hybridfree/eevblog-posts huggingface dataset:
Just a shot in the dark (  IC identification help )  - Page 1
Forum section: electronics / repair

author: gearheadgeek
author_rank: Newbie
timestamp: July 11, 2024, 09:54:25 pm
content: Hey guys I did something stupid I let the magic smoke out but anyway. It is a Chinese device but unfortunately I can’t read the rest of the marking so this is a shot in the dark to me and I wear trifocals it looks like a 555 timer I can see some markings but I was thinking maybe you guys may have run into one of these IC with similar markings. If not Advanced thanks anyway

author: Ian.M
author_rank: Super Contributor
timestamp: July 11, 2024, 10:04:47 pm
content: I think we can be fairly sure its *NOT* a 555 timer. However without seeing the rest of the board and having an idea of its application all we can do is guess from the remaining markings.

author: thm_w
author_rank: Super Contributor
timestamp: July 11, 2024, 10:37:18 pm
content: You need to reverse engineer a schematic or find someone else who has taken apart the same device and has a photo.

author: wraper
author_rank: Unknown
timestamp: July 11, 2024, 10:44:18 pm
content: At least give some context about what it is. Showing a picture of IC with destroyed marking with no other info and not even a PCB picture is not helpful.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 11, 2024, 11:32:40 pm
content: We definitely need a LOT more information, what is the device it is used in?, what is the identifier on the PCB, is it U5? (in case someone has diagrams for it).

author: DaJMasta
author_rank: Super Contributor
timestamp: July 12, 2024, 07:21:02 am
content: TR___6

author: Harry_22
author_rank: Frequent Contributor
timestamp: July 12, 2024, 08:31:33 am
content: TR4...Take photos from different angles to the light.
Just bricked a field meter powered by a NXP LPC2292/2294 - Page 1
Forum section: electronics / repair

author: Bicurico
author_rank: Super Contributor
timestamp: December 23, 2024, 07:26:08 pm
content: Just bricked a field meter powered by a NXP LPC2292/2294 an I need help.Is it possible to JTAG this? How to figure out the pins? What software?If I get another device, what are the chances I can read the flash to program it on the bricked one?Thanks.My day is ruined.

author: u666sa
author_rank: Frequent Contributor
timestamp: December 24, 2024, 03:08:23 am
content: You should have some sort of a header on the PCB.
Just Turned on My Datron 4000A and after 20 minutes Poof - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: June 26, 2022, 04:25:31 pm
content: Just Turned on My Datron 4000A and after 20 minutes Poof blew a tantalum and whew what a smell.First power up in three years.

author: Gyro
author_rank: Super Contributor
timestamp: June 26, 2022, 06:31:43 pm
content: Right alongside a row of pristine looking Rifas, now there's irony!Datrons do seem to eat Tant beads, particularly after storage. Their PCB lead spacing isn't ideal - lead stress during hand assembly cracks their encapsulation and allows moisture in.

author: TiN
author_rank: Super Contributor
timestamp: June 27, 2022, 04:04:20 am
content: Typical. See tantalum in high-end calibartor =strike them colderm...replace on sight.

author: bdunham7
author_rank: Super Contributor
timestamp: June 27, 2022, 04:33:25 am
content: Quote from: TiN on June 27, 2022, 04:04:20 amNot just high-end...

author: branadic
author_rank: Super Contributor
timestamp: June 30, 2022, 12:43:12 pm
content: I'm currently in the process of a full recapping on my Datron 4000A as well. In a view days from now my replacement list will be complete and I can then share it here. I replace almost all of the tantalum caps by proper electrolytics except for two caps: a 100nF/35V and a 470nF/35V.https://www.eevblog.com/forum/repair/datron-4000a-getting-at-test-points/msg4248334/#msg4248334-branadic-
Jutai LED string controller half-dead - any ideas? - Page 1
Forum section: electronics / repair

author: Krotow
author_rank: Regular Contributor
timestamp: February 05, 2024, 01:46:17 am
content: Friend have a Christmas LED strip with several "annoyance modes" and both monochrome and1-wire RGB LED stringsupport. Model is JT-ELF/FC31V15W-I1-JP44 with rated 31V 15W output, made by Changzhou Jutai. It use JT-022 chip as LED controller. From PCB design controller chip look like rebranded PIC12F508 in SOIC-8 package. Something failed and now LED strip glow with a third of former brightness. "Annoyances" works as nothing happened so LED controller chip most likely is not damaged. No signs of water damage inside casing either. My bet is on LED controlling MOSFET-s Q4 and Q5, who might degrade with time and doesn't fully open anymore. Maybe somebody seen this output power loss fault before and already know the cause?BigClive dissected one of thesefew years ago. Unfortunately that was different model without LED mode controller.PSU/LED controller casing:PCB top side:PCB bottom side:Did my homework and reverse engineered the circuit. Also cause was kinda curiousCZJUTAI_FC31V15W.pdf(52.02 kB - downloaded 71 times.)

author: Krotow
author_rank: Regular Contributor
timestamp: February 05, 2024, 11:27:06 pm
content: Spent an evening with this thing. +30V after rectifier diode, +4V on controller chip Vdd. Also +30V onLED+and 1.2V with 4V control pulse packets onLED-. That look, erm... fine. Maybe the real problem is in friend's LED string? It might become damaged after using it two years outside house. I'll ask him to bring one of his used LED strips me too.Found a bug in my reverse engineering - LED mode switching actually happen by shorting PIC pins 4 and 5 to ground through push button. Corrected and uploaded reversed circuit here.Got curious about current return path. Found no actual way for current return in negative side. The only visible connecting is via controller chip GPIO-s that seems very wrong for 2A current. Maybe I missed some trace, but have no idea where it is.

author: Krotow
author_rank: Regular Contributor
timestamp: March 13, 2025, 06:56:48 pm
content: Threw the thing into a shelf and forgot about it. Few days ago accidentally found it and decided to either fix it or throw out. Already learned before that Changzhou Jutai LED drivers use custom design controller IC JT-022 and not a PIC or other universal MCU. The controller acted like good one so there was only 4 transistors left. Soldered them out and tested... as turned out, Q1 and Q2 (FTC8050HH, BJT NPN) was completely open at both directions. Bridge MOSFETs Q3 and Q4 (NCE60P04Y, P-ch) was fine.FTC8050HH was nowhere to found (even in Ali), however substitute SS8050(Y1) was available at local electronics shop. Thing is up and running again, spewing out +/-31V PWM at full height as expected.Just curious how PIC or ATtiny instead of JT-022 would make this LED driver more expensive in mass production. For some time I had an wish to replace JT-022 with ATtiny13.
JVC LCD TV problem - bad TCON, probably? - Page 1
Forum section: electronics / repair

author: andy29
author_rank: Newbie
timestamp: October 14, 2020, 06:33:35 pm
content: Hi everyone... could I possibly ask for a little advice about my TV?This is an old CCFL thing, a JVC TV LT-32DR1BJ. A while ago it suddenly went dark - the same across the whole picture, and not like the backlights or inverter had gone, in fact with some images it makes you think it's fixed itself, but no, it hasn't. Ghosting and weirdly saturated colours too. Checked all of the voltages and capacitors I could since I couldn't find a service manual, and after finding messages here and a video someone did on Youtube, I decided it was most likely the gamma chip on the TCON board.Got a replacement board through and that gave a different set of problems - more washed out than dark (so backlights are definitely ok), and weird moving patterns when the brightness is below a certain point. The gamma chip is a different model too but the board is the same part number. Then also noticed that one of the inductors is cracked. I've attached a photo of the replacement one with that cracked inductor, and that one together with my original one. I'm aware that eBay boards seem to push the definition of 'new' but if it worked I wouldn't mind for the price.So... a) is the cracked ferrite on that inductor as bad a thing as it seems, and b) should I still have had more success with the replacement board, does it point to something maybe being wrong on another board, or maybe this replacement has other problems too?Thanks for any ideas

author: limtk55
author_rank: Newbie
timestamp: October 17, 2020, 03:23:18 am
content: How about a little process of elimination :Reattach the old TCON board to TVGet a CCFL tester and check your CCFLs one by one. Replace the faulty tubes and turn on TV.If problem persists :Swap Inductor(old) with Inductor(New)Connect new TCON to TV and test.If image issues persist :Swap Gamma IC(old) with Gamma IC(new)Do a test.....you get the idea....

author: andy29
author_rank: Newbie
timestamp: October 18, 2020, 11:05:32 pm
content: Definitely makes sense... thank you.

author: Technomaniac
author_rank: Contributor
timestamp: October 19, 2020, 01:41:03 am
content: I suppose you know about replacement board PART NUMBERS - That it's the number on the PAPER STICKER that you have to match - the bare boards may be identical and have the same screenprinted numbers, but different components fitted and different links, etc. for different models of receiver, or different countries versions.
JVC "lt-42c550" LCD TV: on, but no backlight - Page 1
Forum section: electronics / repair

author: eti
author_rank: Super Contributor
timestamp: November 02, 2021, 11:09:17 pm
content: Hello.I thought I'd ask here, where actual expert engineers gather, rather than speculating with amateurs on YouTube comments.I have been given a JVC "lt-42c550" - my friend said it was taking longer and longer to come on, but would come on eventually, after about 10-15 seconds (immediately I now think "bad caps" based on what's coming up next...)So now he brought it over and it comes on - you can see the LCD when lit with a flashlight, but the backlight isn't working. I found one YouTube video where a bloke replaced two caps and fixed his (similar model) TV.Any "JVC" experts? I'll bet it's not even made by JVC! I'm used to servicing CRT TVs and VCRs, and stopped doing that in the 90s.Thanks chaps.

author: Brumby
author_rank: Unknown
timestamp: November 03, 2021, 12:03:42 am
content: I will say at the outset that I'm no expert here - and haven't performed any such repairs - but from my observations of similar failure and repair reports, I can support your observation that bad caps seem to be very well represented as a common fault..... and, yes, it seems full in-house manufacturing is not seen much these days.

author: eti
author_rank: Super Contributor
timestamp: November 03, 2021, 04:21:40 am
content: Removed PSU board, will check for faults and bad caps later today

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 03, 2021, 10:01:45 am
content: Leds burning down are very common in older TVs as they age.In fact, I usually found more damaged LEDs, but "luckly" they were shorted, so the backlight still worked, until one of them failed open.If it's for yourself and you don't want to spend money in new leds strips, a cheap fix is to short the open leds with a wire.The LED circuitry works at constant current, it will work fine, won't overload anything.Unless there're contiguous damaged leds, the light difference isn't very noticeable.Otherwise replace ALL the leds, or you'll have to fix them every 3-6 months. They all have the same running hours, so it's likely for others start failing.

author: GlennSprigg
author_rank: Super Contributor
timestamp: November 03, 2021, 11:27:29 am
content: Sorry if I'm "barking up the wrong tree" hahaha...Of the numerous Laptops I've worked-on/repaired, the problem with them is virtually always the BackLight Controller Board itself,behind the bottom of the screen outer escutcheon. Easy access, and very cheap to fix/replace! However, I realize that what youhaveis a TV.I found ONE video though, that explains how just one of the backlight LED's can take it down, and how he tests allthe individual LEDS's, to find the faulty one. Interestingly, he uses his Multimeter on 'Diode' test setting, as the power supply! whichlights up the LED's too, due to the extra voltage to overcome forward-biasing, and won't be affected/bothered by shorts.
JVC PRX518S Startup circuit hot divider resistor - Page 1
Forum section: electronics / repair

author: rossi32s
author_rank: Newbie
timestamp: January 21, 2024, 12:02:25 am
content: I got a JVC PRX518S in and all output transistors were shorted and a few SMD diodes in the output circuit. Additionally R610 24K 1W in the main supply voltage divider circuit was toast too. After doing the output repair I powered it up and noticed R610 is still getting extremely hot. I, for the life of me, cannot find anything under thermal or testing, causing it to get extremely hot.Attached is the schematic page 6 D-3 is where the voltage divider that supplies VPRI, which goes to B-5 on the same page. If i lift D609 out of the circuit R610 does not get hot. I have checked all components in that circuit and all components in +15 control.I am missing something somewhere.. any ideas? Schematic attached.
JVC RX-552V A/V Receiver now cares where I stand - Page 1
Forum section: electronics / repair

author: Maplewood_Ken
author_rank: Newbie
timestamp: March 12, 2024, 01:25:28 am
content: This receiver, purchased second-hand, has given good service for a number of years. However, when listening to music on FM radio, it now matters where I stand or sit in the room, which it formerly did not do. Depending on my location, the sound is great, or the sound has strong fuzz overlaid. I am sure there is a term for this phenomenon, but unfortunately I do not know what it is and my searches based on guessing were not productive.An education on terminology would be a help, and ideas about ways to fix this that do not involve my donning a tinfoil hat would be very much appreciated.Thank you for reading.

author: Haenk
author_rank: Super Contributor
timestamp: March 13, 2024, 06:31:30 am
content: I don't know how old you are, but there we're comic strips dating to the 50s - family is sitting in front of a TV, dad is fiddling with the antenna.That issue still persists. You need to better direct your antenna, get an external antenna (on the roof) or depending on the age of the receiver, change the frequeny by a bit.I assume this is an issue of waves reflecting uncontrollable within your room.Back then, the best fix hast been a roof antenna, or coax cable, If available.
JVC TM H1700G Dead power supply - Page 1
Forum section: electronics / repair

author: emiku393
author_rank: Newbie
timestamp: June 06, 2025, 05:16:40 pm
content: Hello, I need some help on this JVC TM H1700G that is currently dead.I took some measurments and fuse is fine and capacitors seem ok too.Any help to get it back to life is much appreciatedhttps://www.dropbox.com/scl/fi/bim2xcbgmzvmtxbkkoa2m/jvc_tm-h1700gu-ge_sm.pdf?rlkey=9cw6teddlbx05soxcw5wk7fq1&e=1&st=4ytew1j4&bmus=1&dl=0

author: fzabkar
author_rank: Super Contributor
timestamp: June 06, 2025, 10:51:47 pm
content: Is the standby supply (STB7V) running?Next check the supplies at transformer T901 (53V, 14V, 7V, 14V).

author: emiku393
author_rank: Newbie
timestamp: June 07, 2025, 06:13:15 pm
content: There is no 7v standby

author: fzabkar
author_rank: Super Contributor
timestamp: June 07, 2025, 06:21:21 pm
content: Troubleshoot the area around IC902 (STR-L472). R922 (open circuit) and C939 (high ESR) would be typical suspects, assuming the main fuse is intact.WARNING: The main bulk capacitor may be holding substantial voltage even after power is switched off.

author: emiku393
author_rank: Newbie
timestamp: June 09, 2025, 06:57:59 pm
content: Verified main fuse and output voltage of the bridge rectifiers D920 and D901 and they output around 170v each.Checked components R922 and C939 as well as adjacent to IC902 but all them seem to work.Thinking it might be IC902 itself.

author: fzabkar
author_rank: Super Contributor
timestamp: June 09, 2025, 07:03:21 pm
content: I would first confirm that the 7V standby voltage is not shorted to ground, then I would replace the IC.

author: D2236
author_rank: Regular Contributor
timestamp: June 11, 2025, 03:43:35 am
content: Check R927, the current sense resistor in series with the source of the internal MOSFET.

author: emiku393
author_rank: Newbie
timestamp: July 30, 2025, 06:01:02 am
content: Checked for 7v stanby it is indeed shorted, will continue to look around.Edit: I replaced IC902(STR-L472) and now have 7v stanby and it powers on, but still no picture..
JVC TM-H1900G Monitor Recovering Menu and Control - Page 1
Forum section: electronics / repair

author: sunomo
author_rank: Newbie
timestamp: January 19, 2022, 10:46:38 pm
content: Hi everyone,I have a JVC TM-H1900G which I successfully modified with RGB input years ago. I added a SCART port connected to the IC jungle (IC501). The SCART input can be enabled or disabled with a switch.One day when I tried to repair a plastic panel inside, I accidentally forgot to connect the ground so I had a short. When switched on again, the pictures were ok but not the menu and any control from the front panel including the volume and the brightness. When I press them nothing happens.The problem is for sure in the signal input board. In fact I also have a JVC TM-H1900CG from which I exchanged the board. In this way the menu appeared again correctly.I hope to be able to repair this input board. I think that if the problem was into IC501 I was unable to see anything. More likely the IC701 (M37207MC-316SP) IC702 (AT24C08-H1750C) Microcomputer with Memory are the defective part, since they are connected to the keys and to the remote directly.Is it possible to find somewhere these chips and to program them correctly?Circuit maps can be found here:https://archive.org/details/51961-s/51961-S
JVC VCR power supply oddity - Page 1
Forum section: electronics / repair

author: MisterStiggy2
author_rank: Newbie
timestamp: June 10, 2025, 11:54:21 am
content: Hi folksI recently acquired a JVC VCR (a fancy high-end HR-S9700EK S-VHS, and well worth keeping!) with an unusual power supply fault.The machine powers up and plays tapes fine - however, I noticed a burning smell after a while.I disconnected it from the mains, found the appropriate service manual online (thanks, Elektrotanya:https://elektrotanya.com/jvc_hr-s9700ek.pdf/download.html) and looked for what was causing the smell.It was quickly traced to LF5002 (highlighted in red on the accompanying circuit-diagram extract), which forms part of the mains filter. Its four windings were visibly-frazzled, and so the component had clearly passed too much current.I fitted a replacement removed from a scrap machine, but the same problem occurs when the machine is powered up (luckily the top cover was removed, so I could see what was going on and kill the power to avoid further damage!). As before, the VCR otherwise behaves as it should.I would welcome any suggestions as to what I can do to fix this problem (as I have VHS tapes I want to transfer). Has anyone come across this or a similar fault?Many thanksMartin

author: MisterStiggy2
author_rank: Newbie
timestamp: June 10, 2025, 12:10:52 pm
content: I forgot to mention...before replacing LF5002, I used a multimeter to check the adjacent circuitry for any components that might have gone low-resistance or short-circuit.Everything seemed OK.

author: D2236
author_rank: Regular Contributor
timestamp: June 10, 2025, 09:32:27 pm
content: Check C5002. It may be one of those bad RIFA type capacitors. On other forums, people state that the general quality of the capacitors used in various JVC VCR PSU models were not good, and often low 85 deg C rating for the EL caps.

author: amyk
author_rank: Super Contributor
timestamp: June 11, 2025, 02:21:50 am
content: Check what the idle power consumption is with the PSU disconnected from the rest of the machine, especially how much current it's drawing from the mains.

author: MisterStiggy2
author_rank: Newbie
timestamp: June 27, 2025, 05:03:49 pm
content: In the end, it turned out to be the HT reservoir capacitor (C5006, 68uF/400V).This was completely open-circuit - it's amazing that the machine worked at all.I guess that the smoothing caps on the DC rails did their job, throwing me off the scent...
JVC VR-5535x - Strange issue and fix (?) - Page 1
Forum section: electronics / repair

author: michalism
author_rank: Regular Contributor
timestamp: December 19, 2022, 08:56:43 am
content: Hello all, and warm season greetings.I'm working on this old JVC amplifier, which I bought in the flea market. After some basic clean-up and checks, I stored it away as I had other projects to work on.Last week I got it on the bench for some more thorough checks and final restoration.Then I discovered that one channel was not working- not completely silent, but for sure there was a problem there. I noticed that when I turn the volume all the way up, it there's some signs of life but still not proper playback. I'm pretty sure this issue was not there last time I checked, but since I have kept no notes, I can't be sure.I checked and replaced all electrolytic caps on the main amplifier board, and then set-off to do some signal tracing and voltage checks.To my surprise, when the signal tracer probe touched point 602 on the schematic, there was a loud pop, and the speaker started playing normally. It played for a few seconds then got silent again. Touched the probe again, same thing. Even when touched with a screwdriver, it would start playing for a few seconds or minutes then get silent again.After a couple of days testing and scratching my head, the amplifier is playing fine now! I had let it play two or three times for a couple of hours each time and it is stable. I have even tested it with an oscilloscope (1kHz tone, 120mV p-p on AUX input.) and seems perfect!But I'm still worried that this may come back later on unless I understand what was the problem and why it is fixed.I want to get to the bottom of this not only to learn, but also because this will soon be my main amplifier, and I want to make sure I leave no stone unturned.I'm attaching the schematic of the unit, the service manual exceeds the 4Mb limit, but I can try to cut it in pieces if it helps.Any help would be much appreciated!!Thank you very much in advance!Michalis
JVC X30 Power Supply Sumida IV95260 Repair Help - Page 1
Forum section: electronics / repair

author: vk
author_rank: Newbie
timestamp: December 12, 2020, 02:35:48 am
content: Hi I have a Sumida IV95260 SMPS power supply from a JVC X30 Projector. The initial issue was that the projector wont power on. This is from my friend and hence dont know what was the status of the LED error code. As per him, the Power LED turn on and nothing happens after that.I thought its a SMPS related issue and found that that the Power supply is not outputting voltage required. I dont have a schematics of the board, and hence made a circuit diagram from the board. I can see the SMPS IC NCP1271 is getting power and is in error state because of the lack of Feedback from the Secondary section. I checked the Primary Section MOSFET and was found to be ok. I dont want to work on the live main power, so, I created a 120V DC power from a 36V using a voltage Tripler to get the board working. I can see the primary section is working ok up till the Mosfet. Disconnected the Transformer to see any shorts in the output and could not find any. Except that the resistance between the 12V rail and ground is 23 Ohm because of 6 parallel 181 Ohm resistors.Checked the Secondary side by supplying with external voltage to see any shorted components, but cant see anything.As I can see there is an onboard 5V Generator that supplies power to NCP1271. Shorting two pins at the connector gets that section working, but cant see any reason why the SMPS is not working.Parts changed so far:Opto-couplersNCP1271Primary side Switching Mosfet.Has anyone worked with this model SMPS. Just need some guidance to see if am missing something to get this SMPS enabled properly.SMPS-min.pdf(1136.46 kB - downloaded 334 times.)

author: vk
author_rank: Newbie
timestamp: December 12, 2020, 08:25:24 am
content: Issue Solved. Its was a resistor issue. a 10Ohm resistor became 100K and prevented the Mosfet to turn on.All good, thanks for looking....
JYE Tech DSO 068 - Page 1
Forum section: electronics / repair

author: Warmbells
author_rank: Newbie
timestamp: November 02, 2020, 08:57:56 am
content: Hi,I wonder if anyone can help?I purchased one of these kits some years ago but i had not completed it when I was taken into hospital where I spent some time. whilst I was in hospital my wife had a tidy up. I only came across the kit a couple of weeks ago and thought I would finish it but I can no longer find any assembly instructions and the instructions on the JYE Tech site are for a later version. I'm looking for where the test signal is taken from but have not yet figured it out.any help would be gratefully appreciated.many thanks,Gerald

author: Peabody
author_rank: Super Contributor
timestamp: November 02, 2020, 02:19:00 pm
content: I don't know anything about the 68, but they have a forum, although at the moment it isn't displaying properly for me. But the main site has a Contact link at the bottom, and in my experience they do respond. They could probaby just send you the docs for that version.

author: Chris56000
author_rank: Frequent Contributor
timestamp: November 02, 2020, 10:29:24 pm
content: Hi!According to JYE's Web Site, there were only two versions of the DSO 068 released "in the wild" – Version "F" and Version "H" – I attach the "F" version documentation below!Chris Williams

author: Warmbells
author_rank: Newbie
timestamp: November 02, 2020, 11:25:46 pm
content: Thanks for the link to the F version, I think I must have the H version as I managed to see (with a magnifieing glass) this text PN:109-06800-00HGerald
k04bb status - Page 1
Forum section: electronics / repair

author: ME
author_rank: Frequent Contributor
timestamp: May 09, 2025, 06:41:59 pm
content: Is k04bb site down againe? , I get this message when trying to download: Warning: mkdir(): No space left on device in /var/www/html/getsimple/admin/inc/theme_functions.php(544) : eval()'d code on line 67

author: Andy Watson
author_rank: Super Contributor
timestamp: May 09, 2025, 07:13:43 pm
content: I went there yesterday. It was ok but there was a message saying that the server was operating at its limits and there may be some difficulty connecting.

author: Greybeard
author_rank: Frequent Contributor
timestamp: May 09, 2025, 09:20:40 pm
content: Short test:Working without a problem.Edit: Download doesn't work (same error message)

author: ME
author_rank: Frequent Contributor
timestamp: May 10, 2025, 04:41:06 am
content: I just tried it , I get the same message for anything ie manual that i try and download!.The site seems ok untill i try and download anything.

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: May 10, 2025, 05:01:37 am
content: Quote from: ME on May 10, 2025, 04:41:06 amI have the same issue as you. Downloading a document does not succeed.

author: ME
author_rank: Frequent Contributor
timestamp: May 10, 2025, 11:00:25 am
content: its not just me then.

author: ME
author_rank: Frequent Contributor
timestamp: May 15, 2025, 09:28:22 pm
content: I still get this : Warning: mkdir(): No space left on device in /var/www/html/getsimple/admin/inc/theme_functions.php(544) : eval()'d code on line 67

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: May 15, 2025, 10:12:03 pm
content: Maybe you can contact Didier so that he can correct the issue ?

author: ME
author_rank: Frequent Contributor
timestamp: May 19, 2025, 05:11:57 am
content: Who is Didier ?.

author: Mickle T.
author_rank: Frequent Contributor
timestamp: May 19, 2025, 05:15:34 am
content: Quote from: ME on May 19, 2025, 05:11:57 amhttps://www.qrzcq.com/call/KO4BB

author: ME
author_rank: Frequent Contributor
timestamp: May 19, 2025, 05:30:37 pm
content: ive mailed him to inform him of the site issues.
K6T4008C1C SRAM test failure real? - Page 1
Forum section: electronics / repair

author: Dan N
author_rank: Contributor
timestamp: October 03, 2024, 09:09:48 pm
content: Using information fromthis thread, I tested a Samsung K6T4008C1C-DB70 SRAM on an XGecu T48 (HM628512, K6T4008C1C and AS6C4008 should be equivalent). It gives the error shown in the attached pic. Does 09# Addr.Bus mean chip pin A9 or does it mean tester pin 09?I haven't tested an SRAM before on the T48, do you think this is a real failure and not just an invalid test? There's one post on the XGecu forum where a T56 gave a similar error (00# Addr Bus Open Circuit) but nobody replied.
Kapta Security DVR repair - Page 1
Forum section: electronics / repair

author: BrentChivers
author_rank: Newbie
timestamp: May 15, 2023, 12:06:08 pm
content: Hi all,long time lurker, first time poster.I am trying to diagnose and repair a security camera DVR box, this one labelled a Kepta 1116.Problem:- Short beep to signal its powering on- Nothing follows for 1second(ish)- Short beep to signal its powering on againI was looking at the power supply side of the PCB, like there might be a short circuit which causes a reset, then repeat, but all the caps and diodes look good. I've removed caps C203 & 2C207, but that seemed to only change the tone of the beep.Ideas on where I should probe next?
Thanks for your help.  - Page 1
Forum section: electronics / repair

author: aiako
author_rank: Newbie
timestamp: October 28, 2019, 01:17:37 am
content: Thanks for your help

author: fzabkar
author_rank: Super Contributor
timestamp: October 28, 2019, 03:12:13 am
content: Is the CL-25 service manual of any help?https://elektrotanya.com/kawai_cl25_digital_piano.pdf/download.html

author: aiako
author_rank: Newbie
timestamp: October 28, 2019, 12:35:23 pm
content: Thanks for your help.

author: aiako
author_rank: Newbie
timestamp: October 28, 2019, 11:22:00 pm
content: Thanks for your help

author: fzabkar
author_rank: Super Contributor
timestamp: October 29, 2019, 11:17:44 pm
content: That's 1.7W. I wouldn't be surprised by that. Sorry, I have no ideas other than to check any diodes in the key matrix.

author: Synthtech
author_rank: Regular Contributor
timestamp: October 30, 2019, 10:50:39 am
content: Try playing it from another keyboard via MIDI. Also check that MIDI local hasn’t been turned off which would keep the instrument from responding to its own keyboard. Then try and play another MIDI keyboard or module from the Kawai. The result of these tests will tell you a lot.

author: aiako
author_rank: Newbie
timestamp: October 30, 2019, 08:34:00 pm
content: Thanks for your help.

author: Synthtech
author_rank: Regular Contributor
timestamp: October 31, 2019, 07:13:17 am
content: Page 30 of the owners manual explains how to set MIDI local on and off. Worth checking that it is on.
Kawai Digital Piano: Power fuse keeps blowing - Page 1
Forum section: electronics / repair

author: zeteroo
author_rank: Newbie
timestamp: April 24, 2022, 04:51:12 am
content: I've had a Kawai MP10 now for 6 years. About three years ago the power input fuse blew. I subsequently replaced it.And about 6 months later the same problem occurred and the keyboard was not powering up even with a new fuse. I then found a schematic online for a similar keyboard (the MP8) and changed over a capacitor or two on the power input board. It seemed to work fine for a while, now the fuse has blown again. Unfortunately for the life of me, I cannot find any paperwork on which capacitor I actually changed (perhaps it was both). I suspect it was the blue safety capacitor (https://au.mouser.com/ProductDetail/Murata-Electronics/DE1E3KX472MB5BA01?qs=Fnw9rlXk%252BwzlEkoY78eC8w%3D%3D) (Mfr. No DE1E3KX472MB5BA01). I also replaced the fuse with a one that reads F160AL250 (Recommended on the schematic reads 160mA/250V Inrush-withstand).I have attached some photos of the AC power board, the transformer, and the DC power board. I've also attached the schematic which differs slightly (there is no choke coil on the AC power board for instance).I have no idea why this is happening. Maybe my electronics knowledge is lacking, but if the fuse is blowing before the step-down transformer, it would mean that the problem has to exist only on that side of the electronic component, i.e., the power board, AC inlet plug and wires.Thanks in advance for any advice.

author: Audiorepair
author_rank: Frequent Contributor
timestamp: April 24, 2022, 07:45:20 am
content: The F160 fuse is the wrong type. That is a fast blow fuse, you need a slow blow.That will be marked T160.Perhaps this is the only problem.

author: zeteroo
author_rank: Newbie
timestamp: April 24, 2022, 08:39:03 am
content: Yep I seemed to have got that mixed up. I can't quite remember either the first time around what fuse I was using or why I had to replace the safety capacitor. I've learnt a valuable lesson to keep detailed notes on this stuff!
Kay Elemetrics Corp 837 Attenuator broken toggles  - Page 1
Forum section: electronics / repair

author: magnetchief
author_rank: Contributor
timestamp: February 20, 2024, 02:59:55 pm
content: hi.A coworker asked me if I could take a look at a variable attenuator box produced by Kay Elemetrics Corp.The two 30 dB toggle switches were not operating correctly.Disassembled it to find that the two toggles had snapped off inside of the housing.I assume these are proprietary to Kay and not available via typical sources.I can find a company, Lintech Components that lists many parts by name and part number but no real description.Would anyone be aware of a parts diagram, breakdown for this device. If I could find the part number for the switches maybe then I could track down some replacement parts.Many thanks..https://www.lintechcomponents.com/product/manufacturer/80138/show
Kay M710 Spring Reverb repair - Page 1
Forum section: electronics / repair

author: belzrebuth
author_rank: Frequent Contributor
timestamp: November 12, 2023, 11:52:20 pm
content: Hi all,A friend gave me a Kay M710 Spring Reverb in bad physical condition and it's not working properly.A previous repair attempt probably burned a Ge transistor (Q10) and the guy replaced it with a 2n3906 as-is (at least he got the pinout correct!).The rest of the circuit seems okay when trying to trace it along the schematic and I get a signal on the output but I hear a constant loud buzz and very little of the actual effect passes through.The signal before it hits the effect is badly distorted.I don't know what the culprit is as of yet but I guess the first stage should be properly biased and it's not since it was meant for a germanium transistor.Can I somehow modify that part to actually work with a 2n3906?I've tested all the other transistors with a transistor tester and they seem to work okay so since this transistor is missing and it's not that easy or quick to find a replacement could anyone help into modifying the circuit a bit to make it work with a silicon pnp?!

author: t1d
author_rank: Super Contributor
timestamp: November 16, 2023, 02:12:17 am
content: Please give us the part number for the failed transistor. I can not read it on the schematic. (Maybe post a larger schematic.)I am thinking that a germanium replacement, or substitute, can still be sourced. There are boutique supply houses, for just this sort of thing. Tubes and such... If you want to maintain that vintage sound, you are going to want to steer clear of modern adaptations, as much as possible.Noise can get into vintage audio gear in lots of ways... Certain wire pairs must be twisted... Wire routing paths must be done in a certain way - like running them close down on the chassis... Ground loops... Etc. Make sure the chassis earth ground connection is solid - no rust under the washer, etc. and that the earth ground wire is 100% all the way to the end of the wall plug. If it is an old/original cable, just replace it.HTH.

author: floobydust
author_rank: Super Contributor
timestamp: November 16, 2023, 03:27:34 am
content: The schematic shows no bias resistor for the reverb-line driver transistor 2N408 20V 70mA 150mW hFE 65.Without it, I would expect lots of distortion. I don't know if leakage current provided it (bias) from C4 or the Ge transistor itself. The original sound of this reverb might have been a bit "dirty"? I don't see a control for wet/dry.But a 2N3906 is fine, I would say it will just need to be biased into Class A. It depends on the coil DC resistance if this will be a problem, i.e. the transistor idling current say 10mA through the coil.Ideally there should be bias resistors and a coupling cap to the reverb coil, parts I would add unless it upsets the original grit.For it's age, all the electrolytic capacitors will be dead, dried out C8 and C5 would cause hum and buzz.
KB Electronics KBIC-125 schematic - Page 1
Forum section: electronics / repair

author: Jester
author_rank: Frequent Contributor
timestamp: April 11, 2022, 02:42:12 pm
content: Does anyone have or no where I can get a schematic for a KBIC-125 DC motor drive?The drive I have is OLD dated 1987It actually works fine, I want to drive the speed with a dc voltage instead of the external POT and seeing how the pot is connected in the actual circuit would be helpful.Thanks

author: jpanhalt
author_rank: Super Contributor
timestamp: April 11, 2022, 03:39:34 pm
content: After a bit of a search, I found an extra, new KBIC-125 that I bought in about 2003. I never throw away the manuals, but I couldn't find this one. (My stuff is spread currently between 2 houses 42 miles apart.) But, I did pay $50 for it.Attached is a picture of the installation on my Prazi miniature lathe. I also found this online:Quote from: onlineAs I recall, the KB controls I have can all be operated by a potentiometer or variable DC voltage. None of them are current controlled.Maybe that helps. I will probably go to the other house Thursday and will look for the manual there.

author: Jester
author_rank: Frequent Contributor
timestamp: April 11, 2022, 09:27:06 pm
content: Attached is a hodgepodge of info and KBIC schematic from various sources. It does give a feel for the circuit if anyone needs to troubleshoot a defective unit.Regarding controlling speed with an external source, looks to be easy as long as you keep in mind that that bottom leg of the pot is sitting at 1/2 MAINS voltage (178Vp-p), waveforms below.One observation is that this thing 60Hz hums like crazy, I prefer the silence of a VFD. Tests were performed on an unloaded treadmill motor.
KBIC-125 (5 Triac version) schematic - Page 1
Forum section: electronics / repair

author: Jester
author_rank: Frequent Contributor
timestamp: April 03, 2023, 03:21:22 pm
content: I'm, trying to repair an old KBIC-125 motor controller. Schematic would be helpful.The board has designators SCR1-5 along the heatsink, so quite different than the KBLC-240 schematics floating around.anyone have a source for the schematic?

author: Swake
author_rank: Frequent Contributor
timestamp: April 06, 2023, 07:43:38 pm
content: There are not many components on that board. I you really want a schematic you could reverse engineer it easily.Much quicker however is to measure / check those components in place. A simple multimeter is likely enough. If you have a doubt remove them and measure out of the board.

author: Swake
author_rank: Frequent Contributor
timestamp: April 06, 2023, 07:44:52 pm
content: And download the datasheet for that chip. There will likely be an application note for it somewhere too.

author: alpher
author_rank: Frequent Contributor
timestamp: April 06, 2023, 09:53:19 pm
content: I seem to remember that years ago KB controlls came with schematic included in the box. To bad they all ended up in garbagge can. My advice, just buy a new one, not worth the effort to repair IMHO.
KEB F5 13F5B1D vfd - Page 1
Forum section: electronics / repair

author: llevanic
author_rank: Newbie
timestamp: August 31, 2025, 06:24:16 pm
content: Hello everyone, this is my first time writing on this forum.First of all, hello to all members, I hope we will have a pleasant cooperation in the future.I have a question for the subject mentioned frequency regulator.The input is 400v three phases, I have a breakdown and I am going to the service, I opened the regulator and found a breakdown on the IGBT, see everything around it and in it is burned. Does anyone have experience is it possible that only the IGBT burned or is it possible that other components are also burned?Visually everything looks fine except for it.Thanks in advance for your answers

author: Swake
author_rank: Frequent Contributor
timestamp: September 01, 2025, 05:34:55 pm
content: Yes, plenty of stuff might have failed. It depends a lot on the root cause of the failure. The FET might have failed by itself or as a consequence of some other component failure. Eventually it was some external cause such as an issue with the motor. Or whatever else.
Keithley 177 Flashing 0000 on all AC functions - Page 1
Forum section: electronics / repair

author: J-R
author_rank: Super Contributor
timestamp: October 08, 2021, 05:55:11 pm
content: I have a Keithley 177 that I am trying to repair. The biggest issue is that whenever AC is selected, all the digits just blink 0000 continuously in both voltage and current modes (and all ranges). Also, all resistance, DCV and DCA functions work perfectly and are completely spot on, EXCEPT for the 20mV and 200mV settings which both read a bit high and there is not enough adjustment range to correct it.Following the manual (http://web.mit.edu/8.13/8.13d/manuals/keithly-177-dmm.pdf), under the AC Converter Checks (page 5-9), I got to step 5 and the output was bouncing around 8V instead of being 1V.Has anyone seen this behavior or have any suggestions on what the problem could be?

author: bdunham7
author_rank: Super Contributor
timestamp: October 08, 2021, 06:12:19 pm
content: I've no time at the moment for more than a quick look at the schematic and an offhand guess, but it looks to me like your U103 (AD636 TRMS converter) is bad. Astonishingly (to me) Mouser has them in stock in the TO-100 package!

author: J-R
author_rank: Super Contributor
timestamp: October 10, 2021, 08:22:38 pm
content: Thanks for the suggestion, but unfortunately that part is more money than I paid for the entire unit! So even if it is bad I probably wouldn't replace it. But I suppose I could consider removing the part and at least testing it.

author: bdunham7
author_rank: Super Contributor
timestamp: October 10, 2021, 08:50:46 pm
content: Quote from: J-R on October 10, 2021, 08:22:38 pmYou're new at this, right?Seriously, there are some US sellers on eBay that have it, maybe have a look.

author: J-R
author_rank: Super Contributor
timestamp: November 05, 2021, 06:19:37 am
content: Quote from: bdunham7 on October 10, 2021, 08:50:46 pmEh, yes and no, have a few resuscitations under my belt so far: 2 out of 3 Fluke 8050A, 8840A, HP3466A, Keithley 197A and now this 177.Tinkered some more. Turns out the DC modes actually were all working perfectly after I did a complete calibration, so odds were good for just the True RMS-DC converter being bad.TP1 was 8V, but pin 6 on U103 (AD536AJH) was always -0.9V no matter the input or external adjustments. I tested all the components connected to it and they were fine. Found the data sheet on the AD536A series so was able to get all the pinouts. Pulled it out and it was for sure a goner. No chance getting this back to life with spare parts from the bin, though...I was able to locate the similar AD536AKH from a reputable US seller for $20 delivered. Got it installed and ran once more through a complete calibration and all is well.Cute 19,999 count relic for my "collection".
Keithley 179A, V and A dead - Page 1
Forum section: electronics / repair

author: khs
author_rank: Regular Contributor
timestamp: November 21, 2019, 08:18:19 pm
content: Last days I ordered from evilbay a tested(!) Keithley 179A 20A.I have two, but some of my boards I make have three power supply voltages so it's fine to see all three currents during the first power up.The "new' 179A looks like new, but during the first test volt and ampere readings failed. Only Ohm readings were fine.All fuses were OK and no sign of damage was visible.Checking the power supply voltages using the LO input as reference I noticed the +-15V were too low and not stable.Checking the connection of the LO input to ground I noticed the LO input was not connected to ground. But is should be connected via R154 (a 0.01 ohm resistor) if not in ohm mode.The ohm switch was OK. This is not bad, because I assume removing the mode switch without damaging the whole board may be quite difficult.If the ohm switch is OK and there was no sign of a damage of the wires on the pcb visible it should work. Or I have overlooked something.Following the wire from the ohm switch to R154 the wire disappeared under CR111.And a second view showed a tiny piece or blank chopper more or less under CR111. This was the end of the wire.After removing CR111 it was visible under CR111 this piece of the wire was blown. Before and after CR111 the wire on the pcb was fine so the repair was simple.P.S. The picture of the CR111 could be better, but the piece of blank wire should be visible.

author: lowimpedance
author_rank: Super Contributor
timestamp: November 21, 2019, 10:18:38 pm
content: Quote from: khs on November 21, 2019, 08:18:19 pmSorry too blurry, I cannot see what your talking about. Are you saying there was a thin wire, (fuse like !?) under CR111 that had gone open cct ?.

author: khs
author_rank: Regular Contributor
timestamp: November 22, 2019, 09:02:51 pm
content: Quote from: lowimpedance on November 21, 2019, 10:18:38 pmHere a better picture. I've removed CR111 to show the damaged wire better.Yes the width of this part of the wire was not as wide as the rest of the wire, so it was more or less a fuse.I've learned the fuse must be fast to protect the wire. Otherwise the wire protects the fuse...