Consumer electronics "war stories"

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OK, so it appears there is very little to discuss on this group in areas  
like repairing audio components, amps, receivers, power supplies, etc these  
days.

I "tune in" here almost daily and rarely find anything of interest to me.

Maybe we could share some "war stories" of cool repairs we have done in the  
past.

Re-live some past glories?

The first time you traced down a bad reset line for a microprocessor?

That integrated amp that blew a channel about once a year until you caught  
that bias diode occasionally opening up?

Sansui 5000A's? (yuck)

Crappy Euro caps in Tandberg tape decks?

Those times you sweated whether you could even get this thing put back  
together?

Any more recent successs stories to brag about?

C'mon, don't we all enjoy patting ourselves on the back, really?


Mark Z.  


Re: Consumer electronics "war stories"
On 03/12/2015 12:34, Mark Zacharias wrote:
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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

Re: Consumer electronics "war stories"
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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.


Re: Consumer electronics "war stories"
On 12/3/2015 6:34 AM, Mark Zacharias wrote:

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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


Re: Consumer electronics "war stories"
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.

=========================

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

 http://www.rfcafe.com/references/popular-electronics/me-technician-you-engineer-february-1963-popular-electronics.htm

Have fun

Mark


  




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




    

  

Re: Consumer electronics "war stories"
On Fri, 4 Dec 2015 07:13:43 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

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For a very short time in the 1980s, Kenwood manufactured amplifiers
with wrong value resistors at various locations.  The first one was a
bear because I had never seen a Japanese company make that kind of
mistake.

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Re: Consumer electronics "war stories"
On Saturday, December 5, 2015 at 4:30:21 PM UTC-5, Chuck wrote:
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arts from the stock room, onto a protoboard like breadboard.
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ime , no problems.
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s that they  could not get to work.
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c cap with a 10 printed on it between the two stages.
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=
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bleshooting  a new box design.  The picture was black and white and they co
uld not figure out why there was no color.  Looking into the box I  saw a c
rystal marked 3.579545.
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s your problem and walked away.  :-)
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engineer-february-1963-popular-electronics.htm
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Lawsuits over the years have shown their companies to be just as liable occ
asionally, too (like with Nomura, Sumitomo, Mitsubishi, Toyota, Honda, Mazd
a, Hitachi and others...)  I think that things are done less purposely with
 regards to American markets, though.

Re: Consumer electronics "war stories"

On Saturday, December 5, 2015 at 4:30:21 PM UTC-5, Chuck wrote:
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At college I had a lab with the same thing. We designed simple circuits and  
built them and took measurments on them.  There were boxes of parts that  
were suspose to be the same parts.  Some of the parts were either bad or out  
of spec.  Not on purpose, they just got that way over the years.  Me and a  
person I was with usually could locate the bad parts and get our project  
going first. Got to be a joke that the ones that got theirs to work had the  
lucky box with all good parts for that design.




Re: Consumer electronics "war stories"
On Thursday, December 10, 2015 at 1:00:55 PM UTC-8, Ralph Mowery wrote:
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I was teaching one such lab, with bar magnet/coil experiments, and had
an inspiration.   I got some iron filings and sheets of paper, and  
had the students lay the paper over their bar magnet and sprinkle
the filings over it.

There were a dozen bar magnets in the 'materials' box, and half of 'em had odd
fields.  One had five identifiable poles.   Using only the dipole-type
bar magnets, the class got better compliance than usual with the
expected behavior of poles and coils in motion.


Re: Consumer electronics "war stories"
On Thursday, December 3, 2015 at 12:34:56 PM UTC, Mark Zacharias wrote:
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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.


Re: Consumer electronics "war stories"
snipped-for-privacy@btconnect.com wrote:
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** 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  

Re: Consumer electronics "war stories"
On Thu, 3 Dec 2015 06:34:55 -0600, "Mark Zacharias"

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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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Re: Consumer electronics "war stories"

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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.





Re: Consumer electronics "war stories"
On Friday, December 4, 2015 at 1:53:47 PM UTC-5, Ralph Mowery wrote:
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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.

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

Re: Consumer electronics "war stories"
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Was that the type with the CD cartridge, like a trunked automotive unit?  
Those things were all such garbage.

Re: Consumer electronics "war stories"
On Mon, 7 Dec 2015 17:21:35 +0000 (UTC), Cydrome Leader

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No.  It was a 5 disc carousel.  Kenwood didn't have a design in the
pipeline so they outsourced it.

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Re: Consumer electronics "war stories"
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Sort of sad somebody messed up a carousel. The cartridge based changers  
were infuriating.

Anything that requires extensive soldering and screwing around with that  
medical type tape to open up, like portable tape/CD players and now  
cameras suck too.




Re: Consumer electronics "war stories"
On Thursday, December 3, 2015 at 7:34:56 AM UTC-5, Mark Zacharias wrote:
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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.


Re: Consumer electronics "war stories"
On 12/3/2015 6:34 AM, Mark Zacharias wrote:
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  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.

Re: Consumer electronics "war stories"

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In a similar vein to your remote story, we sold an $1800 Tandberg
cassette deck that came to the shop over and over again for not
responding to the transport keys.  In the shop it always worked
perfectly.  I decided to go to the customer's house after work to see
what the problem was.  At his house, the keys didn't work.  I spotted
a light dimmer on the wall.  Turning it off and the deck worked
perfectly.

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