hybridfree/eevblog-posts huggingface dataset:
Twoway radio with U-Blox G6010-ST not working? - Page 1
Forum section: electronics / repair

author: oh2ftu
author_rank: Regular Contributor
timestamp: February 13, 2023, 06:24:27 am
content: Hi there.I've got a two-way radio (let the make and model be a secret for now) that utilizes an U-Blox G6010ST chip for GPS.The chip is not detected. No schematics are available for the radio, neither access to any debugging.It's in a QFN56 package, so attaching probes can be a bit daunting.Here's a link to a datasheet.What I've been able to deduce so far:- Voltage is present on most VDD-pins, except VDD_C0 and VDD_C1 (these are internally generated?)- The crystal/oscillator seems bad -> this has been swapped, no change- TXD1 pin seems to be high all the time (can be normal?)I might be able to post a picture tomorrow of the general layout.I've swapped the GPS chip from another radio, but I fear I might have cooked it. The symptoms are the same however.Any ideas what I should check? I do have a scope and DMM but it has "been a while" since I last did any debugging like this. Actually, I've never gone this deep.
TY250a CDI - Page 1
Forum section: electronics / repair

author: Nide1
author_rank: Contributor
timestamp: April 13, 2021, 07:47:29 pm
content: I'm trying to fix this CDI off a motorbike for a friend, but I can't identify this component, any help would be very much appreciated.Sorry about the scratch I had to dig it out of resin.Can somebody tell me how it triggers without a trigger coil?ThanksNide1

author: perieanuo
author_rank: Frequent Contributor
timestamp: April 14, 2021, 11:19:14 am
content: hi,it's some standard scr, maybe you can asume 8A/800V or more voltage for that scran example:https://uk.farnell.com/littelfuse/2n6509g/thyristor-25a-800v-to-220/dp/9557202?ost=scr&searchref=searchlookahead&krypto=3GlvHFpf67F0Fnt5OX5rOiqhs82qrJQpYPfyT0GYWc1WwzViUtRPo6Z8vbehamwVnuRuJJAQWcUtCRFUyTFhN7bcMNXOa4dTzfqAyggO4UeV21H3psWI%2BOXN22wf5qAR

author: Nide1
author_rank: Contributor
timestamp: April 14, 2021, 02:08:41 pm
content: Thanks for the reply perieanuo, I thought it must be SCR.Can anybody tell me how to work out gate current/voltage in simple layman's terms.Thanks, Nide1.

author: perieanuo
author_rank: Frequent Contributor
timestamp: April 14, 2021, 04:47:24 pm
content: gate voltage here is irrelevant, gate current is given i guess by the ignition coil vie 1u5 cap, rectifier diode and 86ohm//diode and 1k resistor, and the zener limits the peaki didn't do any calculations, but there are 'normal' gate current scr's and more senzitive ones, i think a normal one will do the trick, like i pointed beforeseehttps://uk.farnell.com/c/semiconductors-discretes/thyristors/thyristors-scrsthe normal ones are like 8-10mA senzitivity on gate, either you use a 'normal' either a <1mA one, but my bet is it's a regular one, in that environement a sensitive gate is not desired if you design such a thing, automotive is noisy and threshholds are generous

author: Nide1
author_rank: Contributor
timestamp: April 14, 2021, 07:41:55 pm
content: Thanks again perieanuo, I'll get a 2N6509G and give it a go, I've tested everything else in the circuit so we should see a spark.To buy one which comes with stator plate will cost a 100 to 200 pounds and he said he always liked how the engine ran, so worth doing.Thanks again.Nide1.

author: perieanuo
author_rank: Frequent Contributor
timestamp: April 15, 2021, 01:15:20 pm
content: ok, just please keep us informed

author: Nide1
author_rank: Contributor
timestamp: April 17, 2021, 07:29:39 pm
content: Hi,I fitted SCR(BT151-500R) and it worked like a dream, the best spark he had ever seen.So thanks again perieanuo.He's got to sort the carb/fuel out, but I've done my bit.ThanksNide1

author: perieanuo
author_rank: Frequent Contributor
timestamp: April 19, 2021, 06:48:33 am
content: you're welcome, glad to hear it works, you can now press thanks to my postbest regards, pierre

author: Nide1
author_rank: Contributor
timestamp: April 19, 2021, 08:09:24 pm
content: I thought I put a picture of the bike.
Type of connector - Page 1
Forum section: electronics / repair

author: gaminn
author_rank: Frequent Contributor
timestamp: June 10, 2019, 03:11:35 pm
content: Hi,what is the name of this connector (both male and female)? I would like to buy it on Mouser or eBay but don't know its name. It has approx 1.25mm pitch.Thanks

author: chris_leyson
author_rank: Super Contributor
timestamp: June 10, 2019, 03:34:43 pm
content: Molex Picoblade

author: gaminn
author_rank: Frequent Contributor
timestamp: June 10, 2019, 03:53:47 pm
content: Not sure. The lower part of female connector (solid white area) is much more longer than what I can see e.g. here:https://www.molex.com/molex/products/family?key=picoblade&channel=products&chanName=family&pageTitle=IntroductionThis connetor is in Chinese tablet on Li-pol battery (female) and PCB (male).

author: No.Mad
author_rank: Regular Contributor
timestamp: June 10, 2019, 04:05:35 pm
content: Quote from: chris_leyson on June 10, 2019, 03:34:43 pmIt doesn't look like Molex PicoBlade, but it's fairly similar and same pitch so I reckon it's should be fine to use it as substitute.

author: chris_leyson
author_rank: Super Contributor
timestamp: June 10, 2019, 05:19:15 pm
content: Sorry Gaminn, your're right guys it's not a Picoblade, the two locking pips on the crimp housing are located on the top, as shown in the picture, whereas in the Picoblade they are located on the bottom.Might be close to Hirose DF13A-7P-1.25. The crimp housing would be DF14-7S-1.25C
U1173 Connectivity Cable - Page 1
Forum section: electronics / repair

author: onesystem
author_rank: Regular Contributor
timestamp: October 29, 2023, 03:25:38 pm
content: My once perfectly working U1173 cable for DMM U1273AX stopped being recognized by Windows because prolific chip is too old... I was not about to buy a new comm cable for 50 bucks on eBay... I bought instead a DSD TECH SH-U06A USB to TTL Serial Uart Adapter with PL2303GC Chip on amazon for 11 bucks, desoldered the chip and swapped it with the old one in U1173 - it now works perfectly. In case anyone else has the same problem and is willing to go through soldering trouble.I do not know if this will work for all serial port adapters - but it did for this one!

author: onesystem
author_rank: Regular Contributor
timestamp: October 29, 2023, 06:02:20 pm
content: Here are the pics.If anyone has a source of reputable prolific chips, let me know. I bought a full USB Comm device since I knew they will have a legit chip. I much rather get chips as they are cheaper plus no left over clutter.

author: tooki
author_rank: Super Contributor
timestamp: October 31, 2023, 08:13:34 am
content: LCSC seems to have them.

author: zrq
author_rank: Frequent Contributor
timestamp: October 31, 2023, 07:44:38 pm
content: you can find old versions of prolific drivers online that still works with pl2303hxa.
U1272A strange measurement results (solved) - Page 1
Forum section: electronics / repair

author: cos
author_rank: Contributor
timestamp: January 16, 2023, 11:08:43 am
content: Some time ago I purchased a second hand U1272A.Recently it started showing strange results: large errors on many ranges and on the ohms range with inputs open some 16 Mohms i.l.o. "OL".This was caused by resistor R34 (in red shrink sleeve) on the main PCB.R34 is soldered into 2 hollow stand-offs and has a value of approx 1080 ohms.The side which is connected to the J1 input socket (V, ohms, capacitance and diode test) was loose and could be lifted out without any effort (see attached picture).Resoldered both sides which solved the problem.Note on the old topic about the input impedance of the Low Z and OFF positions.In those positions input J1 is connected to the COM terminal J2 via R40, PTC1 and PTC4.I measured respectively approx. 280, 832 and 819 ohms (@ approx. 15 degrees C).
U1461A Dim Oled - Page 1
Forum section: electronics / repair

author: Fallenrecruit
author_rank: Newbie
timestamp: November 04, 2024, 07:19:58 am
content: Hey Brains trust, I have a U1461A that is suffering from a case of crap oled screens, it uses the u1273-26501 display module so I was hoping that A drop-in replacementhttps://www.aliexpress.com/item/1005005585282010.htmlwould work but I am having no luck.Has anyone tried them? I am also looking into going the other option of replacing it with a SSD1309 8080 if the firmware mod can be done

author: CapLeaker
author_rank: Regular Contributor
timestamp: November 04, 2024, 11:16:10 am
content: On EBay there is a display that fits your meter for $100.
U16 on PCB of Noyafa NF-8209S cable tester emitter - Page 1
Forum section: electronics / repair

author: stryker
author_rank: Regular Contributor
timestamp: April 15, 2024, 09:52:50 am
content: Hi everyoneI have a Noyafa NF-8209S network cable tester that's dead. It's the smaller of the two units, the emitter. On disassembly there's a SOT23-5 component at the battery connection end of the PCB marked U16 that's now just a scorched remnant.If by any chance you've got one of these I'd love to know what the markings are on that? I've not been able to locate any images.Thanks in advance,Geoff
U3402A repair - problems with PSU, UART - Page 1
Forum section: electronics / repair

author: nikodem
author_rank: Regular Contributor
timestamp: March 29, 2023, 12:02:27 pm
content: Hi all!I have Agilent U3402A on my bench for repair now. Before I start any detailed description - could anyone please measure the power supply output voltages on the J602 in a working device?Thank you in advanced

author: pbs74
author_rank: Contributor
timestamp: March 30, 2023, 03:06:44 pm
content: I have the Escort 3146A, should be same as U3402A, as Agilent bought Escort and rebranded products.I cannot find schematics for either model, but voltages for J602 in my Escort were (a bit strange values)Black: 8.9VBrown: GndRed: 5VOrange: GndYellow: 16.5VGreen: GndBlue: - 1.95VPurple: Gnd

author: nikodem
author_rank: Regular Contributor
timestamp: March 30, 2023, 11:57:52 pm
content: Quote from: pbs74 on March 30, 2023, 03:06:44 pmThank you, that's suprisingly helpful. My DMM is forcing the blue one to be around 1 V - when I disconnect the cable, it goes back to around -2 V. The resistance on that line is ok (in the range of Mohm, both directions), but this is a valuable starting point for this repair.Will it be okay if I add some more specific questions regarding that device in the future? beeing able to reference to a working device is really helpful.

author: pbs74
author_rank: Contributor
timestamp: March 31, 2023, 10:54:45 am
content: Quote from: nikodem on March 30, 2023, 11:57:52 pmI just got mine as NOS (new old stock) so depending on risk of ask I might turn down, but feel free to ask. I think it is a nice meter, especially for the price I gave. It is within same digits as my Keithley 2000 and very close to my Fluke 189, and although none are recently calibrated, the agreement indicates correct values.

author: nikodem
author_rank: Regular Contributor
timestamp: March 31, 2023, 05:11:53 pm
content: Quote from: pbs74 on March 31, 2023, 10:54:45 amI got mine as broken, hoping that it will be something relatively simple to repair (this is not the first instrument I'm repairing, but by far the newest, and this means lack of proper service manual and high level of integration)... We'll see where it will get me

author: lern01
author_rank: Regular Contributor
timestamp: January 18, 2024, 09:38:58 am
content: Quote from: nikodem on March 31, 2023, 05:11:53 pmHow to enter calibration mode for u3402a. thanks!
U8903A Audio Analyzer - Page 1
Forum section: electronics / repair

author: Omicron
author_rank: Regular Contributor
timestamp: May 29, 2022, 05:49:20 pm
content: I have a broken Agilent U8903A Audio Analyzer. The output sections seem to work fine, but both the input sections show an amplitude value that seems off by some large scale factor when doing measurements. Also, the device throws an error when doing a firmware update, I suspect when it tries to flash the DSP for the output section. This leads me to think that maybe some flash or EEPROM chip containing the calibration values is bad.Anyone encountered this issue before?
Ubiquity wifi puck - Page 1
Forum section: electronics / repair

author: wafflehatjoe
author_rank: Newbie
timestamp: August 28, 2020, 07:59:27 pm
content: I got bored today and disassembled one of my ubiquity wifi puck things and noticed something a bit odd, there's an area that looks like it should have a can over it. I was wondering if anyone could confirm that it should have a can or notalso anyone ever toss some antennas on to the antenna ports? these pucks were purchased second hand so idk who was inside before me. they are fully functional from what i can tell

author: cdev
author_rank: Super Contributor
timestamp: August 28, 2020, 09:03:10 pm
content: Lots of electronics comes ready for more RF shielding but without it. Your wifi puck likely can have an antenna added but defaults to some included antenna(s) like perhaps the white things at the very bottom of the picture. Cant really tell.

author: wafflehatjoe
author_rank: Newbie
timestamp: August 28, 2020, 09:22:59 pm
content: yea the 2 metal bits off either side are the included antenna. my main curiosity was if whoever had this before me removed the can and it originally came with one, but that seems like a lot of work on there part
UE boom wireless speaker wont charge(or atleast says it doesn't) - Page 1
Forum section: electronics / repair

author: CoopedUp
author_rank: Regular Contributor
timestamp: September 21, 2019, 08:58:50 pm
content: I have a UE boom speaker and when I plug it the Bluetooth module gets hot to the touch, it draws .75 amps and then slowly goes down to .35 ish. when I charge the battery separately and put it back in it says battery critically low. is it possible there is a short on the usb interface causing the chip to get full voltage instead of a signal or would it be something else... Thanks
Is my common cathode diode assembly broken? - Page 1
Forum section: electronics / repair

author: scsi
author_rank: Contributor
timestamp: July 24, 2019, 07:24:10 am
content: Hello all,I am testing ultrafast rectifier diode with DMM (internal schematic attached)pins 1 - 2 reads diode drop (0.6V) reverse (infinity)pins 2 - 3 reads diode drop (0.6V) reverse (infinity)pins 1 - 3 reads shortIs this a normal behavior?

author: daqq
author_rank: Super Contributor
timestamp: July 24, 2019, 07:35:55 am
content: Should not be. Are you sure you have the right diode?

author: scsi
author_rank: Contributor
timestamp: July 24, 2019, 07:46:52 am
content: original part in question is U1640G in TO-220 package and it is from SMPS so it must be ultrafast rectifierdesoldered one pin and it still reads short accros 1 - 3 pins.

author: ogden
author_rank: Super Contributor
timestamp: July 24, 2019, 07:59:37 am
content: Quote from: scsi on July 24, 2019, 07:46:52 amOh, you are measuring in-circuit. Then your initial measurement was OK because often those diodes are used in parallel, pins 1-3 tied together. Why you still measure short between anodes - dunno. Perhaps you think you desoldered one pin but actually did not?

author: scsi
author_rank: Contributor
timestamp: July 24, 2019, 08:41:14 am
content: QuoteMight be, these double sided commercial pcbs are pain to desolder without damaging the pads.Thanks for the info!

author: exe
author_rank: Unknown
timestamp: July 24, 2019, 09:28:20 am
content: I propose title "is my common cathode diode assembly broken?".

author: David Hess
author_rank: Super Contributor
timestamp: July 24, 2019, 02:27:44 pm
content: Quote from: ogden on July 24, 2019, 07:59:37 amOr the two diodes are connected to different points on the same transformer winding producing the same result.
Ultrak stopwatch EEPROM dump needed - Page 1
Forum section: electronics / repair

author: Jonny
author_rank: Regular Contributor
timestamp: September 13, 2025, 01:14:21 am
content: Hey all. Must be same model as per internal image as it looks like there was a re-design of board but sold under same model number still. Must be from a working unit as trying to ascertain if it contains program data or only lap time data.Cheers
Ultrasonic cleaner refurbishment - Page 1
Forum section: electronics / repair

author: powerdoc
author_rank: Newbie
timestamp: May 27, 2023, 07:20:02 pm
content: I have a Crest ultrasonic with separate generator and tank. I purchased it used a few years ago and now want to use it. It appears to have a problem with the coax cord which is damaged outside the tank and also appears to have been repaired internally inside the tank assembly, although for the life of me, I can't see how that might have have become damaged, but I digress. The ultrasonic transducers themselves show no defect in connection to the tank or discoloration from over heating. What type of coax is generally used (before you ask, I already called Crest and their answer, of course, was to send it to them for repair) for ultrasonic generators with a BNC connector? Also, can I test the generator by just hooking it up to my scope and checking for a waveform? Many thanks, in advance, for any helpful information.
Ultrasonic cleaning of PCBs - Page 1
Forum section: electronics / repair

author: watchmaker
author_rank: Unknown
timestamp: February 20, 2025, 07:06:52 pm
content: I have a 4 qt cleaner for my business. What cleaning solution is recommended for modern and also old PCBs?Some of the old thru hole boards have a sticky feel to them that resists IPA and acetone (I know, I know) but I was desperate.I looked on Google but as is usually the case, came away confused.Thanks!

author: jpanhalt
author_rank: Super Contributor
timestamp: February 20, 2025, 07:37:30 pm
content: Try ZEP heavy duty acrylic floor stripper diluted with water. For removing old solder flux, I use 1 part ZEP to 3 parts total. For just dirty old boards a higher dilution, maybe 1:6 total or even 1:10 total may work. Neat, it will remove well cured machinery enamel. I have had no problem with electronic parts and have been using it for a few years now. It takes about 1 minute in an old Bransonic circa 1980's.Of course you need to rinse. I use tap water then a quick (1-2 minutes) with DI water in the Bransonic.

author: Runco990
author_rank: Frequent Contributor
timestamp: February 20, 2025, 08:19:35 pm
content: Well, there are many home brew concoctions, but the recommended solution is distilled water and Branson EC. It costs a lot, but it's a concentrate so goes a long way. I use it where I MUST be sure that there is NO residue on a board.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 20, 2025, 09:05:14 pm
content: Branson EC SDS:QuoteBoiling points:Ethanol amine 338°FButyl cellosolve 340°FMorpholine 264°FZEP is butyl cellosolve with a little ethanol amine and water.Both should probably be rinsed. At the same equivalent concentrations of organics, neither leaves a residue.
ultrasonic microphone membrane replacement? - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: February 03, 2022, 05:52:24 pm
content: I have a ultrasonic microphone that I had to repair and I lost the membrane the small SMD mic was glued toIt looked like some kind of fabric, kind of like thin 'tea cozie' or something. It would be suitable for maybe one of those semi see through window curtains, the white lacey ones, the material was too stiff for clothing... maybe it would be suitable for those cloth 'pauldrons' that rich people used to wear in like the 1500's.Any ideas? Bandwidth is 100KHz. I don't mean the black foam diffuser thing, the microphone is basically a aluminum tube with a connector on the end with a SMD part glued to a membrane on the top that the microphone diffuser sits on. I need that membrane.
Ultrasonic washing tank transducer problem - Page 1
Forum section: electronics / repair

author: Andrea 83
author_rank: Newbie
timestamp: February 23, 2022, 03:28:50 pm
content: Hello everybody! My name is Andrea, I write from Italy and I am a new member of this wonderful forum. Passionate about electronics since I was a child, over the years I have equipped my small hobby laboratory. I thank the administrator for admitting me, I always follow his videos from which I draw inspiration and new information. I open this Topic for a failure of an ultrasonic cleaning tank. Unfortunately, one of the two piezzielectric disc transducers has been destroyed and cannot be supplied by assistance because it is out of production and cannot be repaired. The model is Soltec Sonica 2200eth S2. On this occasion I used a cad program, KiCad, for the first time to draw the driver scheme, unfortunately the pilot circuit is in the resin and has only access to the frequency regulation. Forgive me for any mistakes. Can someone help me understand what changes are needed to mount the sandwich drivers or adjust to make it work with only the driver left. Thanks to those who respond.

author: fzabkar
author_rank: Super Contributor
timestamp: February 23, 2022, 06:07:19 pm
content: ZD1 appears to be drawn with the wrong polarity.

author: cdev
author_rank: Super Contributor
timestamp: February 23, 2022, 06:38:58 pm
content: Peizo disks are widely available and cheap. It might be easy to replace the blown out one.

author: Andrea 83
author_rank: Newbie
timestamp: February 23, 2022, 06:48:30 pm
content: Quote from: fzabkar on February 23, 2022, 06:07:19 pmTrue I missed it!Thank you!it is the first time that I have done a reverse enginering drawing with CAD. I was wrong to report on the drawing. On the PCB it is actually in antiparallel configuration. I should have removed it to read the voltage that is written on the bottom.

author: Andrea 83
author_rank: Newbie
timestamp: February 23, 2022, 07:00:22 pm
content: Quote from: cdev on February 23, 2022, 06:38:58 pmUnfortunately I only know that it is 7000pF, 50mm in diameter, black material therefore pz4, and that the generator power declared by the tank manufacturer is 520wP.P. and 260w max. Probably the output voltage is 190VRMS and the frequency 45kHz. I should ask the manufacturer if he gives me the data of the transducer. I have seen that in the USA they are more easily found but the shipping costs are very high about 75 €.
Unable to access service menu in Philips 107P50 CRT monitor - Page 1
Forum section: electronics / repair

author: hanakp
author_rank: Regular Contributor
timestamp: July 02, 2019, 08:52:00 am
content: A friend has suffered severe brain trauma and is unable to use most LCD monitors (they flicker at high frequencies). But paradoxically, he can use old CRT monitors. Now he asked me to fix dynamic focus on his Philips 107P50/00 (center of the screen is sharp, corners are blurry). I found service manual and there are controls for the dynamic focus in the service menu... except I'm unable to enter it. The manual describes the procedure on page 11 and again on page 12, but it just doesn't work. I also tried different combinations and sequences of the buttons, but to no avail. When I use the prescribed sequence, the screen flickers gray for a while, then normal picture pops up. But no service menu. Isn't there some other trick to this (short some pins on the PCB to enable it for example)?http://www.go-gddq.com/upload/2009_08/09080814547229.pdf

author: hanakp
author_rank: Regular Contributor
timestamp: August 14, 2019, 11:57:34 am
content: It turned out the service menu didn't work because I used a notebook with too modern graphics card (Geforce 1070) as a signal source. It had only HDMI output, so I used an active HDMI to VGA converter. When I connected the monitor to a VGA output on an old PC with Radeon HD79xx, the service menu worked at the first try. Curiously, it also worked when I used a HDMI output and the converter on the old PC. I guess it's not so surprising, there is not much incentive to support the obsolete VGA interface in new GPU drivers.
Unable to display cursors and messages in Tek 2465B after LPVS "recapping" - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: December 16, 2020, 01:12:52 pm
content: Dear all,I am working on this 2465BCT for a while.First I had to recap and fix the A5 board, which I managed to succeed thanks to the help of this forum.I managed to adjust DAC and run CAL08 to try to have a better display, which was a little jittery.Since I could not reduce the jitter, I thought it would be a good idea to replace all the electrolytic capacitor in the LPVS since they all have 1991 date codes.I replaced one by one at a time to avoid errors (C1115 / C1132 for example).All new caps were bought from Mouser.when I powered up the scope I could see the error message PUSH A/B TRIGGER once.After pushing this button the message display vanished, and it is impossible to display any message no matter what is the position of the READOT INTENSITY control.I noticed also that it is not possible to display the cursors.To this moment I have checked the following:1 - A5 +1.36V and -1.25V ==> OK2 - J119 voltages ===> all on spec. (specially +10.00V)I think the problem is that the calibration constants are not valid anymore since the power supply voltages have changed.However it is NOT POSSIBLE to start any calibration routine since I CAN'T READ THE MESSAGE DISPLAY.How to I proceed?Thank you in advance,Roger

author: rodd
author_rank: Regular Contributor
timestamp: December 16, 2020, 08:14:13 pm
content: Hi,After some more testing, I noticed that if I move the REDOUT INTENSITY slowly, I can obtain a bright spot in the display with the coordinates X= 5 div and Y = 6 divThis spot can be transformed in a kind of square by further adjusting this control..

author: YetAnotherTechie
author_rank: Regular Contributor
timestamp: December 17, 2020, 01:01:28 am
content: you have to go back and check all that you did, not the calibration memory. Looks like a short somewhere, maybe a cap instaled reversed. Check the voltage at the pins and see if it matches the silkscreen and the cap polarity.
Unable to find SOT-23 Code anywhere, please help - Page 1
Forum section: electronics / repair

author: HexValic
author_rank: Newbie
timestamp: June 30, 2021, 06:36:39 pm
content: Hello all,I am having difficulty identifying an SOT-23 device with the code 1412 (the 12 is on 90° angle to right of the 14). I have scoured the smd codebook,http://www.s-manuals.com/smd,and more but alas have ended up empty handed. Was hoping someone on this forum may be able to shed some light for me. (Btw, this is out of a Toshiba PA2417U 18V 1.1A power adaptor for and old Toshiba Satellite T1910 I'm refurbishing.) I have posted a pic for your consideration.Thank you for your time,Bob

author: gamalot
author_rank: Super Contributor
timestamp: June 30, 2021, 07:08:45 pm
content: DTA114EKAhttps://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/dta114ekat146-e.pdf

author: fzabkar
author_rank: Super Contributor
timestamp: June 30, 2021, 07:38:11 pm
content: http://www.smdmark.com/en-US/search/code?id=14
unable to identify IC VT221F  - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: June 09, 2022, 12:00:40 pm
content: helloTrying to identify the IC and get the datasheet of VT221F used in Advantech PCM9375 Mother Board schematicsphoto attachedThanks in advance

author: gamalot
author_rank: Super Contributor
timestamp: June 09, 2022, 12:45:19 pm
content: It should be VT221FCX-ADJ - PMIC from Volterra Semiconductor (acquired by Maxim in 2013), unfortunately I can't find any more info on it.

author: hitecelec
author_rank: Regular Contributor
timestamp: June 09, 2022, 01:26:32 pm
content: Thanks
unable to identify the sot-23 component - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: December 13, 2023, 10:15:07 am
content: hello AllNeed helppicture attachedthanks in advance

author: fzabkar
author_rank: Super Contributor
timestamp: December 13, 2023, 05:20:49 pm
content: Lots of possibilities, eg VN0605T.https://web.archive.org/web/20210507171632/https://www.vishay.com/docs/70212/70212.pdfhttp://markingcodes.com/search/c/v2A photo of the PCB would help to put the part in the context of its surroundings.

author: BlownUpCapacitor
author_rank: Frequent Contributor
timestamp: December 13, 2023, 07:17:29 pm
content: First result on google gives me this:https://gridchoice.com/shop/general/10176-transistor-fet-v2hac-17pcs.htmlLooks like a N-channel FET according to the site.
unable to identify this device  - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: December 01, 2023, 08:46:04 am
content: helloTrying to identify this IcJPEG attached. looks like analog devicesThanks in advanceAnand

author: hitecelec
author_rank: Regular Contributor
timestamp: December 01, 2023, 08:56:54 am
content: helloI think ADG736
Unable to perform CAL08 in a Tek 2465B- now vertical position not working (4 ch) - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: September 22, 2022, 08:29:51 pm
content: Hi folks,I was performing the CAL08 procedure as suggested in other trend to fix a four rows of dots that are showing on the screen.First, I could not adjust grid bias trimpot (R1878) because the spot was MUCH MORE brighter than the line of dots for the entire pot range.The the display flickered and the dot became a lot less brighter but still brigter that the dots, but I decide to move on.When I started the geometry adjustment moving R4350, the scope rebooted and the vertical position controls for all the channels are not workingThe scope is able to display the calibration signal, but it is high "up" for CH1 and CH2.Just in case I checked the voltages at J119 and they are all fine.I went to the troubleshooting chart but it is very "vague" to me.It says " if the problem happens on the four channels the problem can be:1- channel switch2- delay line3- Vert Output Amplifier4- Hybrid Power SupliesI do not have enough knowledge to proceed.Any suggestions?Thanks to all,Roger

author: rodd
author_rank: Regular Contributor
timestamp: September 23, 2022, 07:49:48 pm
content: Another observation:The scope is capable of displaying a signal that is aplied to any of the channels.The gain and sweep time seems to be working.However, I can not change the position of teh waveform that is displayed.Is this an indication that the problem is in the A5 board?Roger

author: MathWizard
author_rank: Super Contributor
timestamp: September 24, 2022, 07:12:46 pm
content: When you say you moved R4350, is that a trim pot on the inside of the machine? or a knob on the outside ?If it's inside, did u maybe short something with a screw driver ? Or maybe it's an old trim pot, that's dirty/corroded, or cracked ?IDK the circuits or this scope, but can u check the voltage(s) out of R4350 to see if it changes ?What do u mean the scope rebooted? Did it have a short or something and trip some protection ? Maybe something in your adjustment circuit failed when u changed it.
Unable to Reassemble Tektronix 134 Current Probe Amplifier, Mechanical Troubles - Page 1
Forum section: electronics / repair

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 26, 2022, 08:37:45 am
content: This is a vintage Tektronix 134 Current Probe Amplifier made in the late 1970s. You can find more information, including photos and manuals from here:https://w140.com/tekwiki/wiki/134Last year I disassembled the enclosure to check for a suspected fault, but I've been unable to reassemble it forever since due to a mechanical problem. The difficulty is reinstalling the washer behind the BNC connector.The BNC connector is screwed onto the faceplate with one screw (or perhaps two? but my memory was that only one mounting hole was actually used, and it matches the diagram in the service manual, so I think my memory was correct), and the washer is located at the back side of the BNC connector. The problem, however, is once the faceplate is put back into place, the back of the BNC connector becomes inaccessible to fingers, screwdrivers, or tweezers. So I'm unable to screw the washer back onto the connector.Please advice.The only solution I'm seeing is temporarily unscrew the PCB, so it can move freely to open a gap, but the PCB itself is also interlinked with everything else... Despite my admiration of the engineering marvels in vintage electronics, I really hate the point-to-point construction. It's 3D puzzle wrapped in an enigma. Assembly and Disassembly must be done in a very particular order, otherwise components would be inaccessible. And in this case, I think the design is virtually a bobby trap - it takes one second to unscrew it, but it seems that it requires dismantling everything to put it back into place...(I'm in the process of attaching photos and images, but it's too large to be attached in one post. Please recheck the post after 5 minutes).Done.

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 26, 2022, 08:40:09 am
content: More attachments.

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 26, 2022, 08:41:30 am
content: More attachments.

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 26, 2022, 08:42:59 am
content: More attachments.

author: niconiconi
author_rank: Frequent Contributor
timestamp: November 26, 2022, 08:44:38 am
content: Final attachment.

author: Hamelec
author_rank: Regular Contributor
timestamp: November 26, 2022, 09:57:56 am
content: why dont you fix the self securing nut (part# 16) with some glue before? (NOT using super glue, because that will run into the thread). It will hold the nut in place for further assembly..
Unable to save NVRAM Contents of a TDS684A to floppy - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: January 26, 2021, 11:19:10 am
content: Hi folks,I have been trying to read the content of the Dallas DS1486 of my TDS684A before trying to desolder it.The battery is really low since it is necessary to run SPC calibration every time I turn the scope off.I have tried the tools developed by Madao ( tdsNvramMinimalFloppyDumper and tdsNvramFloppyDumper) but neither is able to produce any dump file.When using the tdsNvramMinimalFloppyDumper, I tried different timings to turn the NVRAM protection switch to 'unprotected, but could make it work.If I try tdsNvramFloppyDumper, the floppy led flicks one time but nothing is written to the disk.There is a problem in this instrument since I get an error when trying to format the floppy on the scope, but I can see the file contents of the floppy and create a new directory in it.I have tried a second floppy drive and the results are the same.My questions are:1- Since it is possible to read and write to the floppy, why is it not possible to format it?2- Is there any known issue with this tool with TDS series A scopes?3- Are there other tools known to work on these scopes?Thank you,Roger

author: rodd
author_rank: Regular Contributor
timestamp: January 27, 2021, 10:45:48 pm
content: Just an update.I opened the floppy drive to clean it.Also I was able to find another lot of 1.44 disks.Now I was able to format the disks on the scope, but neither versions of the toll works.Maybe I am not doing the memory protect switch "magic" right.Can anyone help on this?Thank you

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 21, 2021, 08:30:31 am
content: Old topic I know, but have you tried updating your firmware to the latest via GPIB?I had the same problem with the floppy tools not working until I updated the firmware on my TDS784C then it all worked fine.https://www.eevblog.com/forum/repair/unified-tektool-released-!-(firmware-flash-tools-for-old-tds-series)/msg3758918/#msg3758918
Undersized PCB trace as fuse... Should I repair it? - Page 1
Forum section: electronics / repair

author: trevers
author_rank: Contributor
timestamp: November 19, 2020, 12:59:52 am
content: My Bosch washing machine's motor control board has failed. After removing the board I found that there seems to be purposefully undersized traces being used as a brute force "fuse". In the attached picture I show the failed traces. There are two of them on either side of a NTC. Do you think that I would be risking fire if I repaired the trace with either conductive paint or a piece of wire wrap wire?Thoughts?

author: langwadt
author_rank: Super Contributor
timestamp: November 19, 2020, 01:27:13 am
content: soldering in a single strand from a wire is probably not worse that what was there but, a burned fuse is seldom the cause of the problem

author: TheMG
author_rank: Frequent Contributor
timestamp: November 19, 2020, 02:21:50 am
content: If those fusible traces blew, they probably blew for a reason. Check for shorted transistors (likely IGBT type).

author: JFJ
author_rank: Regular Contributor
timestamp: November 19, 2020, 12:40:31 pm
content: Quote from: trevers on November 19, 2020, 12:59:52 amBridging the trace with a suitably sizedsurface mount fusewould be a safer and more predictable option.
Understanding a Power supplies voltages-Help please. - Page 1
Forum section: electronics / repair

author: djsb
author_rank: Super Contributor
timestamp: May 03, 2020, 09:31:02 pm
content: I'm trying to simulate this power supply using Qucs-s, LTspice and Micro-Cap 12. I can't figure out how it works and if the 0v rail is positive and at what voltage.I basically want to provide another circuit with the same voltages WITHOUT having to build/simulate this power supply. I can usually reduce a supply like this to batteries. Not this time. Can someone help me to figure it out? Thanks.

author: George Edmonds
author_rank: Frequent Contributor
timestamp: May 03, 2020, 09:59:22 pm
content: HiThis supply provides -12VDC and -18VDC the ground/0V is tag point 6 or U1/6Hope this helpsGeorge

author: james_s
author_rank: Super Contributor
timestamp: May 03, 2020, 11:14:15 pm
content: Voltage is always relative, 0V just denotes the reference point, in other words it's "ground".

author: George Edmonds
author_rank: Frequent Contributor
timestamp: May 03, 2020, 11:33:09 pm
content: 3. 1 .8. SUPPLYThe plus potential of the - 1 2 V and - 1 8 V supply a re connected to circuit zero. Both sources are stabilized.The un stabilised voltages are produced by rectifier 405 on unit 2. The output voltage, divided by resistors637/638/639, is compared with the reference voltage across zener diode 404 via operational amplifier 322.The output voltage of operational amplifier 322 controls series transistor 3 1 1 v ia current amplifier 3 1 2 .The offset-voltage of the operational amplifier is reduced b y resistor 64 1 . The short-circuit it current of the - 1 2 Vsupply is l limited by resistor 645.The stabilizing circuit for the - 1 8 V supply is the same as given for the - 1 2 V suppy. The reference voltage isthe - 1 2 V supply. The output voltage is compared with the reference voltage via voltage divider 635/636.A separate secondary winding of the mains transformer supplies the voltage for the scale illumination ( lamps8 1 1 ... 8 1 3) and for the il illumination of the indicator via switch 803/1 A ( button CAL).This is the explanation given in the service manualThe circuit zero (0V) is U1/6 which is the instruments common which may or may not be connected to the metal case work or the incoming mains supply CPC (earth)George G6HIG

author: coromonadalix
author_rank: Super Contributor
timestamp: May 04, 2020, 01:56:37 am
content: Your ground is "indeed" pin 6 or u1/16You could say : your supply / floating ground is pin3 of the board going to the transformer pin 12, when you debug psus like this you tend to go on the common point of the 2 main capacitors (1000uf) for the meter groundSure you will have the 12volt difference and the 18 volt too, relative to the floating ground, it could play some tricks with the circuit ground, if you dont know where to take your measurementsThey used the pin 6 u1/16 pin as a ground to simplify the op amps supply pins ... thats the way i see it, no need for additional psu voltages for them.my 2 cents
understanding analoug meter movements - Page 1
Forum section: electronics / repair

author: Audiofanman
author_rank: Contributor
timestamp: August 23, 2025, 04:15:47 pm
content: Hello all,I have an inexpensive vertical panel mount 1mA, 250Ω full deflection mA meter and while most of the ones I bought for other projectshave been reasonably accurate this one must have taken a hit while in shipping.I wasn't too upset as I bought this one with the full intent of it being a sacrificial test box for my education...When I opened it up, I saw the tail piece rubbing, and with a little bend the needle moved without impingement.Unfortunately, (or fortunately for my education) it still appeared off enough in its readings, and its return to zero not being reliable that it beckoned me to dig deeper.Fast forward a bunch of discovery's (aka, things I probably should NOT do Lol) later, the nut for the zero adjust became loose..Yup, time to put the shovel down as I don't see daylight anymoreNow that Im much deeper than expected, the typical "trial and error" is not helping...I have scoured the I-way for as much as I could find. A few days later, 3 or 4 old articles posted here and there, a few knowledgeable folks across a few forums added insight. Most of the content spoke about balancing and cleaning.At no point did I read about setting initial hairspring tension.Is the hairspring in a "neutral" position when on an already mostly balanced pointer ORis the balance of the pointer part of and integral to the hairsprings action ?Reading all of the articles I could find say to first adjust the zero so the pointer reads zero before balancing,but now Im wondering if those authors assumed that the hairspring was already mostly correct.In a perfect world I'd imagine the steps to be ...1) set hairspring so no tension is applied to pointer and pointer is at zero while the face plate is in the vertical position (How its designed to be mounted).2) secure hairspring lock nut.3) balance pointer, rotate meter so zero is horizontal to pointer pivot add/remove weight so pointer is horizontal and at zero.. Rotate so zero is vertical of pivot, add remove side weights so pointer remains at zero.4) verify zero adjust still on in typical mounted position5) If zero off, re-adjust for zero and verify pointer balance.Again, in a perfect world, the feedback loop from 5 and 3 above would be TINY...What Im getting is such a large change, that the "feedback" loop is too big, like some sort of preload on the hairspring is required...Hoping someone has some insight on this chicken or egg chase I'm on..

author: Audiofanman
author_rank: Contributor
timestamp: August 23, 2025, 05:04:29 pm
content: Quick update.. I blindly have 0 being an actual 0 and 1mA exactly at full deflection.0.5 mA is half deflection.Not sure how I stumbled on needing more tail weight, but managed to add a seemingly imperceptible amount of weight... good enough.Im still interested in the question above though.
UNI-T UPO 2000CS series, UPO 2074 CS - need firmware - Page 1
Forum section: electronics / repair

author: avrusb
author_rank: Newbie
timestamp: July 12, 2024, 07:03:23 am
content: Hi thereI recently got a UNI-TREND oszilloscope UPO2074CS with an interrupted firmware update. It starts up with message in picture 1. When I put in a blank USB stick in, it searches for Firmware (USB stick blinks) and then gives up. (picture 2)I can't ask the former owner, he is deceased.I already looked on UNI-T website, could not find anything related to the UPO2000CS series. And I already emailed to tech support, no answer.If anyone has the firmware for UPO2074CS and perhaps the software for PC, would be appreciated!
Uni-t UPO2104CS Oscilloscope Flash dump required - Page 1
Forum section: electronics / repair

author: kkamel
author_rank: Contributor
timestamp: December 07, 2022, 04:25:33 pm
content: HiMy Uni-t UPO2104CS failed after firmware update, it hangs on Uni-t red logo, when I try to reflash it detects the USB but still fails to reflash.I need full NAND flash dump urgently as it is my only scope, can anyone help?Thanks

author: coromonadalix
author_rank: Super Contributor
timestamp: December 07, 2022, 05:29:01 pm
content: hiHave you asked Uni-T ?? if there is other ways to recover your unit ?
Uni-t UT139B Incorrect Measurements - Page 1
Forum section: electronics / repair

author: Lebronics
author_rank: Newbie
timestamp: April 17, 2025, 06:02:55 am
content: Hi people!!Since two years I've been working with my UNI-T UT139B multimeter without problems. Since monday, it started to work wrong.The first thing I noticed was when I was measuring my house supply voltage (it should be around 220v), but my device showed 190v. Later I've tried to measure a 9v battery and it showed 7.5v.I've compared my device with other and I've realized mine was broken. I've opened it, all apears to be in excellent conditions. I've cleaned it but the problem continued.Anyone had a similar problem? Anyone have an idea about which could be the problem?Thanks in advance!

author: Sorama
author_rank: Frequent Contributor
timestamp: April 17, 2025, 06:05:25 am
content: Quote from: Lebronics on April 17, 2025, 06:02:55 amHave you checked/replaced the internal battery?

author: Zenith
author_rank: Frequent Contributor
timestamp: April 18, 2025, 12:09:25 pm
content: If the battery doesn't have enough life left in it, you should have a low battery warning on the display. It's worth fitting a new battery anyway. I think it's two AA cells.If that doesn't fix it, open it and have a look for anything obviously wrong, such as a loose wire, or something causing a short. A lot of faults are caused by simple things, such as bad connections.If it's a genuine non-obvious fault, the DMM is probably scrap. Equipment at that price is not designed to be maintained and I doubt you could find a service manual or even a schematic.

author: MathWizard
author_rank: Super Contributor
timestamp: April 19, 2025, 04:21:35 pm
content: I'd measure some known voltages, and resistances on the different ranges, and write them down or put in a spreadsheet, and see if there's a clear pattern. Maybe some resistor or switch, or solder joint, in the input signal path is having a problem.
Uni-T UT210E PRO Current Reading Error/Failure and Repair - Page 1
Forum section: electronics / repair

author: Mrnt
author_rank: Contributor
timestamp: March 11, 2025, 04:45:58 pm
content: This post is intended to help anyone else that experiences this particular symptom with their UT210E or UT210E Pro ...My Uni-T UT210E Pro recently failed wrt making current measurements. All other measurements (AC/DC volts, Ohms, Hz, NCV) seemed fine, but when each of the three AC current ranges was selected it read 0.000, 00.00, 000.0A respectively and for DC it read "OL". This behavior was the same regardless of whether the device was clamped around a cable carrying current or not.After double checking the rotary selector switch was working correctly, I probed the current detection circuit using theschematic (attached to post #6 in the thread)and discovered the quad op-amp U4, which is set up as an instrument amplifier, was toast - equal voltages of 0v or something small applied at its input pins 3 and 6 produced something fantastical (like rail voltage) at the output pin 14. According to the schematic this is supposed to be a OPA4330, but on my device it was a Chinese knockoff.To repair - remove the board by unplugging the flex cable, desoldering the green wire and unscrewing the 3 black screws as indicated below:Cover the area surrounding U4 with Kapton tape, paying special attention to the speaker right next to it, and then remove the chip and clean up as required before replacing. Replacement part OPA4330AIPWR is available fromMouser, Digikey.Replacing U4 with a real OPA4330 has fixed the problem, though I am not sure what caused the original part to fail - perhaps attempting to measure too high of a current can overdrive the inputs of the op-amp to point of failure?