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.

amdx wrote:

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.

Heh, anyone else reading this, before you toss it, check ebay for the
completed listings on both working and non-working audio stuff from the
70's and 80's, it's nuts.

Even if that 828 was broke, it seems to fetch $100-$150 and the working ones
$200 on up.

Some of the top of the line ones from back then (pio sx-1980, sansui 5500 i
think) in the thousands. This isn't the old tube stuff like Fisher and
Marantz, just the popular solid state crap from the 70's and 80's.

The power amps and speakers don't follow but anything with receivers and
turntables from that period, you probably can make back what you paid for it
new, and then some.

-bruce

In article , en
says...

On Thu, 03 Dec 2015 06:34:55 -0600, Mark Zacharias wrote:

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

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.

And what was the charge for that?

$1 for resetting the switch and $9,999.00 for knowing which one?

Jamie

On Saturday, December 5, 2015 at 2:44:26 PM UTC-5, Jon Elson wrote in rec.crafts.metalworking:
OK, we got one of those fancy energy-saving washing machines. After a few
years, it started having trouble filling with water. I replaced the
solenoid valve assembly twice over about 6 months, and then started
invetigating deeper. The control board had a micro and about a dozen
electeromechanical relays on it. The one for the cold water valve
eventually developed contacts burned so bad that I was able to diagnose it.
I replaced it with a solid state relay, and all has been good for several
years. I gues the cold water valve gets cycled the most often, so that
relay got burned up first. No problem yet with any of the others.

Yeah, obviously a current relay or just that kind of an interface or something. Tell 'em about it, so they can buy you a whole new one.

You can't get anything if you stay silent. (I learned that the hard way)

On Thu, 3 Dec 2015 06:34:55 -0600, "Mark Zacharias"
wrote:

Any more recent successs stories to brag about?
C'mon, don't we all enjoy patting ourselves on the back, really?
Mark Z.

I haven't bothered to write anything new, but in 1994, I scribbled
this list for Wired Magazine, which never bothered to print it or pay
me:
http://members.cruzio.com/~jeffl/nooze/support.txt
I'm not sure I could call these success stories, but since I got paid
for most of the repairs, I guess it qualifies as successful.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

En el artículo , Jeff
Liebermann escribió:

http://members.cruzio.com/~jeffl/nooze/support.txt

Good fun. Thanks for posting that.

Number 10 reminded me of this:

https://en.wikipedia.org/wiki/Lp0_on_fire

My first-ever call out to a Unix system was to this very message.

--
(\_/)
(='.'=) Bunny says: Windows 10? Nein danke!
(")_(")

Mike Tomlinson wrote:

En el artÃ*culo , Jeff
Liebermann escribió:

http://members.cruzio.com/~jeffl/nooze/support.txt

Good fun. Thanks for posting that.

Number 10 reminded me of this:

https://en.wikipedia.org/wiki/Lp0_on_fire

Ah, we had a couple of those. We had a fairly large 360 system at
Washington University. 1401 and 7094, then 360/50 and then 360/65.

One of the routines that made one think of CIA dead drops in the middle of
the night was the routine for printing paychecks. (I guess vendor checks
were similar, too.) They had the box of continuous form checks locked in a
bank vault in the basement of the administration building. The box was
taped shut with signatures across the seal. When they opened the box, two
people had to be present and they had to sign a log sheet with the serial
number of the top check. They carried the box to the computer center,
loaded it into the printer and the program printed a sample form with VOID--
VOID--VOID all across it, but other info in the right place so they could
align the forms. When all was OK, they told the program to print the
checks. Then, they had to fill out and sign the log sheet reporting which
forms serial # were used in the aligning process and the first and last
forms serial # of the printed check run. Then the whole process was
reversed to get the box sealed and locked into the vault. During the whole
process, nobody was ever supposed to leave the side of the printer.

Well, imagine the confusion when in the middle of the print run the printer
started sparking and set the continuous forms checks on fire! I heard about
this 2nd hand, but apparently the accounting guys were running around like
decapitated chickens! They didn't even know how to properly log what had
happened.

I'm pretty sure we had another paper on fire event, but it was just standard
print output that time.

Jon

Well I guess it is my turn.

NAP bigscreen no sound - vertical control IC.

Everything runs off the data and clock lines. This IC does the "S" correction and things like that pertaining to linearity. It is of course bus addressed. The one line, data or clock, doesn't matter, was clamping the signal down to like 2 volts. Leaky. That meant the data from the EPROM was not read when the unit got initialized so it did not know which sound system it had and never upped that.

Sony 32" loses green and blue - adjust vertical height.

This was an interesting comedy of failure mode. Apparently when they came out with AKB a had to be done to the CRT aperture grill frame. It reflected too much. The CRT had just been replaced. The way I figure it they used a dud from a non-AKB set. When the pulses feeding the cathodes to detect the current got to the frame they reflected like all hell and told the circuit there was too much green, and then blue as the circuit drifted a bit and brought the lines over the metal. I found this out with the scope. I mean, there is no green but it is getting alot of green feedback. WTF !

And THEN, to adjust the vertical you use a service menu. Guess what color the numbers and letters are in that menu. They were not red but if you left the set on for a while all you had was red.

I got some good ones about cars too.

wrote:
Well I guess it is my turn.

NAP bigscreen no sound - vertical control IC.

Everything runs off the data and clock lines. This IC does the "S" correction and things like that pertaining to linearity. It is of course bus addressed. The one line, data or clock, doesn't matter, was clamping the signal down to like 2 volts. Leaky. That meant the data from the EPROM was not read when the unit got initialized so it did not know which sound system it had and never upped that.


I had a similar fault in an Universum CRT TV set. It came with an all white screen sympthom that I traced to the RGB decoder matrix IC holding its RGB outputs to 0V. Replaced the IC, no joy. It was I2C controlled and I even built a simple interface to send commands from the PC, it seemed to ACK fine and all looked right. If not initialized at turn on the raster remained black but as soon as the outputs were activated in any way it would go full white.
Finally found the problem: it received a sandcastle signal from the sync processor IC that had the top pulses too low so the RGB IC was not locking on them. The picture improvement IC also connected to this signal had a leaky input and was eating half the signal.

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

It's definitely not consumer electronics, but here goes.

I used to work at a company that made flight simulators. My official
job was writing code to make the navigation instruments display
correctly, according to the simulated position of the aircraft, which
frequencies the radios were tuned to, the position of circuit breakers,
etc.

Some of the laws of nature at that particular job included:

1) Techs string wire.

2) Programmers write programs.

3) Techs never make mistakes when stringing wires.

4) No programmer could ever possibly understand the intricacies of
stringing wires. Therefore, any complaints by programmers about the
wiring can usually be disregarded.

5) Any persistent complaints about the wiring can be remedied by telling
the programmers to work around it in the code.

Never being one to obey the laws of nature, I brought in my own meter
and checked things out when the sim didn't seem to work right. My boss
knew that I had something of a clue; I had been giving "how to read a
schematic" lessons to a few of my cow-orkers (in software) who were also
new hires or just wanted to know how. He basically told me that he
didn't mind me doing my own checks as long as I was careful with the sim
hardware, and that I should expect the techs to get mad at me if they
ever saw me doing it.

I couldn't get the right DME indicator to light up in one sim. (It was
a box in the instrument panel with three 7-segment displays and a couple
of buttons. It was supposed to display how far the airplane was from a
particular radio station.) After a few rudimentary checks of my code, I
wrote up a "right DME inop" trouble ticket. The technician wrote back,
"Wiring checks to print, DME sent for repair". Sure enough, there was a
hole in the panel. When it was again filled, I tried again...no joy. I
swapped the left and right indicators - hmm, the problem stayed with the
socket instead of following the indicator. I broke out the wiring
diagram and my own personal multimeter and started chasing around behind
the panel - no wires or pins for power on the right DME socket. (It was
something like a DB25 or DB37, with individual "crimp and poke"
contacts.) I dutifully re-opened the ticket, and the tech dutifully
wrote "wiring checks to print" and closed it again.

About this time, the sim was shipped to the site, even though it was
broken. The standard process was to completely build the sim at the
factory, test it out, ship it to the site, certify it, and put it in
revenue service. For sites that were far away from the factory, this
practice was generally followed, because it was expensive to ship people
to site to finish working on the sim. However, the site that was
closest to the factory (~3 hr drive) was notorious for the following:

Factory: We will have the sim done on $DATE.

Site: No no no! We've already sold time on that sim to customers on
$DATE-30days and we can't reschedule! We *must* have it here
sooner!

Factory: Why did you do that? The sim will not be done on
$DATE-30days. It will be broken and unusable for training.

Site: We don't care.

Factory: If we ship it at that time, it will suck.

Site: We don't care!!! Ship it shipit SHIPIT!!1!

Factory: sigh OK.

(time passes)
Site: Well you got the sim to us on time but it sucks! Everything's
broken and we can't put the customers on it! Fix it fixit
FIXIT!!1!

Factory: sighs deeply, starts phoning rental car agencies and hotels

So I get to the site and the site manager is bugging me about the right
DME indicator. I walk in to the site maintenance shop and tell the
techs there I need some connector pins, the crimper tool, some wire, and
a bench power supply. They are extremely wary of this as they have
experienced "programmers with screwdrivers" before, but they give me the
requested items and follow me into the sim, probably in hopes that my
body will shake and jerk in interesting ways as I electrocute myself.
I put the pins on the wires and put them in the (still vacant) slots on
the right DME connector. Wires run out under the panel to the power
supply, which temporarily gets the co-pilot's seat. Fire up the sim,
hit the power supply, and whaddayaknow - DME love for all. I
disappointed the techs, but the site manager was very happy.

I pointed out the relevant page in the wiring diagram book, so the site
techs could get it wired in correctly. I figured they had a lot more
experience than I did in fixing factory screwups. They were satisfied
with this, and I got to go home.

Matt Roberds

En el artículo , escribió:

Factory: We will have the sim done on $DATE.

Site: No no no! We've already sold time on that sim to customers on
$DATE-30days and we can't reschedule! We *must* have it here
sooner!

Factory: Why did you do that? The sim will not be done on
$DATE-30days. It will be broken and unusable for training.

Site: We don't care.

Factory: If we ship it at that time, it will suck.

Site: We don't care!!! Ship it shipit SHIPIT!!1!

Factory: sigh OK.

(time passes)
Site: Well you got the sim to us on time but it sucks! Everything's
broken and we can't put the customers on it! Fix it fixit
FIXIT!!1!

Why does that sound so horribly, horribly familiar?

Brrr. Memories I'd rather forget.

--
(\_/) Tyson Fury: #homophobe #bigot #throwback #missinglink
(='.'=) #neanderthal #misogynist #redneck #dickhead
(")_(")

wrote in message ...
Mark Zacharias wrote:
Maybe we could share some "war stories" of cool repairs we have done
in the past.

It's definitely not consumer electronics, but here goes.

I used to work at a company that made flight simulators. My official
job was writing code to make the navigation instruments display
correctly, according to the simulated position of the aircraft, which
frequencies the radios were tuned to, the position of circuit breakers,
etc.

Some of the laws of nature at that particular job included:

1) Techs string wire.

2) Programmers write programs.

3) Techs never make mistakes when stringing wires.

4) No programmer could ever possibly understand the intricacies of
stringing wires. Therefore, any complaints by programmers about the
wiring can usually be disregarded.

5) Any persistent complaints about the wiring can be remedied by telling
the programmers to work around it in the code.

Never being one to obey the laws of nature, I brought in my own meter
and checked things out when the sim didn't seem to work right. My boss
knew that I had something of a clue; I had been giving "how to read a
schematic" lessons to a few of my cow-orkers (in software) who were also
new hires or just wanted to know how. He basically told me that he
didn't mind me doing my own checks as long as I was careful with the sim
hardware, and that I should expect the techs to get mad at me if they
ever saw me doing it.

I couldn't get the right DME indicator to light up in one sim. (It was
a box in the instrument panel with three 7-segment displays and a couple
of buttons. It was supposed to display how far the airplane was from a
particular radio station.) After a few rudimentary checks of my code, I
wrote up a "right DME inop" trouble ticket. The technician wrote back,
"Wiring checks to print, DME sent for repair". Sure enough, there was a
hole in the panel. When it was again filled, I tried again...no joy. I
swapped the left and right indicators - hmm, the problem stayed with the
socket instead of following the indicator. I broke out the wiring
diagram and my own personal multimeter and started chasing around behind
the panel - no wires or pins for power on the right DME socket. (It was
something like a DB25 or DB37, with individual "crimp and poke"
contacts.) I dutifully re-opened the ticket, and the tech dutifully
wrote "wiring checks to print" and closed it again.

About this time, the sim was shipped to the site, even though it was
broken. The standard process was to completely build the sim at the
factory, test it out, ship it to the site, certify it, and put it in
revenue service. For sites that were far away from the factory, this
practice was generally followed, because it was expensive to ship people
to site to finish working on the sim. However, the site that was
closest to the factory (~3 hr drive) was notorious for the following:

Factory: We will have the sim done on $DATE.

Site: No no no! We've already sold time on that sim to customers on
$DATE-30days and we can't reschedule! We *must* have it here
sooner!

Factory: Why did you do that? The sim will not be done on
$DATE-30days. It will be broken and unusable for training.

Site: We don't care.

Factory: If we ship it at that time, it will suck.

Site: We don't care!!! Ship it shipit SHIPIT!!1!

Factory: sigh OK.

(time passes)
Site: Well you got the sim to us on time but it sucks! Everything's
broken and we can't put the customers on it! Fix it fixit
FIXIT!!1!

Factory: sighs deeply, starts phoning rental car agencies and hotels

So I get to the site and the site manager is bugging me about the right
DME indicator. I walk in to the site maintenance shop and tell the
techs there I need some connector pins, the crimper tool, some wire, and
a bench power supply. They are extremely wary of this as they have
experienced "programmers with screwdrivers" before, but they give me the
requested items and follow me into the sim, probably in hopes that my
body will shake and jerk in interesting ways as I electrocute myself.
I put the pins on the wires and put them in the (still vacant) slots on
the right DME connector. Wires run out under the panel to the power
supply, which temporarily gets the co-pilot's seat. Fire up the sim,
hit the power supply, and whaddayaknow - DME love for all. I
disappointed the techs, but the site manager was very happy.

I pointed out the relevant page in the wiring diagram book, so the site
techs could get it wired in correctly. I figured they had a lot more
experience than I did in fixing factory screwups. They were satisfied
with this, and I got to go home.

Matt Roberds



Wow. Lots of times I'm too lazy to read to the end - but this was great!
Loved it!

mz

How about another slant on "War Stories" ?

The least competent, most alcoholic, etc tech person you ever had to work
with or follow after they got fired?

When I was first starting in consumer electronics repair, (my first job in
the business, actually) I was hired to replace "Karl". He had a resume - in
the '70s a well respected shop paid for him to come over from Germany.

By my time however - apparently a broken down alcoholic.

He would "repair" tons of stuff, bill out huge amounts (paid on commision)
then abscond when the re-do's became too much.

I was charged with fixing his re-do's and generally cleaning up the chaos he
had left behind.

Next job - another shop. They had just fired the SAME GUY. Same situation.
Re-do's coming in one after another. Angry customers. Piles of screws and
small hardware in a pile on one corner of the bench. Dis-assembled units all
over the place, and I mean ALL OVER. A Teac A-4010 in about four different
parts of the shop. No pressure... I'd never even seen one before.

Next job - SAME DEAL. By now I was getting pretty good at
reverse-engineering other peoples screw-ups, but - really?

A couple examples:

Auto-reverse car cassette deck. He didn't have the correct drive belt, so he
had SUPER-GLUED the ends of the old belt together. Played about 2 mnutes, if
that.

A Marantz 1060 integrated amp (re-do) with a blown channel. He had substuted
a driver transistors with a similar package item. Unfortunately, the part he
used was a VOLTAGE REGULATOR IC and not even a transistor.

He had his "groupies" though. Some customers followed him from one job to
the next.

About 1987 Bang & Olufsen in Chicago contacted our shop for a reference on
this guy.

We were rolling on the floor!

Gave him an absolutely GLOWING reference. We could think of nothing funnier
than the prospect of this guy working for B&O.

(no he didn't get hired)


Good times.

On Fri, 11 Dec 2015 06:02:13 -0600, "Mark Zacharias"
wrote:

How about another slant on "War Stories" ?

The least competent, most alcoholic, etc tech person you ever had to work
with or follow after they got fired?

When I was first starting in consumer electronics repair, (my first job in
the business, actually) I was hired to replace "Karl". He had a resume - in
the '70s a well respected shop paid for him to come over from Germany.

By my time however - apparently a broken down alcoholic.

He would "repair" tons of stuff, bill out huge amounts (paid on commision)
then abscond when the re-do's became too much.

I was charged with fixing his re-do's and generally cleaning up the chaos he
had left behind.

Next job - another shop. They had just fired the SAME GUY. Same situation.
Re-do's coming in one after another. Angry customers. Piles of screws and
small hardware in a pile on one corner of the bench. Dis-assembled units all
over the place, and I mean ALL OVER. A Teac A-4010 in about four different
parts of the shop. No pressure... I'd never even seen one before.

Next job - SAME DEAL. By now I was getting pretty good at
reverse-engineering other peoples screw-ups, but - really?

A couple examples:

Auto-reverse car cassette deck. He didn't have the correct drive belt, so he
had SUPER-GLUED the ends of the old belt together. Played about 2 mnutes, if
that.

A Marantz 1060 integrated amp (re-do) with a blown channel. He had substuted
a driver transistors with a similar package item. Unfortunately, the part he
used was a VOLTAGE REGULATOR IC and not even a transistor.

He had his "groupies" though. Some customers followed him from one job to
the next.

About 1987 Bang & Olufsen in Chicago contacted our shop for a reference on
this guy.

We were rolling on the floor!

Gave him an absolutely GLOWING reference. We could think of nothing funnier
than the prospect of this guy working for B&O.

(no he didn't get hired)


Good times.
Mark,

In the early 70s there was a company that sold strips of rubber of
various sizes with a razor blade, jig and a tube of super glue that
was supposed to be used to make belts for consumer electronics
equipment. I had never seen super glue before so I tried it. Once.

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On Fri, 11 Dec 2015 10:46:52 -0600, Chuck wrote:

In the early 70s there was a company that sold strips of rubber of
various sizes with a razor blade, jig and a tube of super glue that
was supposed to be used to make belts for consumer electronics
equipment. I had never seen super glue before so I tried it. Once.

Those are still sold and work reasonably well:
https://www.google.com/#q=o-ring+splice+kit

The trick is to cut the o-ring or whatever at an angle. That does
three things:
- It increases the surface contact area so that the glue has a better
grip.
- It converts some of the stresses from tension to shear, where
cyanoacrylate adhesives are stronger.
- When used as a compression seal, crushing the glue joint does NOT
crack the rather brittle glue joint.

The only gotcha I've run into is dealing with tight turns such as very
small diameter drive pulleys. Cutting the o-ring at a large angle
causes the glue joint to be longer. Too long, and it will crack if
wrapped around a small pully. Just size the angle for covering no
more than about 60 degrees around the pully, and I think it should be
ok.

Note: Super glue doesn't work if there's little contact area, so
splicing thin and flat belts doesn't work. I've had some luck using
contact cement with these, but not reliably.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"I was charged with fixing his re-do's and generally cleaning up the chaos he
had left behind. "

Steve's TV, I doubt they are still around. Quit, went back a couple of times. One time they needed bo TV techs but needed an audio tech. Figured, hell I'll give audio a whirl. Not that I hadn't done any, just not exclusively.

Well there is this whole big stack of recalls (or redos) from the last guy. The Delco 2000 series car stereos. The guy's bench setup had a common ground for the speakers and he blew the audio output chip out of EVEY ONE OF THEM.

These are true four channels radios but not quad. these are not some elcheapo LAXXXX six buck chip. They were DM-165 mostly and they were over twenty bucks each, and he blew BOTH of them in each radio.

That was one of my last commission jobs. I made money. And after that SNAFU was cleared up the boss(es) standing around said "We're finally making money on audio". That part was a bit hellish. Back then we didn't even have a Hakko and those Delcos were among the first things that (regularly) came in that two sided boards with plated through holes.

Every last one of them. With the type B tape decks in them the belt would break and it would not eject, so no radio either. So many customers decided to pry the tape out, breaking the cassette guides. The belt is a buck, a set of these plastic pieces it twenty. Even though they were assholes who cost themselves some money there, they did happen to notice when the front speakers didn't work anymore after they got it back.

And then they bring it back and because of the common ground the bench speakers would play the L-R like the back channels of a quasi quad unit and when you turn the balance to one side it would sound almost normal. "Nothing wrong with it". Yeah right.

You can't really work techs on commission anymore. Back then, so many repairs involved simple parts that it could work with a guy who is good. There were shops though that I would not. If I do not see a good parts department **** that. I ain't coming in and diagnosing all this only to wait weeks to complete the job to get paid. What's more, forget the free estimate, I ain't doing it.

When the shop[ makes money, the tech makes money on commission. One place I did work commission worked out pretty well. I was running though some of my old **** and part time, one week I made $480 in 12 hours. One week I worked about 30 hours and took home $775. And that was in the 1980s. Later, that job converted to hourly, at a quite good rate. It was slightly less money but it was steady. I liked the money steady and they liked the fact that I could no longer refuse jobs.

And that paid off for them.

Actually, now this is a LONG time ago and at $23 an hour, they threw me a set I had already been stumped on before. they said it is a do or die. It may have been a contract job, and when you cannot fix a contract job that is very bad. You can't just refund the money, you have to buy them another TV.

This was an RCA CTC 169. (I should have put thios in my other post but did not recall it then) Intermittently it would start up with the OSD shifted and no sound. Now this was a normal symptom for this chassis and I do not recall what the fix was, but in this case where the OSD is usually shifted to the right, this one was shifted to the left. (or vice versa but you get the idea, the other way)

it would never do it with the chassis flipped up. About ten people resoldered almost every joint on the board to no avail.

RINALLY I got it. It was a weak 503 KHz crystal at the jungle IC. the hell you say ? Well when the micro tells the set to come on it expects a source to come up right away which is scan derived. this feeds the EPROM which then reads its contents into RAM with the specific setup info and settings.

I started noticing that when this happened, the HV did not come up immediately. What it was is the crystal was weak or whatever and the oscillator took too much time to start. The micro is only sensitive to that data for a limited time and the window was closed by the time the EPROM spoke up. That chassis had a system that is operable without an EPROM. When it is in that mode it uses a set of parameters that do not match the hardware installed. Actually I do not recall ever seeing a CTC169 without an EPROM, but other models did. Some of them would autoprogram first time they were turned on after being unplugged. Those were the elcheapo models, but of other chassis'. I guess they used the same micros or at least similar code in them though.

So we got :

No sound - 503 KHZ crystal for horizontal osc.
No sound - vertical shaping IC.
Loses blue and green after CRT replacement - adjust vertical height.

I'd like to see some weirder ones than that.

Any more recent successs stories to brag about?

If you enjoy reading such stories, there are quite a few in the "Made
by Monkeys" section of various trade magazines. These highlight
quality control and design failures:
http://www.electronicsweekly.com/made-by-monkeys/
http://www.designnews.com/archives.asp?section_id=1367
If you're planning on designing the next big thing in consumer
products, or are wondering why some things just can't be repaired,
these columns (blogs) should be mandatory reading.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Been there done that. Good site. The name seems to imply it is a comedy site but it is not. I hope people are not too disappointed.

Mark Zacharias wrote:


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

I was called in unofficially to have a look at an X-ray machine in a
university crystallography lab, there was an intermittent fault which
shut it down after a few seconds of operation. The running time was
getting shorter and shorter and the manufacturers had given up on
finding the fault.

On the way there, I mentally ran through what I could remember about
X-ray machines (apart from the obvious dangers) and realised that most
of what I knew had come from reading my father's hand-written course
notes in the 1950s; they dated from when he was trained as an army
radiographerat the outbreak of WWII. I knew what an X-ray tube looked
like as a symbol, but what did one look like in reality?

On being introduced to the faulty machine, I glanced around the room and
saw a number of copper-and-glass objects on a shelf - and concluded that
they must be spare tubes. Luckily, the manufacturers had furnished a
full set of circuit diagrams and the lab had managed not to loose them,
so I knew what I was dealing with, even if I didn't initially know how
most of it worked. The circuits were all discrete components with
intermixed transistor, diode and relay logic.

By the end of the first day, I had gained a fair idea of how the power
supplies and safety circuits worked and had been instructed in the
necessary safety drill by the technician, so I was able to fire the
machine up and watch what happened. The fault showed up, but it all
happened so quickly that I wan't able to spot what was going on.

Luckily, on the morning of the second day, I happened to spot the tube
current meter flicker downwards and the voltmeter kick upwards just as
the fault occurred. Careful monitoring of the primary of the mains
transformer showed unstable mains voltage, which the control loop had
been over-compensating and then tripping out on over-voltage.

The cause was a burnt contact in the main contactor, so I stripped it
down and sandpapered the contacts, much to the amusement of the staff.

Fault cured - machine saved from the scrapheap.


--
~ Adrian Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk

How to operate a tube caddy.

During the early 1970's, I ran a 2way radio service shop. Running it
was an accident because no sooner was I hired, everyone else either
quit or promoted themselves sideways, leaving me as the sole employee
and later as part owner. This condition lasted for a few months of
serious overwork, until I was finally able to hire an employee. The
shop:
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/PMC02.html

A major part of the operation was maintaining a mountain top radio
repeater site:
http://802.11junk.com/jeffl/pics/Old%20Repeaters/slides/Santiago-01.html
When something went wrong, the ritual was to load up the company
pickup truck with everything imaginable, drive 12 surface miles to the
base of the mountain, drive 16 miles up a windy dirt road to the top,
fix something, and repeat the ritual in reverse. 6 to 8 hrs was the
typical round trip time.

Replacement tubes were carried in a tube caddy. For those who have
never seen a tube caddy, the individual tubes were stored in small
personalized cardboard boxes, inside a wooden carrying case like
these[1]:
https://www.google.com/search?q=tube+caddy&tbm=isch
My new employee would identify the dead or dying tube, extract a new
tube from the tube caddy, insert the new tube into the radio, insert
the dead tube into the cardboard box, and replace the box into its
place in the tube caddy. Do you see a problem here?

That worked for about 3 months when I discovered that my new employee
couldn't seem to fix anything. Various theories were offered, but
nothing worked. One day, my employee had a cold, so I had to do the
drive up the mountain. Oddly, I also couldn't seem to fix anything
either. Then, I noticed that some of the tubes I was using as
replacements were obviously ancient and really didn't belong in
service. Hmmm...

Upon returning to civilization, I tested almost all the tubes in the
tube caddy, and found that well over half were dead[2]. When I
mentioned it to my new employee, it took him a while to understand
what had happened. I suspected that the thought the tube caddy
somehow rejuvenated dead tubes. I resisted the temptation to thrash
him about the head, because he was bigger than me. I later found him
a job with a competitor.


[1] I still have a tube caddy full of tubes awaiting the demise of
semiconductors.

[2] Tube testing algorithm. If the tube tester says it's bad, it's
bad. If the tube tester says it's good, it still might be bad.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Mark Zacharias wrote:
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.


I was in a block of flats to look at a curious problem in their terrestrial TV reception. Whenever the communal stairs/hall lights were on, all TV sets in the block lost signal.
The stairs lights were controlled by a timer relay that kept the lights on for a few minutes after any push button was hit, so every time someone entered and hit the light the neighbors TV signal went out for a few minutes.

I started checking the terrestrial antenna head amplifier and found it lost mains power whenever stairs lights were on. I also observed that four or five lights in the stairs did not illuminate and some push buttons didn't activate the lights. That one had me thinking for a while and I drew this diagram to understand what could possibly be going on the

Head amplifier wall plug
N L
| |
| |
|--light bulb--| |
|--light bulb--| |
|--light bulb--| |
X | |
|--light bulb--| |
|--light bulb--| |
|--light bulb--| |
| | |
| relay |
| | |
| +-----+
| |
N L
Mains supply

That turned out an accurate representation of the problem, I found "X" was a badly burned electrical terminal inside a connection box. With relay open, the bulbs happened to be in series in the neutral going to the head amplifier and because its small current draw it had enough voltage to work. With relay closed, only light bulbs before the break illuminated and the head amplifier got the L pole in the N wire through the non-working bulbs, so no voltage to work.

Sometimes a small victory makes you feel just as good as a big one.

Picked up a somewhat non-functional Micronta 22-220A multimeter. A little
rough but the FET meter circuit worked - voltage readings weren't too far
off and the zero control did it's job so I knew all that stuff was OK.

But the resistance function acted as though there was a 4 ohm or so resistor
across the leads all the time, and the battery was draining at about 100 mA
in Ohms function even with no leads attached.

Of course the 9.1 ohm Rx1 resistor was bad, but replacing it did NOT change
the symptom.

After finding a schematic (not many out there...) I did find a component
labelled "SA1" shorted at 4 ohms or so. The item resembled an MOV and I can
only assume SA stood for spark or surge arrestor.

Removing it mostly fixed the ohms function, and I decided a couple of
back-to-back 25 volt zeners would offer enough protection to satisfy my
needs.

Still the ohms zeroing was erratic. Cleaning the function / range switch and
ohms pot til I was blue in the face did not resolve the problem. It was
kinda usable but it kept bugging me.

I tried putting a current meter in series with the test leads but couldn't
really get a usable correlation between pushing, poking wiggling the
function switch etc and the action of the meter which might zero fine, then
show up to several ohms even seconds later with probes shorted.

It occurred to me that I could put a resistor (say 4.7 ohms on this range)
across the probes and put a 'scope across that resistor to better see what
the DC voltage there was doing.

Oh, yeah. the voltage as viewed on the 'scope varied wildly and looked
"noisy" as the funtion switch was wiggled or tapped.

But I had cleaned that switch umpteen times.

Well, there was another switch - a leaf switch, going to the negative
battery terminal hiding under the front face and also actuated by the
function knob.

A quick cleaning of those contacts and the meter works like new.

A small victory to be sure, but made me feel as good as a big one.


Mark Z.

"Mark Zacharias" wrote in message ...

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.







A very distant fellow band member of mine once confided in me that he one
day discovered his next door neighbour had the same television that he had.
He had many hours of glee from sneaking up to their window and randomly
firing his remote control at their TV.


He also ended up being prosecuted for stealing commission cheques meant to
be mailed to our management company.

Not a particularly nice bloke.



Gareth.

On 13/12/2015 22:31, Gareth Magennis wrote:


"Mark Zacharias" wrote in message ...

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.







A very distant fellow band member of mine once confided in me that he
one day discovered his next door neighbour had the same television that
he had.
He had many hours of glee from sneaking up to their window and randomly
firing his remote control at their TV.


He also ended up being prosecuted for stealing commission cheques meant
to be mailed to our management company.

Not a particularly nice bloke.



Gareth.




On practical joking, this was to wind-up my parents , when I was aged
about 10.
A syncronous mains driven/timed mantle clock . I was intrigued by this
little flipper/kicker thing that operated when you turned on the power.
If you disengaged it with a match, then half the time , when switching
back on, the clock would go backwards.

"N_Cook" wrote in message
...

On practical joking, this was to wind-up my parents , when I was aged
about 10.
A syncronous mains driven/timed mantle clock . I was intrigued by this
little flipper/kicker thing that operated when you turned on the power.
If you disengaged it with a match, then half the time , when switching
back on, the clock would go backwards.

That reminds me of a clock we had when I was growing up. On the back was a
small wheel and you had to spin it in the direction you wanted the clock to
run when it was plugged in.

In article ,
says...

"N_Cook" wrote in message
...

On practical joking, this was to wind-up my parents , when I was aged
about 10.
A syncronous mains driven/timed mantle clock . I was intrigued by this
little flipper/kicker thing that operated when you turned on the power.
If you disengaged it with a match, then half the time , when switching
back on, the clock would go backwards.

That reminds me of a clock we had when I was growing up. On the back was a
small wheel and you had to spin it in the direction you wanted the clock to
run when it was plugged in.

If only one could "turn the clock" back and recapture one's long-gone
youth that way...

Mike.

On 12/14/2015 10:08 AM, MJC wrote:
In article ,
says...

"N_Cook" wrote in message
...

On practical joking, this was to wind-up my parents , when I was aged
about 10.
A syncronous mains driven/timed mantle clock . I was intrigued by this
little flipper/kicker thing that operated when you turned on the power.
If you disengaged it with a match, then half the time , when switching
back on, the clock would go backwards.

That reminds me of a clock we had when I was growing up. On the back was a
small wheel and you had to spin it in the direction you wanted the clock to
run when it was plugged in.

If only one could "turn the clock" back and recapture one's long-gone
youth that way...

Mike.


I wouldn't be 21 again on a bet.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

About 3 weeks ago, I was blessed by the addition of a Samsung
Syncmaster 243T 24" 1920x1200 LCD monitor to my repair backlog. It
had been sitting around the donors office for a year or two, so nobody
could recall why it was retired. I plug it in and it appears that
everything is working. I have two similar LCD monitors at home for
running my flight simulator. A third monitor would make a start on a
wrap around cockpit window view. (actually 4 is about right).

So, I take home the monitor, being careful not to bash in the screen
like I did the last monitor I took home by planting the groceries dead
center in the middle of the panel. It arrive safely, I plug it in,
and nothing works. No power, no pilot light, no messages, no nothing.

I'm not exactly equipped at home to fix monitors, so I drag it back to
the office where it sat around for a few days. I plug it, and
everything works normally. I check for intermittents by beating on
the monitor, but nothing happens.

At this point, a sane and rational person would tear the monitor
apart, look for problems, probe around with a volts-guesser, determine
the culprit, and fix it. Nope. I'm out of bench space and have no
room to work on a big monitor. So, I drag the monitor home again, and
once again, it's dead on arrival. So, I drag it back to the office
for the 3rd time, where it once again works perfectly.

This would be a good time to guess the cause (although I haven't
really revealed enough info to make a proper deduction).

I still haven't ripped it apart to see what's going on, but I do have
a good guess what's wrong. It probably has the usual bulging
capacitor problem in the power supply. I keep the office at 72F (22C)
to keep the customers happy. At home, I prefer something around 65F
(18C). The workbench, where I do my testing is not very well heated,
and is probably colder. Outside temperature is now about 43F (6C).

Bulging electrolytics are detected by measuring the ESR, which
increases as they leak. Heating the caps lowers the ESR back down.
Cooling the caps raises the ESR back up. Incidentally, this is why
some devices run merrily when warm, but won't turn on when allowed to
cool off. The Samsung monitor is likely teetering between working
when warm, and not running when cold.

I'll disclose what was really wrong after I fix it, probably next
year.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
About 3 weeks ago, I was blessed by the addition of a Samsung
Syncmaster 243T 24" 1920x1200 LCD monitor to my repair backlog. It
had been sitting around the donors office for a year or two, so nobody
could recall why it was retired. I plug it in and it appears that
everything is working. I have two similar LCD monitors at home for
running my flight simulator. A third monitor would make a start on a
wrap around cockpit window view. (actually 4 is about right).

So, I take home the monitor, being careful not to bash in the screen
like I did the last monitor I took home by planting the groceries dead
center in the middle of the panel. It arrive safely, I plug it in,
and nothing works. No power, no pilot light, no messages, no nothing.

I'm not exactly equipped at home to fix monitors, so I drag it back to
the office where it sat around for a few days. I plug it, and
everything works normally. I check for intermittents by beating on
the monitor, but nothing happens.

At this point, a sane and rational person would tear the monitor
apart, look for problems, probe around with a volts-guesser, determine
the culprit, and fix it. Nope. I'm out of bench space and have no
room to work on a big monitor. So, I drag the monitor home again, and
once again, it's dead on arrival. So, I drag it back to the office
for the 3rd time, where it once again works perfectly.

This would be a good time to guess the cause (although I haven't
really revealed enough info to make a proper deduction).

I still haven't ripped it apart to see what's going on, but I do have
a good guess what's wrong. It probably has the usual bulging
capacitor problem in the power supply. I keep the office at 72F (22C)
to keep the customers happy. At home, I prefer something around 65F
(18C). The workbench, where I do my testing is not very well heated,
and is probably colder. Outside temperature is now about 43F (6C).

Bulging electrolytics are detected by measuring the ESR, which
increases as they leak. Heating the caps lowers the ESR back down.
Cooling the caps raises the ESR back up. Incidentally, this is why
some devices run merrily when warm, but won't turn on when allowed to
cool off. The Samsung monitor is likely teetering between working
when warm, and not running when cold.

I'll disclose what was really wrong after I fix it, probably next
year.


Going to look bad when it is a bad power cable or socket.

Could be the capacitors. A number of years ago when the bad capacitors were
in many computers a friend had a computer in his basement that sometimes
came on and sometimes not. He left the cover off of it and would put a
light bulb next to the computer to heat it up. The computer wold come on
and work fine unless he shut it off , then he had to heat it up again with
the light bulb.

On 16/12/15 03:09, Ralph Mowery wrote:
"Jeff Liebermann" wrote in message
...
About 3 weeks ago, I was blessed by the addition of a Samsung
Syncmaster 243T 24" 1920x1200 LCD monitor to my repair backlog. It
had been sitting around the donors office for a year or two, so nobody
could recall why it was retired. I plug it in and it appears that
everything is working. I have two similar LCD monitors at home for
running my flight simulator. A third monitor would make a start on a
wrap around cockpit window view. (actually 4 is about right).

So, I take home the monitor, being careful not to bash in the screen
like I did the last monitor I took home by planting the groceries dead
center in the middle of the panel. It arrive safely, I plug it in,
and nothing works. No power, no pilot light, no messages, no nothing.

I'm not exactly equipped at home to fix monitors, so I drag it back to
the office where it sat around for a few days. I plug it, and
everything works normally. I check for intermittents by beating on
the monitor, but nothing happens.

At this point, a sane and rational person would tear the monitor
apart, look for problems, probe around with a volts-guesser, determine
the culprit, and fix it. Nope. I'm out of bench space and have no
room to work on a big monitor. So, I drag the monitor home again, and
once again, it's dead on arrival. So, I drag it back to the office
for the 3rd time, where it once again works perfectly.

This would be a good time to guess the cause (although I haven't
really revealed enough info to make a proper deduction).

I still haven't ripped it apart to see what's going on, but I do have
a good guess what's wrong. It probably has the usual bulging
capacitor problem in the power supply. I keep the office at 72F (22C)
to keep the customers happy. At home, I prefer something around 65F
(18C). The workbench, where I do my testing is not very well heated,
and is probably colder. Outside temperature is now about 43F (6C).

Bulging electrolytics are detected by measuring the ESR, which
increases as they leak. Heating the caps lowers the ESR back down.
Cooling the caps raises the ESR back up. Incidentally, this is why
some devices run merrily when warm, but won't turn on when allowed to
cool off. The Samsung monitor is likely teetering between working
when warm, and not running when cold.

I'll disclose what was really wrong after I fix it, probably next
year.


Going to look bad when it is a bad power cable or socket.

Could be the capacitors. A number of years ago when the bad capacitors were
in many computers a friend had a computer in his basement that sometimes
came on and sometimes not. He left the cover off of it and would put a
light bulb next to the computer to heat it up. The computer wold come on
and work fine unless he shut it off , then he had to heat it up again with
the light bulb.

We had a couple of old Fujitsu "Eagle" disk drives - 500MB or so -
inherited when we started a company in 1990. These were about 25-30kg,
and 500x350x700mm in size - so you needed two strong sets of hands to
get them on and off the rack mountings (they were on slides).

Anyhow, as they got older, the spindle bearings became sticky, so they
wouldn't spin up after a power fail that was long enough for them to
cool down. We used to get them off the racks, with one bloke at each
end, then power them up and give a sudden lateral rotation to break the
stiction of the bearings. Quite a risky business, coordinating two
blokes to do that suddenly enough without dropping the drive, but it
worked a number of times before we made enough money to afford to
replace them.

We started a software company with 25 initial employees (staff buy-out)
and a grand total of 2.2GB of storage - in the entire company. Imagine that!

Clifford Heath.

On Tue, 15 Dec 2015 11:09:55 -0500, "Ralph Mowery"
wrote:

Going to look bad when it is a bad power cable or socket.

Nope. Both passed the wiggle test.

Could be the capacitors. A number of years ago when the bad capacitors were
in many computers a friend had a computer in his basement that sometimes
came on and sometimes not. He left the cover off of it and would put a
light bulb next to the computer to heat it up. The computer wold come on
and work fine unless he shut it off , then he had to heat it up again with
the light bulb.

I'm getting that now on my home desktop computah. I don't bother to
heat the house much at night. When I wake up, it's about 45F (7.2C)
inside the house. When I turn on my desktop computah, the fan makes
some odd noises but eventually quiets down. The hard disk seems to
boot normally, but usually some programs add oddly or crash. I reboot
and they then act normally. It's probably read errors on the hard
disk, but SMART shows nothing interesting. At this time, I boot to
the BIOS screen, wait about 10-15 mins, and then boot normally.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 16/12/15 10:15, Jeff Liebermann wrote:
On Tue, 15 Dec 2015 11:09:55 -0500, "Ralph Mowery"
wrote:

Going to look bad when it is a bad power cable or socket.

Nope. Both passed the wiggle test.

Could be the capacitors. A number of years ago when the bad capacitors were
in many computers a friend had a computer in his basement that sometimes
came on and sometimes not. He left the cover off of it and would put a
light bulb next to the computer to heat it up. The computer wold come on
and work fine unless he shut it off , then he had to heat it up again with
the light bulb.

I'm getting that now on my home desktop computah. I don't bother to
heat the house much at night. When I wake up, it's about 45F (7.2C)
inside the house. When I turn on my desktop computah, the fan makes
some odd noises but eventually quiets down

Take the fan out and refit it, rotated 90 degrees.

The bushings wear the holes elliptical, and the rotation changes the
vibration modes.

"Jeff Liebermann" wrote in message
...
I'm getting that now on my home desktop computah. I don't bother to
heat the house much at night. When I wake up, it's about 45F (7.2C)
inside the house. When I turn on my desktop computah, the fan makes
some odd noises but eventually quiets down. The hard disk seems to
boot normally, but usually some programs add oddly or crash. I reboot
and they then act normally. It's probably read errors on the hard
disk, but SMART shows nothing interesting. At this time, I boot to
the BIOS screen, wait about 10-15 mins, and then boot normally.



If I got out of bed and it was 45 F, I would be looking into the heating
system first. I don't function when it is that cold.

Sounds like you may want to look into a solid state drive for the computer
so it will start up cold.

Ralph Mowery wrote: "
"Jeff Liebermann" wrote in message
...
I'm getting that now on my home desktop computah. I don't bother to
heat the house much at night. When I wake up, it's about 45F (7.2C)
inside the house. When I turn on my desktop computah, the fan makes
some odd noises but eventually quiets down. The hard disk seems to
boot normally, but usually some programs add oddly or crash. I reboot
and they then act normally. It's probably read errors on the hard
disk, but SMART shows nothing interesting. At this time, I boot to
the BIOS screen, wait about 10-15 mins, and then boot normally.



If I got out of bed and it was 45 F, I would be looking into the heating
system first. I don't function when it is that cold.

Sounds like you may want to look into a solid state drive for the computer
so it will start up cold. "


If I got out of bed and it was that cold, I would be looking
into some INSULATION first! Something 'Murricans seem
to be averse to, even after decades of evidence in favor
of it.

Um.... Um....

Have you checked the receptacle at home? And for proper polarity?

Some monitors will not function if not properly polarized. Just a thought.

Peter Wieck
Melrose Park, PA

On Fri, 18 Dec 2015 07:49:23 -0800 (PST), "
wrote:

Um.... Um....

Who when where how why what?

Have you checked the receptacle at home? And for proper polarity?
Some monitors will not function if not properly polarized. Just a thought.

I don't think that's the problem of I would have been electrocuted
long ago. However, it was worth checking, especially since I did my
own wiring. So I dug out my tester:
https://en.wikipedia.org/wiki/Receptacle_tester
and walked it through the maze of power strips and extension cords.
Everything tests just fine.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

One of the advantages of my office location is that it's very
centrally located. Within about 500ft is the intersection of 3
freeways, the main drag into Santa Cruz city, and smaller roads
leading directly to nearby cities. All roads lead to my office, which
is both a benefit and a problem. Besides making it easier for my
customers to drop in, it also attracts a motley assortment of people
that just happen to be driving by my dead end street, and just happen
to in the mood for trashing my day with inane conversation.

One memorable day, I had 4 of these visitors perched on benches and
chairs (I only have two chairs in the office to make sure they're not
very comfortable). I was working on replacing some caps in an ATX
power supply. Of course, I wasn't paying attention and accidentally
soldered the caps in backwards. With the cover off, I plugged in the
power supply, and continued the discussion with my visitors. Suddenly,
several of the caps decided this would be a excellent time to explode
and launch oily confetti all over the office. Everyone, except me,
dived for cover under or behind tables and boxes. I just continued
talking as if everything was perfectly normal and nothing unusual had
happened. The visitors soon made a rather hasty exit. Oddly, they
must have told their friends, because my office was free of unwanted
visitors for at least a week or two.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Once upon a time, I was temporarily put in charge of marine radio
manufactories production test department while they searched for
someone to replace my predicessor, who had apparently gone missing,
insane, or both.

Among the test techs was one who followed instructions dilligently,
but usually failed to understand what was expected. The techs were
told that in the transmitter RF chain, if they couldn't identify which
device lacked sufficient gain, they could just replace each device in
turn until the culprit was found. This was possible because there
were only 7 devices involved, and the most likely culprits were the
cheap TO-92 devices found at the oscillator end of the chain.
Unfortunately, that was not communicated to this individual, who
proceded to replace devices starting with the rather expensive 25 watt
VHF RF output transistor. Nobody said noticed until I went to the
parts room to replace a 25 watt device that I had blown up in
engineering, and was informed that production test had grabbed all the
available stock. I also noticed that someone had prefixed some of the
printed test procedures to include turning the power on to the test
equipment. I survived for about a month and was very happy when the
company finally hired someone to replace me.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

One of my customers in the computah repair business own a large house
that had been converted to college student housing. My guess is about
15 students crammed into every possible available space. I was hired
by the owner to maintain the Comcast internet, NAS server, printers,
phone system, wiring, and wi-fi, which are all part of the package.
The prime directive was to do everything necessary to prevent the
students from burning down the house, which I interpreted to mean not
let them make any changes or additions to the wiring or equipment.
That has worked fairly well by the honor system for about 8 years.

This morning, I get a phone call that the internet and some of the
phones are down. Upon interrogation, I determine that some of the
"makers[1]" in the house had "optimized" the performance of the
Comcast cable modem and VoIP systems yesterday. My initial guess was
that they had managed to scramble the ethernet cables on the 24 port
managed switch running several VLAN's. Unlike ordinary ethernet
switches, a managed switch with traffic logging, required that the
correct cable be connected to the correct port.

I had previously suggested that someone should take photographs of the
wiring for this exact purpose. Amazingly, the students found the
flash drive in the envolope that I had place in plain sight, and were
able to display how things were wired before the system was
"optimized". They were able to bring things back online in only a few
additional minutes (I could see the switch come up from home via SNMP)
and only waited a full hour before someone bothered to phone me that
it was fixed and I need not waste a service call to the house.

With such a wonderful example of initiative and organized
troubleshooting, I think there may be hope for our next generation of
our country's leaders.


[1] Make trouble, make a mess, make love, make things break, make a
quick exit, etc...
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Any more recent successs stories to brag about?

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


Mark Z.

Okay, one more. True story... This wasn't so much a difficult repair as it was the circumstance. 1980, hot summer day and my new girlfriend (who would be my wife) is having her HS graduation party when her parent's early 70s tube Magnavox console blacks out in a cloud of smoke leaving a clean horiz line. I was 21 at the time and looked younger, but of course being a TV tech I was asked to look at it. I pulled the chassis out and the area around the vert centering control was pitch black. That and the cigarette smoke and wood stove deposits made seeing what else was burned nearly impossible.

I borrowed the garden hose and a bottle of Fantastik (TM) and soaked the bottom of the chassis and rinsed so it sparkled, then left it out front in the hot sun. Later in the afternoon I put in two 10 ohm 5W resistors in place of the vert cent control and put it together, touched up the height and lin and it worked fine for a few more years.

When my father in law tells the story, he said that when he saw me hosing out the TV guts in the front yard he was thinking "oh sh$t I'm going to have to buy a new TV tomorrow".