hybridfree/eevblog-posts huggingface dataset:
JBL D112 MOD - Page 1
Forum section: electronics / repair

author: Mick B
author_rank: Regular Contributor
timestamp: January 05, 2021, 08:54:00 pm
content: I an very new at this but an not afraid to let the smoke out if I learn something from it.I have this JBL D112 subwoofer and the integrated AMP-IC S64AMI is not available and that's what has blown! I would like to replace the output amp with maybe a few 2SC5200/2SA1943 using as much of the existing circuitry as I can, there is nothing wrong with the Pre-Amp or Power Supply and it was recaped about 2 years ago. ANY idea's will be entertained, I have a large supply of components so this will cost almost nothing if it can be done at all. Please note: I have a few schematics of different revisions with what looks like minor component change. I'm only posting one if this grows legs I'll add more pictures and documents. It's a business doing pleasure with you.Thanks Mick
JBL E250P subwoofer repair - Page 1
Forum section: electronics / repair

author: mjrpainless
author_rank: Contributor
timestamp: October 04, 2019, 11:48:05 pm
content: Hey all,I have a subwoofer that I'm trying to troubleshoot.The driver was blown. I measured some AC noise on the output with the unit powered on, and no input connected.I'm usually pretty good at these things, but this thing has been a pain. Any help, or pointers would be greatly appreciated.I am beating my head against the wall. And am looking for some guidance. I have posted the service manual.

author: don.r
author_rank: Frequent Contributor
timestamp: October 05, 2019, 12:40:33 am
content: Test output transistors for shorts. I'm working on a bench dmm that has a shorted op amp (44K Vdd to Vss) and that was causing a big AC ripple on the power rails.
JBL EON 15 P-1 speakers, troubleshooting advice needed - Page 1
Forum section: electronics / repair

author: MojoLuca
author_rank: Newbie
timestamp: August 11, 2025, 06:52:13 pm
content: Hi everyone, this is my first post here after a few years of reading around, really looking forward to learn and enjoy the forum.So I recently got this pair of old JBL active speakers from a local pub. After cleaning the mains sockets and switches, one works and the other powers on but no sound.Here's the schematic (page 3)https://assets.yoreparo.com/attachments/qx8XbC1seMZQYL7MdD6Yy9NlhDS5yQVSlbs1Obi3.pdfDrivers tested in ohms and show same resistance as the working ones.Upon inspection of the power amp board I found C21 exploded like a pop corn, replaced it but still no sound.Checking the voltages with the drivers disconnected I have both +/- rails (V1 +39V and -39V; V2 +79V and -79V), +15V and -15V are also present and stable.The major difference I've found is that on TP10 MUTE (bottom middle in the schematic) on the working one I have about -14.5V and on the silent one the same voltage but positive.I've started testing the semiconductors and other capacitors but haven't found anything obvious yet and would need some advice for troubleshooting. Even better if someone can explain how the mute circuit works.ThanksLuca
JBL EON 518S powered subwoofer blowing fuses succesful repair  - Page 1
Forum section: electronics / repair

author: fixy88
author_rank: Contributor
timestamp: February 20, 2020, 04:56:49 am
content: I'm posting this here in case someone else runs into this issue, as I'm guessing it will come up for a lot of users of this subwoofer.I was gifted this sub as the user had replaced it and wanted it out of their storeroom. It was dead but they didn't give me any further info. I checked the mains fuse which was open. Fuse was replaced and the unit worked fine and continued to work fine with daily testing for several weeks. Then one day the fuse blew on powering up.I opened the unit and removed the power supply PCB from the rear panel. I found the bridge rectifier on the primary side shorted and the NTC in the soft start circuit partly destroyed. The rectifier was replaced and the power supply powered up with a current limiting bulb in series with 240 connected directly to the power supply pcb. It appeared to be working ok so the bulb was removed and powered up again. One of the 2 680uf 200v caps on the primary side exploded. This was removed and testing showed no other damage. Caps were replaced and the power supply ran fine on the bench so was refitted to the rear panel and connected to the other boards. It was refitted to the sub and powered up, again one of the 680uf caps exploded and the other bulged. Unit was removed, tested, caps replaced and ran fine on the bench.These units use a small PCB mounted to the IEC connection. This board is used to autosense the mains voltage. A relay is used to bridge a jumper across the bridge rectifier/mains caps to double the voltage for 120v use. This relay briefly engages during power up even when connected to 240v as the voltage comes up in the sense circuit. The relay was found to be stuck in the 120v position which caused the caps to explode.Power supply was tested again, damaged caps replaced and with the 120v/240v selection relay connections removed is now working fine.I'm no expert, but using a cheap relay in that briefly cycles to voltage doubling position on every power up, seems to me to be asking for trouble.Schematics for the PRX 618s are attached - it uses the same boards with slightly different components in some locations.

author: fzabkar
author_rank: Super Contributor
timestamp: February 20, 2020, 05:42:25 am
content: I would remove the relay in 240VAC regions, or replace it with a jumper wire in 120VAC regions. Add a label to the ratings plate, if necessary.(Actually, if it goes "doof, doof", I would probably take a hammer to it.)

author: fixy88
author_rank: Contributor
timestamp: February 20, 2020, 06:02:19 am
content: Quote from: fzabkar on February 20, 2020, 05:42:25 amYes it's a really bad design decision in my opinion. I've left it disconnected in this unit.
JBL EON 618s Repair - Page 1
Forum section: electronics / repair

author: Fishmcmuffin
author_rank: Newbie
timestamp: March 08, 2022, 02:08:30 am
content: Hello,I am looking to have four JBL EON 618s amplifiers repaired that no longer power on. I think its due to bad power in our glassblowing studio.Thanks so much!Jacob

author: james_s
author_rank: Super Contributor
timestamp: March 08, 2022, 02:12:44 am
content: What exactly are you looking for? Somebody here to repair them? A referral to a shop that can fix them? It might be helpful to indicate your approximate geographical location as you probably are not going to want to ship several vintage amplifiers if you can avoid it. We're a bunch of engineers and hobbyists that discuss engineering topics, not a repair service.

author: Fishmcmuffin
author_rank: Newbie
timestamp: March 08, 2022, 02:18:36 am
content: Apologies, I thought by posting in the repair forum I was in the right place.I live in Philadelphia, Pennsylvania in the USA. I'm looking for all four of the amplifiers to be repaired into working condition, or a referral to someone who can fix them for me. I don't mind shipping the amps as I do Ebay for a hobby and pack boxes often.I haven't been able to find a single soul to repair these units, but after today I feel confident someone on this forum can point me in the right direction.I'm cool shipping or driving them locally!

author: james_s
author_rank: Super Contributor
timestamp: April 03, 2022, 01:19:14 am
content: Well you're certainly allowed to post here and maybe you'll find somebody that wants to take on the job, it's mostly people posting asking for advice on things they're working on repairing themselves though. I would advise against shipping stuff to random people who say they'll work on it though, you never really know how skilled a person is and it's too easy for them to just disappear with your stuff.
JBL Flip Essential 2 - Page 1
Forum section: electronics / repair

author: Lol
author_rank: Newbie
timestamp: July 16, 2025, 10:19:49 pm
content: In this case I speak of a Essential 2 JBL, the main plate is a 40-Flipse-MAE4G, the button plate (play, vol+, vol- and bt) 40-Flipse-kyb2g, and that of Power and battery level is a 40-Flipse-Leb2G, the microcontroller in charge of interpreting the signals of the buttons is the buttons STM8S005C6T6, after making a restart, of the chip, which is connecting the charger and pressing Play and Vol+, only responds to the Vol+ and Vol- buttons, the Play button and the BT button, do not respond to pressing them and only sounds music with the auxiliary. The symptoms before the reset were, that at the time of wanting to light the horn, it did not turn on and only when connecting the charger, automatic lit the Power button, and showed the battery levels; More than no button reacted, and only music sounded with the auxiliary. The behavior of the buttons after the reset: the buttons close the circuit and everything, even when I press them shows me the level of load (after a few seconds it does not show the load level but the device works, I will assume that it is a factory program) and after doing what you tell me nothing, the difference is that when I press the buttons that do work to raise and lower volume in automatic it shows me the level of load and with these level of load and That I let go of the load level (not when I press them, it shows me the load level, until I let them go; said otherwise shows battery only while they are pressured, until I stop pressing them, only there it shows it) with the other nomas I press and quickly show them, these until stop pressing, therefore the BT and Play button do not make their work, not if it is relevant, what can be happening?
JBL LSR305 no tweeter! - Page 1
Forum section: electronics / repair

author: wisehorn
author_rank: Newbie
timestamp: April 28, 2022, 08:45:09 am
content: Hi all,I bought a pair of JBL 305s on eBay and I'm saddened to discover one of the tweeters isn't outputting anything.Going by Dave's teardown here :... it looks like the crossover is DSP based. If I'm getting woofer output, does that mean the chips probably haven't blown? Hopefully it's just a dead speaker coil right?I don't have my multimeter with me right now but I'll go out and get one to measure the resistance across the tweeter terminals.Any advice welcome!
JBL SB350 sound bar. Firmware sought. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: January 01, 2025, 12:53:02 pm
content: Hi, I looking for the firmware for my JBL SB350 sound bar that stopped working on new year's eve. I have tried everything that I could find online and a firmware problem is all that's left to check. Thanks!

author: m k
author_rank: Super Contributor
timestamp: January 04, 2025, 09:31:26 pm
content: People around here are sceptical, you must specify those everything.

author: Paceguy
author_rank: Regular Contributor
timestamp: January 05, 2025, 12:36:31 am
content: What would people be skeptical about ? I looked online to see if there are any common problems with this model of soundbar. One of lists of things to check has as the last possibility is the firmware being faulty. They suggest going to the JBL site and downloading the firmware onto a USB drive and then running it via the soundbar's USB port.There is nothing available on the JBL site.What happens is when I turn the soundbar on, the power button light immediately comes on white and stars flashing instead of being orange and being needed to be pressed to power on. Nothing can be done to stop it from flashing. According to the owners manual, a flashing power light indicates the the sound bar is in mute mode and by pressing either the + or - button will take it out of mute mode which on mine, is not the case.If anyone here thinks that my intension is to hack JBL's sound bars, it's not the case. Back in the late 70's, I was a service tech at the then Canadian distributor of JBL and Harman/Kardon. I just want to get my sound bar back up and working.Anyone's help or advice would be much appreciated. Thank You.

author: m k
author_rank: Super Contributor
timestamp: January 05, 2025, 05:29:28 pm
content: Who knows what people think.Can you verify that button press is recognized somewhere inside?

author: Paceguy
author_rank: Regular Contributor
timestamp: January 06, 2025, 11:06:10 am
content: I would open it up if there were screws thatcould be removed to be able to open it. No screws like many things made these days.

author: m k
author_rank: Super Contributor
timestamp: January 06, 2025, 05:22:14 pm
content: Beginning of the video is an opening ceremony.

author: Paceguy
author_rank: Regular Contributor
timestamp: January 22, 2025, 12:57:33 pm
content: Good news it's fixed by a simple re-set. Works fine now.
JBL Vibe Flex Case Not Working - Page 1
Forum section: electronics / repair

author: LaXRoX
author_rank: Newbie
timestamp: May 20, 2025, 03:58:26 am
content: Hey! So a few weeks ago my JBL vibe flex case fell in the sink, I got it out after probably 5 seconds and there was no light, no nothing. When I put my earbuds in (which i had been wearing at the time so they thankfully are fine) they would not power off or charge like they are supposed to. So I put the case in rice and left it for 24 hours. Came back nothing, figured they were toast. A week later a family member was looking at it and then just brought a heat gun to it. That surprisingly fixed the case and it has worked up until 3 days ago. I went on a plane (to a place with a much more humid climate than mine) and maybe dropped the case I cannot fully remember. But the case was the same as before, no lights, no charging, wont charge, and no turning my earbuds off when i put them inside. I flew back tonight and now while the case still generally does not work, while trying to get inside it the light turned on and my earbuds charged a little bit. So maybe I should just wait but I do want to get inside just to see what happened. Anyone have any ideas of what happened or know how to get inside the case as it is proving QUITE difficult. In his video on the waves which are pretty much identical, he doesn't show how to take the case apart which was the one thing I need.Thanks!UPDATE: A day later and the left side shockingly works perfectly fine. Right side was able to charge the earbud but stopped working after unplugging the case.

author: Poroit
author_rank: Frequent Contributor
timestamp: May 20, 2025, 07:33:44 am
content: G'day LaXRox,This video may assist you.As you are aware , Water and Electronics don't mix so you need to get the internals dried as soon as the accident happens.
JBL VRX932LAP Amp - Shorting IGBTs when applying power. - Page 1
Forum section: electronics / repair

author: beavernuggetz
author_rank: Newbie
timestamp: November 16, 2023, 01:37:49 pm
content: Hello everyone,I am working on 3 of theseJBL Class-D Amplifiersfor a DJ friend of mine. The initial issue was of course some sort of power surge fried some components on the board.On the underside of the PCB, theGB20B60PD1 IGBTswere blown to pieces (literally) and on the top there were lots of SMD components which are near the IGBTs which were also shorted.I gathered the list of dead components and ordered replacements from DigiKey and Mouser. Once all the parts were replaced but without having the TL494 (Switching Controller) & FAN7380MX (High-Side Gate Driver IC) connected to avoid frying the SMD components all over again, supplied power to the amp, and after a few seconds the current limiter light bulb became very bright indicating there was a short somewhere; sure enough, the newly installed IGBTs were fried while the SMD components were unaffected.Without the IGBTs on the board, applied power again, measured 17 volts between SMD resistor R604 (SMPSREF) and the U1J diode which is the proper voltage for the amp to power up as shown in thisYouTubeVideo.Please find the schematics attached, if you go on to page 6 the IGBTs are shown there labelled as Q605 & Q606 (see attached picture).What could be the cause of these IGBTs shorting out as soon as power is applied? I'm not an expert by any means, my knowledge is middle-of-the-road but do own good test equipment and my soldering skills are pretty good IMHO.Any feedback would be greatly appreciated.
JBL Xtreme 2 chip identification - Page 1
Forum section: electronics / repair

author: malgranda
author_rank: Newbie
timestamp: January 28, 2022, 05:52:51 pm
content: Hi,I'm trying to fix a JBL Xtreme 2 and the chip U25 is burned so bad that the markings have disappeared.Does anyone know what chip it is? It seems to be some kind a of voltage regulator.

author: malgranda
author_rank: Newbie
timestamp: February 20, 2022, 04:26:44 pm
content: Finally got an answer from a JBL support center so I'll leave the chip name here if anyone else is looking for it.IC DC DC SY8201 XTREME2

author: e7p
author_rank: Newbie
timestamp: June 19, 2022, 11:55:06 am
content: Hi, thanks a lot for sharing this information as my U25 burnt the exact same way.Did you were successful repairing it by replacing the part?Edit: If my calculations are right, this part is a quite common DC/DC step-down converter configured for 1.2 volts output. I have a couple very similar with the same pinout lying around, so I tried replacing the broken SY8201 with a MP2459GJ-Z (and adapted the value of the two R2 resistors from 19k to 30k). Unfortunately in my case the EN pin of the step-down won't get active anyway (maybe because of another fault). I think I'll see if I can get a cheap replacement board on ebay or the like...

author: Supa.tramp
author_rank: Newbie
timestamp: April 12, 2023, 06:05:12 pm
content: Hi guys, i have the same problems! Someone connected another AC adapter to JBL, and the U25 chip was fried! On the chip was this code ENAFB. I have replaced this chip with a new SY8201 (15%OFF | 10PCS/LOT 100% New SY8201ABC SY8201 EN2PA SOT23-6 Chipsethttps://a.aliexpress.com/_mOJTOwo) On this chip the code is: ENE0F. The problem is somewhere else on the board, because the chip is getting hot in 2 seconds after i plug the AC adapter. If someone had identify other components that can get bad, please post. I could 't find any schematic online.
JBL Xtreme ver 1 non responsive - Page 1
Forum section: electronics / repair

author: powrpacks
author_rank: Newbie
timestamp: August 18, 2025, 02:46:05 am
content: I have a JBL xtreme first gen. It has a new battery, fully charged, will not turn on with battery or plugged in. When plugged in, the power button lights and battery charge indicators show battery is charging. Does not power on. I've tried all the reset shortcuts shown in service manual and on youtube. I've measured tp600 for 3.3v, tp605 for 5v, tp606 for 10v and tp604 for 18.9v and all voltages are present while plugged in. While running on battery, There is no visible response to buttons but was able to verify 8.9v at tp606 for about 3 seconds, then goes off. I measured other areas and found the correct voltages as well after pressing power, but all would drop after a couple seconds. I'm assuming there is an error causing shutdown, but do not know how to isolate the error. Old service manuals had a theory of operation to assist with sequences but this manual is very basic. I also have not figured out the pinout acronyms shown in the manual, which also causes confusion.. I have also scanned all the components under microscope searching for signs of heat damage, corrosion, etc. but haven't found any evidence of component failure. I would really appreciate some insight from anyone that may have some on this unit!Thank you-Kevin
JCD 8898 IC shorted - Page 1
Forum section: electronics / repair

author: Niethate
author_rank: Newbie
timestamp: March 22, 2023, 05:39:31 pm
content: Hello,Does any one know which ic this is on the jcd 8898 trying to fix it or is there a schematic for

author: coromonadalix
author_rank: Super Contributor
timestamp: March 22, 2023, 08:20:16 pm
content: clean the top of the ic and check for markings ?

author: Niethate
author_rank: Newbie
timestamp: March 23, 2023, 03:17:42 am
content: There ar no markings on it.

author: GGMM
author_rank: Frequent Contributor
timestamp: March 23, 2023, 08:26:47 am
content: Hi,Why did you unhook that chip?What was the breakdown?cdt

author: GGMM
author_rank: Frequent Contributor
timestamp: March 23, 2023, 08:28:54 am
content: If the iron was no longer working, it comes to 99% of the diode zener 5v on this PCBThen replace with a classic zener other than SMDcdt

author: GGMM
author_rank: Frequent Contributor
timestamp: March 23, 2023, 08:34:42 am
content: My first blacout ---> the zener 5vThis is my second blackout herehttps://www.eevblog.com/forum/repair/my-station-iron-hot-air-explosed-ref-jcd-8898/msg4711205/#msg4711205if it can help youNow working nicecdt

author: Niethate
author_rank: Newbie
timestamp: March 24, 2023, 11:26:44 pm
content: The chip gave me a short when I removed the chip all the shorts where gone

author: Niethate
author_rank: Newbie
timestamp: March 24, 2023, 11:31:03 pm
content: I fixed the iron by changing the bta transistor, the heater doesn't work so I tested the components that I changed and it was all shorted again when I tried the heater so when I removed the chip all the shorts where gone

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 26, 2023, 02:22:42 am
content: Perhabs a S3F94C8 mcu, seems common inHot Air stations.

author: Niethate
author_rank: Newbie
timestamp: March 26, 2023, 12:21:54 pm
content: Thank you will buy one and let you know how it went

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 26, 2023, 12:38:17 pm
content: It's a mcu, so replacing it won't make it work, must be programmed, I doubt you could do that easily, nor getting the original firmware.At this point, just get a new station, or try to find a new board.

author: GGMM
author_rank: Frequent Contributor
timestamp: March 26, 2023, 03:07:40 pm
content: Hello,I don’t quite understand your breakdown.You say a short circuit, but on what?Is it on the mains? Is it all blown up and the fuse?I don’t see this circuit blowing the power.When you say the iron worked and not the hot air, was there the temperature indication of the soldering iron?Etc...cdt
JDS6600 Signal Generator Firmware hack? - Page 1
Forum section: electronics / repair

author: weakbit
author_rank: Newbie
timestamp: April 20, 2021, 05:29:21 pm
content: Hello,due I bought today 2pcs used JDS6600 Generators but I made a misstake I don't know that are some JDS6600 exist with 60MHz so I think. But I get only the lite one with 15MHz. What can I do? Is it possible to make apatch inside the Generator to patch a new Firmware that extend my Frequency range to 60MHz? If yes how I can get this Firmware and how I can load it up to the µC?Best RegardsVolker from Vienna

author: MarkMLl
author_rank: Frequent Contributor
timestamp: May 02, 2021, 07:53:36 pm
content: These devices have been discussed extensively in the past, with contributions from the manufacturer.I don't know what other members of the community feel about this, but while almost everybody agrees that "hacking for the purpose of interfacing or fixing bugs" is above board, "hacking to upgrade to a more expensive model" is somewhat less so.MarkMLl

author: fzabkar
author_rank: Super Contributor
timestamp: May 03, 2021, 03:36:57 am
content: What I don't like is when a manufacturer designs a full featured model and then creates artificial performance classes by crippling the firmware. I also don't like badge engineering where a manufacturer targets two different markets with essentially the same product.AISI, the OP's hack is a way of fighting back against these objectionable practices. I don't have any ethical problems with it.

author: MarkMLl
author_rank: Frequent Contributor
timestamp: May 03, 2021, 07:52:15 am
content: Quote from: fzabkar on May 03, 2021, 03:36:57 amMaybe, maybe not. But I'd suggest that having manufacturers of all sizes be comfortable about this forum is to everybody's advantage, since on the one hand it gives members of the community a way of saying "we think this might be an undetected design flaw" and on the other hand it allows members of the community to quietly criticise the sort of commercial policy you are complaining about.The gripping hand is that, like it or not, there is an overall community of users and vendors. Even if they don't always see eye to eye, it's to everybody's advantage that they're polite to each other.MarkMLl
JennAir Oven/uWave Wall Unit Errors F6E0/F6E8 - Page 1
Forum section: electronics / repair

author: fuzzoli
author_rank: Regular Contributor
timestamp: May 26, 2025, 01:23:50 am
content: I've started taking a look at my mom's JennAir Oven/Microwave wall unit (JMW2427W) that has intermittent operation along with error codes F6E0 and F6E8.I have not put any meters to the boards yet to test for the continuity related to those error codes, but here is what I've found so far:- Both error point to a communication loss between boards- The System Information screens imply (by name only) an SPI-type protocol, but there doesn't seem to be enough wires between boards for that. It almost looks like a 1-wire-ish hook up.- The problem is definitely intermittent, as if you clear the codes, both the oven and microwave seem to work for a while.- Initial visual inspection of caps look like none have blown their tops.- The "normal" troubleshooting such as turning the power off for a bit, does not resolve the issue.- Initial visual inspection for scraped insulation / shorts around the communications wires does not seem to be present. A Google search said a lack of gromets on the sheet metal might cause issues.So my question to the Eevblog World is: Has anyone seen this type of behavior in a JennAir (or equivalent) appliance? I'd love to be able to save my mom $4-5k for a new oven.I should be able to get back with some meter readings in the next few days.Thanks!

author: thm_w
author_rank: Super Contributor
timestamp: May 26, 2025, 11:08:03 pm
content: A good percentage of caps will fail without any bulging visible. Always test with an ESR meter or at least capacitance meter on your DMM if you don't have that.Photos might help.For others,F6E0: The oven could not execute the function. There may a problem with the Appliance Control Board, or the associated wiring.F6E8: There may be a problem with the Microwave Appliance Manger Control or the associated wiring.Seems to have a sort of built in test menu:https://www.youtube.com/watch?v=khmu8gnlAbI
Jensen stereo not storing settings - Page 1
Forum section: electronics / repair

author: PaulAm
author_rank: Frequent Contributor
timestamp: October 06, 2020, 07:16:48 pm
content: I got skunked with this unit (seller kept dribbling out little bits until the feedback window expired and I was too far into it to just cancel the entire thing). It's a Jensen VX7528 radio/nav/cd/dvd/bluetooth etc unit. It seems to operate fine except that it is not saving various option settings (equalizer settings, turning beep on/off, turning cameras on/off, etc) although it does save the station presets. This is highly annoying since the defaults are not very good.Jensen customer service is not helpful. They said 1) try the reset and 2) if that doesn't work replace the radio.On top of everything else, Jensen discontinued this model.I'm probably going to open this up and see if I can see anything. Anyone have any experience with this kind of problem? Any clues as to what I should look for?
Jetway motherboard repair (Part ID and schematic request) - Page 1
Forum section: electronics / repair

author: mudpies
author_rank: Newbie
timestamp: March 25, 2021, 08:20:03 pm
content: Hi all. I have a pile of Jetway NF36-2600 motherboards for repair that I am working my way through and I have a couple that eluding my efforts to diagnose. One has cooked dfn-8 that I need to replace but I cannot for the life of me identify it by its markings. Any assistance to ID it would be appreciated. I have the tech manual but if there should happen to be a schematic lying around that someone could make available it would be also appreciated. The only markings on it is "3540 B".-Respectfully

author: perieanuo
author_rank: Frequent Contributor
timestamp: March 26, 2021, 08:15:32 am
content: maybehttp://www.anpec.com.tw/ashx_prod_file.ashx?prod_id=716&file_path=20131204184522372.pdf&original_name=APL3540.pdfanyway prepare to repair sometimes without schematic, for some mosfet it's easy to trace 3 tracks regarding also VDD/VSS (anyway for mobo VSS is GND and Earth at same time with some rare exceptions)the schematic you pull from the mobo tels you if it's p or n channel, you know the voltage, just estimate the current, put some equivalent mosfet and test, can't be worst than beforetime is money

author: amyk
author_rank: Super Contributor
timestamp: March 26, 2021, 01:33:05 pm
content: Posting pictures is the best way to get a part identified, since you may misread the markings and the packaging and surrounding components also provide a significant clue.That said, APL3540QBI appears to be correct according to seller's pictures:https://www.1688.com/huo/detail-557215615453.html

author: mudpies
author_rank: Newbie
timestamp: March 26, 2021, 07:27:59 pm
content: perieanuo: Thank you so much, I believe you nailed it. The data-sheet lines up with the board values.I do a lot of these sans-schematic but some just turn into a PITA. Most end up being shorted caps pulling down the voltage. Some run me in circles.amyk: Thanks for the suggestion. I will certainly keep it in mind going forward and I have taken a shot of the same component from another board currently on my bench for comparison.Thank you both for your timely and helpful replies.-Cheers
Jetway NU93B-2930 with spurious reboots - Page 1
Forum section: electronics / repair

author: theonetruestickman
author_rank: Newbie
timestamp: March 13, 2021, 02:22:21 am
content: Hey folks,I picked up a Jetway fanless box for cheap recently, but it won't stay running more than 10-15 minutes. As far as I can tell it's an older rev. of the JBC311U93 box - I don't have the external antenna jacks. Motherboard is NU93B-2930:https://www.jetwaycomputer.com/JBC311U93.htmlhttps://www.jetwayusa.com/dl/manual/G03-NU93-F.pdfFirst thought was overheating but CPU temp wasn't really getting above 40C. There was a ~0.7mm gap between the CPU die and heatsink, so now after shimming it the CPU stays around 25C on all cores and still has the reboot issue.I've swapped RAM out, removed the onboard MSATA drive, and removed the wifi card. This happens no matter if the machine is booted into an OS or is just sitting in BIOS - still reboots every few minutes, so I'm thinking this points to a hardware issue.I've also tried multiple power supplies. The board has a 9-24v listed input range, and the same behavior on a 12V AT supply I have on my workbench as a 16.5V IBM laptop adapter. Both should have adequate current capacity for the board (>3A) as far as I can tell and should have fairly clean power. (Caveat - haven't put my scope on the power lines yet. And don't have a digital scope that can trigger/capture.)I'm a bit at a loss as to where to start, beyond watching power rails. Anyone else seen similar issues or have experience with these boards? Don't see much for Jetway in the search. I was really hoping this thing would work as a compact workbench rig.

author: amyk
author_rank: Super Contributor
timestamp: March 13, 2021, 03:16:12 am
content: Is the interval between reboots nearly constant?Look for "watchdog timer" or similar setting in the BIOS.There's a "watchdog sample code" item at the very bottom of that page.As an aside, I like the instructions for flashing BIOS there:Quote

author: theonetruestickman
author_rank: Newbie
timestamp: March 13, 2021, 04:12:56 am
content: Dang, watchdog timer was on, thanks for noticing that. I never knew what that setting was for - guess I gotta learn something new 20 years into computing.I had discounted that before because it didn't seem like the time was consistent enough but that is now clearly demonstrated my own internal reference issue. I'm over an hour uptime now."Wait in suspense" should definitely be used more in technical literature.

author: amyk
author_rank: Super Contributor
timestamp: March 13, 2021, 05:34:32 am
content: It's a common feature, a lot of SBCs with Atoms have a watchdog. Of course if your experience has only been with more mainstream desktop PCs and laptops, this would not be familiar.
JL Audio M400/4 mobile audio amplifier repair - need schematics - Page 1
Forum section: electronics / repair

author: AMR Labs
author_rank: Frequent Contributor
timestamp: December 05, 2021, 02:27:15 pm
content: Got this JL Audio M400/4 mobile (Marine) 4-channel Class-D audio amplifier in non working condition, owner purchased a new one and passed this one on to me. Designed to work from a 12V (14.4V) supply, and specs are 75W RMS x4 @ 4-ohm. Supposedly pretty decent brand that has a reputation of good quality build...https://www.jlaudio.com/products/m400-4-marine-audio-m-series-amplifiers-98271Problem with this one is no audio output at speaker terminals, and scoping those terminals shows a slight DC offset of +0.3V along with a 1.7Vpp about 462KHz signal which I would think indicates that the amplifiers are oscillating. An input of a 1KHz test signal and/or changing any of the input switch/level settings has absolutely no effect on the output.Found considerable ripple on several of the DC rails (+/-5V, +/-15V) and so far found and replaced a couple of dried out (85-C !!) dead caps -go figure using those inside a hot mobile amp. The main inverter output (based on TL494/KIA494) which is +/-25V seems clean, and I tested one of the caps in the filter bank just to get a sense of their condition, and it was ok for both value and ESR. At least those are 105-C, but brand is "SAMXON", and they seem to be getting very slightly warm to the touch (around 30-35C) so must be struggling a bit with the switcher output although for now they appear to be getting the job done.I am looking for schematics (or the service manual). Manufacturer website does not provide anything further than the owners manual, and web searches also don't come up with anything else but same manual or sales brochures. Does anybody know where I could get the schematics of this amplifier, or even of a similar model of the brand which I could at least use as a general guide. All circuit boards are 3-layer (with heavy ground plane in the center layer) with plenty of jump connections between layers, and most components are SMD (except filter caps among others), so its not easy to try figuring out the circuit by looking at the board.
Joffra Dry Block repair by a TikTokker - Page 1
Forum section: electronics / repair

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 11, 2024, 07:01:06 pm
content: I didn't have the time at work to look at this, plus it had already been sent out and we were told it was BER. Turns out you can get a TikTok person to fix it. The MD found him, I am too old to be a youth and too young to be creepy enough for it.https://www.tiktok.com/@retrosix/video/7390263865562484001I wish he had asked if we wanted a new fan as it needs a new one as a few fins have left for other places.Does anyone know how to adjust the temp as it's a degree or so out at the moment?
jovy  turbo ir benchtop station - Page 1
Forum section: electronics / repair

author: peter2
author_rank: Contributor
timestamp: October 21, 2021, 08:18:55 pm
content: Please can help somboby with this station.i looking for a heating element for the handheld of this station,or a picture from the inside of the handheld.spare part are need.or a number from the spar part,or sombody that can help me please.or somboby that have this station and can make a picture for me,i will verry happy with it.

author: lunacyworks
author_rank: Contributor
timestamp: October 24, 2021, 05:08:14 pm
content: Doesn’t that station have two hand held item an hot air and an iron.
Joy-it JDS6600 - signal clipping - Page 1
Forum section: electronics / repair

author: notadave
author_rank: Contributor
timestamp: June 02, 2021, 05:59:33 am
content: Let me first say that I like my JDS6600, it has nice functionality at a mass product price, but after using it for a few times the CH2 is now defective.My Joy-IT JDS6600 Rev.15 has an offset and clipping issue with one of the two channels. Thanks to the two channel nature and the rather obvious fault, I was able to trace the issue back to one IC. Sadly all the important ICs were "scrubbed". The tops and labels were removed. The function of the broken IC is to shift the signal from the range of 0 to 840mV down to -350 to +350mV and drive a lower (200Ohm) impedance. The possibly broken SOIC-8 that makes the difference is connected to two SOT-23-6 U4, U6 which provide an input that does not require a resistor in between. The output of the defective IC is phase inverted.Here is what I measure at the pins:1. Non-inverted out2. Some Feed-back port for the unused non-inverted out 1k Ohm3. The used input4. -5V5. 0V6. Some Feed-back port for the inverted output 100 Ohm7. The used inverted out8. +5VThe IC is very likely a differential output OpAmp as is used for driving ADCs (Example, which can not be the same.). One of the pins must act as V_OCM, likely either 5 or 6.U4 and U6 show at their six pins:1. Signal In2. GND3. 0V4. Signal Out same as in5. 3.3V6. 3.3VThey might act as high input impedance buffers.Speculation: The IC seems to generate a differential output from a dual differential input, but I could not see that the differential output feature was used to drive anything.The Pin usage afaik is:1. Out+2. In-3. In+4. -5V5. GND (Unused In-)6. Unused In+7. Out-8. +5VThe IC can not be a dual normal OpAmp, it must have an internal feature to remove the offset. I know such ICs are available but can not name one.Instead of replacing the IC, I could replace the entire circuit, replace the function, not the IC. I would have to find a way to wire in a small PCB in such a way that it is 50MHz compatible. It could be done elegantly by stacking a tiny interposer PCB in-between, exposing enough of the original pads to get the heat under.I can think of two ways to remove the offset: to build a 10Hz 2. order lowpass and subtract the result from the input or to go high impedance and make it a HP at 10Hz using 1uF 10V Cap. The first way has the problem of phase shift between the subtracted signals the second way might have trouble at >10MHz due to the high impedance. The IC doesn't seem to do it either way from the outside, I can not see the DC, average on any of the pins, nor do I see a large external capacitor.

author: cinealfa
author_rank: Newbie
timestamp: May 30, 2024, 01:55:23 pm
content: Did you ever figure out what was the chip was?
JPS NIR-10 DSP  eproms - Page 1
Forum section: electronics / repair

author: pizzigri
author_rank: Regular Contributor
timestamp: July 16, 2020, 01:34:19 pm
content: Hello everyone!I have been given a defective JPS NIR-10 DSP meant for HAM radio use. As far as I can see, everything seems allright, except for the sockets for the firmware U9 and U10 are empty. Possibly cannibalized for a better looking/condition unit.Obviously, there's absolutely no support anywhere for this thing.I am looking for a dump of ver. 4.0 of these EPROMs, so that I can put it back into service! SN is 11868, and the paperwork that I have includes a sheet for a 4.0 firmware upgrade (possibly the reason there's no chips inside it). Actually I dont even know what type PROMs or EPROMs this thing uses, so if someone knows, could you also tell me? It's a 24 pin DIL package.Willing to pay a reasonable amount for a programmed pair of chips, since even if someone does have the hex files, 99% I'll have to purchase a writer for this once single use anyway.Photos of the unitThank you!!! FrancoETA:Forgot to add that Benny Hillman, from JPS Tech Support, did answer telling me that support for all ham products ended in 2002. And that he has absolutely nothing in regards to the NIR-10, except the manual, that he sent me via email...

author: pizzigri
author_rank: Regular Contributor
timestamp: November 26, 2020, 02:01:04 pm
content: Just to update: I connected to Doug K4DSP, the original designer of the NIR-10 and he was kind enough to give me his last set of ROMs so that I could make the DSP work. So, a big THANK YOU Doug, and to all that have helped me in this little endeavour.Franco
JRC 7662D Voltage Inverter - Page 1
Forum section: electronics / repair

author: AERVBlog
author_rank: Unknown
timestamp: February 28, 2024, 08:13:54 pm
content: Hello everybody. This is my first post here and I hope the brain trust can help me. I have a bunch of Dorrough Loudness meters to fix and for the most part I have but I've run across a problem that is just driving me crazy. The negative 9 volts for these is produced by a JRC7662D IC. When they work the output voltage is around -9.05V when they don't work I get -0.7V. After a bunch of fiddling around I discovered that sometimes if I lift pin7 the darn thing will work again but not always. Pin 7 isn't connected to anything. I did a video on badly made boards for these meters but in the current bunch that is not the problem.The thing only takes 2 external parts in this configuration, a 10uF electrolytic and a 100uF electrolytic. The 10uF goes across pins 2 and 4 and the 100uF goes from pin 5, output, to ground. Comparing one working unit to a non-working unit the only thing I can see is that pins 2 and 4 are missing the square of about 4.4KHz on the one that doesn't work. The things are very flakey and will work sometimes and not others. Like as I was writing this I checked for voltages and the unit I have been fussing with for over an hour suddenly started working!Has anyone had any experience with either this 7662D or the Dorrough part #1761042-6 usually paired with a model 10A-D display boardI have included a part of the schematic as an attachmentThanks for any help you can give.Dave

author: factory
author_rank: Super Contributor
timestamp: February 28, 2024, 09:10:58 pm
content: Not used the 7662, but have worked on items using the 7660, they also use a 10uF cap, which gets replaced due to it's age (30+ years old) & electrolyte leakage problem, occasionally the IC is dead too. New ones are still made by Microchip or Analog Devices under part numbers TC7662 or ICL7662 (or in my case TC7660 or ICL7660).David

author: AERVBlog
author_rank: Unknown
timestamp: February 28, 2024, 09:43:39 pm
content: Thank you. At least I won't have to rely on maybe real from Ebay. I have ordered a bunch of Low Z caps, as low as I can get them anyway. I had to get surface mount bu there is room. We will see if that helps.

author: CaptDon
author_rank: Super Contributor
timestamp: February 29, 2024, 03:32:46 am
content: Mike Dorrough was supposed to be the rocket scientist of audio gear. Sounds like he cut corners in the production part of his devices. We used those panel mount 'Loudness Meters' retro fitted into all of our Pacific Recorders BMX boards. I actually never had one fail even after 20 years or more.

author: AERVBlog
author_rank: Unknown
timestamp: February 29, 2024, 03:39:31 am
content: For the most part they did a really good job and they were cool looking to boot. I have actually only found a few badly built boards and think that could happen to anybody. Since I have seen so many with the same problem I have to conclude it must be design. Not bad just starting to show weak spots, maybe the need for special caps. Don't know but will see.
jtps28m smps can't figure out how the vcc to the tl-494 gets generated - Page 1
Forum section: electronics / repair

author: wcurlew@juno.com
author_rank: Newbie
timestamp: December 28, 2021, 02:29:37 am
content: Working on a smps from jetstream. Looks like the power for the tl-494 chip comes AFTER the switch transformers. Can't figure out how the supply starts up. Getting a sawtooth on the VCC pin of the tl-494. Schematic attached.

author: shakalnokturn
author_rank: Super Contributor
timestamp: December 28, 2021, 02:26:21 pm
content: To me it seems that it should self oscillate due to T2 xfmr (T2D winding), then when there's enough voltage on output TL494 kicks-in and regulates by controlling pulse width.My first suspects would be C22, C19, C18, C7. (Then any electrolytic stuffed in a hot spot...)

author: wcurlew@juno.com
author_rank: Newbie
timestamp: December 29, 2021, 05:44:28 pm
content: Thanks shakalnokturn, I was wondering what that extra winding was for. I did check the ouput diode pair and it looked good, I'll sniff around the caps and maybe scope the input to the T1A transformer to see if the oscillation is there. Bill

author: Bud
author_rank: Super Contributor
timestamp: December 29, 2021, 09:31:25 pm
content: Check if 5V appears on pins 13,14,15 as the regulator is trying to start, and check or replace C15 capacitor .

author: amyk
author_rank: Super Contributor
timestamp: December 29, 2021, 10:31:10 pm
content: This is a common topology in older PC PSUs - it starts as a self-oscillating half-bridge and once the secondary gets enough voltage, the TL494 takes over. I've written about it before here:https://www.eevblog.com/forum/beginners/old-at-computerr-ps-issue/C15 is suspect, but I would check all the electrolytics and replace them anyway.
Jts 111R / Carvin em901 - Desperate for LCD parts - Page 1
Forum section: electronics / repair

author: EEVPiobee
author_rank: Contributor
timestamp: December 20, 2024, 01:50:15 pm
content: Hello Eevblog community!I'm tasked with repairing a Carvin EM901 inear wireless monitor system with a broken LCD display.About the unit:These were designed in the later part of 2000's but are still in production as of 2024 (but signs show they likely to be phased out in a not so distant future)The unit I have to fix is a June 2024 production.About the issue:The current faulty part only shows black dots all over the 128x64 pixel it has, no matter what. And no matter on which controller it's plugged in.Since I have another fully working unit (of the same gen/rev) to swap parts with, I was able to confirm that only the LCD is at fault.About the part:So far, the info I have:Lcd is a green back-lit, 128x64 dot matrix with a 28 pin ribbon connector. (I manually counted the pixels on the working unit.)The ribbon seems to have a 0.6 or 0.7 mm pad spacing on the Zif connectorIt seems that the glass screen is 1.3 inch in diagonal if I measured correctly.So far, I scoured the internet but can't find the match I need. I don't care for backlight color. If it fits and displays, it's good for me. I don't mind scavenging, but I want to order multiple units at a reasonable cost.The back-lit still works to technically I would only need the glass part with the ribbon. The main Issue is either I find a 1.3 inch display but it has a 30 pin ribbon cable with the wrong zif cable or I find the correct ribbon with the wrong screen size.Nothing on Digikey, and I must have spend countless hours on AliExpress/Alibaba

author: EEVPiobee
author_rank: Contributor
timestamp: December 20, 2024, 06:14:32 pm
content: More photos

author: amyk
author_rank: Super Contributor
timestamp: December 22, 2024, 07:03:39 am
content: Have you tried asking the manufacturer?Besides the physical size, there is also the question of whether the pinouts are compatible (even if the number of pins is correct) and the controller instruction set is the same.