hybridfree/eevblog-posts huggingface dataset:
Hard time with a HP 5385A with a repaired board - Page 1
Forum section: electronics / repair

author: pizzigri
author_rank: Regular Contributor
timestamp: October 21, 2020, 01:02:27 pm
content: Hello everyone!I finally received a HP5385A counter from an eBay seller located in Israel, I believe these were used by some military unit. The counter was described as “perfectly working” and the price was right, about 100 $ - although it actually more than doubled with postage and custom taxes by the time it reached me.However, the counter has a hard time reading low level signals, so I tried to look for the problem, and I found a rather sloppily made repair on th board. R2, a 51.1 Ohm 1% resistor, that from the diagram I imagine being the internal terminator, somehow burned and was replaced with apart that I am not very familiar witha Vishay RLR/C military metal film resistor of the correct value, see images. The two resistors (R3 and R1) at its sides are badly scorched as is a small capacitor (C1), which have been left on the board. Also, lots of black flux caked on the board. There’s also signs of an IC replaced, U6, a Harris 1858 (wonder what that is).So my question is:The problem I see reading a frequency below the 3-4V level, can it be caused by this resistor?Should I replace the two resistors around R2 and the capacitor?Can theblack fluxburned frp! cause a problem?There are other things, but those I can cope with, like a broken off rear BNC for the ref input.Edited to modify after some research.Thank you guys!

author: Grandchuck
author_rank: Super Contributor
timestamp: October 21, 2020, 07:21:06 pm
content: I would clean the board. You could test the adjacent resistors but they are probably OK.If the input signal was large enough to cook the termination resistor it probably also damaged a solid state device down the signal chain. Check the schematic to see which devices are close to the input connector and check them.

author: Grandchuck
author_rank: Super Contributor
timestamp: October 21, 2020, 08:56:32 pm
content: CR6, CR7, Q2 could be damaged.

author: pizzigri
author_rank: Regular Contributor
timestamp: October 22, 2020, 05:37:03 am
content: Ok! Cleaned the board, and will check the components today... there was a huge amount of crud, used a whole glass worth of 99.9% ethyl alcohol. The BNC connectors were also very dirty inside with black stuff (?) in them.

author: pizzigri
author_rank: Regular Contributor
timestamp: October 22, 2020, 11:01:10 am
content: Welll.... it worksThe internal TCXO is off by 2.5 hz vs my gpsdo and drifts too, but that will be taken care of with Miti’s ocxo board for this counter.So the gunk actually created the problem??? I didn’t do anything else but clean it. Both diodes tested good (0.725V) and the rest too so after the clean up i reassembled the thing and firef it up.Nice! Thank you
Harman Kardon HK6500 Audio amp repair (huge output with no input) - Page 1
Forum section: electronics / repair

author: Jadon
author_rank: Newbie
timestamp: June 25, 2022, 05:47:22 pm
content: I've got a Harman Kardon HK6500 Amplifier that was working fine about 5 years ago and then put into storage as we ha no use for it. The other day I got it out and plugged it in with a bookshelf speaker of mine connected, and in about 5 seconds it fried it completely. There was a slight hum, and while turning up the volume on the amplifier to see if I could hear the music, I just heard sizzling from the speaker. (Its beyond fried, was perfectly fine before this operation).I put the amplifier output on my scope with no input connected and volume at 0, as well as with an input and varying the volume and its putting out a 102V peak to peak waveform no matter what I do!!!!The frequency is <1Hz, and a weird shape but consistent. I have no idea where to start, nothing is getting hot, no fried components (that I can see), and no immense power draw.Any ideas on where to go next?
HARMAN KARDON HKTS220SUB/230 humming noise - Page 1
Forum section: electronics / repair

author: Charlie86
author_rank: Regular Contributor
timestamp: March 22, 2021, 05:35:18 pm
content: I have a problem with in HARMAN KARDON HKTS220SUB / 230. It started humming even if it is not connected to any source. The sound is very similar to that in the video.https://youtu.be/CkMOZc1W9JwI found a service manual but unfortunately I can't help myself with it.https://elektrotanya.com/harman_kardon_hkts_220.pdf/download.html#dlI also tried replacing three capacitors and a resistor from link below, but Subwoffer is still humming.https://www.ebay.com/itm/Reparatur-Set-V2-0-fuer-das-Netzteil-HKTS210SUB-230-Harman-Kardon-13-Teile-/363266392654Any idea, how to repair it?

author: cdev
author_rank: Super Contributor
timestamp: March 22, 2021, 06:13:23 pm
content: Is it the power transformer? If so, maybe you can replenish the varnish and dry it out in an oven. Search on transformer hum. Sometimes a vacuum is also used to suck out the air so the the varnish penetrates deeper.

author: Charlie86
author_rank: Regular Contributor
timestamp: March 22, 2021, 06:18:22 pm
content: Hi,It uses switching power supply. Humming is comeing directly from speaker. Speaker vibrates.

author: cdev
author_rank: Super Contributor
timestamp: March 22, 2021, 07:13:04 pm
content: You should check the capacitors for bulging or leaking, and/or high ESR. Loss of the filter function from caps drying out will make such a hum. Nine times out of ten, this is whats wrong, unless the receiver is fairly new.
Harman Kardon Omni10 bluetooth issues, upgrade still possible? - Page 1
Forum section: electronics / repair

author: Aheld
author_rank: Regular Contributor
timestamp: March 04, 2024, 06:36:23 pm
content: Hi Forum,I have a HK OMNI10 bluetooth speaker with amazing sound (older version, no official support anymore). This speaker has bluetooth connection issues, from my point of view, due to firmware issues.I'm wondering if anybody found a solution for this nice speaker?Br. Axel
Harman Kardon SR-300b FM tuner repair - Page 1
Forum section: electronics / repair

author: Arty30
author_rank: Regular Contributor
timestamp: February 02, 2024, 11:31:13 pm
content: Hello all, I am doing my best to resurrect a mid-late 60s Harman Kardon receiver. It is a model 300b with just an FM tuner, the 400b was identical but with an AM tuner. I have gotten the amplifier section working apart from bad hum at any volume. I will tackle that later, but right now the tuner is completely dead apart from very faint music from somewhere. I have found a stronger source of sound around the tuning condenser and IF stages. It really doesn't help that there is no schematic anywhere so if anyone has a lead let me know. said source of sound doesn't really lead me anywhere else except to a little black 4 terminal device that looks like a transistor. It says SES6518 and 157TID on it. I'll post a picture but I would like to try to identify it, whether is is a transistor or transistor pair of some sort. not having a schematic or good idea how tuners work it's hard to tell what part the signal is originating from and where it's going.

author: fant
author_rank: Contributor
timestamp: February 02, 2024, 11:58:16 pm
content: Are transistor, 99,9 % germanium type.Very difficult to find replacement.My suggestion is to have a signal generator and follow the path of the RF.Probably the IF is 10,7 MHz.Without a signal generator and an oscilloscope, will be very difficult to find the trouble.Mandi

author: Arty30
author_rank: Regular Contributor
timestamp: February 03, 2024, 05:23:52 pm
content: good to know, I have a scope and a 30MHz RF signal generator. I took some voltage measurements on the device in question and saw what seems to me like transistor like voltages. between the two outer pins was 0.7 to 1.5V, and other combinations was 6 to 8V. I couldn't really tell what could be the base, collector or emitter based on those numbers so I'm not sure what the pin is that has sound, whether it's the output or input to the device. there's just noise on all the other pins. I'm using a signal tracer by the way, a scope probe attached to an amplifier with a speaker.
Harmon Kardon AVR171S/230  and HS350 - Page 1
Forum section: electronics / repair

author: geobee
author_rank: Contributor
timestamp: April 27, 2022, 06:40:42 am
content: Hi all, have these two Hi Fi amps in at the moment, both with the same fault. Both have distorted output on all channels, main and surrounds, but neither amp is going into protect mode. The audio is just very weak and distorted. I haven't come across anything like this before, maybe someone can share some knowledge on them.
Harmon Kardon PSU - Page 1
Forum section: electronics / repair

author: AdamHerbst
author_rank: Newbie
timestamp: April 01, 2024, 04:26:30 am
content: Hello Everyone,Very new to how everything works and im wonder why im not getting any voltage on the secondary side of the SMPS.With all the different feedback ic's being interlayed with eachother its hard finding a point to start at. Im guessing both Power_hi, and VCC_AMP_on have to be pulled up in order to work. The 7VD goes to a 3.3V converter into the mcu which controls the transistors. But the transformer that ouputs 7VD is controlled by the IC?What would be the best way to diagnose as to why the SMPS is not working? Thank you in advance for your time and knowledge~ Adam

author: xavier60
author_rank: Super Contributor
timestamp: April 01, 2024, 05:59:05 am
content: ST+5V is the first thing that needs to be up.
Harris 92693 DC motor speed controller  - Page 1
Forum section: electronics / repair

author: comand
author_rank: Newbie
timestamp: January 14, 2025, 10:23:18 am
content: Hi, l have Veglia speedometer from Iveco truck 1995 year, it has Harris 92693 IC that inputs sine wave signal from 2 pin speed sensor and converts it to pwm controlled pulses that drives speedometer needle, also there is flyback from dc motor Hall speed sensor. Cannot find specification for this IC or any similar IC. Can someone give an anvise which IC can handle with sine input with 18 volts amplitude and drive dc motor with hall flyback?

author: comand
author_rank: Newbie
timestamp: January 14, 2025, 10:32:51 am
content: more pictures
harrison produces really tough bastards - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2021, 01:52:35 am
content: So I was working on my old HP harrison power supply and it was like extremely disgusting so I dunked it into a ultrasonic cleaner at various angles to clean it up. Nothing bad happened, I dipped the trim pots and everything all together on the unit because I literally bought it for like $20 ages ago and I don't even need it, I use it as my nasty electroplating supply. I am sure we all have some beater we don't want to touch.Does anyone else do this? I was almost thinking the switch is going to break, but I put it upright and flooded it with deoxit and actuated it alot, same with the potentiometers, I let stuff drip in there. I did the cleaning with an air supply.Not that I recommend this, but I believe this 7.5V supply is from 1960 and it held up to that ultrasonic beating quite well. Maybe I will take a picture if I replace the screw holder on the chassis because it won't look decent until then.It's just something I was extremely fed up with and it felt like it could outlive me on the shelf, plus it had all sorts of weird crust on it. So these are built good enough that you can treat it like a small lawnmower engine. The rinse water looked like someone poured a bunch of mud in there*save for the panel meter!*If you have something extremely foul and you have a weak stomach and not enough time, you can give it a try, I almost considered that equipment borderline unusable and the interior condition was so dirty it made me paranoid about weird short circuits when I looked inside.

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 21, 2021, 03:26:07 am
content: It wasn’t a power supply but I dunked the entire head of a very foul and dirty Bausch & Lomb stereo microscope in the Branson. Knowing my mechanical limitations, I didn’t want to disassemble the zoom assembly and I couldn’t get to all the dirt. Two passes, some rinse agent and it was pretty darn usable.

author: Runco990
author_rank: Frequent Contributor
timestamp: March 21, 2021, 09:24:56 pm
content: I have run stuff like this through the dishwasher and then baked dry in a lab hot air oven.No problems. Even hosed out a VCR with a garden hose that someone spilled champagne into... it was given to me... then dried in the sun. It ran great for another 6 years!

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2021, 09:34:57 pm
content: hahaha that story is really funnyis it like a bad party prank or did someone trip and fall on a VCR with a glass? i guess you might never know, but the interesting part is.. was it powered?this comes to mindlol

author: Bud
author_rank: Super Contributor
timestamp: March 21, 2021, 10:34:32 pm
content: I once dealt with a walkman cassette player that the owner accidentally dropped in a bucket with liquid honeyI disassembled it, soaked in warm water rinsed and dried. Worked just fine after.
Hart Scientific 1590 SuperThermometer - Page 1
Forum section: electronics / repair

author: CalMachine
author_rank: Frequent Contributor
timestamp: March 08, 2020, 12:07:42 am
content: Awhile back I picked up one of these that is in need of repair and it's finally next in line on my list of projectsWould anyone happen to have a copy of the schematics or service manual?Thanks for any provided information!
Has anyone disassembled an IR189USB fluke cable? - Page 1
Forum section: electronics / repair

author: rauldm
author_rank: Regular Contributor
timestamp: December 02, 2019, 02:41:03 am
content: I bought a Fluke 289 FVF kit, but the USB came with problem, I return my kit to store, they sent me a new kit, again same problem, only works with IR3000FC, finally I discovery, if I put the connector with 5 mm clearance between meter, it works, I put a dark plastic film inside the connector on IR LED and works too, I showed this to Fluke, they sent me new USB cable and it works finally. I think if I unassembly the connector and change the IR LED resistor it can works normally, but I don't want damage the connector case.Regards.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 02, 2019, 02:51:51 am
content: theres was a thread herehttps://www.eevblog.com/forum/buysellwanted/w-t-b-fluke-ir189-usb-usb-cable-280180-series/msg1436629/#msg1436629The third post if i recallThere was an clone still sold on ebayhttps://www.ebay.com/itm/USB-optoisolated-IR-adapter-for-Fluke/182450421884Some googlefuu will show you schematicsBut for the transmission problems i think thre was an issue with the comparator used vs the voltages references, something like thisFor dismantling the case, i would use an brand new xacto blade and slowly make a way between the 2 case parts

author: ABC123
author_rank: Newbie
timestamp: July 05, 2025, 05:59:44 am
content: It's easy. Do 3 movements at the same time as in the photo.
Has anyone done backlight mod on HP 437B? - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: June 26, 2021, 04:42:00 pm
content: I have an HP 437B power meter. As it is common to this era of HP gear, it uses LCD screen with very poor back lighting. Yesterday, I took it apart hoping to see an easy way to replace the light source, but I couldn't find obvious way to do this. I know some other HP stuff has side lit LEDs but this is not the case. In fact, I couldn't find anything that would light up.Has anyone done backlight improvement on this piece?

author: gabiz_ro
author_rank: Regular Contributor
timestamp: June 26, 2021, 06:33:01 pm
content: If space is problem and size of LCD you may try some Electroluminescent (EL) Tape StripIf you find for LCD size,there are many sizes and color variants.

author: Miti
author_rank: Super Contributor
timestamp: June 27, 2021, 11:25:06 am
content: Yeap, see here:https://www.eevblog.com/forum/testgear/hp3478a-backlight-my-version/msg3254516/#msg3254516
Has anyone else seen this chip - Page 1
Forum section: electronics / repair

author: rhinonimi
author_rank: Newbie
timestamp: April 22, 2025, 05:32:20 am
content: I have a Bluetooth led controller board and this is the main chip. It receives the Bluetooth inputs, sends signals to the addressable leds, receives the IR signal and microphone signal. I can not source it. Is there any equivalent?

author: fzabkar
author_rank: Super Contributor
timestamp: April 22, 2025, 05:50:47 am
content: This appears to be the manufacturer:http://www.yichip.com/yc11xx
Has anyone ever used a STM32  to unbrick an APC SRT model? - Page 1
Forum section: electronics / repair

author: jordanz82
author_rank: Newbie
timestamp: March 14, 2025, 04:26:58 pm
content: Hi,I've seen lots of posts regarding unbricking an APC SMT1500. I was wondering if anyone knoes if an SRT model can also be unbricked with the same method? Would the pin connection be different?Thanks in advance for any help you can offer!
Has someone succeed update the FLUKE 199c to 225c? - Page 1
Forum section: electronics / repair

author: willinsau
author_rank: Newbie
timestamp: August 19, 2023, 01:42:10 am
content: I have a 199c(v8.04) and just noticed it can be updated to 225cbut links looks don't work anymore.Has someone succeeded and know how to update it?Regards,
Have an SMIQ?  I need pictures of the bottom feet. - Page 1
Forum section: electronics / repair

author: DaJMasta
author_rank: Super Contributor
timestamp: August 22, 2019, 04:50:22 am
content: I've got an SMIQ03B with no bottom feet and would like to make some 3D printed replacements for it. I've been able to find some images of them from various angles that I could use as models and the unit itself for hole placement, but I'm not actually sure how they attach to the chassis - I would guess a screw and two pins, but It's difficult to tell how the pins snap or otherwise hold on with just the sheet metal chassis.This is where you can help: can you take a picture of how the feet attach to the chassis metal on the inside? Bonus points for any overall measurements of the feet - helps reduce the number of prototypes and better match the originals.In return, it may take me a week or two, but I'll upload the models to thingiverse so you can print your own replacements.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 23, 2019, 09:57:44 pm
content: A little update, it appears the SME and SMT series generators use the same feet, so if you've got one of those and want to help, that would do nicely!Gotta do a test print, but I think I've got a good copy of the encoder wheel (uses a 6mm round shaft) in all plastic (original is a split tube with a metal ring for reinforcement).

author: tautech
author_rank: Super Contributor
timestamp: August 23, 2019, 10:38:48 pm
content: Links and guys here might be able to help:https://www.eevblog.com/forum/testgear/replacement-knobs-feet-and-fittings-for-test-equipment/

author: langwadt
author_rank: Super Contributor
timestamp: August 23, 2019, 10:47:46 pm
content: https://www.eevblog.com/forum/testgear/new-project-rs-smiq03b/5/?

author: DaJMasta
author_rank: Super Contributor
timestamp: August 23, 2019, 11:13:47 pm
content: Quote from: tautech on August 23, 2019, 10:38:48 pmI intend to again be a contributor :pThanks for the link to the other project - those don't appear to be that similar to the original feet, though I'm sure they do the job. However, that does help explain the mounting holes on the bottom.Pictures of the originals (harvested from ebay listings that show the bottom of the unit) are attached.

author: eb4eqa
author_rank: Regular Contributor
timestamp: August 25, 2019, 11:15:15 am
content: I designed and printer exactly what you need some time ago, but quickly got into another thing and never shared it with anyone.Here they are, ready to print:https://www.thingiverse.com/thing:3825300Regards,Roberto EB4EQA
Have i shorted my ps3 controller - Page 1
Forum section: electronics / repair

author: OverclockVintage
author_rank: Contributor
timestamp: December 23, 2021, 06:16:41 pm
content: I've opened it to clean the analog pots, and as it has a battery i think i may have shorted it.The picture shows how it is now.Edit: Shorted with my fingers or the contact cleaner.

author: OverclockVintage
author_rank: Contributor
timestamp: December 23, 2021, 09:41:29 pm
content: Update: It was actually a problem on the flex pcb, already fixed it.
Having standard electlytic caps on hand - Page 1
Forum section: electronics / repair

author: tkamiya
author_rank: Super Contributor
timestamp: March 31, 2022, 07:05:37 am
content: As many bargain test equipment collector would know, electlytic capacitors are common failure items. I'd like to stock most common values inhouse, but I can't seem to find name-brand pieces in a kit. (like Nichicon or Panasonic) Does anyone here do this? If so, how/what did you source them?

author: Berni
author_rank: Super Contributor
timestamp: March 31, 2022, 07:50:28 am
content: It probably varies too much from equipment to equipment.But these caps are usually not critical in value and the modern equivalents are quite a bit smaller in physical size. So you can often get away with a different one. Like a 100uF 50V cap might fit into the place of a 100uF 35V one. Or if the original one was 150uF you can probably replace it with a 220uF while still fitting on the PCB footprint.You can have a look trough the service manuals of the equipment you have on your "wana buy" list to get some numbers.More of a problem are weird shape capacitors found in some old equipment. Those axial elcos are often seen in old gear but are pretty rare today. The really big ones are the screw-down cans with wire terminals and such. Those big ones rarely fail but i seen some people open them up, gut it out and put a modern equivalent inside (since the modern one is 1/4 the size physicaly)So id say as long as you have the common values at a decently high voltage rating of 35V or more you can fix most gear.
HDMI Monitor Problem - Page 1
Forum section: electronics / repair

author: aarondunleavy
author_rank: Newbie
timestamp: July 13, 2020, 04:48:53 pm
content: Hello,I have no experience with electronics but thought I'd post here to see if anyone can help. Thanks in advance for any advice, much appreciated.I have a Dell S2415H monitor and was trying to use a HDMI splitter between the monitor and a TV. I accidentally powered the HDMI splitter with a 12v power supply instead of the required 5v, and whilst doing so the splitter has fried a component on the main board of the monitor through the HDMI cable. The monitor has now been discontinued so it's tricky to find a replacement, but as I use it as a dual monitor setup I really need it to be fixed to sit alongside my other monitor and to avoid having to replace both.The front of the board seems fine but the culprit seems to be on the rear side which I've circled. On my other identical monitor the component is labelled 50H1G.Any help in finding a solution would be greatly appreciated.Thanks,Aaron

author: amyk
author_rank: Super Contributor
timestamp: July 14, 2020, 01:21:18 am
content: If the monitor was powered with 12V instead of 5 then I could see it being anRP100N251BLDO that got fried (that one has an absolute maximum input of 5.25V, so 12V would definitely have caused that sort of damage), but your mention of the damage coming in via the HDMI cable suggests it may be something else; anIXD5127shares the same 50Hxx marking and 5-pin package, is also rated at a damaged-by-12V 6.5V maximum input, and its purpose as a voltage detector also seems like it may be for detecting if HDMI is plugged in.Then again, there's also the possibility of the 12V damaging something else more important in a less-visible way, which then shorted to ground and took out the LDO.Figure out which of the above two parts it could be (it might even be something else entirely) from the pinout --- they both have NCs but on different pins.Edit: IXD5127 datasheet says last two characters are the lot code and excludes G, I, J, O, Q, and W, so it is likely to be the LDO or something else. This is not looking too good... prepare for the worst.

author: Rasz
author_rank: Super Contributor
timestamp: July 14, 2020, 11:39:05 am
content: 1 what are the current symptoms?2 find power rails on the pcb, measure resistance to ground3 remove fried element, try to power monitor without it and describe what happensEdit: ... or buy $30 replacement board and move on with your life "https://www.ebay.com/itm/Dell-S2415H-Main-Board-4H-2FT01-A01-P-N-5E2FT01004/173991795226
Headphone connector fix. - Page 1
Forum section: electronics / repair

author: Hextejas
author_rank: Frequent Contributor
timestamp: January 04, 2022, 12:31:12 pm
content: I have a long cable that connects my headphones to my sound system. This is because my wife insists on watching other stations from me.Part B plugs into Part A and it works just fine as long as there is a good connection. However the connection is very loose and I have to wiggle them around so as to be able to hear from both ears. It will fall out if I hold them vertically.I was thinking that I might be able to put a small dab of solder onto Part B, along the shaft, wherever a brass colored portion is shown. So then it seems that there will be a some kind of connection anywhere along the shaft. I can sand it down if it gets to be too thick.What do you think or would there be another solution ?Thanks

author: fordem
author_rank: Regular Contributor
timestamp: January 04, 2022, 01:31:02 pm
content: Attempting to tin the plug will require a significant amount of heat and will risk damage to the internals - just replace with a better quality product - or - treat yourself to a wireless headset.

author: Ian.M
author_rank: Super Contributor
timestamp: January 04, 2022, 02:04:36 pm
content: That adapter is cr@p. Sh!tcan it and make a decent one!Adapting from a 1/4" jack to a 1/8" (3.5mm) jack-plug is mechanically reasonably stable if the adapter is designed to be minimum length, with the 1/8" jack recessed into the 1/4" plug, but going the other way with a rigid adaptor like yours is always dodgy due to the leverage on it from any cable movement.Either buy a 1/8" jack-plug and a trailing 1/4" jack, and make up a flexible adaptor with screened cable, that does not strain the 1/8" jack-plug or jack, or simply chop off the 1/4" jack-plug and fit a 1/8" jack-plug to the long cable.N.B. Its probable the equipment's 1/8" jack headphone socket is already damaged. If you are lucky, simply resoldering it may restore reliability, but its far more likely you'll need to do PCB repair and maybe even replace the socket.
Headrush FRFR112 powered cabinet - Page 1
Forum section: electronics / repair

author: jammindude64
author_rank: Newbie
timestamp: July 04, 2024, 01:10:24 am
content: Hello, new to the group , Jan here, i work on Guitars and am trying to learn how to fix Amps and need help , i cannot find a schematic for this cabinet, it keeps cutting out and when it does the two led on circut board go out but the main power to cabinet stays on, how would i check with a multimeter, anyone who can help, it would be greatly appreiated, and if anyone needs help with Guitars, just give me a holler, Jan

author: Vicus
author_rank: Regular Contributor
timestamp: July 06, 2024, 06:40:18 pm
content: Well I have a Fender jaguar that has no output. What is wrong?Now considering that your speaker is two order of magnitude complicated than a guitar. It's impossible to answare your question. You have to be more specific and to have quite advanced electronics knowledge.
Headrush Guitar Effects pedal board restarts during bootup - Page 1
Forum section: electronics / repair

author: Yamin
author_rank: Frequent Contributor
timestamp: June 10, 2019, 06:08:40 pm
content: Hi guys, I've got a guitar effects pedal board in for repair. Basically what happens is when the power switch is pressed, the boot-up sequence starts and then quickly turns off. The switch doesn't turn on the power supply but it turns on the processor(the switch doesn't latch). When the mains is connected to the device there always is standby power.Anyway first I thought it was something to do with the power supply - it checked out ok. No hiccups whats so ever, However I found out the following - there is a voltage regulator on the main board. I measured the output of the regulator and it measures 12V, but one the power on switch is pressed the voltage goes down until the device turns off and then the voltage at the regulator output climbs back to 12V. I figured there was a short somewhere on the main board, how I came to that conclusion - I removed all the wires going from the main board to other boards and still get the same behavior when the power switch is pressed.The model of the pedal board is very new so there are no service manual/schematic. So tracing where the problem could be is very hard. However I came across a potential breakthrough, I noticed some corrosion at the USB chassis pin. I measured resistance between pins and noticed that between D+ and Gnd pin I got a reading of 4.6 ohms. That seems a bit odd, could this be the issue?Any help on the issue will greatly appreciated.Thanks in advance.

author: joletopo
author_rank: Newbie
timestamp: December 14, 2022, 11:56:29 pm
content: Hello Yamin,Finally did you solve this problem?Thanks for your supportRegards

author: nikifena
author_rank: Regular Contributor
timestamp: June 09, 2024, 11:42:54 am
content: I did it!I fixed one headrush with the same issue.The problem was a short inside the processor. Here you can check my video:
Headset microphone dead. Special wire/wiring? - Page 1
Forum section: electronics / repair

author: Korbit
author_rank: Newbie
timestamp: August 06, 2022, 04:08:28 pm
content: Hello,I tried to repair my headset. The microphone is not working anymore since its cable got broached to mechanical stress.From Ali I bought a cable to solder the strings together, but the mic still isn't working.I might have not enough knowledge about the wiring or is it highly likeable, that cables do touch and thats the cause of still not working?Also the little on-switch was porous and has cracked out in the repair process.Any recommendations what to try next?Thanks in advance.

author: Nicholas1
author_rank: Newbie
timestamp: August 07, 2022, 01:11:55 pm
content: Some of those wires are covered in an enamel coating, which insulates the wire. If they aren't soldered together properly, there will be no electrical connection.I recommend for you to disconnect the wires, burn off the enamel coating (don't burn the copper), and try solder them together again. If you have a multimeter, you can check for continuity at by probing both ends of the wire to make sure your solder joint has created an electrical connection.

author: Korbit
author_rank: Newbie
timestamp: August 11, 2022, 09:32:37 pm
content: Good idea.Do you consider it wise, replacing these fine wires to more solid ones? (Space requirements of the thicker rubber isolation coated ones aside)

author: Audiorepair
author_rank: Frequent Contributor
timestamp: August 11, 2022, 11:10:49 pm
content: It is probably wiser to learn to properly solder the enamelled wires to retain their flexibility.This is actually rather difficult, you will need the hottest soldering iron you have to burn away the enamel and properly tin these cables.From the photos it doesn't look like you have got there yet.If you use a multimeter to check for continuity while doing all this, you will find that the headphone speakers will make audible clicks when the meter is connected to it, and very often the microphone will do the same but much quieter, a quick and dirty way of testing whether they work/are connected or not.
Heat seal connection repair - Page 1
Forum section: electronics / repair

author: varjag
author_rank: Contributor
timestamp: October 04, 2024, 06:42:30 pm
content: Hi,Had anyone ever successfully repaired a heat seal flex cable to LCD connection before? Quick search is not very encouraging.I have a cable to a small display with contacts on the flex sheared right outside the contact area on perhaps 1/4th of the length. One option as I see it is to push in the cable under just a fraction of mm and to re-heat to establish the bond to existing contacts. Another I guess is to order a new cable, obtain anisotropic adhesive, clean deposited pads on the display and make a new heat seal?It's possible to order flexi cables naturally but in this application are carbon contacts required? I assume it's some speciality mask and deposit process, is there any vendor not in "call us for a quote" price range doing that?It's bleak either way so not holding my breath but any hints would be appreciated.
Heater controller type and replacement - Page 1
Forum section: electronics / repair

author: mulo
author_rank: Newbie
timestamp: May 23, 2021, 11:28:46 am
content: I am a newbie. On one of my machines has a siemens Statotherm heater controller that has gone bad. Its function is to intermittently on and off a contactor that supplies power to a heater. There is a dial to control on off time or heat. There is no input feedback.What type of controller is it called. Any alternative? I tried thyristor controller. But I will have to change wiring and bypass contactor

author: andy3055
author_rank: Super Contributor
timestamp: May 24, 2021, 01:42:05 am
content: I cannot think of the name off hand. May be "thermostatic control" (?) Old electric cookers had this type of controls. Within the switch, there is a bimetallic strip with a very fine gauge heating element wound around it.As the current passes thru it, the heat will bend the bi-metal strip and that operates a pair of contacts that breaks the supply to the heating element as well as the wire wound around the bi-metal strip.

author: andy3055
author_rank: Super Contributor
timestamp: May 24, 2021, 01:44:19 am
content: Something like this:https://good-appliance.com/products/wb24t10027-ge-electric-range-burner-control-switch-for-2100w-burner

author: perieanuo
author_rank: Frequent Contributor
timestamp: May 24, 2021, 04:29:05 pm
content: https://uk.farnell.com/c/automation-process-control/temperature-controllersjust choose one that can control your contactor and have the same sensor input (or just buy the sensor and use him in the right place), it's really simple and standardised all over the place in industryregards,pierre
Heathkit AR-2000 - Page 1
Forum section: electronics / repair

author: tggzzz
author_rank: Super Contributor
timestamp: November 25, 2022, 01:56:25 pm
content: TheHeathkit AR-2000was a medium-high quality domestic tuner-amplifier, 2*20W RMS output into 8ohms, tape + mag phono + ceramic phono inputs, and an LW/AM/FM and SW tuner.When I was young in the early 1970s and "Hi Fi" music was a hot topic, my parent's 1950s mono record deck and valve Heathkit amplifier weren't cutting the mustard any more. So my father and I assembled a Heathkit AR-2000 tuner-amplifier together as a project over the Christmas holidays. I'd stuff the boards during the day, he would check them after work, and I would solder them. ISTR buying an Antex 25W soldering iron for the job - standard decent quality at the time.I've recently "repossessed" the AR2000, and decided to see if it would work and how good/bad my assembly skills were.Summary:the front panel LES bulbs had mostly failed. Easily replaced, thanks to fleabaya 100mA fuse had blown, but since it was only carrying 25mA, I just replaced thatit appears to work (with a 40us risetime!), but I haven't connected it to loudspeakershame about the scuffed cabinetthe scale illumination is as uneven as ever, but that was normal thenthe soldering isn't bad, and certainly nowhere near the (lack of) quality that some Heathkit gorillas perpetrated!

author: Specmaster
author_rank: Super Contributor
timestamp: November 25, 2022, 03:13:48 pm
content: Nice looking receiver and pretty good inside as well, nice and clean and soldering looks to be perfectly OK to me.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 25, 2022, 03:15:36 pm
content: Theses where the "good years" easy to build and troubleshoot

author: themadhippy
author_rank: Super Contributor
timestamp: November 25, 2022, 04:36:14 pm
content: QuoteThe 18w version is still my everyday iron of choice,must be 40+ years old and still going strong.

author: CaptDon
author_rank: Super Contributor
timestamp: November 26, 2022, 03:24:03 pm
content: That stretched out design sure eats up counter space!!!

author: Specmaster
author_rank: Super Contributor
timestamp: November 26, 2022, 03:44:39 pm
content: Quote from: CaptDon on November 26, 2022, 03:24:03 pmTrue, but that might also be a reason why so many of the old gear is still going strong today, plenty of natural ventilation to keep things cool?
Heathkit IM-2260 DMM Full Manual? - Page 1
Forum section: electronics / repair

author: fuzzoli
author_rank: Regular Contributor
timestamp: January 11, 2022, 03:51:05 am
content: Has anyone ever seen the full manual for the Heathkit IM-2260 meter? The partial manual can be foundhere.Now the partial manual has most of the good stuff (schematic, board layout, calibration info), but it would still be nice to have the full manual.Thanks!
Heathkit IO-12 Loose wire - Page 1
Forum section: electronics / repair

author: Davemiller1985
author_rank: Newbie
timestamp: December 12, 2024, 09:10:13 pm
content: hi, i recently got this heathkit IO-12 from my father and was cleaning the pots when i noticed a wire had come loose. it is a black wire coming from the horizontal gain knob. i do not know where i can find this on the diagram or where it may go. i have attached 3 pictures in hopes that someone can help me. i have also attached a diagram of the area nearby the pot and the whole diagram.edit: i have learned that this device has been open possibly multiple times as it came from a school/college.

author: Andy Watson
author_rank: Super Contributor
timestamp: December 12, 2024, 10:44:04 pm
content: Difficult to see, but I think the wire is coming from the counter-clockwise (CC) end of the Horizontan Gain. In which case it should go to ground - 0V. It might have been connected to the chassis.

author: Davemiller1985
author_rank: Newbie
timestamp: December 12, 2024, 10:53:01 pm
content: there is a red wire attached to the same point which goes to ground. sorry about the quality, im using my laptop

author: FIXITNOW2003
author_rank: Regular Contributor
timestamp: December 13, 2024, 07:21:09 am
content: a copy of the original assemble book is here (plus many others )https://www.vintage-radio.info/heathkit
Heathkit IT-1 Isolation Transformer - Page 1
Forum section: electronics / repair

author: justaskin
author_rank: Newbie
timestamp: November 29, 2023, 01:20:08 am
content: Pulled out a Heathkit IT-1 that I acquired a while ago to assess it's condition. I replaced the decayed power cord with a new molded polarized plug lamp cord, put in a correct 2A fuse, and crossed my fingers and flipped the switch (it seemed to be in pretty good condition, so I skipped the powerstat/dim bulb setup on this one).All the smoke stayed inside, but the voltmeter only went half scale to about seven eighths scale when the knob was turned from stop to stop.While I had the unit apart, I looked at the working parts, and the knob rotated a wiper, like a powerstat, across one of the transformer windings.Next step will be to see if the device's meter corresponds to actual output, but if, as I suspect it will,does anyone have any thoughts as to what else I might check?TIA

author: Andy Watson
author_rank: Super Contributor
timestamp: November 29, 2023, 01:48:43 pm
content: Sounds like it's working."The transformer has an adjustable slider that allows the output voltage to be adjusted between about 90 VAC and 130 VAC. The front panel includes a 0 - 150 AC VOLTS meter that measures the output voltage, ... "https://www.w6ze.org/Heathkit/Heathkit_018_IT1.pdf

author: justaskin
author_rank: Newbie
timestamp: November 29, 2023, 04:23:03 pm
content: Well that's fascinating, and thanks very much for the pdf! It's "fascinating" because I think of Heathkit gear as being well thought out and engineered, and it seems odd to have that narrow a range. Guess I can put that particular antique up on the shelf with my collection of misfit toys, but this time it will have a manual ;-)
Heathkit V-7 VTVM battery eliminator help needed. - Page 1
Forum section: electronics / repair

author: Paceguy
author_rank: Regular Contributor
timestamp: June 13, 2025, 12:10:35 pm
content: Hi, Has anyone here modified their Heathkit V-7 VTVM with the battery eliminator kit using the LM317? I would like the wiring plan to be able to install mine. I see on line that some add a 1000UF cap and a 1N4007 diode. The wiring of everything is not too clear. Can those who have done it help me out please.

author: med6753
author_rank: Super Contributor
timestamp: June 16, 2025, 07:35:09 pm
content: This circuit should fulfill your needs. Tap into the 6.3VAC filament. The 1uf capacitors are solid tantalum and should be placed close to the LM317 to prevent oscillations. The minimum output voltage of an LM317 is approx 1.2V so you should be able to set 1.55V or 1.6V maximum. Once the correct voltage is set you can measure the resistance of the trim pot and insert a fixed resistor of that value if desired.

author: floobydust
author_rank: Super Contributor
timestamp: June 16, 2025, 10:03:08 pm
content: Thisblogthe guy stuffed in an Aliexpress LM317 board. Careful it is tricky to see the 1N4007 he seems to tap AC off the dial lamp. The diode is hidden inside the green heatshrink.Same mod is available oneBayfor IM-11, IM-18, IM-28 etc.

author: Paceguy
author_rank: Regular Contributor
timestamp: June 22, 2025, 01:45:43 pm
content: Thanks to med6753 and floobydust for the info. I ordered the LM317 board from ebay and will install it when it arrives.
Heathkit vtvm IM-11 voltage readings needed - Page 1
Forum section: electronics / repair

author: jimthegreek
author_rank: Contributor
timestamp: October 07, 2024, 07:48:10 pm
content: I am working on repairing a Heathkit IM-11 vtvm. I am having some problems with the dc calibration and setting the ohms adjust.Does anyone have some voltage readings for this? I have the schematic and the complete manual. Thanks.

author: floobydust
author_rank: Super Contributor
timestamp: October 08, 2024, 10:59:44 pm
content: I've never seen the voltages posted (other than Heathkit's two for the PSU) and there are a few high impedance nodes, typical multimeter loading would upset some voltage readings around the tube's grids.One challenge is the power supply secondary is not using input(-)/chassis as common.Instead, it is sorta middle-referenced by the AC BAL pot R5, to give +50 to +70VDC at C1(+) and -60 to -85VDC at C1(-).As a start, check you have around 110-150VDC across the filter cap C1 (and it should be a newer part).Then, between common (ground) and each end of C1 for around +50VDC and -60V, to make sure balance can be in the ballpark.With power off you can also check resistors etc. there are many 22MEG parts that can age.I would get DCV working first. You can measure tube voltages on 1.5VDC range and post here, to help figure out what is going on. Or tell us about what it is doing.hi-res scanhttps://www.byan-roper.org/steve/manuals/Heathkit/IM-11-VTVM.pdfother threads:https://www.eevblog.com/forum/testgear/heathkit-im-11-vtvmhttps://antiqueradios.com/forums/viewtopic.php?t=269163https://www.eevblog.com/forum/repair/repair-heathkit-im-11-vtvm
Hedge trimmer PCB repair - Page 1
Forum section: electronics / repair

author: Johnh2
author_rank: Newbie
timestamp: September 10, 2025, 11:16:18 am
content: Hello,My electronics knowledge is limited, but I'm trying to repair a broken hedge trimmer. Smoke came out while it was running and it stopped. I think the mosfets? have gone on its PCB. Its a brushed motor. I think the PCB is a battery protection circuit, temperature/under voltage.A couple of questions. Is it worth trying to replace the mosfets? What should I replace them with. I can't read the part number?Many thanks

author: Gyro
author_rank: Super Contributor
timestamp: September 10, 2025, 12:29:04 pm
content: Hi John, welcome to the forum.The two MOSFETS appear to be wired in parallel (not great practice for equal current sharing), so should be the same part number. I don't recognise the manufacturer but the 55N03L is a fairly common 30V 50A N-Channel part from a variety of (probably more reputable) manufacturers.It's quite possible that the MOSFETs are the only casualties, just failing due to excessive motor current, getting stalled for instance. The drive circuit should have been protected but the series gate resistor. The current sense resistor (R001) appears to be intact (worth checking though). The motor back EMF protection diode (between P+ and P-) looks a bit suspicious though, there is a mark on top and solder balls on the side. I can't read it clearly, but if it is 'S3M' it is an ordinary 3A diode (although the 1000V rating is a bit excessive, most manufacturers just limit the number of voltage ratings they stock). These may be left from manufacture, but if it has failed short circuit, it would be a very good reason for the MOSFETS to blow. Establishing the exact forensic trail is a bit difficult.Replacing these parts shouldn't cost much and is probably worth a try in terms of reducing e-waste.P.S. Purchase the MOSFETs from a reputable supplier, RS, Farnell, CPC etc. Parts purchased form Aliexpress or ebay will probably be fake (there are a few UK ebay sellers that sell parts from the above distributors at a large mark-up. Although I hate their greed, occasionally these can work out cheaper for small numbers to avoid shipping charges).

author: Johnh2
author_rank: Newbie
timestamp: September 10, 2025, 01:41:34 pm
content: Hi Gyro,Thank you so much for the helpful info! With a bit of luck you have saved the trimer from landfill and have certainly taught me something.I'll check what you recommended and order the parts.Thanks you.John
Heidenhain Nd710 powers supply section repair - Page 1
Forum section: electronics / repair

author: Pat P.
author_rank: Newbie
timestamp: August 12, 2020, 12:17:15 pm
content: I have a Heidenhain Nd710 that seems to have a blown power supply section. Been trying to trace the fault basically at the component level, but no luck!The only voltage I am showing at the connector to the main board is 30v (which I am assuming is for the VFD). A good portion of the board is covered with silicone, so it's proved to be a little tricky. Is there any chance anyone has a schematic for this?

author: Pat P.
author_rank: Newbie
timestamp: August 12, 2020, 08:39:53 pm
content: Actual power supply is a YCL NAD-16c.Looks like might be a faulty smps controller chip KA3842A - Vref output on pin 8 is showing less than 1 volt, should be 5V.I'll order one up and see if that fixes it.

author: MadTux
author_rank: Frequent Contributor
timestamp: August 12, 2020, 09:00:43 pm
content: Fixed a Heidenhain Positip 850 with bad PSU some time ago, there the SMPS startup resistors were fried, so the chip didn't get the power for initial startup.

author: Pat P.
author_rank: Newbie
timestamp: August 13, 2020, 12:57:34 am
content: checked all of those, were fine. I think it may have been a power surge that took the IC out, I'll order a couple at $.40 each just in case.

author: Pat P.
author_rank: Newbie
timestamp: August 18, 2020, 07:50:48 pm
content: Turned out all was due to a bad electrolytic cap. marked 82 uf, tested at 60uf and 37ohm esr. substituted 100uf and good to go!