Consumer electronics "war stories"

My favourite was the car audio cassette player, ie no record function. It recorded vinyl record clicks on to any prerecorded tape played in there. Answer at end of spoiler defeat, run of +

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The pinch wheel had a tiny piece of magnet fragment embedded in it

My first computer was a Franklin Ace 1000 that was give to me broken. It had complete schematics so I was able to trace out what was in fact a bad reset signal going to the CPU. Pretty sure it was a 74S161 (something that ran hot and wasn't LS series) that had to be swapped out and it was fine again. Donor chip came from an arcade machine board. Looking that part up I see it's a 4 bit counter- if that's correct it may have someting to do with the video timing signals which were a weird hack in the Apple ][ which this machine was an improved clone of.

I posted this an hour ago, but it hasn't shown up, so I'll do it again.

Back 30 years ago I stopped at a consumer electronics/TV repair shop and presented my resume. I had been to many manufacturer service training seminars and had a hand full of certificates of completion. The owner looked it over and said, "I just hired a guy, I wish you came in earlier." So I went home and about 45 minutes later he called and said, "I see you have a lot of Sony training, I have this projection TV in here that nobody can fix, I'd be happy to pay you for looking at it." So I drove down and got the manual, noted the problem was, no output from the 3 tubes. I started poking around in the HV section, and within minutes the owner said, hey you got it working! I didn't know it was working ;-} I put my head out front and it had an output. Hmm, I unhooked my scope probe and the picture went with it. From there, we, more he, figured out one of the other techs replaced a cap with 1/10 the proper value, the scope probe hanging on the test point had enough capacitance to make the set work. He hired me that day, it was good, within two blocks of my house. So, I got a job by accident. Mikek

One of my favorite stories is from electronics lab in college.

We had to build a small two stage transistor audio amp in the lab with parts from the stock room, onto a protoboard like breadboard.

My lab partners and I were experienced hams and got ours working in no time , no problems.

The PHD proffesor called me over to help him troubleshoot another groups that they could not get to work.

The design had a 10uf cap between the two stages.

I looked at the other groups breadboard and immediatly saw a tiny ceramic cap with a 10 printed on it between the two stages.

I pointed to the cap and said, that doesn't look right.

Got an A in that lab.

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Oh another one.

I worked for a company that made CATV settop boxes. I wandered into the lab where a group of young engineers were stuck troubleshooting a new box design. The picture was black and white and they could not figure out why there was no color. Looking into the box I saw a crystal marked 3.579545.

On a total whim, I put my fingers on the crystal.

The picture immediatly snapped into color!!!!

I was amazed myself but didn't let it show....I just cooly said, there is your problem and walked away. :-)

And lastly, in the same vein you will all enjoy this story

Have fun

Mark

Mark... ====================

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My favourite - I was working for a Pro PA hire compoany in London. They ha d supplied a monitor system for a BBC recording of Public Image Ltd at Maid a Vale Studios, London. The system was buzzing like crazy and none of the Sound Company or BBC engineers could work out why. They were about to pul l the whole gig. They sent me down as a last faint hope.

It was obviously some kind of mains problem, but everything seemed to check out fine on multimeters. Earths, Neutrals were all at 0v. Eventually I decided to plug in my scope, to discover that instead of a nic e straight line accross the display, it was massively modulated. Clearly the scope's Earth wasn't a proper Earth but had some mains on it. I then was able to track down the fault - one multi-way extension cable att atched to the many, many pieces of equipment had Earth and Neutral reversed , thus connecting all Earths and Neutrals in the middle of the studio as we ll as back at the mains Intake.

Ripped the offending extension out, the buzzing ceased immediately, and the BBC and Public Image Limited got their recording and the Sound Company did n't lose the gig or it's reputation.

Gareth.

The receiver tech was flummoxed by one of those large 1970s Pioneer receivers. It had a problem none of us had seen before and we were a high volume audio chain. There was slight audio distortion on both channels, only on FM. We all worked commission only so I was the only one to volunteer to help him out. To cut to the chase, the receiver had an over designed mute circuit that was 3 or 4 stages deep, At the deepest stage there was one of the Sanyo electrolytics that became a common failure item many years later which was slightly leaky.

I've got another one. In the early 80s there were these 19" Hitachi tvs that ghosted. It looked exactly like a bad delay line. By that time I ran the TV service department for the same company. We had just switched over to the big box store concept and I was inundated with broken tvs. Out of desperation, I switched out the CRT and the ghosting disappeared. We sold 1000s of these sets and I saw the problem 3 more times.

And another. Kenwood sold these Funai made cd changers that never worked properly. All of them would come back with skipping or not playing discs problems. Kenwood came out with 3 or 4 mods, none which worked. Sometimes they would work for months before they came back. Somehow I found out if the mechanism retaining springs were stretched so the mechanism didn't sag at all, the problem disappeared. Called up Kenwood and they put out a mod kit that included strong springs which also didn't allow any downward movement of the mechanism.

Last one. There were these very expensive ADS cd players which would play any disc except a ,very popular at the time, Jimi Hendrix Ryko disc. Couldn't find any electronic or mechanical problems. I slightly moved the CD turntable slightly down on the spindle and this disc and all other discs would play.

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The one pops to mind took couple of years off my life. It was an old Hitac hi built RCA projection TV (circa 1981) that had blown fuses in the power s upply, but nothing showed a short resistance wise. I replaced the fuses an d it powered up, only the geometry didn't look right. When I went to conne ct the cable back on to it to see exactly what the picture was like a blind ing flash and arc appeared at the RF connector and it blew the fuses again. Working pretty much on my stomach in a cramped house, I traced a hot side /cold side short all the way back to the end of the line, which was a leaky deflection yoke (vert winding to horiz winding). It seems the horiz windin g was on the hot side of the chassis and the vert winding was on the cold s ide. How it didn't blow the vert IC or horiz deflection output is a myster y.

Many electronic devices will have a common problem. It may take a while to find it,but once found, the first thing to look for.

I worked for a large company and we had a new building built and equipment installed. All was fine for a while, the some heaters for the process got where they would not come on if cut off. I was the first one to get a call about this. Took about 2 or 3 hours to troubleshoot this as it was the first time anyone had worked on it. Found a bad plug in time delay relay was bad. After that a simple one point voltage check would usually tell the relay was bad. Next time it only took seconds to change out the relay and was usually done any time they would not come on. 99.9% of the time that was the problem. As that place operated 24 hours a day, the peopel in production was told about it and told the electrician that showed up to change it out if they did not know what the problem might be. Saved lots of late night phone calls.

In the late 80s early 90's I worked on VCR's. The Fisher FVH 906, had a tuner that went defective, no schematic, a replacement part only. That's ok under warranty, but after that, the part cost was to high to get a repair ok. So one day, I decided to see if I could find out what the cause of the failure was. I started spraying parts with freeze mist and found when I hit a 1uf 35V cap the picture came back. I made a lot of repairs, replacing that same cap on a whole bunch of tuners. I'd do the same thing every time, dribble 2 or 3 drops of freeze mist on the cap and the picture came in.

I had a customer bring in a remote for repair, it checked out fine. He took it home and called saying it didn't work. I talked to him a bit and found he had just install new CFL lights. I suggested he shield that light and try it. It worked, I had just read about that in a trade magazine two days previous. Mikek

I got in early on the VCR curve, they were expensive, commanding high service rates, then when prices dropped we had a high volume of repairs, rode it down until the price was close to $200, then I moved to Florida. A year later the tech that took my place said he came in a couple days a week to repair the few that came in. I repaired a little over 11,000 vcr's in ten years, it was a good time.

** I know of a similar example involving a 30kW, 3 phase lighting system for live entertainment here in Sydney. Was back when lighting consoles communicated with triac dimmer racks via 0-10V analogue signals. The system seemed to have a mind of its own, lights came up and varied about with all faders set to zero. Bringing one fader up affected many others.

After hours of fruitless searching, the culprit was identified as the AC plug on the lighting console itself which had neutral & earth reversed.

Seems a roadie had fitted a new plug after accidentally damaging the original and told nobody.

.... Phil

One of my first chances to stick my chest out and strut was shortly after I checked aboard my first duty ship during my stint in the Navy in mid-1964. Barely 20 years old, I was assigned to overhaul & repair of UHF shipboard radio transmitters.

The ship had a small calibration lab, which was staffed by a PO1, a PO2s and a couple PO3s (POs are Petty Officers... enlisted men) who had all been to the elite Air Force PMEL calibration school in Colorado. One day, after all the cal lab techs had a shot at it and several of the other bench techs had also been called in to try fixing it,, I was called in to take a shot at repairing a new HP 524D 10MC digital counter from another ship. It just wouldn't show any indication of trying to count... all the displays just sat at zero no matter what the input signal looked like.

I sat down and took a look at the schematic, hooked a scope probe to the output of the gate tube, a 6AL5. No pulses. Hooked the probe to the gate input to the gate tube. Good gate pulses. Hooked the probe to the signal input of the gate tube. Good squared pulses that followed the frequency of the input signal. I asked for a 6AL5 tube, plugged it in, and Voila! everything came to life.

Made me feel kinda good that it only took me about 10 minutes to fix what had stumped 9 or 10 good techs for several days. From that day until now, I have had an affinity for test instruments, especially those used for time & frequency measurement.

Dave M

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** Ok, here is a wacky one:

I once had a customer who rented out DJ systems: turntable & mixer consoles , stereo amps and speakers. DJs back then owned a collection of LPs and gen erally rented audio gear on a daily basis.

So I got this TT console with the complaint while it started off OK, it was losing volume & changing tone after a while becoming duller and duller unt il full treble was needed to correct it.

The story sounded dubious, but I checked out the mixer thoroughly using hot air and an all day soak test - result negative, it worked fine all the tim e.

Handed it back to the hire business guy and a week later it was returned wi th the SAME complaint plus some hostility that I had clearly not fixed it. Naturally it passed all tests again.

I had a chat with the hire guy and he agreed to use the console himself at a gig and of course it worked fine all night. Next time it went out on hire , he got the same complaint from the same DJ - who was by now ropable that nothing had been done about the problem.

So my hire guy paid a visit to the venue where the gear was being used, his first. When he walked in, he was nearly deafened by the volume and the sou nd was absurdly shrill. On approaching the DJ and noticing that volume and treble controls were all maxed out - he was told:

" See what I mean ??

Sounds piss weak and there's no treble."

.... Phil

Chances are he'll never hear his grandkids cry.

Somewhere in the eighties we installed a custom-built control system in a 24/7 assembly line for SIL ceramic hybrid circuits. Subcontractor of subcontractor job.

One night I was called in for an unexpected stop. Inside the plant I was 'greeted' by the crowd of tech support people and blaming managers gathered around our equipment. On my way to the control system I came across one of the typical mushroom emergency stops along the production line. By habit I twisted the knob and felt the release spring. I worked my way to the control panel and engaged the start. Within seconds the crowd silenced and fled the scene: the line was up.

We were never again called in.

About 1981 I was still in tech school and not even really a technician yet.

(I was SO green).

Third semester, servicing phase. There was an old GE tube chassis color set with intermittent color sync. It was a "re-do" which the prior class had failed to fix correctly.

I got to the burst gate amp and saw there was a much smaller signal at the grid than called for.

Also, there was a neon lamp in the grid circuit which was supposed to drop

75 or so volts and the drop was much higher than expected, plus the lamp glowed somewhat faintly at it's base instead of lighting fully.

I couldn't get the instructor to order a miserable 75 cent neon lamp. He kept me running around checking this cap or this resistor, etc.

Finally I went around him to another instructor, explained my logic and got the lamp ordered.

Fixed the tv. My instructor never really forgave me for that.

Mark Z.

Things that are second nature to us now were "learning experiences" back then, yes?

At my first job as a tech, about the second piece I ever worked on was a Pioneer SX-828.

Yup - the infamous "blue Sanyo cap" scenario.

Except I had never heard of that and had no tech support or even a more experienced tech along side me.

I was totally on my own, as I usually was during the first 15 or 20 years of my career.

Symptom: one channel gone, just a low hiss. Preamp issue.

Tracing signal - got it, don't got it, and so on.

In the tone amp, DC voltage low at collector of one transistor.

1.5uF Sanyo coupling cap to base was leaky, driving that stage into saturation.

Felt really good about that one.

Mark Z.

Most of them have microchips (that you can't open up and repair). And they have software and wireless or hard wired connections to larger facilities elsewhere where techs can come in and review the software.

Many problems seem to be caused from malware or spyware (maybe some even from the government or other places) that intentionally interferes with the intended software provided by the company on the package's label.

Right now, I'm not even working. I'm just sitting around looking at space cartoons and video games.

I had an SX-828, bought it sometime in the early 70s. Been so many years, I don't recall the problem, but I tossed it about two years ago, just too much stuff.

Mikek

Here's one.

Onkyo cassette deck, circa 1986. Perhaps a TA-630 or some such.

Played just fine in PLAY mode.

In REC mode only, the auto-stop would trigger at random times.

Partially open bridge rectifier. One of those little black round ones. In PLAY mode the voltages held up, but in REC mode the additional load of the bias oscillator dropped the voltage enough to cause the problem.

Ripple waveform was definitive. Showed 1/2 wave pattern where it should have been full-wave.

Mark Z.