hybridfree/eevblog-posts huggingface dataset:
R3273A IF board repair - Page 1
Forum section: electronics / repair

author: AndyDJF
author_rank: Newbie
timestamp: November 19, 2024, 07:13:21 am
content: Hello, I bought a refurbished Advantest 26.5GHz spectrum analyzer R3273A that was nicely working for a year, then it suddenly showed a fault in the IF board. The displayed signal level drops around 30dB when RBW is set between 100KHz and 3KHz, then returning at correct level at RBW of 1KHz and narrower or at 300KHz and wider.I have no schematics but I guess the specific amplifier is probably faulty, maybe simply a leaking capacitor or something like that.Can anyone help with schematics for any similar Advantest spectrum analyzer R327x?Many thanks,Andy

author: fzabkar
author_rank: Super Contributor
timestamp: November 19, 2024, 07:25:36 am
content: Did you look here? I see an R2371.https://elektrotanya.com/showresult?what=advantest&kategoria=All&kat2=All
Racal Dana 1995 Counter Locks Up After Self Test - Page 1
Forum section: electronics / repair

author: Bimmerdude
author_rank: Newbie
timestamp: July 07, 2021, 01:34:47 pm
content: Hello,I have a 1995 Racal Dana frequency counter that locks up after power on. When the power is switched on, it displays 1995 then the display goes blank as well as no response with the front panel push buttons. All the buttons seem to be ok, since these Racal Dana 19XX counters are know for button problems. The commercial data doesn't explain much. It does talk about the power-up sequence, and what the counter is suppose to do (ex, when power is applied, 1995 is displayed, then goes into self-test mode then goes to default settings, or if an error occurs, it will display it).Any help will be greatly appreciated. I'm stumped on this one.Thanks,Daniel

author: Andy Watson
author_rank: Super Contributor
timestamp: July 10, 2021, 10:24:58 pm
content: Tricky! I would start with the easy-fixes first - i.e. re-seat all the connectors and then move on to the chips that are in sockets. If that doesn't work start checking the power supply voltages and that they are free from ripple/noise. Then it gets tricky. The CPU must have power - check on the actual pins of the chip - it must have a clock and not be held in reset (as minimum requirements).Are you aware of the Racal forum on google groups ? They might have more specific advice.https://groups.io/g/RacalDana

author: CJay
author_rank: Super Contributor
timestamp: July 11, 2021, 08:40:34 am
content: Also, make sure the reference is selected correctly, running and of sensible amplitude, frequency, shape etc.
Racal-Dana 2101 Microwave Counter Repair - Page 1
Forum section: electronics / repair

author: TheDefpom
author_rank: Frequent Contributor
timestamp: March 12, 2021, 01:25:21 am
content: I thought I would share this here, there doesn't seem to be many of these units around.

author: on4top
author_rank: Regular Contributor
timestamp: March 12, 2021, 05:00:32 pm
content: nice one !Still struggle with mine after change caps ( 80% was really bad ) .I use to have full service manual in pdf .. can't find it anymore

author: TheDefpom
author_rank: Frequent Contributor
timestamp: March 12, 2021, 05:37:31 pm
content: Quote from: on4top on March 12, 2021, 05:00:32 pmThe manual was hard to find, I had to purchase a Racal Dana collection CD from eBay to get it, but at least I now have a load of manuals !I’m not home at the moment otherwise I would add others now, I did post it on my Patreon when I did the pre release video post.

author: on4top
author_rank: Regular Contributor
timestamp: March 12, 2021, 05:50:47 pm
content: Have to check al my garbage harddrives .. must have it somewhere .I think i got it from a yahoo groups member of the racal-dana group when it still existed . ( i bought the unit 3-4 years ago at Hamfest in Germany )https://photos.app.goo.gl/G8kxvNwsqobnyRvq8Some small hardware differences with yours .

author: eevcandies
author_rank: Regular Contributor
timestamp: March 13, 2021, 11:28:10 am
content: If the keyapd goes bad an ALPS brand SKEGACA010 fits perfect, no lead bending, no stem adjustments, no nothing, just solder in. However, the finished button height may be 1mm or so higher (barely noticeable, or not noticeable if you replace all the switches). The caps fit only slightly snug, maybe even "good enough", but who wants to lose one ?? So add a drop of rubber cement & you will be in the winners circle. This switch has recently been discontinued in 2021...so buy them while you can. I bought 100 for $23 (& then another 100 more) from onlinecomponents.com (they are supposed to get more of them in stock). Arrow's pricing is next best.https://www.mouser.com/datasheet/2/15/SKEG-1371040.pdfMouser prices is $$$. Apparently the style is called a "joint stem" type, which may help in more searches.https://www.eevblog.com/forum/repair/racal-repair-idea-quick!/

author: Andrejka
author_rank: Contributor
timestamp: November 15, 2021, 07:28:15 pm
content: Hello,Maybe someone can help me with Racal Dana 2101 counter GPIB board EPROM dump?I have fitted GPIB board from model 1998, but does not work, different firmware.Many ThanksAndrej

author: factory
author_rank: Super Contributor
timestamp: November 15, 2021, 07:53:46 pm
content: Quote from: on4top on March 12, 2021, 05:50:47 pmSomeone has added the manuals to ko4bb;http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=Racal/Racal_Dana_2101David

author: George Edmonds
author_rank: Frequent Contributor
timestamp: November 15, 2021, 08:09:43 pm
content: HiFor your information, The Racal-Dana support group still exists, it is at RacalDana@groups.io.Owner/Moderator
RACAL DANA 4008 - Page 1
Forum section: electronics / repair

author: lionelkjh
author_rank: Frequent Contributor
timestamp: November 30, 2022, 05:58:45 pm
content: Goodnight all! I am looking for the service manual for the RACAL DANA 4008 table multimeter; does anyone have it? (because on the internet I did not find anything?) Thank you for your answers

author: Andy Watson
author_rank: Super Contributor
timestamp: November 30, 2022, 09:54:13 pm
content: Racal and Thurlby Thandar (TTi) have been known to re-badge each other's instruments (I'm not sure who was the OEM). Try searching for Thurrlby 1503 or 1504 - it looks very similar.

author: lionelkjh
author_rank: Frequent Contributor
timestamp: December 01, 2022, 08:31:59 am
content: Hello; thank you for this quick feedback!

author: mendip_discovery
author_rank: Super Contributor
timestamp: August 04, 2023, 04:48:46 pm
content: I had the same question and from what I can see it is a TTi 1504 due to the AC Voltage Range being in the 32 V range rather than 16 V plus the 1504 is an RMS not "Average Sense".FYI this came in alongside several Fluke 8010A to my work for 1705 calibration and they are used in the aircraft industry even now.
Racal-Dana 5004 multimeter - dead display - need manual - Page 1
Forum section: electronics / repair

author: psykok
author_rank: Frequent Contributor
timestamp: April 22, 2020, 07:36:00 am
content: Hi,I scored recently a nice Racal-Dana 5004 multimeter.Appart from the missing covers, the instrument looks in very good shape.I received it today and after a quick check, it looks like that nothing get displayed on the front panel.I was wondering if someone is owning the service manual fro this multimeter?Alex

author: autotel
author_rank: Contributor
timestamp: April 22, 2020, 08:13:33 am
content: I sought for it on Ebay, and interestingly I found that some people sell the manual, in CD format. What if you can find it for download? Also remember to search in the internet archive (archive.org), where you can usually find the more obscure stuff. I hope you find it!

author: psykok
author_rank: Frequent Contributor
timestamp: April 22, 2020, 09:11:49 am
content: I have not found the documentation for the 5004, but the one for the 5005 is available here:http://ftb.ko4bb.com/manuals/198.21.21.21/Racal_5005-5006_Digital_Multimeter_Service_Manual_1981.pdfFortunately the 5004 share apparently a lot with the 5005.I think it will be good enough for a start.After a quick check I found a missing component in the voltage reference area.Originally component (AR3) was a AD542.I replaced it with a LF536. After this operation the multimeter was not giving more signs of life.I check the temperature on thee ICs close to the OPA I replace and I almost burned my finger on U11.Apparently the dumb ass who did some repairs on this unit did install U11 in the wrong way . After a closer check, same for U10.Figers crossed, I turned the unit on .... magic it works again, or at least it's displaying something and oing a boot sequence.
Racal Dana 5006 DMM anyone have the original firmware? - Page 1
Forum section: electronics / repair

author: picburner
author_rank: Frequent Contributor
timestamp: March 19, 2025, 08:48:50 am
content: I am repairing this Racal Dana 5006 from which the BT1 battery and the LM399AH voltage reference have been removed.Of course these replacements will require a complete calibration of the instrument but I am not concerned about this, I have everything I need to do this.With a temporary replacement, while waiting for the original components to arrive, I was able to verify that the instrument works globally apart from some oddities in remote control via gpib.These oddities probably depend on the fact that the firmware of this instrument is either not the original one or a couple of eproms have changed some data over time.These doubts came to me because the firmware chips were of different brands, to read the U27 with the eprom programmer it took me hours (always different results) and from the comparison with the firmware of a Racal Dana 5004 found on the net: the eproms U28 and U30 are identical while the eproms U27 and U29 differ in a few dozen bytes.I tried to disassemble the firmware contained in my U27 eprom and indeed, at the point where there are differences, a jump leads to an address out of alignment with respect to the U27 of the 5004.In essence: Does anyone have this multimeter in working order and could kindly make me a copy of the firmware?I also do a quick teardown since it is not a very common instrument from what I see.
Racal Dana 9035 - Page 1
Forum section: electronics / repair

author: RikV
author_rank: Regular Contributor
timestamp: November 08, 2023, 01:48:23 am
content: My latest toys on the way from Germany are Racal-Dana. A 9015 and a 9035. Both defective. No further info so far. Some docs would be helpfull, I found different manuals on the www (all identical, incomplete copies) but no schematics! Not available from the usual suppliers either. Can anyone help me out with the schematics???

author: RikV
author_rank: Regular Contributor
timestamp: November 09, 2023, 11:09:50 am
content: Turns out there are two separat "parts" for the manual. Finally found the complete manual (july 1986), it also has a "trace-back" history.I will upload it to the usual suspects for everyone to enoy.
Racal-Dana 9087 - Page 1
Forum section: electronics / repair

author: YU7C
author_rank: Regular Contributor
timestamp: November 05, 2020, 11:12:13 pm
content: Hi,it's a strange that 9087 doesn't have it's repair topic?Let's start.I bought mine very cheap, few years ago from UK ebay. It's not in good condition, very dirty, faulty, almost all caps have leaked...I had already decided to get rid of him, but my friend from a job, drew my attention about its impressive phase noise. So I decided to repair it, or to try?First, battery was bad so I replaced it.Then, it has error 51 with indication to IC7 on NVM board. So I'm looking for one memory chip.Second error is 80 - Reference Generator loop out-of-lock.The switch int/ext ref. osc was in bad condition, so I opened and cleaned it.Now, have strange behavior, when is switch to EXT position (w/o external reference connected), the 9087 has error 82, and when is in INT position, has error 80. In fact I was expected an opposite errors.Bad things is that my Oscilloscope and Spectrum analyzer is not here, and can't check the reference. Will do that next week.73 de Voja/YU7C

author: George Edmonds
author_rank: Frequent Contributor
timestamp: November 06, 2020, 07:58:10 am
content: HIThe biggest problem that you have is lack of a complete service manual. It was designed, to a NATO contract, to be repaired by module replacement only.There is something like 107 electrolytic capacitors on one board alone that need replacement.The fault that you have with the reference is standard for them.Try posting onhttps://groups.io/g/RacalDanaBetter still bin it, I did.73 George G6HIG Dover UK
Racal RA6790/GM - Page 1
Forum section: electronics / repair

author: simba15
author_rank: Regular Contributor
timestamp: August 14, 2023, 06:08:39 pm
content: So my repairs continue down the line!I have a Racal 6790 that is not in good shape, the dreaded backup battery leaked!It power on and has a real fit!~ All displays light, then the freq display goes blank.I cleaned some corrosion off the board and tried again.This time, messing with the power switch ( on-off a few times) the freq display will work and even change with the main knob, but only for 500ms, after this the Fault light comes on.Power rails all test ok, I suspect the fault is with the A6A2 Board.The tantalum caps seem ok (C13,C14)C17 on the other hand seems iffy, Across reads ~40ohm, but once removed, Q7 Drain is still ~40ohm to gnd (this is the reset line to the CPU)I noticed that Q7 and Q6 are listed as TIS74 but on my board they are 2N4392. Can I replace with TIS74?Any ideas if these values are OK, or should I start replacing Q7, caps, ect.

author: w3jn
author_rank: Newbie
timestamp: August 14, 2023, 07:46:12 pm
content: Before you go any further, check the filter caps. I had a 6790 that acted really wonky; all the filter capacitors were pretty much open and the regulators weren't able to deal with the ripple. Just poke at each power supply output with your meter on AC; the ripple will show its ugly head if the caps are bad.
Rangehood electric motor blowing thermal fuses - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: June 25, 2019, 09:17:49 am
content: I got a rangehood electric motor that is running a bit hot. Second time it burns it's thermal fuses @ 120 celcius.I am not sure but at that temperature will the enamel melt and short some of the winding?Is there anything to te done, considering the motor performs perfectly in all 3 speeds?

author: Psi
author_rank: Super Contributor
timestamp: June 25, 2019, 09:25:36 am
content: Quote from: gkmaia on June 25, 2019, 09:17:49 amsorry but I think that has already happened, that's why it's running hot.
Rare 200W lamp controller - Page 1
Forum section: electronics / repair

author: e.sotillet
author_rank: Contributor
timestamp: July 10, 2021, 01:31:58 pm
content: Hi folksI have to repair a 200W lamp controller for medical aplications. I picked up the circuit schematic and found that the mosfet gate is not being driven. But what makes me very curious to understand how it really works. The topology is similar to a buck converter but the mosfet's parasitic diode is always directly biased. How is the control of the lamp achieved? I'm missing something?The IR2110 is used partially, only the high driver is used (to drive the floating gate) and the pulse come from a SG3524 working at 21kHz.https://drive.google.com/file/d/1Z8Z2dHkkOLJZcQzb7nLI5AtQV1d9BGhh/view?usp=sharingBest regards.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 10, 2021, 03:20:50 pm
content: It appears to be drawn exactly backwards. Are you sure about the connector roles?Tim

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 13, 2021, 03:43:03 pm
content: hi,works kinda voltage regulator, like pdf sgx524 says, nothing fancythe schematic you extracted is incomplete and eronate for surebut for repair, should do, chack pwm ic, caps, transistors and should be fine after replacing themtry a smaller dummy load before validating pwm feedback is working for at least some minutes

author: e.sotillet
author_rank: Contributor
timestamp: July 13, 2021, 07:39:36 pm
content: Yes, you were correct. The connection was wrong. The fault was no pulse in the mosfet's gate. I solved it by replacing the IR2110.Best regards
Raspberry PI4 repair - Page 1
Forum section: electronics / repair

author: Aurgelme
author_rank: Contributor
timestamp: December 15, 2024, 09:07:57 pm
content: Hi,This is my first attempt at repairing a pcb with surface components, and I thought that 3 defective pi4s I had lying around were a good start.After buying a cheap infrared heater and hot air station, and many youtube videos, I got started.Took a chance to buy some ic chips from aliexp and orginal DA9090 from pihut.Have now repaired 2 of the pi's, since only the power manager da9090 was defective.The last one was not completely healthy after 12V inputbut after soldering in a new DA9090 it booted up, but USB, eth and wifi/bluetooth were missing.Replaced the VL805-Q6 usb controller and BCM54213P eth controller, and now have both usb and wired network.Then there was wifi/bluetooth, which was a disaster, since the wifi ic dropped from the wacum tweezers and made a mess of some of the components left of this chip.I have searched everywhere for component locations, but have not been able to find any info, or pictures since they are located under the metal cover..Does anyone have a diagram or photo of this part on the pi4 pcb?
RAST 5 connector? on EBM PAST FAN - Page 1
Forum section: electronics / repair

author: sylvanoMTL
author_rank: Contributor
timestamp: April 28, 2025, 03:19:52 pm
content: Hi, I have to replace this fan: EBM M4Q045-EF01-52. But it is impossible to find one with the connector.The datasheet p306 (https://www.mouser.co.uk/datasheet/2/120/ebm_papst_M4Q045_CA03_A4-3000948.pdf) is not very detail.It mentions a RAST5 2.8x0.5mm blade terminal.I could only source a fan with a lead and I am trying to source a cable mounted connector of the same type.Can anyone direct me to the correct connector?

author: sylvanoMTL
author_rank: Contributor
timestamp: April 28, 2025, 03:22:20 pm
content: attaching some pictures of the connector

author: sylvanoMTL
author_rank: Contributor
timestamp: April 28, 2025, 03:24:28 pm
content: and without the housing
Rat Zapper clean yet still blinking - Page 1
Forum section: electronics / repair

author: jetpower
author_rank: Newbie
timestamp: January 23, 2023, 12:09:19 am
content: With thanks to cncjerry for his 2016 Rat Zapper cleaning advice, I did that to my vintage 2021 RZ Ultra after no rats in two years. So now it's 2023, and rat signals are showing up on the kitchen floor. Time to whip out and prime the Rat Zapper for a day or three on the job.On power-up, its red light began blinking. The batteries test fine - 1.5V with over an amp each. Following cncjerry's lead, I opened it up and checked the board - solder joints are clean, albeit with a few hints of possible flux traces or corrosion. After cleaning it with IPA and a paper towel, vacuuming off errant threads so that everything gleamed, I checked the result. No change - blink, blink, blink.The component side looks fine, so I have to conclude that an internal short is likely the culprit. Time is at a premium, so troubleshooting isn't on the menu. All direction is appreciated, up to and including last rites for the executioner.

author: R-1125F
author_rank: Regular Contributor
timestamp: January 23, 2023, 03:11:55 am
content: It is not that complicated. See this threadhttps://www.eevblog.com/forum/beginners/where-can-i-find-circuit-for-electronic-rat-trap/

author: jetpower
author_rank: Newbie
timestamp: February 06, 2023, 04:49:41 am
content: Tx; it was faster to summon Amazon for a side-by-side test. Answer: 4.5v @1.5A doesn't satisfy the new model. It needs a fresh set to wake up the employee. Oh well, it's still less effort to clean than the RZ Classic model, which starts up again and again at lower power.
Rather baffled by DC/small motor separation from gearbox - Page 1
Forum section: electronics / repair

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 29, 2022, 12:24:38 pm
content: Anyone very experienced in or familiar with small motor separation from its united gearboxQuite astounded, feel so powerless to solve in the slightestso anyone has experienced on this as to confidently share the knowledge to us here and now ?

author: Ian.M
author_rank: Super Contributor
timestamp: December 29, 2022, 01:07:50 pm
content: Since you have failed to provide any useful information like a clear photo of the label or of the ends of the motor assembly where any fastenings are probably located, you are on your own mate!Some general notes: The gearbox is normally attached with screws going into threaded holes in the faceplate of the motor. Sometime they are long through screws, sometimes you have to dismantle the gearbox to access them. Even if you succeed in removing the gearbox, its input gear is usually semi-permanently bonded to the motor shaft - either a high force press fit, or adhesively bonded, and will not be removable in reusable condition without specialist tools, and the gearbox will be unusable without a matched input gear.
Ratio transformer RT-30R - Page 1
Forum section: electronics / repair

author: Badwolf
author_rank: Contributor
timestamp: August 25, 2021, 09:27:02 pm
content: Hi all,Few months ago I bought a ratio transformer for repair, model RT-30R.The rotary switches are in good condition and transformers too.However the last decad is not composed of a rotatry switch, but of a kind of potentiometer allowing a continuous adjustment from 0 to 100. This potentiometer is unfortunately totally destroyed and some parts are missing.Having no user manual, I managed to redo part of the diagram using tests and diagrams from other models. I am however stuck on this potentiometer. I have 5 wires available / to connect. I have an idea for 3 of them, but I have no idea what to do with the last 2Could someone with this model RT-30 or the equivalent model RT-20 provide me with some info on this potentiometer or better a manual with the schematic of the device.Thank you

author: 1audio
author_rank: Frequent Contributor
timestamp: August 27, 2021, 05:37:03 am
content: I have an RT30. I'll open it up and take some pictures and check details tomorrow. if you don't see a response PM me a reminder. I managed to find a manual scan I could send that might help. Its generic and missing the schematic however.

author: 1audio
author_rank: Frequent Contributor
timestamp: August 27, 2021, 06:41:04 pm
content: Here are some pictures that should help. I'm pretty sure the pot is a 2 Ohm wirewound. The orange/white wire connects with orange and the black white wire connects with black, the green goes to the fuseholder. The rotational angle will be important to match the indicator. This is in effect an 8 digit AC Kelvin Varley divider.

author: Badwolf
author_rank: Contributor
timestamp: August 29, 2021, 01:47:20 pm
content: Thanks, that's exactly what I needed.I will be able to test this week and publish the schematics

author: 1audio
author_rank: Frequent Contributor
timestamp: August 29, 2021, 05:53:18 pm
content: This link can help:http://www.ciphersbyritter.com/RADELECT/RATIOTRN/RATIOINS.HTMThe box full of transformer will be the most confusing part. My other unit has transformers attached directly to the back of each switch.This is Tegam's manual for the current versionhttps://www.tegam.com/wp-content/uploads/2017/12/DT72B-901-01-Manual-Rev-B.pdfHowever the RT-30 also has isolation and phase reversal that the current Tegam (for $15,000) doesn't have.They are remarkably useful for something so obscure.
Raytheon Sorensen QRD 15-2 Power Supply Documentation - Page 1
Forum section: electronics / repair

author: sacron
author_rank: Newbie
timestamp: December 17, 2020, 08:20:52 am
content: Hello! Would anyone happen to have any documentation regarding this power supply or power supply series (QRD)? Someone on this site has already provided somespec/sales related documentationwith respect to the QRD power supplies, but it doesn't offer much.I recently became the owner of two of these power supplies, but I can't seem to understand how to operate them. I suspect they're either faulty or have had their default settings altered (they were previously used in an industrial setting, I believe). These are the first adjustable power supplies I've ever laid my hands on, so I'm likely way in over my head. Apologies if this sort of thread belongs on a different board!

author: CaptDon
author_rank: Super Contributor
timestamp: December 17, 2020, 06:13:14 pm
content: QRD's were very common and now somewhat of a dinosaur.We have tons of Sorensen stuff around here and lots of manualsin the file cabinet. I'll look and see what is there. I don't thinkwe own anything smaller than 40-2, but I think the manualscover several models. Most of ours PWM the input to the powertransformer and my two biggest problems are open capacitorsin the control circuits and poor connections at the edge connectors.I see every one of our supplies about once every two years becauseit is reportedly 'acting strange'.

author: merox
author_rank: Regular Contributor
timestamp: December 17, 2020, 06:39:12 pm
content: I'll scan the manual tomorrow and upload it to this thread on the weekend.The manual includes a schematic together with the parts list and covers the following models:QRD 15-2QRD 30-1QRD 40-.75QRD 60-.5QRD 20-4QRD 40-2QRD 60-1.5

author: merox
author_rank: Regular Contributor
timestamp: December 18, 2020, 01:16:28 pm
content: I've scanned the manual but unfortunately the resulting PDF too large (approx. 35 MB) to be posted here. I've therefore uploaded it to the KO4BB-Website where the file is under review right now. I'll post a link to the file as soon as the file is out of the review process.

author: sacron
author_rank: Newbie
timestamp: December 18, 2020, 11:36:36 pm
content: Looking forward to it!

author: merox
author_rank: Regular Contributor
timestamp: January 19, 2021, 05:13:33 pm
content: Quote from: sacron on December 18, 2020, 11:36:36 pmSorry that you had to wait a month for it, I didn't expect the review process to take this longHere it is:http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Sorensen/QRD_Series

author: coromonadalix
author_rank: Super Contributor
timestamp: January 19, 2021, 06:28:59 pm
content: thks for the scan, better late than ever
Razer BETTY R5 Not Booting – Is It VRMs, BIOS, or HDMI Chip? - Page 1
Forum section: electronics / repair

author: w0nk1
author_rank: Contributor
timestamp: September 04, 2024, 02:12:57 pm
content: Hi everyone,I’m facing a frustrating issue with my Razer gaming laptop (model RZ09-0195 with the BETTY R5 V3.1 motherboard), and I’m looking for help to diagnose the problem.Here’s the current behavior:- When I power the laptop on, the fans immediately run at full speed, the screen stays black, the keyboard backlight doesn’t turn on, but the status LED pulses green.- TheHDMI chip (PI3HDX1204E)gets quite hot (around 55°C), even with no HDMI cable connected, which seems unusual.Here’s what I’ve checked so far:I replaced theCMOS battery, and it consistently provides 3V.The20V railis present across all the fuses I’ve tested.Both the3.3V and 5V linesare present.TheBIOS chipreceives 3.3V.However, neither theCPU nor GPU gets warm, while thechipset does heat up.After desoldering theHDMI chip (PI3HDX1204E)the behavior is the sameNow, here’s what happened before the laptop completely stopped working:The last time it powered on, it sounded like it booted normally, but both the internal and external screens stayed black. Interestingly, the external screen didn’t show a “no signal” error.Before that, I noticed some strange behavior. After shutting down the laptop, the backlight of the internal display stayed on, and I had to press and hold the power button to turn it off completely.Around the same time, I lost the ability to control the internal screen. It no longer appeared as an option in the display settings.For any ideas or clues, I would be very grateful.P.S.: In the past, the laptop had a faulty SiC631, which I replaced, and it worked fine for about a year after that.CheersMarkus
RC Charger ToolkitRC M8 - calibration - Page 1
Forum section: electronics / repair

author: Sprinkler
author_rank: Newbie
timestamp: January 05, 2020, 12:59:58 pm
content: Do you guys have any idea what could cause such problems (voltage reading)?I don't use it to charge batteries because it's either not possible to calibrate (as seen on the video), or once calibrated (eg. 1s voltage reading - it shows fairly stable readings in calibration menu) it can start to read wrong voltages during charging - especially with higher currents (it's not accurate).Maybe it has something to do with resistors (voltage drop) and them reacting to temperature variation?Overall the voltage reading is inaccurate and fluctuates.It's been this way since the first day.Video:https://streamable.com/l557l
rc-unit exploded inside a Danica power supply - Page 1
Forum section: electronics / repair

author: larsdenmark
author_rank: Regular Contributor
timestamp: May 15, 2021, 04:00:26 pm
content: I have a rather old power supply made by Danica Elektronik, Denmark. Today it exploded and caught fire.There is a component on top of the transformer with the text RC-UNIT PMR 2026 marked on it. On the side it has 0.25 uF and 22 Ohm. Also it says C 7432.As far as I have been able to tell you can't get this component anymore.Can I just substitute with a capacitor and resistor in series with the correct values or is there a reason this is a combined component?

author: Gyro
author_rank: Super Contributor
timestamp: May 15, 2021, 04:18:31 pm
content: A nice example or Rifa metallised paper capacitor plague (forum search for Rifa will give you the idea). Luckily it doesn't appear to have done much damage, you might want to re-terminate the mains lead though.In this case, as you say, it is an RC snubber. The capacitor needs to be Class-X rated for safety. You can purchase suitable encapsulated RC snubber cheaply from most electronics distributors. Most use Polypropylene capacitors.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 16, 2021, 12:01:10 am
content: If it's directly across the mains (i.e. not connected to just the transformer as would be the case for a ferroresonant transformer), just use a X2 capacitor without a resistor.
rc40 fenix bright flashlight bizzare repair - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: April 24, 2021, 06:16:51 am
content: So I did a repair job on my rc40 flashlight by replacing a burned out LED. It was alot of work, I had to use a hot plate to solder it and apply thermal paste and undo loctite threads and all sorts of non servicable crap.When I turn it on, the replacement LEDs do not work, it has 3 pairs of wires going to 6 LEDs. When I try the LED with a power supply after desoldering the wires, they work fine.I also noticed this oddity, when you turn the flashlight on strobe mode, then turn it back into constantl mode, the set of lights that did not work, work, and a different pair of LEDs stop working.I took it apart a long time ago and the circuit is all built in a little cylinder with vertical PCB's and its a bastard to trouble shoot.Can any people that know about these sorts of flashlights give me a clue as to how it might be wired and what the hell is going on that it alternates between LED pairs. They give full brightness, just one randomly chosen section does not work. Clearly the power supply works, and when it blinks, all LED's blink, but a set of 2 in 2 possible positions wont turn on when on constant mode.When I measure the voltage on the pair it decides not to turn on, it measures a low voltage. But the supply cant be broke since it sometimes does decide to turn the ones that dont turn on on, but turn off another one. Like a faulty load switch controller? So all the signal paths have power capability, just one of them does not turn on like it should. But its not a blown transistor since sometimes it does turn on at full brightness so long another one turns off, when switching modes. And it stays on for a long time, so I know its not a PTC.in short, its acting like a flip flop. how does a flip flop form after a failure.

author: coppercone2
author_rank: Super Contributor
timestamp: March 13, 2022, 08:46:51 pm
content: well, the flashlight was sitting open on the bench for a few months and to my surprise when I tested it, it worked as I renemeber. However, when I reassembled it, the two high power LED no longer shine.So clearly its some kind of mechanical issue. I bet its cracked solder joints from the battery spring and the weird construction of the circuit board (I-beam instead of wafer stack).
RCA 35x schematic question - Page 1
Forum section: electronics / repair

author: ttx450
author_rank: Regular Contributor
timestamp: April 08, 2021, 07:48:08 pm
content: Not sure if this is the right area to post this? what does the symbol that looks like a battery mean in the red circle? Says bias for gain data. I know some old radios have a small coin batteries in circuit for bias. the radio I am working on does not. appreciate if someone could explain the symbol in the circuit. thks

author: TimFox
author_rank: Super Contributor
timestamp: April 08, 2021, 08:09:20 pm
content: It means that you should connect an external 3V battery as indicated to force the AGC voltage to a fixed value when measuring the gain.

author: ttx450
author_rank: Regular Contributor
timestamp: April 08, 2021, 08:19:23 pm
content: Quote from: TimFox on April 08, 2021, 08:09:20 pmthat helps, kind of new to working on old stuff. so this is used only to measure the gain. Can I use a external dc power supply to do that? working on a radio that looks to be passed around and fingered many times and does not work, so have to trace everything. thks

author: TimFox
author_rank: Super Contributor
timestamp: April 08, 2021, 10:55:48 pm
content: A DC power supply will work: be careful of polarity.Back in the day, 3V Zn-C batteries were readily and cheaply available. A 3V lithium cell is the modern choice.

author: ttx450
author_rank: Regular Contributor
timestamp: April 09, 2021, 12:16:15 am
content: Quote from: TimFox on April 08, 2021, 10:55:48 pmthanks.. do you know if that is positive or negative 3v, schematic shows 3v? maybe there is more reference material out there for this in the manual that I have not read. I have not read everything, just have been going through schematic and cleaning up the underside. Did not understand that reference. I will read over before I put pwr to it and see if I can find more info relating to the 3v bias. thks

author: TimFox
author_rank: Super Contributor
timestamp: April 09, 2021, 01:36:44 am
content: The schematic clearly shows the positive end of the battery to circuit common (AC-DC sets, without power transformer, do not ground that directly), and the negative end to the AGC line. When operating, the AGC line is typically -13V with respect to that circuit common, according to that region of the schematic.

author: ttx450
author_rank: Regular Contributor
timestamp: April 10, 2021, 12:22:38 am
content: Quote from: TimFox on April 09, 2021, 01:36:44 amthanks tim. working my way across the the bottom, just about done. kind of a mess. keeping finger crossed
RCA LED TV - Funky display after main board replacement - Page 1
Forum section: electronics / repair

author: patrickb7
author_rank: Newbie
timestamp: February 05, 2020, 03:37:55 am
content: Hello all,I'm glad to have found these forums and am happy to join the community, helloI'd like to reach out for suggestions on an issue I've been having regarding an RCA LED55C55R120Q 55" TV. I've recently replaced the main board on this unit as it previously would not power on. Replacing the main board solved that particular issue, but after turning it back on I noticed a new problem had arose. The display appears to be 'fuzzy', or rather text is displayed as pixelated and distorted (see pictures attached).My first thought was a dysfunctional TCON board, yet the display was just fine prior to replacement of the main board. Is it possible that the TCON board could have received peripheral damage during the event causing the main board to fail? I have briefly adjusted some of the display settings in both the user settings and service menu, neither seemed to have any notable effect on resolving the distortion.Any thoughts or ideas would be much appreciated. I am willing to purchase a TCON board but don't want to be too eager to spend more money without a further diagnosis. Thank you!

author: shakalnokturn
author_rank: Super Contributor
timestamp: February 05, 2020, 04:36:36 am
content: Do you have a choice of several panels in the service menu?If you do is setting right?

author: patrickb7
author_rank: Newbie
timestamp: February 06, 2020, 01:31:06 am
content: I was not able to find anything related to changing panels in the service menu, my only knowledge of this area is that it could either be IPS or VA. Do TVs commonly feature more than one type of panel? I'm hoping this could be a source of the issue rather than a hardware malfunction.

author: Rasz
author_rank: Super Contributor
timestamp: February 06, 2020, 10:14:24 pm
content: you could try swapping config eprom from the old board

author: TheMG
author_rank: Frequent Contributor
timestamp: February 07, 2020, 03:12:33 am
content: Quote from: patrickb7 on February 06, 2020, 01:31:06 amManufacturers will often use the same board across a range of different model TVs with different size, resolution, and panel types.Sometimes it can be a simple matter of changing configuration in a service menu, other times it can be much more difficult to change.
RCF HDL-20A Class D Amp - No power. - Page 1
Forum section: electronics / repair

author: beavernuggetz
author_rank: Newbie
timestamp: December 19, 2023, 02:36:21 am
content: Hello everyone,I am having issues with 2RCF HDL-20Aamplifiers which fail to power on. Unfortunately the manufacturer does not provide any sort of schematics which makes this a very difficult repair for someone such as myself with medium level knowledge working with electronics.Both of these amps had shorted Mosfets6R90C6as well as Driver ICS25131Dwhich have been replaced. Also replaced the 2 big electrolytic capacitors, the fuse, cracked Thermistor on the top side, some burned SMD resistors (all on the power/hot side).Checked remaining SMD resistors & transistors and the values match with those from a working amp.Was told (elsewhere) to check voltage at the SMD capacitor (labelled 4 on pic 2) to the right of the1BW Transistorbecause it should get 14-15 volts otherwise the amp will not power on. When I measure a working amp, the volts are indeed approximate 15 but for the one that does not power on the voltage is low and the cap is only getting 3.1 volts.Here are some discoveries made. The 3.1 volts at the SMD cap is the same as what is going across the Zener diode (12 volts capable) on the top left. Both have been replaced to no avail.Another difference is this. There is a small electrolytic capacitor (100uf 35v; first pic at the bottom) which on the working amp is reading as having 27 volts while on the broken one it has absolutely nothing. The capacitor has been tested and both capacitance and ESR come back okay; same values as the one on the working amp.Anyone have any ideas? The first picture shows the top/bottom sides of the PCB side by side for comparison.I labelled the main components on the power side of the main board on the second picture. The third picture zooms into the area with the SMD capacitor in question with the 3.1 volts. The 4th picture is a bit of a mess showing the path of continuity between the 12v Zener diode and the components connected to it including the small electrolytic capacitor (100uf 35v) with no voltage.1 & 2: Big electrolytic caps. Have been replaced.3: 1BW Transistor - Replaced4: SMD capacitor with the low voltage - Replaced5: S21531D: Driver IC. Has been replaced with IRS21531D.6: LMC555CM: CMOS Timer - Replaced7 & 8: 6R190C6 N-Channel Mosfets - Have been replaced with exact match.9: 4702 SMD resistor = 47kΩ. On working system (still attached to the board) it reads 26.68kΩ vs. 40kΩ on faulty one.10: U1JB: Ultrafast Rectifier DiodeAny thoughts, questions, suggestions are welcome and highly appreciated.
RD6006 gone crazy - Page 1
Forum section: electronics / repair

author: markyparky
author_rank: Newbie
timestamp: May 25, 2022, 08:57:23 am
content: Hello guys,I have two RD6006's operating for quite some time with no issues however one of them gone crazy 2 days ago. I was wondering if someone experienced similar symptoms. I have it configured to supply 12V and 1A output and as soon as I connect any load to it then output Voltage immediately drops to something like 8ish Volts and PCU goes to CC (constant current) mode. As soon as the load is removed the voltage (at least the redings on LCD) hikes up to something like 45-50V and slowly drops back to intended 12V. Any ideas please? Thank you!

author: coromonadalix
author_rank: Super Contributor
timestamp: May 25, 2022, 02:10:20 pm
content: and the current settings are ?? still 1 amp or more ??

author: markyparky
author_rank: Newbie
timestamp: May 26, 2022, 07:32:26 am
content: It's now fixed. The output fuse was blown. I would have expected to see 0V 0A reading in case of blown fuse but voila. It's now back to play.

author: Partizans
author_rank: Newbie
timestamp: November 20, 2023, 08:20:14 am
content: I'm curious, in the current model RD6006, for "curve display" are there Chinese characters on display right side (even in English language mode)?
RD6006 series 4mm Terminal/Binding Posts? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: February 18, 2022, 08:45:27 am
content: Hi!Can anyone identify, and provide a link to, the grey with coloured insert 4mm Terminals/Binding posts used on the RD6006 series and a lot of Chinese linear PSUs please?A member commented that it's not a good idea to use green for "Battery Charging" as it can be mistaken for an earth terminal, and I agree, and so I'd like to replace it with one of another colour, when my RD6006W and case/PSU kit arrives!Chris Williams
Re-attach micro USB charging port to kiddies night light - Page 1
Forum section: electronics / repair

author: ksc0pe
author_rank: Newbie
timestamp: April 23, 2025, 10:28:08 pm
content: So the charging port came loose a few days ago. I took the light apart, its easy to understand where the port was attached however it looks to have stripped the copper contacts away from the circuit board, so there is nothing remaining to re-attach to. I bought a replacement female socket with +ve and -ve wires, its not clear if / how / where I can re-attach the charging port.I have attached some photos, hopefully that makes things clearer.Thank you!

author: thm_w
author_rank: Super Contributor
timestamp: April 23, 2025, 10:35:43 pm
content: You'll have to trace the connections back to somewhere else.Seems like you could solder to those via holes on the left and right side of the USB connector (left side = Gnd = black, right side = Red = 5V).If not then maybe across C1.For your other thread you might be able to use the checkbox and the "Remove" button in the top right to delete it?https://www.eevblog.com/forum/repair/re-attach-micro-ubs-to-kiddies-night-light/?topicseen

author: ksc0pe
author_rank: Newbie
timestamp: April 23, 2025, 10:58:21 pm
content: Thank you.Yeah understand, those holes however seem to have no copper either at the back or front of the board (not sure what they are for), and fiddling around with it for 5 minutes I haven't managed to find any copper that I use to trace to another point on the board. I'll have a bit more of a go tomorrow, maybe I am missing something.Tried to remove the message which resulted in "You cannot delete your own topics in this board. Check to make sure this topic wasn't just moved to another board."Thanks again.

author: thm_w
author_rank: Super Contributor
timestamp: April 23, 2025, 11:58:46 pm
content: Did you scrape some of the white soldermask with a knife? I would guess there is copper underneath.There is also that solder pad on the right, if that is connected to one side of C1 then that should be GND.

author: ksc0pe
author_rank: Newbie
timestamp: April 24, 2025, 07:49:39 pm
content: Scratched some of the covering off and found the following connections. So I think the black line should be connected to ground, and the red to +5V. Would that make sense. Thanks!
Re: Capacitor replacement - Page 1
Forum section: electronics / repair

author: rivest
author_rank: Contributor
timestamp: August 04, 2022, 08:27:01 am
content: Hi guys, what's a suitable replacement for this Jensen cap? They stopped production back in 2019.I'm not sure of the function of this giant cap but it is for a welding power supply card.

author: jpanhalt
author_rank: Super Contributor
timestamp: August 04, 2022, 08:35:30 am
content: How do you know it's bad? My TIG welder (Miller Synchro brand) is from 1983 and still has its original capacitors.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: August 04, 2022, 10:28:40 am
content: maybehttps://www.digikey.com/en/products/detail/cornell-dubilier-illinois-capacitor/335PHC850K/5412186?s=N4IgjCBcpgTAnLKoDGUBmBDANgZwKYA0IA9lANogIAM8AHACwgC6xADgC5QgDKHATgEsAdgHMQAX2Jh68ZCDSQseIqQohqLCVKrqAtvg45sggF74AJgAIUmNphSCOJflYAWg0W6sA3Eti5WEAA2eUELbjhEEHYuSF4BEXFiDgBPNnxuTFw0bSAOut of stockhttps://www.digikey.com/en/products/detail/epcos-tdk-electronics/B32373A8406J050/10326892

author: TheNewLab
author_rank: Frequent Contributor
timestamp: October 17, 2022, 12:20:52 am
content: Not sure if this helps. That is likely a really large capacitor. Testing if it is good, using a Blue ESR meter or simiare Dick Smith design is a quick test equipment tool. can also test in-circuit.kinda sorta related? questions regarding using different type of caps? over athttps://www.eevblog.com/forum/repair/capacitor-re-cap-maddness-blue-esr-meter-alternate-type-capacitors-st-receiver/msg4467430/#msg4467430
Re-capping HAMEG 203-6 - Page 1
Forum section: electronics / repair

author: pplaninsky
author_rank: Regular Contributor
timestamp: August 08, 2020, 02:47:50 pm
content: Hello,I am re-capping a old 20MHz Hameg oscilloscope.There is a 2.2uF capacitor in the time base circuit that determines the hold-off delay.The cap on the board was 63V. I have at my disposal only 50V ones.Lookinh at the circuit (attached below) I think that 50V should be OK and the cap is overspeced or they just used uniform parts to reduce cost.I don't really see a reason for a 63V cap.Please, let me know if I am wrong.Full schematics here:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Hameg/hameg_hm203-6_oscilloscope_sch.pdf

author: shakalnokturn
author_rank: Super Contributor
timestamp: August 08, 2020, 03:31:28 pm
content: 2.2μF 50V