Author Topic: What was your easiest repair ever? (Read 62984 times)

dzseki · « **Reply #250 on:** May 21, 2019, 10:34:57 am »

I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair?

Berni · « **Reply #251 on:** May 21, 2019, 11:03:45 am »

Quote from: dzseki on May 21, 2019, 10:34:57 am

I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair?

If you are talking about the old analog HP pulse generators such as the HP 8012 or HP 8082. I bought one of those and i thought it was not working because the power indicator never lit up. But then i noticed it was actually producing an output signal. Upon taking it apart i found that the power indicator is a small incandescent bulb and it just needed to be tightened slightly because it became loose in the socket.

dzseki · « **Reply #252 on:** May 21, 2019, 12:06:03 pm »

Quote from: Berni on May 21, 2019, 11:03:45 am

Quote from: dzseki on May 21, 2019, 10:34:57 am
I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair?

If you are talking about the old analog HP pulse generators such as the HP 8012 or HP 8082. I bought one of those and i thought it was not working because the power indicator never lit up. But then i noticed it was actually producing an output signal. Upon taking it apart i found that the power indicator is a small incandescent bulb and it just needed to be tightened slightly because it became loose in the socket.

Nah, this was a hungarian made one, it has a power LED (which they reported as not coming alive), but it is indeed working eversince.

grifftech · « **Reply #253 on:** May 21, 2019, 02:37:51 pm »

arcade game had no sound output, I tried connecting amplifier to smartphone, still no sound, bring amp home and put jumpers on volume controll connector, amp works fine, connect speaker to game computer, sound comes out, reinstall amp, issue persists, install volume jumper, sound works, reconect volume controll connector and check volume knob, it is turned down all the way, adjust volume, problem solved.

cause: co worker got annoyed with the continuous music in attract mode, so I turned the demo music off

EOC_Jason · « **Reply #254 on:** May 21, 2019, 02:42:54 pm »

I once bought a non-functioning symmetricom syncserver ridiculously cheap off ebay. This was a first-gen model that was a 1U rackmount PC, physical hard drive, tons of fans, etc. But it had an X72 rubidium module, which the price alone that I bought it for was worth that, along with the pci timing card.

What was wrong with it? Dead CMOS battery.... lol. Replaced battery, reconfigured BIOS... worked like a charm.

bitseeker · « **Reply #255 on:** May 21, 2019, 07:12:41 pm »

This thread is wonderful for honing one's troubleshooting "common sense" across many product categories.

Housedad · « **Reply #256 on:** May 21, 2019, 08:10:43 pm »

Had a 12inch disk sander that stopped working. 4 screws to put a brush wire back the connector. But the easiest thing ever only somewhat electrical related was my neighbors old dodge truck He told me it had been running bad for a while and two shops quoted $500 to 1200 to fix. I said let's look at it now. I had him start it and put my hand on the hood, for a minute or so.

Had him shut it off, said cylinders 6 and 8 weren't firing. Opened the hood, found the connectors were off of the #6 and 8 cylinder injectors. Put them back an it started running great and smooth. He thinks I'm some kind of car God now.

bitseeker · « **Reply #257 on:** May 21, 2019, 08:15:34 pm »

Car whisperer.

Housedad · « **Reply #258 on:** May 21, 2019, 08:23:38 pm »

Quote from: bitseeker on May 21, 2019, 08:15:34 pm

Car whisperer.

Not really. Just an old skill my father taught me as a boy in the late 60's. To concentrate and feel the pattern of the vibrations. I spent a hell of a lot of time after that practicing.

tkamiya · « **Reply #259 on:** May 23, 2019, 03:29:12 am »

Mine was an Ebay purchase of Kenwood TS820, a ham radio equipment. Since it was from 80s, it's a solid state and tube final (hybrid). This type of equipment always had a switch on back labeled SG. It means Screen Grid. Turn it off and there is no RF output. It was mainly there to disable the final so a transverter can be used.

Bought this radio with a comment "Receiver works, transmitter no output." While I was cleaning, l looked at the back. Aha. SG is off. Flip the switch and everything works. I have seen several like this since then.

Funny thing is, I let the seller know of my finding. He yelled at me saying his technician of 40 year experience knows what he is doing. No good deed goes unpunished I guess.

bob91343 · « **Reply #260 on:** May 23, 2019, 05:47:25 am »

I had the same issue. I repair ham gear for friends and this is very common, the neutralizing switch shutting down the 6146 screens.

iroc86 · « **Reply #261 on:** May 23, 2019, 10:43:41 pm »

I picked up an HP 6236B triple output bench supply a while back that was listed as "parts only" and had the power cord cut off. It was in really good cosmetic condition, so I bought it mainly to refurbish another functional but not-so-pretty supply that I had. For kicks, I installed a new power cord just to see why it failed, and, you guessed it... no issues whatsoever. It passed all of the output tests, ripple measurements, etc. I can only surmise that the former owner (company) cut off the power cord to avoid liability, even though the unit worked fine. Sadly, my employer also adheres to this practice... and we're not allowed to rummage through the garbage bins.

A close second place for me is an HP 8111A pulse/function generator that was also sold as a parts unit. This one powered up, but threw all sorts of weird error messages and blinky lights on the front panel. All it needed was a thorough switch cleaning and it works great now!

bitseeker · « **Reply #262 on:** May 24, 2019, 05:05:15 am »

I picked up an old HP 3312A function generator. Its output was all wonky. Solution was also to clean the switches.

ChristofferB · « **Reply #263 on:** May 25, 2019, 02:47:54 pm »

Got a neat 80's Yamaha drum machine (RX7) for next to nothing, because on power up, the LCD just displayed full block characters.

First thought was that the processor didn't boot since it looked un-initialized, which would be a bummer. Turned out the coin cell battery had died, and it was as new after swapping that. Don't know why that would make the CPU not run, but maybe it had shorted out.

I almost felt cheated that I didn't get to poke around and troubleshoot in the 8-bit digital hardware

CJay · « **Reply #264 on:** May 28, 2019, 09:11:52 am »

Quote from: ChristofferB on May 25, 2019, 02:47:54 pm

Got a neat 80's Yamaha drum machine (RX7) for next to nothing, because on power up, the LCD just displayed full block characters.

First thought was that the processor didn't boot since it looked un-initialized, which would be a bummer. Turned out the coin cell battery had died, and it was as new after swapping that. Don't know why that would make the CPU not run, but maybe it had shorted out.

I almost felt cheated that I didn't get to poke around and troubleshoot in the 8-bit digital hardware

Used to be a thing with Compaq laptops too, I bought a few at auction in the early 90s which were 'faulty' but just needed a coin cell.

Howardlong · « **Reply #265 on:** August 07, 2019, 08:46:41 pm »

MSO8104A - front panel stopped working during an initial check out.

Was about to go full metal jacket on it, taking it apaaaart, but it turned out two of the rubber buttons had become stuck on due to the printed front panel legend being slightly mis-aligned.

Second time I’ve been caught out with this on a scope, the one before was on a Tek 2465B... some years ago.

bitseeker · « **Reply #266 on:** August 07, 2019, 08:48:13 pm »

Good tip. Thanks, Howard.

ArthurDent · « **Reply #267 on:** August 08, 2019, 12:13:00 am »

I thought I'd mentioned this before but not here, I guess. Recently I bought a GW Instek PSM-2010 programmable power supply on eBay that normally sells new for about $1000 for well under $100 because the seller said that the cooling fan speed was erratic, even with no load, and they weren't sure if there might be other problems as well. This supply has an intelligent fan control and was working normally. I took the gamble that this was the "problem" and lucked out.

bitseeker · « **Reply #268 on:** August 08, 2019, 02:56:01 am »

Sounds vaguely familiar. That is by far the easiest repair, eh? Just change your understanding of the "problem."

m3vuv · « **Reply #269 on:** August 10, 2019, 07:13:07 pm »

until you loose oil presure and screw the big ends!

LazyJack · « **Reply #270 on:** August 13, 2019, 11:46:59 am »

Very easy repair. HP 3325A synthesizer, originally bought for parts to fix an other one. It was advertised as not powering up and the seller accepted a very low offer. Well, it is powering up, and works flawlessly. No repair needed.

A tiny bit harder repair: HP8904A synthesizer with a somewhat rare 600 ohm option. Also advertised as not powering up, however i spotted that it was set to 230V (US seller!) and missing the fuse holder. Well, took a chance again with an embarrassingly low offer and got it. Replaced the fuse holder, plugged into 230V (as I'm in Europe). Lo and behold, it works.

DaJMasta · « **Reply #271 on:** August 15, 2019, 03:22:53 am »

I think I just had mine....

Got an SRS SR830 DSP Lock In Amp that was in good physical condition but wouldn't power up. Arrived, looked decent, had something rattling around in it and a screw that was falling out the back...

So I opened the top cover, pulled out the nut, replaced the screw, looked for loose connections, checked the fuse - the usual - then plugged it in and flipped the switch in the rear. Nothing, ok, well I looked on the front panel and eventually determined there was no power button.... which was odd. Left the power on, got out the thermal camera, basically no heat generation anywhere in the power supply - was the switch disconnected? Maybe something with the transformer windings?

But I was curious if there was some power button I was missing, so I opened up the user manual. First thing it says, switch on the power and hold down the Display key to run the self tests and reset defaults... no reaction on first power on, but I gave it a shot... and it booted up, passed all self tests, and seems to be fine.

My guess is a power failure or the loose bolt caused an issue that needed to reset corrupted power-on defaults. Since the power on sequence didn't seem to do anything, the seller just figured it was dead and didn't want to deal with troubleshooting the failure.

Turned out to be a great use of a half an hour!

Kilrah · « **Reply #272 on:** August 30, 2019, 09:52:25 pm »

New one, family member had a 3 year old hp x360 laptop that failed, powered up less and less frequently until not at all. Obviously they call when nothing works anymore and not before. Took it home, opened it and had a quick look, no obvious liquid damage or burn marks etc, no schematic to be found online so since they were in a hurry to get the data and a working machine I took the SSD out, dumped the user data to an USB drive, took an unused working laptop I had in a pile and gave them that as a replacement. Kept the old one for parts, reused the SSD somewhere else and put the wifi adapter in the parts bin.
A few months later I again come across the machine I hadn't thrown away yet, and before doing so decide to have another look just in case since I had wanted to try one of those x360 things for a while. Took motherboard out again, removed all the shields, and upon close inspection a cap looks somewhat dodgy close to the RAM chips. Yanked it off and what do you know, it powers up great now! Threw a spare small drive in to test for a while and no more issue. So I bought a new decently sized SSD for it, and also ordered a new screen (touch panel was cracked as well). Replaced that and I now have a rather nice laptop with a 4K screen, although a bit underpowered and too big. Still a better way than buying a $2k laptop to "try to see if I like it". Confirms I'd really go for a 13" instead of 15 and definitely go for the best available CPU though.

fourfathom · « **Reply #273 on:** August 30, 2019, 10:51:33 pm »

Perhaps not my easiest, but my favorite:

This was back in the days of vacuum tube TV sets, and ours had lost the vertical sync. I unscrewed the back cover panel and looked at the tube chart (no schematic). I then slowly waved my hand over the components around the sync-circuit tube and got a feeling: That semiconductor diode *right* *there* was bad. I just knew it. So I clipped it out. It was open. I pulled some unknown signal diode from an old computer circuit board I had in my junk box (a two-input transistor-logic nand gate as I recall), and soldered it in. I didn't even know what polarity it needed to be so I guessed.

That fixed it!

And that's how my reputation as being able to fix anything started.

Qmavam · « **Reply #274 on:** August 31, 2019, 04:49:29 pm »

Back in the 80s I repaired VCRs, when they were still expensive.
Fisher had a separate tuner module, when it went bad, you replaced it.
No schematic, it was a module to replace at near $100 cost. After a few
repairs or declines I decided to see if there was anything I could find that could
be the problem.
I started with the freeze spray, bam! the picture appeared. Hmm, so I
warmed it up until the picture disappeared and then dripped the coolant on individual parts
until the picture disappeared. I found a 1uf 16V cap that was the defect.
From then on, it was easy, bad tuner, I'd let a drop or two of the colant hit that cap, picture would appear
I'd replace that cap, it always worked.
Funny thing about VCRs, when a machine came in with a stuck tape (porn)
they never ask the receptionist to get it back :-0
I can't think of any others right off, but I did VCR repair for 10 years, over 11,000
repairs. It became so easy because I saw the same problem over and over. I was at a good shop
with loads of service literature and a good stock of parts. I ordered my own stock.
The owner worked with three big box stores that sent us their store stock (returns) that needed repair
and all of the store extended warranty repairs. (their money maker was the extended warranty)
A sad thing I saw several times were rent to own units, a $220 VCR that was paid for biweekly,
when they finally had it paid off the cost was $1,100.
That's brain dead with no financial self control. Oh that's another topic.
Mikek
I did only VCRs, and everyone else had a different specialty. So, if I had a dog, it was on me to fix it.


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Author Topic: What was your easiest repair ever? (Read 62984 times)

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