hybridfree/eevblog-posts huggingface dataset:
Keysight E4980AL Precision LCR meter corrupted firmware  - Page 1
Forum section: electronics / repair

author: gregelsner
author_rank: Newbie
timestamp: January 02, 2025, 08:28:41 pm
content: Hi All,I am under super pressure to get the Keysight E4980AL Precision LCR back and running. Power outage killed the unit and corrupted the firmware.The meter wont start and reboots itself with a message firmware corrupted please use USB image to recover.I tried the firmware update available on Keysight and it actually detects the USB and performs the update for 20sec. eventually reboots itself and same error message appears about corrupted image.Looks like firmware is storred on W29N08GVBIAA BGA, I can flash it with new firmware but is it even possible to get the .bin or .dumb file with firmware?

author: Aheld
author_rank: Regular Contributor
timestamp: January 03, 2025, 06:56:27 pm
content: Hi,what about FW upload with USB stick?Firmware is downloadable at Keysight Homepage:https://www.keysight.com/us/en/lib/software-detail/instrument-firmware-software/e4980ae4980al-precision-lcr-meter-firmware-update-828043.htmlBr.Axel
Keysight MSO9254A boot up in demo mode - Page 1
Forum section: electronics / repair

author: syau
author_rank: Frequent Contributor
timestamp: July 02, 2019, 08:11:18 am
content: Just got a Keysight MSO9254A which boot up in demo mode (all key/light on the front panel not functional). Reinstall the Infiniium software (5.75) with the same result.Did some google but can’t find any similar report. Do anybody has similar repair experience ?

author: syau
author_rank: Frequent Contributor
timestamp: July 02, 2019, 11:52:29 am
content: Quote from: syau on July 02, 2019, 08:11:18 amFinally get it boot up into the oscilloscope mode after reseat 2 red & blue SATA like connectors but greeted by a “DDR2 Ram Interface Test **FAILED** on MEMCON_1” during application launch. Self test gave “Acq Memory Test Group — FAILED”Channel 1 & 2 show lots of spike, likely due to bad memory. Ch 3 & 4 works fine.Anybody has an idea how to fix the bad memory ?

author: Robert_Sky
author_rank: Contributor
timestamp: July 03, 2019, 02:47:55 pm
content: You are the very rich man.it is worth the 5K.Just a DDR problem and a re-solder may solve it.
Keysight MSOX4104A Backup Battery Repair - Page 1
Forum section: electronics / repair

author: unprintable
author_rank: Newbie
timestamp: August 07, 2021, 05:57:40 pm
content: Hi all,i just failed to replace the backup battery of my MSOX4104A, now the ground contact of the via for the backup battery broken...So my question is, would just a bodge wire to a ground connection near the battery fix that?And please... don't blame me for that mistake, i really know it.Update:Yes, you can just connect it to any near ground.Thanks!Regards,Alex
Keysight N6753 modul - Page 1
Forum section: electronics / repair

author: Ugur
author_rank: Regular Contributor
timestamp: September 08, 2022, 01:04:05 pm
content: Hello ,I am wear N6753 module to Keysight N6702A mainframe, but the device does not communicate with the module, there is no information on the screen that the module is installed.I checked all the regulated voltages on the N6753, good, the fans are working.I couldn't find any service documentation either, any suggestions for this error?
Keysight U1241C Probe Detection Error  - Page 1
Forum section: electronics / repair

author: backpedal
author_rank: Newbie
timestamp: September 29, 2023, 03:08:58 pm
content: Hi AllI have a Keysight U1241C DMM that is acting up:when I remove the test leads and switch the meter on to anything other than the microamp range, it starts beeping and displays the "μAEr" warning.In normal operation, this would only happen if a lead was inserted into the "μ·mA" socket to warn the user that the lead is in the wrong socket.This is triggered by the banana jack bridging the two halves of the split terminal. I have disconnected the spring contact from the back of the jack socket inside the meter and verified that the fault is being caused by the physical jack, but cannot find the short, which I assume is happening inside the jack socket with my other meter. I have tried to clean the socket out and can't see any debris inside it so am out of ideas. Please see the attached pictures for a better idea of what I'm on about.I have tried to contact Keysight but they refuse to provide me any information or as I am a hobbyist and not a business customer.Has anyone experienced this issue or anything similar? Help or suggestions would be greatly appreciated.Thanks in advance,rjm
Keysight U1272A V DC offset error - Page 1
Forum section: electronics / repair

author: Caliaxy
author_rank: Frequent Contributor
timestamp: September 06, 2020, 10:29:16 pm
content: My Keysight U1272A started behaving strangely.All DC voltage measurements have an offset error of about 1.6 V (this happens in “normal”, i.e. non-relative mode). When no voltage is applied (or when the leads are shorted), it displays about 1.6 V. When attempting to measure any voltage (say, a 1.5V battery), it displays that voltage + the offset error (3.1 V, in this case). The offset error can be compensated in “Null” (relative) mode. All the other modes (DC mV, AC V, DC mA, AC mA, R etc.) seem to work fine.Resetting all the settings didn’t help.I tried to store a different reference value (by pressing “Null” while applying an arbitrary voltage). The Null mode still seems to work as it should (it subtracts the new reference from the measured value), but the offset error in “Normal” V DC measurements changed as well (now is about 5.3 V).Has anybody encountered a similar issue??

author: lowimpedance
author_rank: Super Contributor
timestamp: September 06, 2020, 11:27:07 pm
content: I have not encountered this with my U1277a.What firmware version is installed ?.

author: wraper
author_rank: Unknown
timestamp: September 06, 2020, 11:38:46 pm
content: does it change when selecting ranges manually?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 07, 2020, 01:28:32 am
content: Could a calibration correct this behaviour ?

author: Caliaxy
author_rank: Frequent Contributor
timestamp: September 07, 2020, 01:40:22 am
content: Quote from: wraper on September 06, 2020, 11:38:46 pmYes, it does. The reading is higher as you go up the scale:Reading - Scale:2.5V on 3V3.5V on 30V3.5V on 300V3.9V n 1000VTwo other things I noticed while checking that:1. The actual value could be anything in the range of 3-11V when you power up the meter. The longer it's been off, the higher the reading.2. The value decreases while the meter is on (as if a capacitor discharges), on all scales, until it stabilizes to values like the ones above.I can swear this behavior is new...

author: Caliaxy
author_rank: Frequent Contributor
timestamp: September 07, 2020, 01:41:50 am
content: Quote from: coromonadalix on September 07, 2020, 01:28:32 amI don't know how to do that...

author: Caliaxy
author_rank: Frequent Contributor
timestamp: September 07, 2020, 01:57:33 am
content: Quote from: lowimpedance on September 06, 2020, 11:27:07 pm2.0It couldn't be older, I guess... And it's an Agilent, not a Keysight (sorry)

author: fiambre
author_rank: Newbie
timestamp: May 06, 2023, 08:50:49 pm
content: Similar issue here. Offset is only 0,25V negative though. If I leave the meter on reading increase slowly (as it starts negative, increase means reducing the absolute value and approach to zero).Firmware is 2.04I did s VDC calibration, only on "short" (0V) calibration, it helped, offset stabilize at around -20mV now.
Keysight U127A faulty MegaOhms mode  - Page 1
Forum section: electronics / repair

author: KamKong
author_rank: Newbie
timestamp: April 24, 2024, 01:32:55 am
content: Hey guys,Long time lurker 1st time poster.I recently purchased an Agilent U1272A (pcb Rev 005) from ebay. I didn't carefully read the add, the seller didn't offer returns of the unit and I was away for work when the unit was delivered.When I started testing I realized there is only 1 (so far) issue with the meter. In Ohms mode it won't read anything on the Megaohms range and it won't auto-range out of the Megaohms range.At first i thought the ohms mode was faulty but it seems to just be the Megaohms range.When the meter powers on and I short the probes together the meter displays Overload, but if I manually range the meter to any range besides Megaohms it will correctly displays 0 ohms (or the correct resistance value).I dissembled the meter and found residue from battery leakage, i cleaned the board with vinegar, isopropyl alcohol.. nothing doing. (attached picture is of battery leakage residue)The meter works in continuity and smart ohms mode.I checked the spec sheet and measured the test current for each range of ohms mode and everything seems ok (the current for the Megaohms range is 93 nA, my other meter is a Keysight U1242C and doesn't read that low but it seems to pick up something...).I traced the signal path on the board and if I short some test points (bypassing the input jacks) I can get the display to flicker to 0hms but it doesn't stay there and doesn't seem to be conclusive.I don't know if anyone has seen/had a similar issue? Thanks in advance.I also messed up a solder job on the meter and need to replace C35, I read around and it seems to be a ~10pF, 3 kV, 1808 case size can someone confirm?

author: jchw4
author_rank: Regular Contributor
timestamp: May 01, 2024, 09:11:01 am
content: That's some serious corrosion here and it looks like an exact reason for the fault.So it could be either a leakage (i.e. a new current path) or a corroded trace or via (i.e. a missing path).I would first clean up all the corrosion making sure there is none left under the ICs.Personally I would submerge the PCB in vinegar (regular 5% or so) and leave it there for a 2-3 minutes. It's risky, though, but the corrosion is also pretty bad.Then blow the liquid away with compressed air. Wash in tap water, blow with compressed air again. An then leave fully submerged in pure 99% alcogol for a few days. I personally found kitchen ziplock-style bags to be very useful here.If it does not help, I would start hunting for some coroded trace. I.e. taking photos, tracing as usual...

author: KamKong
author_rank: Newbie
timestamp: May 02, 2024, 12:35:49 am
content: Alright thanks for the tips, it's soaking in the alcohol now.Well see how it goes!
Kikusui 418 RC Oscillator help - Page 1
Forum section: electronics / repair

author: yustech
author_rank: Newbie
timestamp: November 29, 2019, 05:52:39 pm
content: Hi, I hope its okay to post here. Bought this unit was told it works fine. Received and test the unit, it doesnt work. I look up and down the internet including emailing Kikusui. No reply. The manual in their site missing the schematic page.Does anyone has the schematic? Or if you have one, would you mind looking inside and tell me the two axial filter caps value and volts. That would be a good start as mine missing both. Thank you sir in advance.
Kikusui 5020 analog scope with wierd and cool sweep error - Page 1
Forum section: electronics / repair

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 25, 2022, 09:25:19 am
content: a few day ago i tested and repaired this old analog scopeKikusui oscilloscope 2ch cos 5020when testing the mag10 feature at high sweep speed and input at 10MHz or so,input is a sinewave, I got the picture attachedsave your time go directly to about 27 mins :-)where the curve is most crasyhttps://youtu.be/DQMB-F0ed4I

author: Chris56000
author_rank: Frequent Contributor
timestamp: December 25, 2022, 07:25:06 pm
content: Hi!This mess looks very much like ripple from the power supply or timebase amplifier itself is getting around the horizontal deflection amplifier circuit due to dried up decoupling/smoothing capacitors, begin with C623 (47 μ 250 V) on the power supply board, also C624 (2μ2 250 V) and C625 (1μ0 160 V) as well – C624 is a local decoupling capacitor for the h.t. line and C625 is a negative feedback coupling capacitor to feed ripple that may be left on the h.t. line back to the error amplifier U602B pin 5 for ripple cancellation!Also make sure that the series pass transistor Q603 (2SB861) isn't defective – this is in the negative h.t. return between chassis and the negative side of the h.t. bridge rectifier – you can use a TIP42C to replace this if necessary!The bridge rectifier CR621 might have a diode duff causing half–wave rectification, if you suspect this, use one of those small round W08G types to replace it!If these components all test OK you'll have to go on to the various smoothing and decoupling capacitors across the various l.t. supply lines!(Glossary: – h.t. = "high tension", l.t. = "low tension")Chris Williams
Kikusui 6100m read voltage low - Page 1
Forum section: electronics / repair

author: kj7zth
author_rank: Newbie
timestamp: September 20, 2025, 05:25:28 pm
content: Hi,I have been given a COS6100m. It seems to work pretty well, crt is clear but not too bright or dim, power supply looks to be good (don't have the right probe to test the -1850v , but the rest are all spot on.) Continuing on going through the calibration procedure, I cannot seem to calibrate the voltage amplitude, per page 100 in the manual. I run out of adjustment on rv109 and my voltage still reads a bit low. Like 4.7 mV p-p, when it should read 5mV p-p.Is there a specific capacitor that might be leaky or bad or some other known component to check? Could it be the 1850v rail that I haven't been able to test yet? Anyone know how to resolve this issue? I know it is older Tech and not as useful as a modern Rigol or Siglent, etc, but it seems a shame to recycle this scope when it is so close to being usable again.Any help at all would be appreciated!Thanks, Jeff

author: watchmaker
author_rank: Unknown
timestamp: September 21, 2025, 02:45:19 pm
content: Send me a PM. I have a PDF of the service manual.Dewey

author: kj7zth
author_rank: Newbie
timestamp: September 21, 2025, 06:37:40 pm
content: I sent a PM. Thanks for the reply!

author: kj7zth
author_rank: Newbie
timestamp: September 22, 2025, 12:16:28 pm
content: Is there anyone here who has experienced this issue or maybe is familiar with this scope and can help me figure out what is causing the voltage to read low?Or am I asking an inappropriate question for this forum? I am new here, and don't want to ruffle any feathers.
Kikusui AC Millivoltmeter 1831 - schematic anyone? - Page 1
Forum section: electronics / repair

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: October 31, 2021, 06:39:39 pm
content: There were various versions, 1831, 1831A, 1831B and so on.Any would do, but 1831 preferable!I tried Kikusui direct and they refuse to supply schematics for even this old (1980s) equipment.Manuals, however, are all on their website.
Kikusui COM7101A Oscilloscope - Horizontal final amplifier bad - Page 1
Forum section: electronics / repair

author: Heatsink
author_rank: Contributor
timestamp: October 20, 2023, 02:28:06 pm
content: Hello community,I am stuck trying to repair this older scope from the 90ties. It is an analog scope, with a digital storage part. The horizontal system stopped working. The final amplifier is a hybrid (H31 in the schematics) that is mounted together with some external components on the horizontal/vertical amplifier PCB. I was able to remove most of the resin from the hybrid and it contains an h-bridge that drives the CRT horizontal plates with 140V. Several resistors were out of spec and a 330 Ohms resistor was burnt. I replaced them and the 330 Ohms burns immediately when I connect the 140V to the module. I am running in circles when I try to understand why, but it measures 140V on one side and 5V on the other. It seems like the wrong transistors of the h-bridge are open and connect the resistor to the 5V rail. All transistors on the hybrid seem okay (diode tester). All resistors are within 10%. Looking at the input pins 10 and 11 (where the signal comes from the motherboard) I can see a lot of spikes where I would expect a clean sawtooth. These spikes are still there when I pull the amplifier pcb, so they come from the motherboard. I am no longer sure whether the issue is the hybrid, or whether these spikes cause the problem. Sorry for my English and the baby oscilloscope that I use to troubleshoot the other one. -- AIso, I desoldered the 4 h-bridge transistors and tested them externally. They are okay.

author: Heatsink
author_rank: Contributor
timestamp: October 21, 2023, 05:38:32 pm
content: Fixed!The spikes were caused by the character generator when it deflects the electron beam to write characters on the screen. I am not 100% sure what the problem was, but removing one of the feeding resistors for the h-bridge from the hybrid and using an external resistor instead did the trick. Happy to have this old scope back!
KIKUSUI PLZ152WA - Page 1
Forum section: electronics / repair

author: msobreira27
author_rank: Contributor
timestamp: September 25, 2019, 12:46:24 am
content: I bought a PLZ152WA on ebay, and during shipping it came damaged (one of the plastic holders of the the heatsink broke). As it was an overseas shipment it was not worth a return. I fixed the holder and after turning it on it Voltmeter was ok but there is no load - keeps the value at zero Amps - I tried loads A and B, followed the instructions from operations manual but no luck - It seems ok extrernally and in pretty neat condition inside - but it does not work. Does anybody has a service manual in pdf for this source or any clue on what may be not working? Thanks!

author: coromonadalix
author_rank: Super Contributor
timestamp: September 25, 2019, 03:05:28 am
content: Ask at Kikusui under an non disclosure agreement, they may provide you the schematics you needdaisuke@kikusuiamerica.comDaisuke TezukaKikusui America, Inc.3625 Del Amo Blvd., Suite 160Torrance, CA 90503Toll-Free: 1-877-876-2807Phone: 310-214-0000 ext.104Fax: 310-214-0014www.kikusuiamerica.comLinkedIn:www.linkedin.com/company/1166040Facebook:www.facebook.com/kikusui.america/

author: TERRA Operative
author_rank: Super Contributor
timestamp: September 25, 2019, 01:00:32 pm
content: I'll shoot an email to their Japanese office to see if they'll send something.

author: msobreira27
author_rank: Contributor
timestamp: September 25, 2019, 08:29:21 pm
content: Fantastic - thanks for the support! By the way, beautiful layout inside! Pure quality!
Kikusui pwr1600L 80v 100A PSU Repair - Page 1
Forum section: electronics / repair

author: tektronixman
author_rank: Newbie
timestamp: March 23, 2023, 09:38:43 pm
content: Does anybody have any service information for this psu The device has stopped outputting after a user calibration, it goes in to constant current mode with zero voltage and current which is not adjustable When put into calibration mode the voltage calibration all woks fine but the current calibration gives no output. I feel this is probably a control issue as there are occasional sporadic alarms Any info would be very welcomeColin Goode

author: coromonadalix
author_rank: Super Contributor
timestamp: March 24, 2023, 10:45:30 am
content: Ask their supportUnder annon disclosure agreementfor other model, i received a full schematic ...
Kimo VTB thermoanemometer - Page 1
Forum section: electronics / repair

author: shakalnokturn
author_rank: Super Contributor
timestamp: September 24, 2022, 12:30:51 am
content: I've been handed a hot wire type anemometer to try to repair.As expected the hot wire sensor is broken... This modelwasa thin glass tube supporting parallel running wires up to the tungsten heated tip.Any clues to where I could find anything similar? I am aware that it will need readjusting if I can find anything.
KINGSHILL electronic load 100 V 20 Amp. manual searched - Page 1
Forum section: electronics / repair

author: DVM-James
author_rank: Contributor
timestamp: August 21, 2025, 02:51:02 pm
content: This old electronic load is working fine so far - but it would be nice to have an user- and service-manual / information about max. power and so.Couldn´t find any information yet. It´s produced in 1987 or later. Picture from front and from removed inside attached.Thanks for help.RegardsHans

author: DVM-James
author_rank: Contributor
timestamp: August 21, 2025, 02:52:26 pm
content: - and the missing front-picture.
Kistler 5134 with corrupted PROM, Firmware Request (FW1.1) - Page 1
Forum section: electronics / repair

author: 2nOrderEDO
author_rank: Regular Contributor
timestamp: December 13, 2022, 01:13:57 pm
content: Hello there,A friend of mine was repairing a Kistler 5134 and found out the problem to be a corrupted PROM firmware. He replaced the memory IC with an EEPROM and programmed a more updated version of the firmware (V1.3) from another of these amplifiers we have around, but it seems to be working only partially. There are some menus in which the screen goes black and the instrument locks (we believe it hits an infinite loop in the new firmware).My friend contacted Kistler to ask for the original firmware file (V1.1), but they said this model is too old and they do not know where it could be. None of the units we have here have this firmware version.So we want to make a general call here on the forum to see if someone knows where to get this firmware, or if someone has this unit an can read and send the ROM. That would be very much appreciated. I attached a picture of the original PROM IC.We thank any helping hand :-)

author: fenugrec
author_rank: Frequent Contributor
timestamp: December 13, 2022, 08:00:43 pm
content: Can't help you, but could suggest alternate routes, depending on how bad you want the original firmware :With a "proper" EEPROM reader, experiment with different supply voltages and readout speeds. Hopefully you can retrieve some, or maybe all data.Scope data pins to find if there are weak drivers (and could use an extra pull-up/down resistor ), stuck bits, and so on. Save every dump attempt just in case.Compare whatever you do manage to dump with the 1.3 image, piece by piece - you may be lucky and find that many sections are identical or very similar. You will need at least a disassembler for this (which CPU ?), or ghidra if you have time for the learning curve.
KKMOON FY6800 pushbuttons - Page 1
Forum section: electronics / repair

author: fant
author_rank: Contributor
timestamp: May 29, 2022, 12:39:05 pm
content: Good morning;I have the FY6800 from about three years and i have had no problems.Now it is some months that the rubber pushbuttons are becoming more and more difficult to work, I have to push them hardly and very often when you push one button the display increase by 4 - 8 steps instead of one.What is possible to do?Thank you in advance
Klipsch R-12SW fixing - Page 1
Forum section: electronics / repair

author: Veketti
author_rank: Regular Contributor
timestamp: June 18, 2023, 11:16:23 am
content: Dear All,I'm trying to fix broken Klipsch R-12SW active subwoofer and have already measured that its power supply is ok. It supplies 35VDC and 5VDC, so I assume the amplifier is the culprint. I measured the power transistor TIP31C and found out that pin 2 and 3 were short. Just noticed that they are soldered together (first picture). So this is always on. I assume this shouldn't be the case because why put transistor there if it's always on? However I'm thinking could the solder melt and short them? Doesn't sound very plausible. Should I cut them separate and test?Visually didn't find any issues, all components look ok. However R36 (3rd picture) has been very hot as the other side of the pcb under that has turned brown. However I'm still measuring 460ohm for this so it hasn't burned open or short. Unfortunately didn't find any schematics for this.Thank you in advance.

author: m k
author_rank: Super Contributor
timestamp: June 25, 2023, 12:57:47 pm
content: What is the overall orientation?Hot can be very hot.Heatsink connection is also a bit less than optimal.

author: Veketti
author_rank: Regular Contributor
timestamp: July 06, 2023, 05:25:20 pm
content: Those legs point down, so in theory that solder could have run down due to overheat. For the heat dissipation, there is extra plate which presses these two components to the plate, which is removed in that picture. Anyhow, I changed that power transistor to a new, but unfortunately that wasn't the culprit. It does not "bang" anymore when power is plugged, but after a while the speaker starts knocking at around 0.5 Hz frequency.

author: m k
author_rank: Super Contributor
timestamp: July 07, 2023, 05:16:03 pm
content: So something is crawling or some unwanted frequencies are summing.I remember 50/60Hz TV timing something from the past but that's too fast.
Knick J152 (Current), S252 (Voltage) DC calibrator - Page 1
Forum section: electronics / repair

author: little.tesla
author_rank: Regular Contributor
timestamp: May 29, 2024, 08:07:59 pm
content: I've just repaired two power supplies of a J152 and S252 calibrator with a lot of issues and I want to share my experience with you. The PSU has a marking 3010 from which I assume they use the same PCB for the 3010 calibrator.On both power supplies I had to replace all of the carbon resistors, since many were open circuit, apart from the ones which were blown. Furthermore, transistors blown, Z-Diode not working, TEA1039 blown and Optocouplers were not okTEA1039The first replacement part I've got did not work from a seller from France. The second "batch" from the USA contained genuine parts and they did work.For a check, supply the TEA1039 with 14V from a lab power supply (in circuit) and one should see the saw-tooth waveform on the frequency setting capacitor and a square wave on the output of the IC. If this is missing the TEA1039 does not work.Transistor:BUX87 450V, 0.5ABUX85G 450V, 2AFJPF5021 500V, 5A <-- used as replacementOptocoupler:TLP580TCET1200 <-- used as replacementOn the primary side there is a regulator with a transistor and a Z-diode which provides the supply for the TEA1039 until it starts up. After that it gets its power from an dedicated winding of the transformator. This regulator has to deliver 14V to the TEA1039 else the PSU will not start. On one PSU the z-diode was bad and the voltage increased to ~20V after some time where the TEA1039 went into a overvoltage mode and did not work properly.The feedback can be tested by supplying the 5.2V PSU output with 5.2V and as well supplying the TEA1039 with 14V. As a basic test when varying the voltage on the 5.2V the output of the optocoupler should follow the input of the optocoupler.Capacitors:All capacitors (except ceramics and foil) were replaced with new ones. Tantalum replaced with Al-electrolyticMeasured output voltages:+5.2V+1.8V+34V-34V

author: little.tesla
author_rank: Regular Contributor
timestamp: May 29, 2024, 08:10:08 pm
content: For performing adjustment of the instrument one does need a so called "Passzahl" (unlock code). Does anybody know this unlock code?
Knick JS3010 Documentation needed - Page 1
Forum section: electronics / repair

author: Aheld
author_rank: Regular Contributor
timestamp: November 05, 2024, 06:48:15 pm
content: Hi Forum,I have a Knick JS3010 DC calibrator which is slightly out of spec. I didn't find any variable resistor etc. for fixing.So I'm wondering how to calibrate this device? (Equipment for calibrating this device is available)Badly, I have no documentation for this device.Is there any body who can help me?ThanksAxel

author: u666sa
author_rank: Frequent Contributor
timestamp: November 05, 2024, 08:36:26 pm
content: https://docs.ampnuts.ru/eevblog.docs/Knick/

author: Greybeard
author_rank: Frequent Contributor
timestamp: November 06, 2024, 05:46:18 pm
content: Does anybody know the calibration unlock code of the JS3010?

author: kilobyte
author_rank: Regular Contributor
timestamp: November 06, 2024, 08:19:14 pm
content: Probably Knick can provide them.Some years ago while doing some EPROM Backup etc of my Knick Stuff (J152 S252 JS3010) and repair of a J152 I was curious about the Z80 system. I needed to do a calibration so I tried to find the "PASSZAHL" myself. There is actually a second passcode which grants some sort of full access. But I'm not sure anymore what you could do with that.It looks that the passcode is the same for all of the models from this series J152 S252 ans JS3010I don't want to share it publicly, but can provide them via PM.

author: TomW
author_rank: Newbie
timestamp: July 07, 2025, 05:26:21 pm
content: Hallo "kilobyte",the only documentation for (also my) JS3010 I have is the User Manual EEVBLOG provides under"https://docs.ampnuts.ru/eevblog.docs/Knick/".In this scanned document (as also for the S252) I read to initiate a new calibration routine, a socalled "passzahl" is needed.I need this "passzahl" and beg to get it supplied from you.Thank you in advanceTom

author: Greybeard
author_rank: Frequent Contributor
timestamp: July 07, 2025, 09:03:30 pm
content: Quote from: TomW on July 07, 2025, 05:26:21 pmCheck this:Password (Passzahl) for calibration: 89537
KNIGHT KG-625 VTVM issue - Page 1
Forum section: electronics / repair

author: Crambone
author_rank: Frequent Contributor
timestamp: July 02, 2023, 11:48:06 pm
content: KG-625 VTVM issueI’m having an issue with this VTVM but here is a little info on the unit and what was replaced first.All resistors with the exception of a 91M as I dint have one have been replaced with new Metal Oxides since I had to lift an end on most to test I figure I would replace. The only Electrolytic Cap was replaced 20uf 450v. All pots have been removed, opened, cleaned. Tube sockets have been cleaned and all seem snug.I also tried and tested 3 ea 12AU7 and 2ea 6AL5 so I don’t believe the tubes are bad. I only have a Sencore Mighty Mite VI to test with.I also carefully cleaned all the contacts on the switches.OK so here is what’s happening when I try to calibrate.I did check all the voltages shown on the schematic, they are a bit high but I’m using a digital Meter so I expect that. The one’s I do have a ? On are pins 3 & 8 on the 12AU7. Schematic shows 1.6v and I’m seeing 3.4v on pin 8 and 3v on pin 3.The meter zeros mechanically fine.When I turn the meter on the needle stays pegged right but when I connect the probe too the ground I can zero with front control.The 1.5 VDC calibrates no issueThe .5 VDC calibrates no issueThe VAC calibrates no issueSo the Ohms oh the Ohms. I put in a new tested C battery. Ok it zeros fine and then aligns to the infinity mark on the right just fine. But when I try to test ANY size resistor it just pegs the meter left?I should also mention I checked every wire and connection was correct per the build manual.1. why does meter peg right with nothing hooked up? Is this normal?2. What can possibly cause the Ohms not to read?What can I be missing?Link to manual file is too large to attach:https://elektrotanya.com/allied_radio_knight_kg-625_vtvm.pdf/download.html

author: floobydust
author_rank: Super Contributor
timestamp: July 06, 2023, 03:51:58 am
content: I don't know what the crickets are about. Are you sure you are setting Ohms function zero and full scale properly? I'm like how does the needle read past the top with a real resistor...To confirm- it's a reverse-reading meter: zero ohms far left, open-circuit far right?What ranges is this happening on? Here is SCH for those that want to follow, it's not complicated although following the switches is surely a form of torture...I would be measuring the plate voltages with it on Ohms zero and open and a test resistor, and what is across R23 27k to see if the middle bias point -50V is reasonable.
ko4bb.com out of service? - Page 1
Forum section: electronics / repair

author: Leo Bodnar
author_rank: Frequent Contributor
timestamp: January 21, 2025, 10:29:34 am
content: Hashttps://www.ko4bb.com/getsimple/index.php?id=manualspacked in for everyone or just me?Leo

author: coromonadalix
author_rank: Super Contributor
timestamp: January 21, 2025, 11:00:45 am
content: was fine 5 mins agothere is still the same message from 2024NOTE: the website is currently near its capacity limit. Some operations (uploads, downloads) may be intermittently unavailable while I work on the problem. Please be patient, hopefully this will be fixed soon (March 16, 2024).maybe he has some hard time maintaining the site etc ... he has interruptions over the time, or financial .... i have doubts for 2025 ...

author: mikerj
author_rank: Super Contributor
timestamp: January 21, 2025, 11:57:22 am
content: I see exactly the same error when trying to download a document.

author: IanJ
author_rank: Unknown
timestamp: January 21, 2025, 12:13:52 pm
content: Error:"Warning: mkdir(): No space left on device in /var/www/html/getsimple/admin/inc/theme_functions.php(544) : eval()'d code on line 70"
Kobo Glo - Page 1
Forum section: electronics / repair

author: Wawavoun
author_rank: Regular Contributor
timestamp: October 23, 2022, 10:50:31 am
content: Hello there !I have a problem with a Kobo Glo (its an electronic reader).The battery charge dont start and the reader dont show any sign of life even connected to a computer via usb.I have check that the supply voltage coming from an usb adapter, goes to the motherboard. So usb adapter, cable and usb socket are ok.Then I have check the LiPo battery. Its a 3.7 V 1200 mAh GN345361 dated more or less year 2014. It show 0 volt, connected or not.The battery dont show any sign of damage like swollen. The only sign before failure was a shorter than before working time after full reload...My assumption is that the problem is here and that I can change the battery and get a working again reader.But powered via a cable and battery disconnected the reader always refuse to show any sign of life.In this case should the reader start or is it normal that they dont work without battery ?Thanks for advice's.Regards.Philippe
KODEN Echo Sounder CVS-126  -  defective SDRAM - Page 1
Forum section: electronics / repair

author: AlexB
author_rank: Contributor
timestamp: September 18, 2017, 02:06:35 pm
content: HelloI found defective SDRAM in KODEN Echo Sounder CVS-126. It gets very hot, very fast. (the one on the right).The LCD won't show anything, just the backlight turns on and ON/OFF is working.An external fuse blew and when it was replaced, the echo sounder wasn't working anymore. I think it was a voltage spike.Part number on SDRAM chip: MT48LC8M16A2P-75 IT:GClosest part number I found in stock for sale: MT48LC8M16A2P-75 IT:GTRhttp://static6.arrow.com/aropdfconversion/25b8a7613c57009f764d08e18edc9430887d9f32/473128mb_x4x8x16_sdram1.pdfI don't understand what TR ending means.Maybe GTR is a new code for revision ? I couldn't find in any datasheet the code GTR or TR.Thank youPS: Maybe someone could help me find the service manual (just in case I would need it). Thank you

author: Armadillo
author_rank: Super Contributor
timestamp: September 18, 2017, 02:35:58 pm
content: A fish finder. Ahh, I repaired one color Lowrance before which is tight sealed dead.I am surprised your koden can be opened so easily.Seems like the manufacturer of these things are very tight lipped, can't find the manual for the Lowrance either.But the circuit should be all the same except the algorithm, method of pulsing, I think.

author: wraper
author_rank: Unknown
timestamp: September 18, 2017, 02:40:53 pm
content: TR means tape and reel packaging. Part is the same. All you should care is MT48LC8M16A2P-75 in the part number and correct package. Actually you don't even need -75, any other speed grade will do as this is the worst speed grade available.

author: AlexB
author_rank: Contributor
timestamp: September 18, 2017, 02:45:36 pm
content: Thank you very muchYes, it was VERY easy to open. Just a plastic cover which came out using a screwdriver (covering the edges of the LCD and the screws), and 7 screws.

author: wraper
author_rank: Unknown
timestamp: September 18, 2017, 02:53:06 pm
content: BTW check if supply voltage for RAM IC is correct. I's not common for SDRAM to fail frying hot by itself.

author: AlexB
author_rank: Contributor
timestamp: September 18, 2017, 04:09:15 pm
content: Yes, I will. Thank you

author: ervin
author_rank: Newbie
timestamp: January 17, 2020, 11:53:29 am
content: Hi can you read bin file of S29JL064H70TFI000 , i have one corrupted need to reflash it

author: AlexB
author_rank: Contributor
timestamp: February 15, 2021, 04:48:52 pm
content: Quote from: ervin on January 17, 2020, 11:53:29 amHelloI am sorry but I can't help you.Good luck.
Kontron 18027-0000-99-0 motherboard - Page 1
Forum section: electronics / repair

author: Li Yang
author_rank: Newbie
timestamp: September 24, 2025, 02:30:05 am
content: I am currently repairing an embedded motherboard from Kontron, model number 18027-0000-99-0, but I am missing some documentation. Can anyone help me with where to download it?

author: coromonadalix
author_rank: Super Contributor
timestamp: September 24, 2025, 08:04:00 am
content: thoses are ETX motherboards found in some equipmentyou can find ETX documentations / standards / pinouts, but for the manuals Kontron may or will be the solution ?Since it's based on AMD Geode you may find some similarities with other boardsgoogle fuu give me this: who seems to fithttps://www.kontron.com/en/products/etx--lx/p88100
Koolertron Juntek Junctek 60MHz-a RF noise issue - Page 1
Forum section: electronics / repair

author: antenna
author_rank: Frequent Contributor
timestamp: January 20, 2023, 04:49:00 am
content: I just wanted to share an issue I had with this product. I wanted to use this as a SSB and AM generator for HF. With the front outputs on or off, the unit will generate RF noise on the set frequency. This is very noticeable if you set it to 27.384MHz with a nearby radio on that channel. Even with nothing connected to the signal generator, its geting out there.Long story short, there is a chip in the back by the TTL socket that generates a terrible square wave full of phase noise for that unmentioned sync out port they don't talk about in the book. I don't know what that chip is because everything was laser etched off, but I did find that lifting the Vcc pin on that chip makes the noise go away and the front stuff will still function normally.
KORAD 3005D  - Page 1
Forum section: electronics / repair

author: Hostar
author_rank: Newbie
timestamp: December 27, 2020, 02:43:43 pm
content: Hello everyone,I am a new member on the forum and first of all I greet you all nicely.I recently purchased a KORAD 3005D PS. Right from the start, I had a bad feeling when I noticed a broken green earth connector. Not the worst case, but a more serious problem is that despite the calibration, the display shows 50mA less output current than it really is. It is NOT range dependent, if I set the max current to 50mA, the output is exactly 50mA, but the display shows 0mA. So even when I set the max current to 1A, the output is 1.003A, but the display shows 952mA. The same story is at 5A.Reading the forum I found all the schematics. A detailed inspection of the board showed nothing special, however I resoldered the pins on the operational amplifiers (TL082), but there is no change. I don' t know if I understand the schematics, but I think that AD1 and AD2 are the analog inputs to the mPC to somehow display the "set" value and the measured value of the current ? Not sure, but I rather repair that and learn something, than communicate with sales on Aliexpress for returning and spend money for shipping.Any help or hints are very welcome.

author: Andreas
author_rank: Super Contributor
timestamp: December 27, 2020, 04:46:28 pm
content: You should search for the "calibration procedure" (somewhere here in the forum).with best regardsAndreas

author: Hostar
author_rank: Newbie
timestamp: December 30, 2020, 06:30:08 am
content: Thanks Andreas, calibration was the first thing I did try.Well, I think I had a bad luck with this order. Calibration works fine on min and max Voltage settings and also I can set minimum mA current, but when I try to switch to max current settings with M4 button, the display shows 1.5A and nothing changes with rotary knob spinning. I also try to change shunt resistor, but it is the same story.Strange thing is, that real output current is correct, just display shows incorrect value, exactly 50mA less than it was set.Just wonder if anyone else has the same problem?
Korad 3305P lab supply no output on channel 1 and 2 (RND rebadge) - Page 1
Forum section: electronics / repair

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: May 22, 2025, 02:21:04 pm
content: I was having strange problems while debugging a circuit, until I realized that my PSU wasn't outputting anything!Everything is ok according to the display, but there's no voltage.As seen in the attached image, in the upper left beside the fan are relays that control which transformer windings to use depending on your requested output. It is then filtered and regulated to whatever you want. It seems none of these relays are engaged, so no power then. This is also evident when I adjust the voltage from lowest to highest, as there would otherwise have been healthy chattering. The relays are controlled from the board behind the front panel, through the ribbon cable.So.. it might seem like some driver chip may be at fault? I assume so, since the display and buttons are happy. These are surface mount components and difficult to trace, but hopefullt not to replace. I'll post whatever I find here, but in case you've encountered something like it or know the PSU well, don't hesitate in giving some clues!

author: kreutz
author_rank: Contributor
timestamp: May 23, 2025, 05:23:59 pm
content: in the KA3005 the relays are driven by a ULN2003 chip, I dont have schematics for the Korad 3305.

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: May 27, 2025, 07:44:50 pm
content: A small update: The relays are controlled by a bunch of discrete transistors (marked to the right in the image), in turn controlled by two of these proprietary "KORAD" ICs, also marked. Transistors seem to be ok, but Vbe is 0.001 on all of them, regardless of my voltage setting. Vce is 12V.Did I fry those chips? You see, previously I tried connecting the two outputs in series, without realizing the PSU has a separate serial/parallel mode. So positive of channel 2 to negative of channel 1. Maybe I shouldn't have done that, but at the same time I can't see why that would be an issue?

author: mvno_subscriber
author_rank: Regular Contributor
timestamp: May 29, 2025, 07:25:20 pm
content: I'm a little bummed here. There are three "KORAD" ICs on this board - two "KORAD1" ICs which I would guess controls / senses voltage and current, and a "KORAD004" IC which seems to handle the buttons, display etc.The KORAD1 chips are fed 3.2V via a regulator stepping down from 12V. So that works. But ICs seem dead. Tried some thermal imaging, I've attached image of both thermal cam and a normal picture highlighting the hot spots, which, for each channel are two dual opamps and a diode on the upper side of the image, and voltage regulators on the lower side.Of course, I have no idea if the KORAD1s are supposed to give off any noticeable heat, but it doesn't exactly weaken the suspicion that these chips are bust. I really don't need another expense right now, but I also don't know where to debug next! :'(Viewpoints welcome!
Korad KA3005 Replacement Rotary Encoder - Page 1
Forum section: electronics / repair

author: MSchalk
author_rank: Newbie
timestamp: January 10, 2024, 06:49:25 pm
content: I didn't see anybody who had linked a convenient spot to get replacement encoders in the USA so from digikey PEC12R-4220F-N0024 is a drop in replacement for the rotary encoder. Same counts and everything.

author: voltsandjolts
author_rank: Unknown
timestamp: January 10, 2024, 08:28:44 pm
content: Quote from: MSchalk on January 10, 2024, 06:49:25 pmYes, I've done the Korad encoder fix with that exact replacement part, it works fine.https://www.mouser.co.uk/c/?q=PEC12R-4220F-N0024https://www.digikey.co.uk/en/products/detail/bourns-inc/pec12r-4220f-n0024/4499652
Korad KA3305p I messed up - Page 1
Forum section: electronics / repair

author: escapekit
author_rank: Contributor
timestamp: September 20, 2023, 03:01:14 pm
content: Hi guys,I am an electronics hobbyist and I do some custom electronics for theatre or escape rooms as a side gig when the oportunity presents itself.I've been using my Korad KA3305p I bought in 2018 following advice on this forum and I am very happy with it.Link to KA3305p:https://shorturl.at/ceru2Sadly I messed it up.I had the "great" idea of placing over the workbench only the front panel, and moving the rest of the unit under the bench.This way I could save precious bench realstate. To do it I just had to make the internal wires longer. Easy enough I thought.Most of them are regular wires, as long as I use the same or bigger wire gauge it should be fine.One of them is a 34 pin ribbon cable though. I don't have any one of those long enough to replace, since I didn't want to order one and wait, I grabed a very long old one I had lying aroud that has 25 pins and frankestained it into the 34pin connectors. (you can see one end of it in the img).Long story short, I messed up the position of the connectors and connected one of the ends in the reverse order. Luckily I pluged the PS with the cover off (I had a bad feeling for the janky wire) and immediately saw a small fire in the main display PCB and disconnected it in half a second.After reversing the connector and plugging it in again, the PS seems to work just fine.In the picture attached you can see the PCB with the burnt component (Q15). I do not see anything else that is obviously damaged, just the sot23 mosfet that was lit on fire for a second.Following the traces it seems like the drain is connected to one of the relays on the board. I assume those relays's function is to use both channels in parallel/series, wich I don't do often, maybe once a year if ever.Questions I would be VERY thankful if you can answer:1 - Am I right in assuming the sot23 part is an N-channel mosfet driving one of the relays?2 - Will it be ok if I replace this burnt mosfet for a new one like this:https://shorturl.at/cvL78and "Bob is your uncle"as Dave would say?Anything else I may have missed?Thnaks a lot and sorry for the long text and bad english.

author: Swake
author_rank: Frequent Contributor
timestamp: September 21, 2023, 06:01:14 pm
content: The other relays are likely driven with the same method.compare and read marking from the other one.

author: escapekit
author_rank: Contributor
timestamp: September 23, 2023, 10:42:05 am
content: Thenks for your response!The marking of all the transistors in this area say 1AM, I even managed to read the A and half an M on the burnt one.A google search led me to this ref: MMBT3904Apparently is a BJT bipolar transistor. (NPN)I guess I could use the aforementioned mosfet but Maybe I'll add the specific part on my next order to ewither mouser or digikey and make sure it stays as it should be.Thanks!
Korad KD3005 help identifying fried component - Page 1
Forum section: electronics / repair

author: Scyth0r
author_rank: Newbie
timestamp: May 02, 2023, 09:59:44 am
content: Hi,I have a Korad KD3005P which is a cheaper version of the KA and also different enough for me to not be able to use the help on that one I found in this forum.As you can see in the attached picture I fried a component on the board directly attached to the outlets by connecting a battery when the supply was turned off. Unfortunately it is so bad that the writing is also burnt. Can anyone tell me what that was? My best guess is to try a IN5408 MIC I still have.Thanks in advance:)

author: Andy Watson
author_rank: Super Contributor
timestamp: May 02, 2023, 10:56:56 am
content: Itiswas a diode. Probably of the 1N5xxx variety. It appears to be across the output terminals - so probably just a bog-standard diode. Any of the 1N500x family would work.

author: macboy
author_rank: Super Contributor
timestamp: May 02, 2023, 12:03:42 pm
content: Also know that this diode fried because the battery was connected in reverse polarity across the terminals, regardless if whether the supply was on or off. The diode sacrificed itself to protect numerous other components from the reverse voltage. Don't worry, it has happened to most of us at some time.