hybridfree/eevblog-posts huggingface dataset:
USB data line protection IC, can't find the part number - Page 1
Forum section: electronics / repair

author: Vicus
author_rank: Regular Contributor
timestamp: March 10, 2025, 11:32:15 am
content: Dear all, I need help to indentify what I think is a data line protection IC. The product is a IK multimedia audio card with a usb link to a computer. The car did power up but no comunication with the pc. I did remove this ic and comunication now work. I think is some TVS diode array but I can't find any that match the pinout. On pin 1 and 2 the data line, on pin 2 GND, on pin 4 and 6 5V from usb and pin 5 NC. Picture attached. The marking is PKt but I can't find any corresponding parts. Thanks.

author: Vicus
author_rank: Regular Contributor
timestamp: March 10, 2025, 11:46:52 am
content: Maybe I found it:https://www.littelfuse.com/products/overvoltage-protection/tvs-diode-arrays/connectivity-tvs-diode-arrays/sp4010/sp4010-02htg

author: squadchannel
author_rank: Frequent Contributor
timestamp: March 10, 2025, 11:51:21 am
content: PUSB2X4Y

author: Vicus
author_rank: Regular Contributor
timestamp: March 10, 2025, 04:28:30 pm
content: And in your opinion why pin 4 and 6 is tied to +5V?

author: Vicus
author_rank: Regular Contributor
timestamp: May 03, 2025, 05:47:14 pm
content: So, I did order SP4010-02HTG but it doesn't fit. Too big. I did order RCLAMP0504FATCT by SEMTEC wich is very similar of PUSB2X4Y but it doesn't work. I will leave it without protection considering the cost of the audio interface is no worth more try.

author: Aheld
author_rank: Regular Contributor
timestamp: May 05, 2025, 08:20:46 am
content: The PUSB2X4Y is outdates, but you can use the IP4220CZ6 device from Nexperia as replacement.It can be that the footprint will not fit perfectly but pinning should be same.The advantage of this device is that the Vbus pins is also protected. At PUSB2X4Y, the Vbus pin is not connected.Br.Axel

author: Vicus
author_rank: Regular Contributor
timestamp: May 05, 2025, 07:14:21 pm
content: It's too big but this is not the point, I think that none of this TVS work considering that in the board pin 4 and pin 6 are connected to Vcc.

author: wraper
author_rank: Unknown
timestamp: May 05, 2025, 07:20:07 pm
content: Quote from: Vicus on May 03, 2025, 05:47:14 pmIt's not. PUSB2X4Y pin 5 is NC, RCLAMP0504FATCT pin 5 is VUSB (5V). PUSB2X4Y's TVS diode must have a very low capacitance for this to work. RCLAMP0504FATCT should work if you run a bodge wire from pin 5 to VUSB.Quote from: Aheld on May 05, 2025, 08:20:46 amNo, only if you do as I suggested above.

author: Vicus
author_rank: Regular Contributor
timestamp: May 05, 2025, 07:27:14 pm
content: In the PCB pin 5 is NC. I did try RCLAMP0504FATCT and the device couldn't be recognize correctly by the PC.

author: wraper
author_rank: Unknown
timestamp: May 05, 2025, 07:31:26 pm
content: Quote from: Vicus on May 05, 2025, 07:14:21 pmShort either of them to pin 5 and RCLAMP0504FATCT should work.
USB receiver repair - Page 1
Forum section: electronics / repair

author: exacto
author_rank: Newbie
timestamp: January 23, 2024, 04:49:52 am
content: Hi, I'm fairly new to electronics repair but have done a few basic repairs and am currently attempting to solder a male USB plug onto a PCB which got torn off. Three of the pins are fine but the one I have highlighted yellow on the attached image has had the pad torn off. I'm happy to run a wire from the pin to wherever it's meant to go but it's not clear to me where that is. Any help would be appreciated.

author: wasedadoc
author_rank: Super Contributor
timestamp: January 23, 2024, 12:59:38 pm
content: That is 5 Volt into the device. Will go direct to the Vcc pin(s) of ICs and/or the input pin of a voltage regulator. Need to see a good photo of the complete board.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 23, 2024, 01:51:36 pm
content: If I needed to place a bet I'd say the cap just below it.

author: exacto
author_rank: Newbie
timestamp: January 24, 2024, 03:33:05 am
content: Thanks for the reply! Here's a photo of the complete board.
usb speakers have emc problems - Page 1
Forum section: electronics / repair

author: austin4705@gmail.com
author_rank: Newbie
timestamp: July 27, 2020, 05:00:15 am
content: i just got some cheap usb speakers with no external power (Logitech s150) and when I plug them into my PC it works but there is that emc static. on my laptop it works fine leading me to believe that its emc related. ik how to fix emc with power with a mains plug, but not with USB power. any ideas? I don't own a female to male USB with ferrite bead but does anyone think that could work? thanks btw.

author: m3vuv
author_rank: Super Contributor
timestamp: July 27, 2020, 07:32:35 am
content: maybe an idea to stick a 0.1uf cap between the usb +5v and ground?,just an idea.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 27, 2020, 11:25:31 am
content: open your speakers to check if they have an added shielding around the speakers magnet, you'll know if they are magnetically shielded too, just in case ?
USBASP - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: January 30, 2022, 09:02:46 am
content: Hello everyone! I am looking for the different software for windows 10 64 bits to use an Arduino programmer that I hope to receive soon.... Could someone help me?? (see picture) Thank you very much

author: razvan784
author_rank: Regular Contributor
timestamp: January 31, 2022, 10:14:13 pm
content: Wow, people are still using USBASP, nice! I myself occasionally use a USBASP clone that I hand-built more some 15 years ago and programmed with a PC parallel portCan't say anything about the Arduino IDE, if that's what you're talking about, that is usually used with boards that include some built-in programmer or bootloader.For just programming AVR microcontrollers with prebuilt hex files, avrdude works perfectly on Win10 64bit.One simple way to get it is to use the Chocolatey package manager. Just install Chocolatey and then runchoco install avrdudein a console.For AVR development with C and Makefiles on Win10 I use the Microchip AVR toolchain, which is gcc-basedhttps://www.microchip.com/en-us/development-tools-tools-and-software/gcc-compilers-avr-and-armand MSYS2https://www.msys2.org/Edit: To use the USBASP on Windows it also needs a driver which is based on libusb; here I don't quite remember the details but I think I used zadig to install the libusb-win32 driver:https://zadig.akeo.ie/

author: lionelkjh
author_rank: Frequent Contributor
timestamp: February 01, 2022, 12:28:13 pm
content: Hello; ok, thank you for this information which already helped me a lot this morning....... In reality, it's to reprogram a Chinese tester MK-328 (display in blue); and I am looking for the 2 original files (hex+eeprom) to fix it.... If someone can help me find them... Cdt

author: Dumidan
author_rank: Contributor
timestamp: February 15, 2022, 01:01:09 pm
content: Hilionelkjh!Here is a dedicated topic:https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/No need to read all over 290 pages (although it would be useful), the last 15-20 pages are uplifting.And here is the software & other info:https://github.com/madires/Transistortester-Warehouse.

author: Dumidan
author_rank: Contributor
timestamp: February 15, 2022, 01:18:08 pm
content: For programming the ATmega 328 MCU I use a USBAVR and an Arduino AVR ISP shield, only for the ZIF socket.On the software tools side I use WinAVR (Programmer's Notepad), AVR tools chain and AVRDUDESS.
Use an simplex impulse clock as a regular wall clock - Page 1
Forum section: electronics / repair

author: electrofix
author_rank: Contributor
timestamp: December 20, 2024, 10:21:16 pm
content: I have a simplex 6310-9075 that I want to use as a normal clock. Currently it is an impulse clock that can receive signals for correction from an impulse system. I do not have the impulse system. All I have is a 24vdc transformer which is the voltage it requires. How would I connect it to bypass the "impulse" system and use it as a regular wall clock? Here are some pictures:
Use diode to feed power from two sources - Page 1
Forum section: electronics / repair

author: Kiss4aFrog
author_rank: Newbie
timestamp: August 18, 2019, 01:40:58 am
content: I have a 2007 Fleetwood motorhome with a LP detector. The old detector had two hots and a ground. One from the house batteries and another from the starting batteries. The replacement detector only has one red and one black lead. The instructions say to cap the starting battery lead and just use the lead from the house batteries. I like the idea of keeping both sources of power just in case something is left on and one of the two banks gets run down. I'd get an exact match detector but that company no longer exists. Can that be achieved by the use of two diodes connecting the two hots to the one lead of the replacement detector? If so what diode would you recommend?MTI 30 series LP detectorhttps://www.mtiindustries.com/PDFs/rv/30_Series.pdf

author: pigrew
author_rank: Frequent Contributor
timestamp: August 18, 2019, 01:51:50 am
content: Yes, since it is somewhat low voltage DC, diode ORing them would work. The diode would reduce the voltage sightly (maybe by 0.5V), but the detector can operate down to 8V, so all would be well. I would use a pair of 1N4007.The downside is that this does not give priority to one source or the other (the one with higher voltage will be discharged). You maybe be able to use multiple diodes in series on the secondary supply to reduce its voltage to be less than the primary supply voltage (as long as the result is at least the required 8V). More complicated circuits with transistors could be constructed to better control the priority.A few uF (10uF 50V) capacitor wouldn't be a bad idea at the output of the diode circuit. Ceramic capacitors would be preferred since electrolytic can have issues with temperature extremes.
Used keithley 2602 SMU misbehaving - Page 1
Forum section: electronics / repair

author: bitter_mike
author_rank: Contributor
timestamp: June 08, 2020, 01:25:42 am
content: Hey all,I'm hoping for some advice tracking down a problem with a used Keithley 2602 dual SMU that I have. The second channel ("Source B") works perfectly: you set it to 5.0000V, it puts out 5.0000V, and correctly measures it's own output as 5.0000V. The first channel ("Source A") is the misbehaving one. It's not regulating its output correctly. If I set it to 5.0000V, it puts out around 5.2V, and that output drifts up quite a bit if I let it sit there, like 10s of mV over the course of a few minutes. This is in comparison to Source B, which is rock steady. Source A is correctly measuring that it's putting out 5.2V or whatever it is, it just won't put out what I tell it to.I'm not particularly experienced in repair of something as complex as this, so I'm hoping someone has a little more experience with this unit than I do. It was really cheap and its sooooo close to working perfectly and I'd like to get it there.Appreciate any help.
Using an LCD display in replacement of a defective VFD - Page 1
Forum section: electronics / repair

author: Z. Khalid
author_rank: Contributor
timestamp: October 22, 2023, 12:30:34 am
content: Hello there!I’m considering using the LCD with the part number ACM4002E-FL-YBW from AZ Displays to supersede the vacuum fluorescent display M402SD10fj from Futaba. Please refer to the attached data sheets..The mode of operation of the VFD is Motorola M68-type parallel mode.Are there any modifications related to the working assembly/LCD (rather than supplying the pins 3, 15 and 16 of the LCD with the appropriate voltages) shall to be taken into consideration?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 22, 2023, 12:55:16 am
content: normally if you are in the same controller series, the character table should be fine say HD44780 or KS00065B ... ST 7066yes pin 3 on some model may need an negative voltage, some contrats is a pot going to ground for a full contrast, no negative voltage needed etc ... depend of the modelsome have the needed stuuf already on the pcb ...the backlight, some are led is 5vdc and other are high voltage ... fluorescent something loll damn its late cant recall lolli dont see the one on the futaba

author: coromonadalix
author_rank: Super Contributor
timestamp: October 22, 2023, 01:02:05 am
content: https://www.ebay.com/itm/195935049078?https://www.ebay.com/itm/134088189740?yes one of them is a shipping disaster .... i would contact the sell to have a real price, not a scam like thisthe other problems could be size, and compatibility, since the futaba has serial parallel modebetter buy another identical one from the link, you could need some trick or add another mcu to do signal conversion etc ... maybe not worth it ??

author: Z. Khalid
author_rank: Contributor
timestamp: October 22, 2023, 02:18:57 pm
content: Thank you for your reply..- M402SD10fj module has HT16514 controller/driver whereas ACM4002E-FL-YBW uses KS0066 (or equivalent as stated in the data sheet).- Unlike LCDs, vacuum fluorescent displays don't require backlighting.- I've already ordered some of M402SD10fj from eBay. Unfortunately it needs a long time to be shipped from the US to the Middle East..
Using different pot resistance for cue knob - Page 1
Forum section: electronics / repair

author: Crumbs00
author_rank: Newbie
timestamp: August 05, 2024, 01:09:38 am
content: Hi all!I’ve got an Ecler Dj Mixer that I’m in the process of servicing. Both the volume knob and the cue/pfl (the one to blend between the cue track and master track in your headphones) both need replacing.The volume pot is fine, I have the correct replacement, however it turns out that the cue/pfl used is a 5kbx2cc pot, however I only have a 50kbx2cc (which is the same pot used for the EQs), and funnily enough, the line of mixers after this one use 50kbx2cc for the cue.Wondering whether the 50kb would still work?

author: m k
author_rank: Super Contributor
timestamp: August 09, 2024, 07:03:33 pm
content: For adjustable resistor you have 1/10 of mechanical scale.For voltage divider you have 1/10 of current.Both ends can be fine, but center can be problematic.So a strong maybe.
Using NiCd charger on NiMh battery?  - Page 1
Forum section: electronics / repair

author: woodchips
author_rank: Frequent Contributor
timestamp: September 01, 2021, 05:56:04 pm
content: Have a very old Makita 18V 8390 drill using the original 1.3Ah NiCd batteries. The chargers all say they will cope with multiple voltages and also NiMh cells. Asked Makita and no reply, as usual.If I recell the battery, do I have to connect the currently unused terminal inside the charger to the battery? If so where? What happens if I don't?Snag is the cost of NiCd or NiMh cells makes re-celling these batteries uneconomic. The NiMh cells came out of some old test gear, they will take a charge but not tried a whole battery full of them. I changed the cells to a Bosch 18V 1.5Ah or 2Ah lithium battery that plugs in, remove to charge in the Bosch charger. At £20 each these were by far the cheapest 18V batteries I found.The drills are all perfectly ok, done an immense amount of work in 15+ years and I am seriously irritated that Makita changed the battery style to force me to buy a new, unwanted, drill. Note that Ryobi didn't with there one+ series.Thanks.

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2021, 06:50:33 pm
content: If a NiCd charger uses negative deltaV to detect charge termination, then it will overcharge and damage a NiMH battery. But I have noticed that many NiMH power tool chargers use temperature rise of the cells to terminate charging and that may work if you change the batteries from NiCd to NiMH. It is still pretty hard on the batteries though.

author: Haenk
author_rank: Super Contributor
timestamp: September 02, 2021, 02:06:20 pm
content: I have one Mafell/Milwaukee drill, that came with NiCd, but the carger stated "NiCd/NiMH", so I replaced the original NiCds by 3rd party NiMH - works flawless (bith charger and drill), though has a bit less power it seems (probably less peak Ampere).If it's printed on the charger, you are good to go, I'd say. (They won't print that on without a reason...)
Using rosin to find a short on a PCB - Page 1
Forum section: electronics / repair

author: Bryan
author_rank: Frequent Contributor
timestamp: January 29, 2022, 09:47:36 pm
content: Stumbled upon this video, interesting never heard of this technique before. Good stuff starts at around the 5:00 minute mark.https://youtu.be/DhsRCpeONwU

author: rob77
author_rank: Super Contributor
timestamp: January 29, 2022, 09:56:41 pm
content: yes it's quite common.. either rosin smoke as he does or rosin dust applied with a fine brush, but i think a quick spray with isopropyl alcohol is faster (you watch where it evaporates quickly).
Using Tektronix FAS in semiautomatic mod with HP3456A DMM - Page 1
Forum section: electronics / repair

author: micaticu
author_rank: Contributor
timestamp: May 02, 2022, 06:36:39 pm
content: Hello everyoneI have just restarted after a long pause my attempts to recalibrate my TDS784C scope.Using an old PC + DOS 6.22 + a GPIB PCIIA ISA card + Tektronix FAS (Field Adjustment Software TDS700C) + my DP8200 calibrator and my HP3456A dmm, I succeeded manually to pass the first part, the CVR_CAL. I stopped before continuing with the HF_CAL step.My target so far is to see if the installation and configuration are solid for the next step - automation.Now I am trying to run the same steps in semiautomated mode.First I have succeed to configure the FAS to automate the calls for the DP8200 and went again through the steps mentioned previously, for the CVR_CAL. Even if I had to turn the CATSTRACE on, in order to solve what I think is a speed (or timing) problem on the GPIB bus, the system went slowly (extremely slowly) through the CVR_CAL steps, controlling automatically the DP8200 settings and asking me only to switch cables and to input the readings from the HP3456A.Happy with this partial success, I tried to enable also in the GCONFIG file the automation of the Dm1 option with HP3456A (as I found the "hp3456a" string, together with other device strings, inside the TEST.EXE file, upon inspection).Unfortunately, after restarting of the FAS, when reaching the point where CVR_CAL is trying to activate the Dm1, and after instructing me to connect the cables to CH2 of the scope, I have an error message stating:"Unexpected call to stubbed out function hp3456a()", followed after I press <Enter> by"DRIVER ERROR-> CANNOT RESET Dm1".And of cause I have to abort the sequence.Did any of you have any experience trying to automate the FAS using an HP3456A? Or any suggestions on how I might solve this problem?Is it possible?Thanks in advance for any input.

author: micaticu
author_rank: Contributor
timestamp: May 05, 2022, 06:31:38 am
content: An update regarding my previous post.Switching from FAS TDS700C to TDS700D, I solved the problem of being forced to run painfully slow, with the CATSTRACE variable switched to ON. With the TDS700D version the FAS runs quickly trough the CVR_CAL steps without any problem or need to set the CATSTRACE to on.The automation of the HP3456A though, is still a problem. It maybe that that the instrument is not supported, even if its name is found buried somewhere inside the TDS700CG.EXE file.Any ideas?
UT 161 B selector - Page 1
Forum section: electronics / repair

author: mzdenkov
author_rank: Regular Contributor
timestamp: June 05, 2024, 08:03:53 am
content: HelloI've dissembled my UT multimeter and i saw a half broken "leaf spring contact"(or how are they called) on its selector .Is this normal or? Because when i look at it, this is a defect, but i stand to be proved wrong.Ive contacted the store where i bought it, but they say this is ok.Best Regards

author: BILLPOD
author_rank: Frequent Contributor
timestamp: June 05, 2024, 06:11:03 pm
content: Good Morning Mzdenkov, If you can return it, do so; don't believe the store telling you it is 'OK', it's not. It might work for a while, but it flexes as you turn the selector knob, and will eventually break at the end opposite the current break, (I believe).

author: coromonadalix
author_rank: Super Contributor
timestamp: June 05, 2024, 06:16:11 pm
content: for sure IT IS not okay return this

author: mzdenkov
author_rank: Regular Contributor
timestamp: June 05, 2024, 06:55:44 pm
content: I had a conversation with the service people.They told me that they've dissembled another NEW unit and compared it to mine, and they saw the same symptoms...So their conclusion was: "this is how manufacturer wanted it to be for better springiness of the contact" - rough translation.+ if i disassemble it again ill lose my warranty.Its like fighting with a wall when you talk to this people, so ill try to solder it together because i know it will break after 1year of usewhich is outside of warranty period.Basically 70€ trowed in the drain.Thanks for your answers.
UT139C repair - Page 1
Forum section: electronics / repair

author: Falkra
author_rank: Regular Contributor
timestamp: April 04, 2021, 04:32:55 pm
content: Hello,I have a Uni-T UT139C and I am trying to repair it.It is faulty : it beeps continuously on every position of the contact switch and the display has every segment ON or does not display anything at all (but the beeping continues).I reprogrammed the 24C02A eprom with factory code (it was modified, probably with a hack that went wrong) using code fromthis topic, using an eprom programmer).I checked for shorts and found Q2 Q3 Q8 and Q9 diodes are shorted when on circuit. Out of circuit they check good. Removing all four didn't clear the short on the motherboard.C16 cap is shorted when meter is set to OFF using selector switch, but not when ON. Contacts of the selector switch are clean and I cleaned them, same for the zebra strip screen contacts.Pictures (not of mine) can be found here :https://lygte-info.dk/review/DMMUNI-T%20UT139C%20UK.htmlI'm a hobbyist, and I'm making progress, I unsoldered and resoldered the SOT-23 diodes correctly with an iron (no hot air this time) and that makes me happy, it's the way to learn, trying on inexpensive stuff.I'm thinking maybe the main chip/cpu is dead.But I don't now how to check this. I'm looking for clues.
UT181A Repair help needed - is my frontend ic toast? - Page 1
Forum section: electronics / repair

author: protonstorm
author_rank: Newbie
timestamp: October 11, 2021, 03:16:54 pm
content: Hi EEV-ersI noticed low resistance readings on my 3 year old UT181A:A 3.9Ohm resistor reads as 0.3Ohm in the Ohm Range and as 0.0033Ohms (3.3Ohms) in the kOhm range.I can't understand where the problem is coming from.From what I can tell, capacitance readings are also slightly low (100nF reads as 84nF) but mV DC seems to be spot-on.What I checked so far:- Checked the 100Ohm resistor for high precision Ohm Range on the back of the PCB, it reads 100 Ohms- I removed the 3 sections of protection transistors (as outlined) - No change- I removed the capacitor near the resistance / capacitance Input (as circled) - No change- I removed the MOVs (as outlined) - No change- I checked the resistors in front of the output and input pins (Pin 26-28) - they seem fine- I can't see anything on the board looking damaged- The 2*2 PTC Thermistors measure 1.15kOhm with only little deviationES51997 Datasheet:https://pdf1.alldatasheet.com/datasheet-pdf/view/456328/CYRUSTEK/ES51997.htmlI have no experience in multimeter repair, so help would be much appreciated, if only to point in some direction.Could it be that the front end IC itself is damaged or needs calibration?
UT61E DC voltage measurements problem - Page 1
Forum section: electronics / repair

author: Buhefade
author_rank: Newbie
timestamp: July 14, 2024, 06:46:32 pm
content: HelloI tried to dig through Ut61e posts but I wasn't able to find similar problem-On DC voltage (both auto/manual) display can't be zeroed even when probes shorted (shows small negative voltage)-gives different results when probes switched. Example: read out +4.5V - > switch probes and same potential read out - 2.4v.-measurements are not sonsistent in overall.Tried:Board nad main switch cleanedVR1 replacedCorrected soldering around main IC

author: Mickle T.
author_rank: Frequent Contributor
timestamp: July 16, 2024, 06:36:11 am
content: If there is no contamination on the printed circuit board and on the switch lamellas, then I see only two reasons for the zero shift of the multimeter: failure of the auto-zero correction capacitor C6 470nF (pin 14) or breakdown of the input circuits of the ADC U1 ES51922.
Ut61e doesnt change ranges in auto mode - Page 1
Forum section: electronics / repair

author: doniceti
author_rank: Newbie
timestamp: October 27, 2023, 07:43:26 pm
content: Hi everybody,My multimeter auto mode doesn't work- it doesn't want to change the ranges. No problems with measurements if I manual choose the range. Has anyone had the same problem or idea what's wrong?Thanks and sorry for bad English!
UT71D burned down. - Page 1
Forum section: electronics / repair

author: Nigmas_2025
author_rank: Newbie
timestamp: August 23, 2025, 07:38:30 am
content: Hello everyone, a reliable UT device has burned out. The short circuit was +5.5 volts and 3.5 volts. I soldered out the processor and chip, and the short circuit was eliminated. I was wondering if it was possible to purchase a replacement chip, as I was very attached to this device, which I had been using for 10 years.
UT71D - Page 1
Forum section: electronics / repair

author: ganteng
author_rank: Newbie
timestamp: October 09, 2020, 08:08:04 am
content: My UT71D is error on displaybut if i sellect SETUP..the display is OKbut if i select any mode the display has errorany suggest for my problem?i'll try to write the bios rom but i don't have itanyone have it?maybe can help for my UT71D problem

author: tkamiya
author_rank: Super Contributor
timestamp: October 09, 2020, 06:24:51 pm
content: I'd try fresh batteries....After that, I'd open that up and see if there is anything obvious going on, like corroded connections, burned components, etc. It was working for you for a while and now it's not, or is this a new purchase?

author: MosherIV
author_rank: Super Contributor
timestamp: October 09, 2020, 09:34:09 pm
content: Some dmm have test mode to test lcd, just keeps all characters on.Usually enabled by pressing a certain button when turning on.So maybe, one of the buttons is stuck on.

author: Jasonbit
author_rank: Regular Contributor
timestamp: October 09, 2020, 10:20:51 pm
content: Hello,Maybe on this webiste you can find what you need to solve the issue (https://www.uni-trend.com/html/product/General_Meters/Digital_Multimeters/UT71_Series/UT71D.html).The error on display does any code appear? Maybe share this issue with manufacturer can help.Maybe you can compare your equipment with this need equipment, on video ()

author: ambrosia heart
author_rank: Regular Contributor
timestamp: October 10, 2020, 01:49:46 am
content: any suggest for my problem?i'll try to write the bios rom but i don't have itanyone have it?See photo. If I2C paths signal ACK( communication signal ) is OK, Bios is needed.If you don‘t know what I am talking about, just let it be.initalizing.JPG(67 kB. 800x600 - viewed 122 times.)

author: ganteng
author_rank: Newbie
timestamp: October 10, 2020, 03:20:27 am
content: any have bios?

author: Mickle T.
author_rank: Frequent Contributor
timestamp: October 10, 2020, 05:43:04 am
content: M430F149 firmware is protected. You will never get it.I think the problem is a bad ADC.

author: rsjsouza
author_rank: Super Contributor
timestamp: October 10, 2020, 11:17:33 am
content: Quote from: MosherIV on October 09, 2020, 09:34:09 pmGiven the state of the meter (did it fall into a pool of mud?) I would open it and perform a thorough cleanup of the board, especially around the rotary switch and around the main IC.And yes, the main IC has internal flash and is protected.

author: payn
author_rank: Newbie
timestamp: July 19, 2023, 05:30:44 am
content: Had same problem.The copper track at the top(top of meter) of the 4MHz crystal had broken just after where it comes trough the board and attaches to the crystal. If I applied a little pressure to the crystal the meter came back to life, however as soon as I released the pressure the fault returned.Difficult to reuse the smd crystal so I replaced the 3.999FSHM with 4MHz one, trimming legs so that they could be soldered to what was left of the through board copper track.
UTG2025A Generator repair (Dump needed) - Page 1
Forum section: electronics / repair

author: XgN
author_rank: Newbie
timestamp: May 30, 2020, 07:30:39 am
content: Hi guys!Bought this Uni-T UTG2025A Function/Arbitary Waveform Generator. It is booting and freezes on the boot logo forever.Inspired by EEVBlog Siglent repair video, I logged booting data (please see UTG2025A_Generator_Boot_Log.txt attached). Seems to be an error kind of RAM or firmware corruption itself. RAMs are on their way to me. Of course, Uni-T does not reply to my inquiry, what's concerning FW. Maybe someone has dumped this generator and would share with me?Thanks in advance!

author: sata-sata
author_rank: Contributor
timestamp: February 17, 2022, 05:19:15 pm
content: https://www.eevblog.com/forum/testgear/uni-t-utg2025/Good afternoon . sorry for posting in someone else's threadwith the permission of the author - I will continueunfortunately I did not see your topic and wrote there. the problem is exactly the same as yours and the log stumbles almost in the same place. . I posted my dump nand , logs , measurements , photos and videos. wonder how you ended up?I posted a lot of information on it in that discussion thread.

author: vlsi14
author_rank: Newbie
timestamp: September 15, 2022, 09:08:13 am
content: hi, i have the same issue. if you have any information solving this problem please e-mail me
UTI-8N05 replacement - Page 1
Forum section: electronics / repair

author: PKTKS
author_rank: Super Contributor
timestamp: March 28, 2021, 06:25:17 pm
content: This little bastard looks and fits like an ordinary thermistor..Uncle google could not find a single reference for UTI.From the common sense these codes 8N 05usually indicate the steady state rating and package..Unsure if an ordinary 3A or 5A would fit this bastard...Anyone familiar with UTI ?ThanksPaul

author: RayRay
author_rank: Frequent Contributor
timestamp: March 28, 2021, 08:05:44 pm
content: Quote from: PKTKS on March 28, 2021, 06:25:17 pmReally? But I found plenty of results for Urinary Tract Infections!For reals though, judging by the markings, it's most likely a 5 ohm one (I'd imagine 5D-9 would be compatible)Have you tried testing it with a multimeter? Also, could you specify what product/model number the circuit board belongs to? I might be able to find the parts lit/schematic for it.See these videos btw:

author: PKTKS
author_rank: Super Contributor
timestamp: March 29, 2021, 01:25:05 pm
content: Lucky me asking uncle goo "thermistor UTI 8N05" ...So he spared me these nasty contagious infections...I am sure their "artificial intel" is very educative...sure there is modern geek python code...My drama is that this little bastard reads 4 Ohms.Any 5D-9 reads at least 5 or 5.5 Ohm..Whatever.. 5D-9 already there.. my other optionsare way bigger like 3 Ohm ...Thanks passing by for the laughPaul

author: wraper
author_rank: Unknown
timestamp: March 29, 2021, 01:37:47 pm
content: Quote from: PKTKS on March 28, 2021, 06:25:17 pmShould be 8mm diameter and 5 ohm nominal resistance at 25oC. Should be similar to WTR08D050Mhttp://www.es.co.th/Schemetic/PDF/WTR-SERIES.PDF. 4 Ohm resistance most likely is within tolerance, although borderline.

author: PKTKS
author_rank: Super Contributor
timestamp: March 29, 2021, 01:50:40 pm
content: Thanks.. the bastard is clearly toasted..is causing inrushs and start problems..I can't trust the 4 Ohm reading..5D-9 for now at least is not causing the nasty inrushsPaul
uyue 8586 5-e : Wot no hot air? - Page 1
Forum section: electronics / repair

author: NivagSwerdna
author_rank: Super Contributor
timestamp: June 25, 2019, 08:46:03 am
content: So whilst using my hot air and soldering station last night I found that the hot air stopped getting hot and the display showed 5-E or S-E if you prefer.On disassembling the handset (after unplugging!) And pulling out the element which is wrapped in a sleeve of some kind... Mica? I found the element was not continuous.Replacement element now ordered.What is the life expectancy of a hot air element? Should I keep spares? Are any of these materials likely to be hazardous making it more sensible to just buy a new wand or station?

author: Yansi
author_rank: Super Contributor
timestamp: June 25, 2019, 08:51:25 am
content: A friend of mine has an old Aoyue 968, that may well be older than 10 years. I have replaced there only the thermocouple wires, but the heating element never failed.My Aoyue 968 may be about 6 years old I guess, no failures yet.
V3500A RF Power Meter Battery Power Issue [Solved] - Page 1
Forum section: electronics / repair

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 31, 2025, 03:57:38 am
content: I have a V3500A RF Power Meter that functions correctly- except it refuses to power on via batteries. It works fine with USB or wall wart power, so the issue seems isolated to the battery circuit.The unit arrived with leaked Duracell batteries in the holder. 🤦I replaced the battery holder (thankfully, it’s an available part), but that only partially resolved the problem.Troubleshooting so far:No continuity from the battery + terminal; the lowest resistance I measured was in the MΩ range.For comparison, I’ll disassemble a working unit tomorrow to try and trace the expected connections.Attached is a high-res photo of the board. If anyone has any ideas or spots something obvious, I’d appreciate your insights.Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 12:00:18 am
content: On the good unit, I get 0.4Ω and 0.9Ω to the capacitors and diode above the + pin. More importantly, I get 0.2Ω to the relay. Including the 4 foot cable not compensated for, that's pretty close to zero.I preemptively ordered some relays when I ordered the battery holders, since that is a mechanical component with the potential to dieeeeeeeeee sooner than anything else. If I'm lucky, replacing that might be a simple solution. That's assuming there's not a gremlin hiding underneath.Anyway, gonna remove it now and see if I can trace the + terminal from there. Might be something hiding underneath the big bastard.Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 01:23:36 am
content: Well, the relay was part of the issue. Unfortunately, the connection from the positive terminal from the battery is compromised somewhere between the two points, but not that I could see. With the relay removed, there was resistance between those two points, but that gradually got pretty low. I assume that's a trace issue.So I put in a jumper wire with the new relay I installed connecting the + battery terminal.I tested it by confirming that powering via USB disconnects the battery terminal from the relay center pin, and ta da, it does what it's supposed to. Now any power option works as expected.Problem solved.Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 01:25:04 am
content: Here it is working perfectly, battery powered. 😎My SML03 output is usually off by about -0.5dB in that range. But only according to every device I used to check it. 😉Thanks,Josh
VACU PRO CLEANER MAXI IPX4 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: March 05, 2024, 01:12:52 pm
content: Hello everyone! I am asking for your help with a breakdown that I am encountering on a VACU PRO CLEANER MAXI IPX4 vacuum cleaner; I found several faulty components on the motor control board: DW1, (5.1v zener short circuit); IC1 (also faulty); R7 burned, and I don't have its value...Everything else has been checked and the engine is functional...Does anyone have an idea?? I am attaching the photos....Thank you for your dedication

author: lionelkjh
author_rank: Frequent Contributor
timestamp: March 05, 2024, 01:15:10 pm
content: the integrated circuit IC1: 501B-8P

author: lionelkjh
author_rank: Frequent Contributor
timestamp: March 13, 2024, 03:20:50 pm
content: Good morning; I have news on my problem: the manufacturer does not deliver the board as a spare part: conclusion, we must therefore help ourselves! However, according to the datasheet, can the integrated circuit: 501B-8P be programmed by the manufacturer, because a memory part is present?? Thanks for your help
Vacuum cleaner makes helicopter sound when working - Page 1
Forum section: electronics / repair

author: david smth
author_rank: Contributor
timestamp: December 31, 2024, 04:39:41 pm
content: The vacuum cleaner makes a noise when you touch the back of the machine or it makes a noise and then disappears but it sounds like a blockage sound but then disappears and makes a noise like a blockage sound while vacuuming. I changed the filters and hose but it didn't fix it. Everything seems normal. It vacuums the floor but it works and sometimes makes a noise like a blockage sound. Could there be a problem with the engine? What would happen if the engine malfunctioned? Would it not work at all or would it make a blockage sound? It doesn't make a normal vacuum cleaner sound, it makes a helicopter sound

author: david smth
author_rank: Contributor
timestamp: December 31, 2024, 04:50:18 pm
content: The vacuum cleaner makes a helicopter sound when it is working. When I first turn it on, I turn it off and on again, then it is fixed. Sometimes it makes a sound by itself. I haven't found a solution yet.

author: david smth
author_rank: Contributor
timestamp: December 31, 2024, 04:55:29 pm
content: I will put a video for you to help me and the picture brand is not a very well-known brand, it is a subsidiary product of Chinese origin, there is a filter inside, there is only no bag

author: themadhippy
author_rank: Super Contributor
timestamp: December 31, 2024, 06:21:10 pm
content: fan blades on the motor rubbing? unless its made by harbin then its normal

author: david smth
author_rank: Contributor
timestamp: December 31, 2024, 06:39:07 pm
content: yes There are gears inside the engine that spinand there is nothing inside, there is a burning smell, it makes a sound like a helicopter, then I turn it off and on, it fixes itself, sometimes it happens on its own

author: Xena E
author_rank: Frequent Contributor
timestamp: December 31, 2024, 06:50:23 pm
content: Motor bearing?X

author: Zero999
author_rank: Super Contributor
timestamp: December 31, 2024, 07:22:24 pm
content: Is the cleaning brush jammed causing the torque limiting clutch to slip?

author: david smth
author_rank: Contributor
timestamp: December 31, 2024, 07:37:04 pm
content: The filter you see in the picture is attached to the back of the vacuum cleaner and makes a different sound when I touch it.

author: max.wwwang
author_rank: Frequent Contributor
timestamp: January 01, 2025, 08:50:24 am
content: First check if, when on, it sucks.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: January 01, 2025, 02:14:05 pm
content: Maye the hose has developed a 'flap', which occasionally breaks loose and partially blocks the flow of air

author: david smth
author_rank: Contributor
timestamp: January 04, 2025, 08:07:21 am
content: Yes, it doesn't happen all the time, the problem happens sometimes, it works normally, the problem rarely happens.
vacuum fluorescent display - Page 1
Forum section: electronics / repair

author: veedub565
author_rank: Frequent Contributor
timestamp: October 14, 2019, 06:28:21 pm
content: Hi, I have an old piece of test equipment (TTC Fireberd 6000A) with a vacuum fluorescent display. I noticed that with the unit powered up, some of the segments are dimly lit, even though they are not displaying anything.I'm not too familiar with this type of display, I've read on another post that it could be a failing display driver. Any thoughts ?Picture attached

author: veedub565
author_rank: Frequent Contributor
timestamp: October 14, 2019, 06:49:22 pm
content: Just to add, the rest of the display does not appear especially dim. And oddly some segments appear super bright. Additional picture attached

author: mzacharias
author_rank: Frequent Contributor
timestamp: October 16, 2019, 04:57:12 pm
content: I would definitely suggest checking power supply voltages. Might get lucky. Typically 6-10 volts AC for the filaments and -30V dc for the main display, probably 5 volts for the driver IC. It's doubtful this is a "chip on glass" type, but you can tell if only about 1/3 of the available pins are used and the rest cut short to the glass. (the ones I've seen, anyhow)

author: PKTKS
author_rank: Super Contributor
timestamp: October 16, 2019, 05:10:45 pm
content: As said above the voltages are first priority.VFDs are regular TUBES - yes indeed valves...But a VFD this size should have a complete integrated controllerunderneath. Voltages for cathode and grid are very tricky to setupand being integrated if just one failed .. the whole chip is replaced.Lucky or not there are know replacements being Noritake the top manf.Compatible list is very short.And they age... like any regular tube they just got used..Need to find out the numbers printed on the assyand verify if the malfunction is really a faulty chipPaul

author: dom0
author_rank: Super Contributor
timestamp: October 16, 2019, 08:04:34 pm
content: Kinda looks like ghosting, so there might be a problem in the filament driving or how the filament voltage is biased relative to the rest of the circuit.Super bright segments indicates that possibly the multiplexing is not working quite right. Perhaps a barely working oscillator providing a rather irregular clock to the VFD driver IC?

author: veedub565
author_rank: Frequent Contributor
timestamp: October 19, 2019, 07:57:08 pm
content: Sorry for the late reply to this, the display is model CU40026SCPB-T21aLooks like there are controller chips on the back of the assy. If I can find a datasheet I'll start prodding about and check some voltages.

author: PKTKS
author_rank: Super Contributor
timestamp: October 20, 2019, 10:06:25 am
content: These fully integrated modules can be replaced as a whole.Depending on price and options it may be even better solution
Vacuum tube filaments wont heat up - Page 1
Forum section: electronics / repair

author: CoopedUp
author_rank: Regular Contributor
timestamp: August 02, 2019, 07:37:36 pm
content: I have a motorola a16w tube radio and I have replaced all of the capacitors and when I power it the filaments don't do anything. I know that the tubes are good I just dont know whats wrong. I measured from pin three of the 35w4 to b- and I got 120 volts. Any help would be appreciated, Thanks.

author: james_s
author_rank: Super Contributor
timestamp: August 02, 2019, 08:47:17 pm
content: The obvious place to start is the filament supply. Is this a radio with a power transformer or is it one of the ones that has all the tubes in a series string? If it's the latter then it only takes one bad connection in the string to make none of the filaments work. Either way start at the source and work your way down the line until you locate the fault.

author: chris_leyson
author_rank: Super Contributor
timestamp: August 02, 2019, 09:34:05 pm
content: It's a 5 tube AC/DC 120V radio so the heaters are in series. Downloaded schematic fromhttps://www.radiomuseum.org.The 35W4 heater wiring seemed a little strange at first but it's a tapped filament optionally used to drive a pilot lamp. You should have 7.5V across pins 4-6 and 27.5V across pins 3-6 assuming the series heater string isn't open circuit. As the voltage on pin 3 of the 35W4 is 120V it would seem to suggest that the heater string is open somewhere. I would check the heater voltage on 50C5, 12BA6, 12BE6 and finally the 12AV6. Either there is an open circuit heater or a dry joint on the PCB. Neat little radio and good luck.

author: CoopedUp
author_rank: Regular Contributor
timestamp: August 02, 2019, 10:14:38 pm
content: Thanks I'll check those things in a bit and then make an update!
Valhalla 2500EP Current Calibrator Repair - No.1020 - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 15, 2022, 10:51:38 pm
content: I repair a damaged Valhalla 2500 EP, and also find a self oscillation problem which is probably what damaged it in the first place.

author: precaud
author_rank: Frequent Contributor
timestamp: July 17, 2022, 12:31:19 pm
content: It's not often that one sells something and then gets to watch someone else troubleshoot and fix itWell done.
Valhalla 2701C (early models) level-shifter upgrade - Page 1
Forum section: electronics / repair

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: June 12, 2021, 01:48:18 pm
content: early VS 2701C had their optocoupler secondary sides supplied with 15 VDC, which was way beyond their datasheet spec of just 5 VDC, and led to quite excessive heating of the optocouplers. hence, when i acquired my early 2701C, i was looking for a simple way of replacing the optocouplers with "fresh" ones, and also adding the extra level-shifter crcuitry that can be found in later models.so here you have it: remove the old optocouplers, put in some milled sockets and piggy-back this three-pcb contraption onto the sockets. it will have slightly improved slew rates over the original installment, so itmaybe necessary to calibrate and re-adjust the unit (on mine, it was).feel free to use itnon-commerciallyfor upgrading your precious 2701C and let me know how it is going.note that this upgrade is only applicable to those early 2701C that don't have implemented the level-shifter circuitry.