoblin
author_rank: Regular Contributor
timestamp: December 28, 2021, 02:09:17 am
content: Judging by the orientation of the input diodes, D101 and D102, it looks like U101 could be a complementary half bridge MOSFET driver with N-channel and P-channel MOSFET devices. "A Input" looks like N-channel and "B Input" looks like P-channel.Good luck with the repair!

author: t4rmo
author_rank: Contributor
timestamp: December 28, 2021, 10:14:02 am
content: In the datasheet list it is used the name 000 h26 but this name it 's not a name of a component" alt="" class="bbc_img" />

author: t4rmo
author_rank: Contributor
timestamp: December 28, 2021, 10:15:16 am
content: yeah thats true but i dont know which commercial low side driver could replace it

author: Jeroen3
author_rank: Super Contributor
timestamp: December 28, 2021, 10:59:25 am
content: Your parts list says for the U101 that it's a MIC4428.Dual 1.5A-Peak Low-Side MOSFET Drivers

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 28, 2021, 12:08:27 pm
content: U101 MIC4428https://www.microchip.com/wwwproducts/en/MIC4428how come can't be correctly read ?

author: t4rmo
author_rank: Contributor
timestamp: December 29, 2021, 03:45:05 pm
content: No no, my fault, the component is the U100, in the list 001 h26, in the electrical circuit is above of the U101.I have already modified the initial image, due to pointing an incorrect component
Unknown FFC connector on extruder - Page 1
Forum section: electronics / repair

author: davorin
author_rank: Unknown
timestamp: July 15, 2022, 08:55:44 am
content: Good morning (o;Has someone an idea which manufacturer does FFC connectors with locks like pictured below?This is from a Qidi 3d printer extruder.thanks in advancerichard

author: chris_leyson
author_rank: Super Contributor
timestamp: July 15, 2022, 09:03:52 am
content: Samtec might have something similar
Unknown Header - Page 1
Forum section: electronics / repair

author: 2X
author_rank: Frequent Contributor
timestamp: January 13, 2024, 09:47:59 am
content: Hello, do you know what is the name of the two headers at the red circles at the attached picture or where can I find them?

author: ArdWar
author_rank: Frequent Contributor
timestamp: January 13, 2024, 10:19:30 am
content: Looks like QLC260P but I'm not sure if it's exactly that or something similar.

author: 2X
author_rank: Frequent Contributor
timestamp: January 13, 2024, 10:26:06 am
content: Many thanks for your reply. What charecteristics have these headers/connectors so to check in order to be sure for what I will buy? In "ordinary headers" connectors I check olny the pins pitch and height.I found the below where I beleive it is the same.High Speed/Modular Connectors QLC-260RQLC260RPart # Aliases:127050-0530https://gr.mouser.com/ProductDetail/ITT-Cannon/QLC260R?qs=g5ciJ0jwZaF0IMAnzMQ5aQ%3D%3D&utm_source=digipart&utm_medium=aggregator&utm_campaign=QLC260R&utm_term=127050-0530&utm_content=ITT%20Cannon

author: 2X
author_rank: Frequent Contributor
timestamp: January 23, 2024, 06:59:54 pm
content: Quote from: 2X on January 13, 2024, 10:26:06 amThis was the right connector:High Speed/Modular Connectors QLC-260RQLC260RPart # Aliases:127050-0530https://gr.mouser.com/ProductDetail/ITT-Cannon/QLC260R?qs=g5ciJ0jwZaF0IMAnzMQ5aQ%3D%3D&utm_source=digipart&utm_medium=aggregator&utm_campaign=QLC260R&utm_term=127050-0530&utm_content=ITT%20Cannon
Unknown IC - Page 1
Forum section: electronics / repair

author: fant
author_rank: Contributor
timestamp: April 23, 2024, 09:12:25 pm
content: Good morning;I am trying to fix a current calibrator, but i cannot find the model of the IC in picture.Should be a D/A converter, from the function on the PCB.Tho output is stuck at 0 Vdc and no current.Any idea about the model?Thank you in advance.

author: wraper
author_rank: Unknown
timestamp: April 23, 2024, 09:18:33 pm
content: https://www.analog.com/media/en/technical-documentation/data-sheets/1446fa.pdf

author: fant
author_rank: Contributor
timestamp: April 23, 2024, 10:04:39 pm
content: wow, wow, wowThank you very much.

author: fzabkar
author_rank: Super Contributor
timestamp: April 23, 2024, 11:36:15 pm
content: https://ipv4.google.com/search?q=filetype%3Adoc+OR+filetype%3Apdf+%22absolute+maximum%22+1446ihttp://markingcodes.com/search/c/1446i
Unknown IC - Page 1
Forum section: electronics / repair

author: brouillon
author_rank: Newbie
timestamp: November 25, 2024, 09:18:52 am
content: Hello there,While repairing an electronic board I found this circuit without reference or hidden on the other side, I cannot identify it, does anyone know what it is and its reference?Thank you.

author: Chalcogenide
author_rank: Regular Contributor
timestamp: November 25, 2024, 09:57:30 am
content: That looks like some kind of high-ish device (power audio amplifier maybe?) that has a "flipped" package that exposes a thermal pad for heat dissipation.The markings are on the bottom, but you need to desolder the chip to read them.

author: brouillon
author_rank: Newbie
timestamp: November 25, 2024, 10:19:59 am
content: Thank you for the response but it's an industrial ic, i think it drives a 3 phase motor!!?

author: coromonadalix
author_rank: Super Contributor
timestamp: November 25, 2024, 11:08:33 am
content: could be anything powerful like igbt, scr triacs etc ... even a mix of many since there is a lot of pins

author: fzabkar
author_rank: Super Contributor
timestamp: November 25, 2024, 05:14:26 pm
content: Intelligent Power Module (IPM):https://www.google.com/search?q=%22Intelligent+Power+Module%22&tbs=isz%3Am%2Citp%3Aphoto&udm=2

author: brouillon
author_rank: Newbie
timestamp: November 26, 2024, 08:13:55 am
content: Thank you.

author: JoeyG
author_rank: Regular Contributor
timestamp: November 26, 2024, 11:23:36 am
content: +1 3 phase power module which has 3 phase H bridge 6 IGBTs in one package and integrage drivers etc.

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 26, 2024, 01:13:26 pm
content: Did you desolder it and looked under? There wasn't any marking?Seems the usual 3-phase driver seen in many appliances, specially washing machines.There're lots of drivers using that package (27-PowerDIP).https://www.digikey.com/en/products/filter/power-driver-modules/296?s=N4IgjCBcpgbFoDGUAuAnArgUwDQgPZQDa4sAzACwCsFIAungA4pQgDK6AlgHYDmIAXwF540EJwAmrALRgADCCYtIIRSBQBPRllaCBQA

author: brouillon
author_rank: Newbie
timestamp: November 26, 2024, 02:11:33 pm
content: it's ok guys i found it. it's FNB35060T an intelligent power module. Thanks to all for your responses.

author: u666sa
author_rank: Frequent Contributor
timestamp: November 26, 2024, 04:06:43 pm
content: Quote from: brouillon on November 26, 2024, 02:11:33 pmCurious. These can be bought?

author: coromonadalix
author_rank: Super Contributor
timestamp: November 28, 2024, 08:47:18 pm
content: yes on some very good sites, lead time seems enormous in some, 37 to 44 weeks, some will have them in 2025 1st quarter ...it is not EOL around 25 to 35$ usd ??

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 28, 2024, 09:20:08 pm
content: What about the FNB35060T6S?Onsemi site says it's "Double stopper", no idea what it is, otherwise seems identical and readily available.

author: Ugur
author_rank: Regular Contributor
timestamp: November 29, 2024, 12:22:29 pm
content: https://www.digikey.com/en/products/detail/onsemi/FNB35060T6S/24627332https://tr.aliexpress.com/item/1005004348259958.html
Unknown IC in Megger MIT525 - Page 1
Forum section: electronics / repair

author: Nicolas666
author_rank: Newbie
timestamp: August 21, 2023, 09:40:15 am
content: Hi all, I need your help to identify a component in a earth tester wich runs on a Li-ion battery.the circuit in the first pic seems to be the charger, it only outputs about 2Vdc instead of 12Vdc, so the battery never gets charged.The QFN case on the second picture is getting hot (35°C) without any load. But I were unable to find any doc on this ref...could you help me to find it ?Thanks a lot, I'm so happy to start contributing to this amazing forum

author: coromonadalix
author_rank: Super Contributor
timestamp: August 21, 2023, 10:43:46 am
content: if you remove the battery does the supply goes up, could be a case of a dead / non chargeable battery ?

author: gamalot
author_rank: Super Contributor
timestamp: August 21, 2023, 12:47:07 pm
content: https://www.ti.com/lit/ds/symlink/bq24600.pdf

author: Nicolas666
author_rank: Newbie
timestamp: August 21, 2023, 02:06:10 pm
content: Thank you very much for your efficiency, GamalotThe funny thing is that I already know and use the BQ chip, but never had to face it in QFN packagenow I know, again, thanks.oh, and for the repair, I found the problem : the rotary switches had been shifted by someone (probably in a previous repair ?), so the functions didn't work as expected, and so does the charging feature.

author: fzabkar
author_rank: Super Contributor
timestamp: August 21, 2023, 05:10:44 pm
content: https://www.ti.com/packaging/en/docs/partlookup.tsp?partmarking=OAQ