I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.

On 12/30/2015 4:10 PM, John Heath wrote:
I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.


Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem.
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few
monitors a day to five or more. In 90% of the cases replacing the caps
and the HOT (and fuse) fixed most problems, changing the caps, HOT and
LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could
spend a day on - if the customer thought it was worth the money.

Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management
process would often watch the laziest employee as he (she) would usually
have the best way of doing the job with a minimum of effort or fuss.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

In article ,
John Heath wrote:

I remember working for a company that imported cheap radios. I took my seat
with the other 20 or so techs repairing radios. Most quotas were in the 20
range while I was only repairing 3 or 5 radios a day. Thinking I would be
handed my pink slip I asked the tech next to myself how he was repairing so
many radios? He pointed to my draw where I had saves some diagrams off the
back of some of the radios. There is your problem he said. You are over
thinking wasting time. You can measure 6 transistors faster than you can
think if they are RF , audio or IF. In short stop thinking and start
measuring. When I looked around I could see that the other tech were
measuring not thinking. I took his advise and my quota when up from 3 a day
to 10. A lesson I did not forget and still use today. I would like to know if
others have found this to be true.

John-

What do you do when all the transistors are good?

Back in the 60s I worked for a year as an electronics troubleshooter.
As I recall, the quota was testing 80 circuit modules per day. The
quota was how many modules were tested, not how successful was the
troubleshooting of failed modules!

Repair records traveled with each module. I noticed that other
technicians would trace a signal, and have the first transistor replaced
where the signal stopped. Sometimes the same transistor would be
replaced multiple times. Once I noticed that the problem was actually
caused by a wrong part, a backwards diode or parts mounted in the wrong
holes, I learned to visually check the modules before testing. My quota
increased dramatically.

I suppose a quota system is necessary, but it does encourage shortcuts.

Fred

"John Robertson" wrote in message
...
Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem.
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few monitors
a day to five or more. In 90% of the cases replacing the caps and the HOT
(and fuse) fixed most problems, changing the caps, HOT and LOPT/Flyback
fixed most of the rest. Leaving 5% as dogs that one could spend a day on -
if the customer thought it was worth the money.


As always there are many ways to attack a problem. If equipment has a
history of some part or parts failing , look at that first. Especially if
it is easy to replace those parts and they do not cost very much. Then if
it still does not work go on to other methods.
At work we had some equipment that 99.9% of the time it was one of two
things, About 80% was a relay, the other large percentage was a circuit
board that we did not repair in house, but changed out. The relay was easy
as it just plugged in. Took about 5 seconds to change. The board took about
30 minuits to change. For the ones that knew the equipment would take one
voltage reading before changing the relay, for ones that did not know the
equipment and called some one they were told to change the relay.

For something like radios ( I repaired the CB radios back when they cost
around $ 200 and up ) I used the devide by two method if nothing stood out
at first glance. Start about half way and inject a signal or listen for a
signal. From that point go about half way to the end and so on.

On Wednesday, December 30, 2015 at 9:09:28 PM UTC-5, John Robertson wrote:
On 12/30/2015 4:10 PM, John Heath wrote:
I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.


Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem.
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few
monitors a day to five or more. In 90% of the cases replacing the caps
and the HOT (and fuse) fixed most problems, changing the caps, HOT and
LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could
spend a day on - if the customer thought it was worth the money.

Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management
process would often watch the laziest employee as he (she) would usually
have the best way of doing the job with a minimum of effort or fuss.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

A friend of mine has an old school arcade machine. No CPUs or monitors in this puppy. Just a pile of relays and paddle wheels. Great stuff. I could not find the tilt detector?

I found a short cut for flat electrolytic condensers in monitors and switching power supplies. First check if condensers that are rounded on top. Failing this use an impedance meter to measure the condenser impedance in circuit without un soldering it. Not un soldering it saves a lot of time. Any condenser with a impedance higher than a few ohms at 10 KHz and you found your problem. The down side is they do not sell condenser in circuit impedance meters so you have to make it yourself. Not a big deal as it just requires 10 KHz at a low impedance with about 100 m volts then monitor the current..

On 31/12/2015 2:19 PM, John Heath wrote:
On Wednesday, December 30, 2015 at 9:09:28 PM UTC-5, John Robertson wrote:
On 12/30/2015 4:10 PM, John Heath wrote:
I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.


Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem.
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few
monitors a day to five or more. In 90% of the cases replacing the caps
and the HOT (and fuse) fixed most problems, changing the caps, HOT and
LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could
spend a day on - if the customer thought it was worth the money.

Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management
process would often watch the laziest employee as he (she) would usually
have the best way of doing the job with a minimum of effort or fuss.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

A friend of mine has an old school arcade machine. No CPUs or monitors in this puppy. Just a pile of relays and paddle wheels. Great stuff. I could not find the tilt detector?

I found a short cut for flat electrolytic condensers in monitors and switching power supplies. First check if condensers that are rounded on top. Failing this use an impedance meter to measure the condenser impedance in circuit without un soldering it. Not un soldering it saves a lot of time. Any condenser with a impedance higher than a few ohms at 10 KHz and you found your problem. The down side is they do not sell condenser in circuit impedance meters so you have to make it yourself. Not a big deal as it just requires 10 KHz at a low impedance with about 100 m volts then monitor the current.


Google "blue meter" or "Bob Parkers ESR meter".

On Wednesday, December 30, 2015 at 10:07:51 PM UTC-5, Fred McKenzie wrote:
In article ,
John Heath wrote:

I remember working for a company that imported cheap radios. I took my seat
with the other 20 or so techs repairing radios. Most quotas were in the 20
range while I was only repairing 3 or 5 radios a day. Thinking I would be
handed my pink slip I asked the tech next to myself how he was repairing so
many radios? He pointed to my draw where I had saves some diagrams off the
back of some of the radios. There is your problem he said. You are over
thinking wasting time. You can measure 6 transistors faster than you can
think if they are RF , audio or IF. In short stop thinking and start
measuring. When I looked around I could see that the other tech were
measuring not thinking. I took his advise and my quota when up from 3 a day
to 10. A lesson I did not forget and still use today. I would like to know if
others have found this to be true.

John-

What do you do when all the transistors are good?


Good question. While the ohms meter is still in your hands from measuring the transistors you touch the volume control. If you hear a click from the speaker the audio is okay. Then the IF and RF with a RF injector probe. With practice it all happens so fast that you quickly know where the problem is.. If it turns out to be a dog then the golden rule is switch your dog for someone else's dog. Often my dog is an easy fix for someone else and their dog is an easy fix for me. Not sure why it is like this. Maybe taking a fresh look at a problem from different shoes.

Back in the 60s I worked for a year as an electronics troubleshooter.
As I recall, the quota was testing 80 circuit modules per day. The
quota was how many modules were tested, not how successful was the
troubleshooting of failed modules!

Repair records traveled with each module. I noticed that other
technicians would trace a signal, and have the first transistor replaced
where the signal stopped. Sometimes the same transistor would be
replaced multiple times. Once I noticed that the problem was actually
caused by a wrong part, a backwards diode or parts mounted in the wrong
holes, I learned to visually check the modules before testing. My quota
increased dramatically.

I suppose a quota system is necessary, but it does encourage shortcuts.

Fred

Yes I know what you mean. With new boards anything can be wrong. Memorizing all the resistors . diodes and transistors can save a lot of time by quickly troubleshooting with your eyes only.

On Thursday, December 31, 2015 at 1:27:12 AM UTC-5, Rheilly Phoull wrote:
On 31/12/2015 2:19 PM, John Heath wrote:
On Wednesday, December 30, 2015 at 9:09:28 PM UTC-5, John Robertson wrote:
On 12/30/2015 4:10 PM, John Heath wrote:
I remember working for a company that imported cheap radios. I took my seat with the other 20 or so techs repairing radios. Most quotas were in the 20 range while I was only repairing 3 or 5 radios a day. Thinking I would be handed my pink slip I asked the tech next to myself how he was repairing so many radios? He pointed to my draw where I had saves some diagrams off the back of some of the radios. There is your problem he said. You are over thinking wasting time. You can measure 6 transistors faster than you can think if they are RF , audio or IF. In short stop thinking and start measuring. When I looked around I could see that the other tech were measuring not thinking. I took his advise and my quota when up from 3 a day to 10. A lesson I did not forget and still use today. I would like to know if others have found this to be true.


Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem..
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few
monitors a day to five or more. In 90% of the cases replacing the caps
and the HOT (and fuse) fixed most problems, changing the caps, HOT and
LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could
spend a day on - if the customer thought it was worth the money.

Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management
process would often watch the laziest employee as he (she) would usually
have the best way of doing the job with a minimum of effort or fuss.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

A friend of mine has an old school arcade machine. No CPUs or monitors in this puppy. Just a pile of relays and paddle wheels. Great stuff. I could not find the tilt detector?

I found a short cut for flat electrolytic condensers in monitors and switching power supplies. First check if condensers that are rounded on top. Failing this use an impedance meter to measure the condenser impedance in circuit without un soldering it. Not un soldering it saves a lot of time. Any condenser with a impedance higher than a few ohms at 10 KHz and you found your problem. The down side is they do not sell condenser in circuit impedance meters so you have to make it yourself. Not a big deal as it just requires 10 KHz at a low impedance with about 100 m volts then monitor the current.


Google "blue meter" or "Bob Parkers ESR meter".

Nice find. Way better than my home brew ESR.

use the Chevy Method....measure then replace the suspect area.

On 12/30/2015 10:26 PM, Rheilly Phoull wrote:
On 31/12/2015 2:19 PM, John Heath wrote:
On Wednesday, December 30, 2015 at 9:09:28 PM UTC-5, John Robertson
wrote:
On 12/30/2015 4:10 PM, John Heath wrote:
I remember working for a company that imported cheap radios. I took
my seat with the other 20 or so techs repairing radios. Most quotas
were in the 20 range while I was only repairing 3 or 5 radios a day.
Thinking I would be handed my pink slip I asked the tech next to
myself how he was repairing so many radios? He pointed to my draw
where I had saves some diagrams off the back of some of the radios.
There is your problem he said. You are over thinking wasting time.
You can measure 6 transistors faster than you can think if they are
RF , audio or IF. In short stop thinking and start measuring. When I
looked around I could see that the other tech were measuring not
thinking. I took his advise and my quota when up from 3 a day to 10.
A lesson I did not forget and still use today. I would like to know
if others have found this to be true.


Well, in my field (arcade game repairs - video, pinball, etc.) we (the
industry) used to trouble shoot monitors looking for the exact problem.
Then some lazy tech started simply replacing all the electrolytic
capacitors in the monitors - and the service rate went from a few
monitors a day to five or more. In 90% of the cases replacing the caps
and the HOT (and fuse) fixed most problems, changing the caps, HOT and
LOPT/Flyback fixed most of the rest. Leaving 5% as dogs that one could
spend a day on - if the customer thought it was worth the money.

Mr & Mrs. Gilbreth (Cheaper By The Dozen) who in their Time Management
process would often watch the laziest employee as he (she) would usually
have the best way of doing the job with a minimum of effort or fuss.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

A friend of mine has an old school arcade machine. No CPUs or monitors
in this puppy. Just a pile of relays and paddle wheels. Great stuff. I
could not find the tilt detector?

I found a short cut for flat electrolytic condensers in monitors and
switching power supplies. First check if condensers that are rounded
on top. Failing this use an impedance meter to measure the condenser
impedance in circuit without un soldering it. Not un soldering it
saves a lot of time. Any condenser with a impedance higher than a few
ohms at 10 KHz and you found your problem. The down side is they do
not sell condenser in circuit impedance meters so you have to make it
yourself. Not a big deal as it just requires 10 KHz at a low impedance
with about 100 m volts then monitor the current.


Google "blue meter" or "Bob Parkers ESR meter".

Indeed, I've been selling those meters since 1999 when I first starting
chatting with Bob Parker (Dick Smith K-7204 kits in those days). Great
ESR meter that works in circuit for roughly values between 4ufd to about
1000ufd.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Wed, 30 Dec 2015 16:10:40 -0800 (PST), John Heath
wrote:

I would like to know if others have found this to be true.

It's true, but only if you have a production line environment. During
the late 1960's, I worked for a company that did warranty service on
mostly consumer tape recorders. We would get the rejects and returns
from the distributor. We had 4 people working the line. One to unbox
and machine and organize the paperwork. One do to nothing but
diagnostics. Me to tear it apart and do parts replacement, more
testing, and reassembly. One more to do more paperwork, a final
check, and reboxing. Anything that couldn't be fixed in 10-15 mins
was put aside for later troubleshooting. Anything with more than 5
faults was deemed not worth repairing. It was quite efficient. As I
vaguely recall, we could do about 4 to 10 machines per hour.

What was interesting was the general lack of test equipment. As you
noted, it takes far too much time to setup and probe. For audio,
putting a finger on the base of a transistor and listening for hum
worked well. To make it quick an easy, we had cardboard templates,
with holes punched for all the common injection points with notes on
what to expect.

Head alignment and channel balancing was a different story. For that,
we had a separate test fixture near final check. It had an audio
generator and oscilloscope, but with a good ear, the scope wasn't
really necessary. Unfortunately, this doubled the cycle time adding
an additional 4 to 10 minutes.

After you've worked on several hundred of exactly the same model tape
recorder, you see patterns of failure. For example, if some component
was inserted backwards on the first 10 or so units, it's a fair guess
that the rest had the same problem. So, pre-emptive replacement was
possible and worked well.

Fast forward 30 years and I'm now doing marine radios and data
transceivers. Over about a 10 year period, I was either involved or
watched at least 5 different product test and QA systems. The one
that worked best was visual inspection. I brought some of the
assemblers into test to do the inspection. They couldn't read a
resistor color code, but they could spot anything that had changed
quite easily. The worst was a complex series of bench tests required
by the customer, which involved a large pile of test equipment. I did
a quick time-and-motion study and found that 30% of the test time was
in setup, changing setup, and teardown. This would have been a great
candidate for computer driven ATE (automagic test equipment) except
that the PC of fashion at the time was an Apple III and RS Model II.
We tried, and failed. So, we continued to use a pile of test
equipment for test and troubleshooting. After about 3 years of this,
some of the rotary switches on the HP equipment started to fail.

Somewhat later, I had changed company and now had a product with
sufficient quantity to justify ATE. The PC of fashion was the HP 9816
with an HP-IB(IEEE488) bus. It controlled a rack full of HP RF test
equipment. I don't have time to go into detail on the setup. When it
worked, it was great and could test, align(tune), print measurements,
print reports, and live test amazingly quickly. When it didn't work,
everything came to a grinding halt. I recall having 4 techs at idle
while someone furiously drove to Fry's to buy a replacement part. I
wanted to build a manually operated backup test line but management
vetoed the idea. Getting all the equipment calibrated at the same
time was tricky, but reduced downtime. ATE would have been a marginal
failure had I not been able to "borrow" test equipment from the
engineering dept.

However, that was production test, not troubleshooting. When the
manual or ATE test line declared something worthy of troubleshooting,
it was NOT done while there were units waiting to be tested. If the
products were cheap enough, they could just be "remanufactured" which
means tear them apart down to the board level, run them back through
board test, and build a "new" unit. This worked well with radios that
had plugin cards. Eventually, there was a backlog of boards to be
troubleshot. Usually between production runs and contracts, someone
would decide that it's time to clean up the backlog. However, instead
of having the test techs do the troubleshooting, the engineer who
designed the radio would be sentence to overtime diagnosing the
boards. Yeah, that was usually me. Unless the problem was trivial, I
would only tag the likely parts, borrow someone that could do the
soldering, retest the board, and send it on to production test. This
worked well when we needed 25 identical board immediately, and was a
total waste of time for 5 or less boards that took too long to setup.

Today, much of what I see is ATE run by techs that only know how to
push the buttons. Troubleshooting is done partly with BITE (built in
test equipment). Parts replacement and soldering is outsourced to a
contractor, specialty shop, or refurbisher. In short, there's nobody
on the production line that knows which end of the soldering iron to
grab, much less how the product actually works. The rule is that
production must continue unimpeded by any form of troubleshooting or
repair. If there is any troubleshooting, it's to fix the production
line and ATE, not the actual product.

Might as well say something about bugs and fixes. With todays fairly
short product lives (typically about 6 months), it's not uncommon for
a company to have 3 or 4 generations of replacement products in
development at the same time. If something is found lacking or
defective in the current product, it is cheaper and easier to simply
wait for the next model to appear in production, and replace it with a
later version. What this means is that NOTHING gets fixed in
production, even when it's a known problem, easy fix, or major
enhancement. If you see products with known design flaws that
continue to be manufactured with the flaws, you now know why.
http://www.designnews.com/archives.asp?section_id=1367

Of course, there will still be independent repair shops (like mine)
that fix things one at a time. They're a dying breed mostly because
of the declining cost of modern electronics. As the retail price of
new hardware declines, the amount of money that a customer is willing
to pay for a repair also declines. As a rule-of-thumb, most customers
will buy a new replacment instead of repairing something when the
repair cost exceeds 50% of the replacement cost. So, if someone drags
in an out of warranty laptop that cost them $500 about 3 years ago, my
maximum bill (parts+labor) cannot exceed $250. Assuming no parts were
replaced, that 3.3 hrs at $75/hr. The number of things I can fix in
under 3.3 hrs is rapidly shrinking. For example, I have an APC XS1300
UPS on the bench that can be purchased new for about $125. In order
to replace one lousy bulging electrolytic capacitor, I've already
burned 2 hrs and I'm not done. Can I bill the customer $150 to fix a
$125 UPS? Nope.

So, the question isn't as much how to troubleshoot, but whether it's
worth you time troubleshooting in the first place.

Happy end of the tax 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

Per Jeff Liebermann:
What was interesting was the general lack of test equipment. As you
noted, it takes far too much time to setup and probe. For audio,
putting a finger on the base of a transistor and listening for hum
worked well. To make it quick an easy, we had cardboard templates,
with holes punched for all the common injection points with notes on
what to expect.

I "repaired" early digital-type equipment in the Air Force.

Quotes because it turned out that all we did was find the failed circuit
boards and replace them - leaving the actual repair work on the boards
to the old-timers.

We were told "Follow your nose".... and that proved to be the way almost
all of the time.... you could locate the board with the failed component
by smell and then visually verify after the board was pulled.

I don't suppose that monkeys could be trained to do that.... but I am
pretty sure than anybody with a room-temperature IQ could....

Six months of technical training at taxpayer expense down the drain....
Oh well.... -)
--
Pete Cresswell

On Thursday, December 31, 2015 at 12:14:59 PM UTC-5, Jeff Liebermann wrote:
On Wed, 30 Dec 2015 16:10:40 -0800 (PST), John Heath
wrote:

I would like to know if others have found this to be true.

It's true, but only if you have a production line environment. During
the late 1960's, I worked for a company that did warranty service on
mostly consumer tape recorders. We would get the rejects and returns
from the distributor. We had 4 people working the line. One to unbox
and machine and organize the paperwork. One do to nothing but
diagnostics. Me to tear it apart and do parts replacement, more
testing, and reassembly. One more to do more paperwork, a final
check, and reboxing. Anything that couldn't be fixed in 10-15 mins
was put aside for later troubleshooting. Anything with more than 5
faults was deemed not worth repairing. It was quite efficient. As I
vaguely recall, we could do about 4 to 10 machines per hour.

What was interesting was the general lack of test equipment. As you
noted, it takes far too much time to setup and probe. For audio,
putting a finger on the base of a transistor and listening for hum
worked well. To make it quick an easy, we had cardboard templates,
with holes punched for all the common injection points with notes on
what to expect.

Head alignment and channel balancing was a different story. For that,
we had a separate test fixture near final check. It had an audio
generator and oscilloscope, but with a good ear, the scope wasn't
really necessary. Unfortunately, this doubled the cycle time adding
an additional 4 to 10 minutes.

After you've worked on several hundred of exactly the same model tape
recorder, you see patterns of failure. For example, if some component
was inserted backwards on the first 10 or so units, it's a fair guess
that the rest had the same problem. So, pre-emptive replacement was
possible and worked well.

Fast forward 30 years and I'm now doing marine radios and data
transceivers. Over about a 10 year period, I was either involved or
watched at least 5 different product test and QA systems. The one
that worked best was visual inspection. I brought some of the
assemblers into test to do the inspection. They couldn't read a
resistor color code, but they could spot anything that had changed
quite easily. The worst was a complex series of bench tests required
by the customer, which involved a large pile of test equipment. I did
a quick time-and-motion study and found that 30% of the test time was
in setup, changing setup, and teardown. This would have been a great
candidate for computer driven ATE (automagic test equipment) except
that the PC of fashion at the time was an Apple III and RS Model II.
We tried, and failed. So, we continued to use a pile of test
equipment for test and troubleshooting. After about 3 years of this,
some of the rotary switches on the HP equipment started to fail.

Somewhat later, I had changed company and now had a product with
sufficient quantity to justify ATE. The PC of fashion was the HP 9816
with an HP-IB(IEEE488) bus. It controlled a rack full of HP RF test
equipment. I don't have time to go into detail on the setup. When it
worked, it was great and could test, align(tune), print measurements,
print reports, and live test amazingly quickly. When it didn't work,
everything came to a grinding halt. I recall having 4 techs at idle
while someone furiously drove to Fry's to buy a replacement part. I
wanted to build a manually operated backup test line but management
vetoed the idea. Getting all the equipment calibrated at the same
time was tricky, but reduced downtime. ATE would have been a marginal
failure had I not been able to "borrow" test equipment from the
engineering dept.

However, that was production test, not troubleshooting. When the
manual or ATE test line declared something worthy of troubleshooting,
it was NOT done while there were units waiting to be tested. If the
products were cheap enough, they could just be "remanufactured" which
means tear them apart down to the board level, run them back through
board test, and build a "new" unit. This worked well with radios that
had plugin cards. Eventually, there was a backlog of boards to be
troubleshot. Usually between production runs and contracts, someone
would decide that it's time to clean up the backlog. However, instead
of having the test techs do the troubleshooting, the engineer who
designed the radio would be sentence to overtime diagnosing the
boards. Yeah, that was usually me. Unless the problem was trivial, I
would only tag the likely parts, borrow someone that could do the
soldering, retest the board, and send it on to production test. This
worked well when we needed 25 identical board immediately, and was a
total waste of time for 5 or less boards that took too long to setup.

Today, much of what I see is ATE run by techs that only know how to
push the buttons. Troubleshooting is done partly with BITE (built in
test equipment). Parts replacement and soldering is outsourced to a
contractor, specialty shop, or refurbisher. In short, there's nobody
on the production line that knows which end of the soldering iron to
grab, much less how the product actually works. The rule is that
production must continue unimpeded by any form of troubleshooting or
repair. If there is any troubleshooting, it's to fix the production
line and ATE, not the actual product.

Might as well say something about bugs and fixes. With todays fairly
short product lives (typically about 6 months), it's not uncommon for
a company to have 3 or 4 generations of replacement products in
development at the same time. If something is found lacking or
defective in the current product, it is cheaper and easier to simply
wait for the next model to appear in production, and replace it with a
later version. What this means is that NOTHING gets fixed in
production, even when it's a known problem, easy fix, or major
enhancement. If you see products with known design flaws that
continue to be manufactured with the flaws, you now know why.
http://www.designnews.com/archives.asp?section_id=1367

Of course, there will still be independent repair shops (like mine)
that fix things one at a time. They're a dying breed mostly because
of the declining cost of modern electronics. As the retail price of
new hardware declines, the amount of money that a customer is willing
to pay for a repair also declines. As a rule-of-thumb, most customers
will buy a new replacment instead of repairing something when the
repair cost exceeds 50% of the replacement cost. So, if someone drags
in an out of warranty laptop that cost them $500 about 3 years ago, my
maximum bill (parts+labor) cannot exceed $250. Assuming no parts were
replaced, that 3.3 hrs at $75/hr. The number of things I can fix in
under 3.3 hrs is rapidly shrinking. For example, I have an APC XS1300
UPS on the bench that can be purchased new for about $125. In order
to replace one lousy bulging electrolytic capacitor, I've already
burned 2 hrs and I'm not done. Can I bill the customer $150 to fix a
$125 UPS? Nope.

So, the question isn't as much how to troubleshoot, but whether it's
worth you time troubleshooting in the first place.

Happy end of the tax 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

Sounds like you touched a lot of bases in the service life. I took a similar path ending up self employed for about the last 25 years. It has changed so much from the old days walking around with a tube caddy cleaning TV tuners. I now walk around with a laptop pinging IP addresses. How did that happen? I think the writing is on the wall. How many shoe repair and watch repair shops do you see. The electronic repair tech could meet the same fate. Just the other day I saw a flat screen monitor sitting in a garbage bin. To see the rain falling on it was too much so I took it inside. When I plugged it in everything worked and it had a VGA plus DVI input! What was that doing in the garbage. My only guess is someone wanted a wider flatter monitor so he or she tossed it out. I am typing on that monitor as we speak. How can one make a living in service with this going on. It is so bad that I have to work on 50,000 dollar LED displays boards. They will still fix those at that price. Just about everything else is disposable. However I have no regrets as electronics has been an existing ride with technology changing so fast that there is never a dull moment.

On 12/31/2015 12:14 PM, John Heath wrote:
On Thursday, December 31, 2015 at 12:14:59 PM UTC-5, Jeff Liebermann wrote:
On Wed, 30 Dec 2015 16:10:40 -0800 (PST), John Heath
wrote:

I would like to know if others have found this to be true.

It's true, but only if you have a production line environment. During
the late 1960's, I worked for a company that did warranty service on
mostly consumer tape recorders. We would get the rejects and returns
from the distributor. We had 4 people working the line. One to unbox
and machine and organize the paperwork. One do to nothing but
diagnostics. Me to tear it apart and do parts replacement, more
testing, and reassembly. One more to do more paperwork, a final
check, and reboxing. Anything that couldn't be fixed in 10-15 mins
was put aside for later troubleshooting. Anything with more than 5
faults was deemed not worth repairing. It was quite efficient. As I
vaguely recall, we could do about 4 to 10 machines per hour.

What was interesting was the general lack of test equipment. As you
noted, it takes far too much time to setup and probe. For audio,
putting a finger on the base of a transistor and listening for hum
worked well. To make it quick an easy, we had cardboard templates,
with holes punched for all the common injection points with notes on
what to expect.

Head alignment and channel balancing was a different story. For that,
we had a separate test fixture near final check. It had an audio
generator and oscilloscope, but with a good ear, the scope wasn't
really necessary. Unfortunately, this doubled the cycle time adding
an additional 4 to 10 minutes.

After you've worked on several hundred of exactly the same model tape
recorder, you see patterns of failure. For example, if some component
was inserted backwards on the first 10 or so units, it's a fair guess
that the rest had the same problem. So, pre-emptive replacement was
possible and worked well.

Fast forward 30 years and I'm now doing marine radios and data
transceivers. Over about a 10 year period, I was either involved or
watched at least 5 different product test and QA systems. The one
that worked best was visual inspection. I brought some of the
assemblers into test to do the inspection. They couldn't read a
resistor color code, but they could spot anything that had changed
quite easily. The worst was a complex series of bench tests required
by the customer, which involved a large pile of test equipment. I did
a quick time-and-motion study and found that 30% of the test time was
in setup, changing setup, and teardown. This would have been a great
candidate for computer driven ATE (automagic test equipment) except
that the PC of fashion at the time was an Apple III and RS Model II.
We tried, and failed. So, we continued to use a pile of test
equipment for test and troubleshooting. After about 3 years of this,
some of the rotary switches on the HP equipment started to fail.

Somewhat later, I had changed company and now had a product with
sufficient quantity to justify ATE. The PC of fashion was the HP 9816
with an HP-IB(IEEE488) bus. It controlled a rack full of HP RF test
equipment. I don't have time to go into detail on the setup. When it
worked, it was great and could test, align(tune), print measurements,
print reports, and live test amazingly quickly. When it didn't work,
everything came to a grinding halt. I recall having 4 techs at idle
while someone furiously drove to Fry's to buy a replacement part. I
wanted to build a manually operated backup test line but management
vetoed the idea. Getting all the equipment calibrated at the same
time was tricky, but reduced downtime. ATE would have been a marginal
failure had I not been able to "borrow" test equipment from the
engineering dept.

However, that was production test, not troubleshooting. When the
manual or ATE test line declared something worthy of troubleshooting,
it was NOT done while there were units waiting to be tested. If the
products were cheap enough, they could just be "remanufactured" which
means tear them apart down to the board level, run them back through
board test, and build a "new" unit. This worked well with radios that
had plugin cards. Eventually, there was a backlog of boards to be
troubleshot. Usually between production runs and contracts, someone
would decide that it's time to clean up the backlog. However, instead
of having the test techs do the troubleshooting, the engineer who
designed the radio would be sentence to overtime diagnosing the
boards. Yeah, that was usually me. Unless the problem was trivial, I
would only tag the likely parts, borrow someone that could do the
soldering, retest the board, and send it on to production test. This
worked well when we needed 25 identical board immediately, and was a
total waste of time for 5 or less boards that took too long to setup.

Today, much of what I see is ATE run by techs that only know how to
push the buttons. Troubleshooting is done partly with BITE (built in
test equipment). Parts replacement and soldering is outsourced to a
contractor, specialty shop, or refurbisher. In short, there's nobody
on the production line that knows which end of the soldering iron to
grab, much less how the product actually works. The rule is that
production must continue unimpeded by any form of troubleshooting or
repair. If there is any troubleshooting, it's to fix the production
line and ATE, not the actual product.

Might as well say something about bugs and fixes. With todays fairly
short product lives (typically about 6 months), it's not uncommon for
a company to have 3 or 4 generations of replacement products in
development at the same time. If something is found lacking or
defective in the current product, it is cheaper and easier to simply
wait for the next model to appear in production, and replace it with a
later version. What this means is that NOTHING gets fixed in
production, even when it's a known problem, easy fix, or major
enhancement. If you see products with known design flaws that
continue to be manufactured with the flaws, you now know why.
http://www.designnews.com/archives.asp?section_id=1367

Of course, there will still be independent repair shops (like mine)
that fix things one at a time. They're a dying breed mostly because
of the declining cost of modern electronics. As the retail price of
new hardware declines, the amount of money that a customer is willing
to pay for a repair also declines. As a rule-of-thumb, most customers
will buy a new replacment instead of repairing something when the
repair cost exceeds 50% of the replacement cost. So, if someone drags
in an out of warranty laptop that cost them $500 about 3 years ago, my
maximum bill (parts+labor) cannot exceed $250. Assuming no parts were
replaced, that 3.3 hrs at $75/hr. The number of things I can fix in
under 3.3 hrs is rapidly shrinking. For example, I have an APC XS1300
UPS on the bench that can be purchased new for about $125. In order
to replace one lousy bulging electrolytic capacitor, I've already
burned 2 hrs and I'm not done. Can I bill the customer $150 to fix a
$125 UPS? Nope.

So, the question isn't as much how to troubleshoot, but whether it's
worth you time troubleshooting in the first place.

Happy end of the tax 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

Sounds like you touched a lot of bases in the service life. I took a similar path ending up self employed for about the last 25 years. It has changed so much from the old days walking around with a tube caddy cleaning TV tuners. I now walk around with a laptop pinging IP addresses. How did that happen? I think the writing is on the wall. How many shoe repair and watch repair shops do you see. The electronic repair tech could meet the same fate. Just the other day I saw a flat screen monitor sitting in a garbage bin. To see the rain falling on it was too much so I took it inside. When I plugged it in everything worked and it had a VGA plus DVI input! What was that doing in the garbage. My only guess is someone wanted a wider flatter monitor so he or she tossed it out. I am typing on that monitor as we speak. How can one make a living in service with this going on. It is so bad that I have to work on 50,000 dollar LED displays boards. They will still fix those at that price. Just abou
t everything else is disposable. However I have no regrets as electronics has been an existing ride with technology changing so fast that there is never a dull moment.


There is always arcade game repair. There is enough interest in that
that most cities need a few people who do house calls.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Thu, 31 Dec 2015 13:46:01 -0500, "(PeteCresswell)"
wrote:

I "repaired" early digital-type equipment in the Air Force.

Quotes because it turned out that all we did was find the failed circuit
boards and replace them - leaving the actual repair work on the boards
to the old-timers.

In my checkered past, I once helped design two direction finders for
the USCG AN/SRD-21 and 22. After shipping a fair number of these
radios, I was given a tour of the local repair facility on Treasure
Island in SF Bay. Sitting pilled in one corner was about 50 radios,
in various stages of cannibalization. So much for spare parts.

We were told "Follow your nose".... and that proved to be the way almost
all of the time.... you could locate the board with the failed component
by smell and then visually verify after the board was pulled.

Yeah, I do the same. I would prefer an FLIR infrared imager, but the
nose will do for now. I also have a NIKKEN #1394 "air wellness air
quality monitor".
http://802.11junk.com/jeffl/crud/Nikken-AQM.jpg
It's a nephelmometer which uses light scattering to detect airborne
dust particles.
http://en.wikipedia.org/wiki/Nephelometer
Overkill:
http://www.esrl.noaa.gov/gmd/aero/instrumentation/neph_desc.html
It's been useful for finding what is burning in the office and
locating the component producing the smoke. I've also used it to
chase down the source of a white dust in a customers air ducts.

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

John Robertson wrote:


Google "blue meter" or "Bob Parkers ESR meter".

Indeed, I've been selling those meters since 1999 when I first starting
chatting with Bob Parker (Dick Smith K-7204 kits in those days). Great
ESR meter that works in circuit for roughly values between 4ufd to about
1000ufd.


** I find Bob's ESR meter useful with electro caps anywhere from 1uF to over 15,000uF. It also checks the ESR of tantalum electros. film caps from about 0.47uF upwards - for shorts and opens.

Another use is with batteries, particularly Lithium button cells plus any type of AA, AA and 9V battery.

As with caps, known good examples are your reference and ESR readings rise as the cell goes flat. A 20x3mm Lithium reads about 10 ohms when new rising to 100 ohms or more at end of life.


.... Phil

On Thursday, December 31, 2015 at 3:28:53 PM UTC-5, John Robertson wrote:
On 12/31/2015 12:14 PM, John Heath wrote:
On Thursday, December 31, 2015 at 12:14:59 PM UTC-5, Jeff Liebermann wrote:
On Wed, 30 Dec 2015 16:10:40 -0800 (PST), John Heath
wrote:

I would like to know if others have found this to be true.

It's true, but only if you have a production line environment. During
the late 1960's, I worked for a company that did warranty service on
mostly consumer tape recorders. We would get the rejects and returns
from the distributor. We had 4 people working the line. One to unbox
and machine and organize the paperwork. One do to nothing but
diagnostics. Me to tear it apart and do parts replacement, more
testing, and reassembly. One more to do more paperwork, a final
check, and reboxing. Anything that couldn't be fixed in 10-15 mins
was put aside for later troubleshooting. Anything with more than 5
faults was deemed not worth repairing. It was quite efficient. As I
vaguely recall, we could do about 4 to 10 machines per hour.

What was interesting was the general lack of test equipment. As you
noted, it takes far too much time to setup and probe. For audio,
putting a finger on the base of a transistor and listening for hum
worked well. To make it quick an easy, we had cardboard templates,
with holes punched for all the common injection points with notes on
what to expect.

Head alignment and channel balancing was a different story. For that,
we had a separate test fixture near final check. It had an audio
generator and oscilloscope, but with a good ear, the scope wasn't
really necessary. Unfortunately, this doubled the cycle time adding
an additional 4 to 10 minutes.

After you've worked on several hundred of exactly the same model tape
recorder, you see patterns of failure. For example, if some component
was inserted backwards on the first 10 or so units, it's a fair guess
that the rest had the same problem. So, pre-emptive replacement was
possible and worked well.

Fast forward 30 years and I'm now doing marine radios and data
transceivers. Over about a 10 year period, I was either involved or
watched at least 5 different product test and QA systems. The one
that worked best was visual inspection. I brought some of the
assemblers into test to do the inspection. They couldn't read a
resistor color code, but they could spot anything that had changed
quite easily. The worst was a complex series of bench tests required
by the customer, which involved a large pile of test equipment. I did
a quick time-and-motion study and found that 30% of the test time was
in setup, changing setup, and teardown. This would have been a great
candidate for computer driven ATE (automagic test equipment) except
that the PC of fashion at the time was an Apple III and RS Model II.
We tried, and failed. So, we continued to use a pile of test
equipment for test and troubleshooting. After about 3 years of this,
some of the rotary switches on the HP equipment started to fail.

Somewhat later, I had changed company and now had a product with
sufficient quantity to justify ATE. The PC of fashion was the HP 9816
with an HP-IB(IEEE488) bus. It controlled a rack full of HP RF test
equipment. I don't have time to go into detail on the setup. When it
worked, it was great and could test, align(tune), print measurements,
print reports, and live test amazingly quickly. When it didn't work,
everything came to a grinding halt. I recall having 4 techs at idle
while someone furiously drove to Fry's to buy a replacement part. I
wanted to build a manually operated backup test line but management
vetoed the idea. Getting all the equipment calibrated at the same
time was tricky, but reduced downtime. ATE would have been a marginal
failure had I not been able to "borrow" test equipment from the
engineering dept.

However, that was production test, not troubleshooting. When the
manual or ATE test line declared something worthy of troubleshooting,
it was NOT done while there were units waiting to be tested. If the
products were cheap enough, they could just be "remanufactured" which
means tear them apart down to the board level, run them back through
board test, and build a "new" unit. This worked well with radios that
had plugin cards. Eventually, there was a backlog of boards to be
troubleshot. Usually between production runs and contracts, someone
would decide that it's time to clean up the backlog. However, instead
of having the test techs do the troubleshooting, the engineer who
designed the radio would be sentence to overtime diagnosing the
boards. Yeah, that was usually me. Unless the problem was trivial, I
would only tag the likely parts, borrow someone that could do the
soldering, retest the board, and send it on to production test. This
worked well when we needed 25 identical board immediately, and was a
total waste of time for 5 or less boards that took too long to setup.

Today, much of what I see is ATE run by techs that only know how to
push the buttons. Troubleshooting is done partly with BITE (built in
test equipment). Parts replacement and soldering is outsourced to a
contractor, specialty shop, or refurbisher. In short, there's nobody
on the production line that knows which end of the soldering iron to
grab, much less how the product actually works. The rule is that
production must continue unimpeded by any form of troubleshooting or
repair. If there is any troubleshooting, it's to fix the production
line and ATE, not the actual product.

Might as well say something about bugs and fixes. With todays fairly
short product lives (typically about 6 months), it's not uncommon for
a company to have 3 or 4 generations of replacement products in
development at the same time. If something is found lacking or
defective in the current product, it is cheaper and easier to simply
wait for the next model to appear in production, and replace it with a
later version. What this means is that NOTHING gets fixed in
production, even when it's a known problem, easy fix, or major
enhancement. If you see products with known design flaws that
continue to be manufactured with the flaws, you now know why.
http://www.designnews.com/archives.asp?section_id=1367

Of course, there will still be independent repair shops (like mine)
that fix things one at a time. They're a dying breed mostly because
of the declining cost of modern electronics. As the retail price of
new hardware declines, the amount of money that a customer is willing
to pay for a repair also declines. As a rule-of-thumb, most customers
will buy a new replacment instead of repairing something when the
repair cost exceeds 50% of the replacement cost. So, if someone drags
in an out of warranty laptop that cost them $500 about 3 years ago, my
maximum bill (parts+labor) cannot exceed $250. Assuming no parts were
replaced, that 3.3 hrs at $75/hr. The number of things I can fix in
under 3.3 hrs is rapidly shrinking. For example, I have an APC XS1300
UPS on the bench that can be purchased new for about $125. In order
to replace one lousy bulging electrolytic capacitor, I've already
burned 2 hrs and I'm not done. Can I bill the customer $150 to fix a
$125 UPS? Nope.

So, the question isn't as much how to troubleshoot, but whether it's
worth you time troubleshooting in the first place.

Happy end of the tax 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

Sounds like you touched a lot of bases in the service life. I took a similar path ending up self employed for about the last 25 years. It has changed so much from the old days walking around with a tube caddy cleaning TV tuners. I now walk around with a laptop pinging IP addresses. How did that happen? I think the writing is on the wall. How many shoe repair and watch repair shops do you see. The electronic repair tech could meet the same fate. Just the other day I saw a flat screen monitor sitting in a garbage bin. To see the rain falling on it was too much so I took it inside. When I plugged it in everything worked and it had a VGA plus DVI input! What was that doing in the garbage. My only guess is someone wanted a wider flatter monitor so he or she tossed it out. I am typing on that monitor as we speak. How can one make a living in service with this going on. It is so bad that I have to work on 50,000 dollar LED displays boards. They will still fix those at that price. Just abou
t everything else is disposable. However I have no regrets as electronics has been an existing ride with technology changing so fast that there is never a dull moment.


There is always arcade game repair. There is enough interest in that
that most cities need a few people who do house calls.

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

I noted you are from Vancouver. I grew up there until about 14 then Montreal and now Toronto. Fond memories of biking down to Kitsilano beach.

I'm a mechanical engineer but I've been in management a long time, I don't get to do much technical stuff.

This week I got called to a gas leak. The emergency response and the mechanics had already been there and confirmed safe to reoccupy, but somebody wasn't so sure and called me.

These things are 80% one problem and 9% the other. The crew that showed up found and fixed the 80% problem, but it wasn't actually causing the leak. The leak was somewhere else. Just because one thing is broken doesn't mean something else isn't broken too.

Once a problem is identified, attentional blindness sets in. Contrary evidence is not just ignored, it cannot be seen.

In this case the pilot light was out in the kitchen, and they assumed the gas smell came from it. They shut off the gas to the kitchen and authorized the building to be reoccupied.

They ignored the evidence the real leak was somewhere else - well, they were incapable of seeing that evidence because they already knew what was wrong.

When I got on scene it took little time to find where the smell was coming from. Partly that's from my bias to try to avoid assigning the cause until I've looked at all the evidence, but partly it's from knowing human nature and knowing if it were the usual problem they would have fixed it the first time, and it obviously wasn't.

I sent the mechanics back and told them where to look, and the second trip they fixed it correctly. Of course I had to keep quiet my part in it, there's always politics in these things.

So yes, fix the most likely fault first, but bear in mind the potential cost of it being something else.

On Friday, January 1, 2016 at 9:41:01 PM UTC-5, Tim R wrote:
I'm a mechanical engineer but I've been in management a long time, I don't get to do much technical stuff.

This week I got called to a gas leak. The emergency response and the mechanics had already been there and confirmed safe to reoccupy, but somebody wasn't so sure and called me.

These things are 80% one problem and 9% the other. The crew that showed up found and fixed the 80% problem, but it wasn't actually causing the leak.. The leak was somewhere else. Just because one thing is broken doesn't mean something else isn't broken too.



Once a problem is identified, attentional blindness sets in. Contrary evidence is not just ignored, it cannot be seen.

In this case the pilot light was out in the kitchen, and they assumed the gas smell came from it. They shut off the gas to the kitchen and authorized the building to be reoccupied.

They ignored the evidence the real leak was somewhere else - well, they were incapable of seeing that evidence because they already knew what was wrong.

When I got on scene it took little time to find where the smell was coming from. Partly that's from my bias to try to avoid assigning the cause until I've looked at all the evidence, but partly it's from knowing human nature and knowing if it were the usual problem they would have fixed it the first time, and it obviously wasn't.

I sent the mechanics back and told them where to look, and the second trip they fixed it correctly. Of course I had to keep quiet my part in it, there's always politics in these things.

So yes, fix the most likely fault first, but bear in mind the potential cost of it being something else.

I hear that. I remember being stuck on a problem so I asked a friend for a fresh look at it. He looks around then thought about it for a minute. He then looked at me and said " if you touch your head and it hurts and you touch you arm and it hurts and you touch your toe and it hurts maybe it is your finger that is the problem ". That was a strange way to put it but he was 100 percent right as I had my scope probe on 1 to 1 instead of 10 to 1 causing a loading problem. It is always a good idea to get a second opinion when you are spinning your wheels.

Another unrelated problem. You being an engineer will enjoy this one. The city has a water leak. They are not sure where the leak is. They can not dig up a whole city block to find it so they use a clever trick. They put two microphones about 50 feet apart where the leak seems to be. Then then record the random sound of water hissing out of the pipe. The two microphones are wired to left and right channel of the recorder. By adjusting the time delay of the right or left microphone they can find the sweet spot where the random noise from one microphone matches the random noise of the other microphone. Once the delay is know they know where the leak is within 1 or 2 feet. That is a clever trick.

There is a similar trick in cabling. You send a pulse down a cable that is about 80 percent c propagation speed. If you hear an echo you have a problem. By timing the echo at 80 percent c you know where the problem is.

"Another unrelated problem. You being an engineer will enjoy this one. The city has a water leak. They are not sure where the leak is. They can not dig up a whole city block to find it so they use a clever trick. They put two microphones about 50 feet apart where the leak seems to be. Then then record the random sound of water hissing out of the pipe. The two microphones are wired to left and right channel of the recorder. By adjusting the time delay of the right or left microphone they can find the sweet spot where the random noise from one microphone matches the random noise of the other microphone. Once the delay is know they know where the leak is within 1 or 2 feet. That is a clever trick. "

HA, HAHAHAHAHAH

HydroTDR

Water Domain reflectometry

Feel free to add your own, this could be fun. Water Wave Technology.

Oh, and sound is so much faster in water, but then that gives alot more accurate transmission, which os probably necessary to make this possible.

WDR. Water Domain Reflectometerty.

Yeah fukit

On Saturday, January 2, 2016 at 2:04:06 AM UTC-5, wrote:
"Another unrelated problem. You being an engineer will enjoy this one. The city has a water leak. They are not sure where the leak is. They can not dig up a whole city block to find it so they use a clever trick. They put two microphones about 50 feet apart where the leak seems to be. Then then record the random sound of water hissing out of the pipe. The two microphones are wired to left and right channel of the recorder. By adjusting the time delay of the right or left microphone they can find the sweet spot where the random noise from one microphone matches the random noise of the other microphone. Once the delay is know they know where the leak is within 1 or 2 feet. That is a clever trick. "

HA, HAHAHAHAHAH

HydroTDR

Hah, I can top that one.

We had a power outage, traced to a break somewhere in an underground line. It was one of those ancient coaxial feeders, and it ran a good quarter mile through the woods, maybe more, it's been a while. How to find the break?

We hired this specialist with a thumper, which is a pulsed high voltage DC. It makes a noise like a gunshot when the arc jumps the gap. You walk the route of the line (which you never know exactly because your drawings are always a little sketchy) and listen.

Usually this works. Not this time - it arced for a while, then somehow the arc welded the break back together. No more pulses, no way to find the spot, we just turned the power back on and let it go.

On Saturday, January 2, 2016 at 10:14:26 AM UTC-5, Tim R wrote:
On Saturday, January 2, 2016 at 2:04:06 AM UTC-5, wrote:
"Another unrelated problem. You being an engineer will enjoy this one.. The city has a water leak. They are not sure where the leak is. They can not dig up a whole city block to find it so they use a clever trick. They put two microphones about 50 feet apart where the leak seems to be. Then then record the random sound of water hissing out of the pipe. The two microphones are wired to left and right channel of the recorder. By adjusting the time delay of the right or left microphone they can find the sweet spot where the random noise from one microphone matches the random noise of the other microphone. Once the delay is know they know where the leak is within 1 or 2 feet. That is a clever trick. "

HA, HAHAHAHAHAH

HydroTDR

Hah, I can top that one.

We had a power outage, traced to a break somewhere in an underground line.. It was one of those ancient coaxial feeders, and it ran a good quarter mile through the woods, maybe more, it's been a while. How to find the break?

We hired this specialist with a thumper, which is a pulsed high voltage DC. It makes a noise like a gunshot when the arc jumps the gap. You walk the route of the line (which you never know exactly because your drawings are always a little sketchy) and listen.

Usually this works. Not this time - it arced for a while, then somehow the arc welded the break back together. No more pulses, no way to find the spot, we just turned the power back on and let it go.

Is the glass half empty or is the glass half full ? The way I see it you repaired the fault by sending a large EM pulse down the line knowing well that this would weld the two wires together therefore fixing the problem. That is the way I would write up the repair report.

For me, it is purely a hobby, with the occasional household appliance or vehicular item intruding on occasion. So 'production' is not an issue, and unless I see my worth, as it were, at very little, spending 12 hours and $20 in parts restoring a pre WW2 Hallicrafters ot 5 hours & $10 on a Dynaco ST120 is a fool's game were it not a hobby. But, as therapy, and as a source of quiet satisfaction, it is unsurpassed.

I tend to be fairly methodical, diagnostics, the repair based on same. Then about a 12-hour burn to make sure whatever it is is actually ready for polite society. No beancounters, no cost limits - a 'bulk' purchase might be 100 very common-value caps, or 20 common transistors, which might last a couple of years.

Peter Wieck
Melrose Park, PA

The st120 is an interesting beast. I did repair one in the 80's AFTER someone made swiss cheese out of it.

On Sunday, January 3, 2016 at 8:24:33 PM UTC-5, Ron D. wrote:
The st120 is an interesting beast. I did repair one in the 80's AFTER someone made swiss cheese out of it.

Yeah - "interesting" is a mild descriptive of a beast that can range from a purring kitten to a rabid wolverine in its behavior. I have three examples in my immediate possession - not one from the same lot or with matching boards...


Peter Wieck
Melrose Park, PA

wrote in message
...
On Sunday, January 3, 2016 at 8:24:33 PM UTC-5, Ron D. wrote:
The st120 is an interesting beast. I did repair one in the 80's AFTER
someone made swiss cheese out of it.

Yeah - "interesting" is a mild descriptive of a beast that can range from
a purring kitten to a rabid wolverine in its behavior. I have three
examples in my immediate possession - not one from the same lot or with
matching boards...


Peter Wieck
Melrose Park, PA



ST-120's.

They're like Harley Davidson motorcycles.

If you love them, if you can fix them, if you don't mind the smell of
carburetor cleaner and the oil stains on your living room floor,

go for it!


Mark Z.