Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....

On 14/12/2015 14:05, Cursitor Doom wrote:
Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....


First analysis instrument to use on removing the case cover - your nose

a) Assume nothing.
b) The nose knows.
c) The complexity of the problem is in inverse proportion to the symptoms displayed.
d) That one problem has been found and fixed does not imply that all problems have been either found or fixed.
f) First cause may be intermittent. What is observed may be secondary.

Peter Wieck
Melrose Park, PA

N_Cook wrote:
On 14/12/2015 14:05, Cursitor Doom wrote:
Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....


First analysis instrument to use on removing the case cover - your nose

smell test is good.

check power, fuses, probe around for expected voltages. For example if
there's any sort of linear regulator check output, input, check voltages
on ICs. I deal with old stuff so there's always some 7400 series logic so
+5 is expected to be all over the place.

Look for burned parts, puffy caps, probe anything in areas with
heat-discolored circit boards, check and resolder and suspect joints by
parts that warms up. Diode check is a great feature on DMMS.

If you're dealing with suspect dried up caps, just solder a new one on
the solder side of the board and see if that helps at all. I like to add
parts on the bottom of the board, get things working then position parts
where they belong if all good.

If these things appear OK, then you have to narrow the problem down and
dig around into what the circuit should do vs. what's happening.

For intermittent problems tap the hell of boards, cable assemblies etc.
Check power supply voltages with the device cold AND after it warms up.

Just came across a machine that would crash fairly often, The problem
appears to be a mix of loose sensor and power connectors, a power supply
that drops voltage as it warms up, plus a dead cooling fan in the
electronics section. Just to keep things interesting, nothing warms up
that much with the service panels removed.

On 14/12/2015 18:02, Cydrome Leader wrote:
N_Cook wrote:
On 14/12/2015 14:05, Cursitor Doom wrote:
Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....


First analysis instrument to use on removing the case cover - your nose

smell test is good.

check power, fuses, probe around for expected voltages. For example if
there's any sort of linear regulator check output, input, check voltages
on ICs. I deal with old stuff so there's always some 7400 series logic so
+5 is expected to be all over the place.

Look for burned parts, puffy caps, probe anything in areas with
heat-discolored circit boards, check and resolder and suspect joints by
parts that warms up. Diode check is a great feature on DMMS.

If you're dealing with suspect dried up caps, just solder a new one on
the solder side of the board and see if that helps at all. I like to add
parts on the bottom of the board, get things working then position parts
where they belong if all good.

If these things appear OK, then you have to narrow the problem down and
dig around into what the circuit should do vs. what's happening.

For intermittent problems tap the hell of boards, cable assemblies etc.
Check power supply voltages with the device cold AND after it warms up.

Just came across a machine that would crash fairly often, The problem
appears to be a mix of loose sensor and power connectors, a power supply
that drops voltage as it warms up, plus a dead cooling fan in the
electronics section. Just to keep things interesting, nothing warms up
that much with the service panels removed.









There is problem with "twizzling" for intermittant soder joint failure,
if it is a PbF board. Its too easy to temporarily "fix" a failed joint.
I start with light touching stuff with a bird feather, while switched
on. Then firmer twizzling.
Then hot air or freezer spray.
Then if I auapect a PbF failure ,an adapted engraver tool with a shaped
nylon bolt in place of the engraving tip, to rattle the board, listening
on headphones , if an audio amp.

N_Cook wrote:
On 14/12/2015 18:02, Cydrome Leader wrote:
N_Cook wrote:
On 14/12/2015 14:05, Cursitor Doom wrote:
Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....


First analysis instrument to use on removing the case cover - your nose

smell test is good.

check power, fuses, probe around for expected voltages. For example if
there's any sort of linear regulator check output, input, check voltages
on ICs. I deal with old stuff so there's always some 7400 series logic so
+5 is expected to be all over the place.

Look for burned parts, puffy caps, probe anything in areas with
heat-discolored circit boards, check and resolder and suspect joints by
parts that warms up. Diode check is a great feature on DMMS.

If you're dealing with suspect dried up caps, just solder a new one on
the solder side of the board and see if that helps at all. I like to add
parts on the bottom of the board, get things working then position parts
where they belong if all good.

If these things appear OK, then you have to narrow the problem down and
dig around into what the circuit should do vs. what's happening.

For intermittent problems tap the hell of boards, cable assemblies etc.
Check power supply voltages with the device cold AND after it warms up.

Just came across a machine that would crash fairly often, The problem
appears to be a mix of loose sensor and power connectors, a power supply
that drops voltage as it warms up, plus a dead cooling fan in the
electronics section. Just to keep things interesting, nothing warms up
that much with the service panels removed.









There is problem with "twizzling" for intermittant soder joint failure,
if it is a PbF board. Its too easy to temporarily "fix" a failed joint.
I start with light touching stuff with a bird feather, while switched
on. Then firmer twizzling.
Then hot air or freezer spray.
Then if I auapect a PbF failure ,an adapted engraver tool with a shaped
nylon bolt in place of the engraving tip, to rattle the board, listening
on headphones , if an audio amp.

I'm pleased to say I don't really deal with PbF stuff. How often do you
find bad joints that looked OK (well, as good as PbF looks) and did have
weird cracking or separating from the part lead?

Do you do repairs with real solder or that fake tin stuff?

Cursitor Doom wrote:

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....
Well, usually that is a very good rule, and saves time chasing what you
THINK the problem must be, when in fact it is something novel you haven't
seen before.

But, then, I have repaired a few thing recently, where past experience told
me what the most likely failure was, and that was the correct thing to fix.

Jon

Cursitor Doom wrote:


Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....



** Troubleshooting is like a maze, there are many starting points and blind alleys to negotiate on your the way to the goal.

Unfamiliar equipment requires a more cautious approach than familiar items.

Always observe the fault carefully *before* starting disassembly and find out what functions work and what do not.

Owner's descriptions are often misleading or fail to mention important issues, but you still need to find out what prompted that description.

Bench tests need to simulate actual use or worst case use, but beware of simulating abuse.

When stuck on a problem, take a break and start over a day or so later.




..... Phil

On Monday, December 14, 2015 at 6:07:52 AM UTC-8, Cursitor Doom wrote:
Anyone care to share their experience on the correct approach to
troubleshooting?

Make a block diagram. It may only be a mental picture, but it's an important
step toward tracking a symptom down.

I taught a class of technicians once, from a local factory... the
block-diagram-exercise got them talking amongst themselves more
productively than any other lesson.

This thread, to me, represents the best of what newsgroups like this are
for.

1. The aforementioned "assume nothing". (probably should have been ALL CAPS)

2. Correlate stated or observed malfunction with:
a.) Visual inspection and yes, often smell checks.
b.) Power supply checks.
c.) Again, check for mechanically intermittent connections.

3. Don't assume too much from DC voltage checks with a multimeter. A 'scope
can often give you the best "eyes" into what the circuit is actually doing.

Nevertheless, a good multimeter can give really great information
interpreting voltage drops, finding leaky or shorted nodes, bias issues,
etc.

Too many people just start off re-capping for example, assuming this fixes
almost everything. I'm sick to death of hearing this from customers who have
been on the internet.

Another thread here, I see...

Mark Z.

Phil Allison wrote:
Cursitor Doom wrote:


Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....



** Troubleshooting is like a maze, there are many starting points and
blind alleys to negotiate on your the way to the goal.

Unfamiliar equipment requires a more cautious approach than familiar
items.

Always observe the fault carefully *before* starting disassembly and
find out what functions work and what do not.

Owner's descriptions are often misleading or fail to mention
important issues, but you still need to find out what prompted that
description.

Bench tests need to simulate actual use or worst case use, but beware
of simulating abuse.

When stuck on a problem, take a break and start over a day or so
later.




.... Phil


"When stuck on a problem, take a break and start over a day or so
later." I cannot tell you how many problems I solved while doing that.
Sometimes getting just getting away from the problem allows clearer
thought.

On 15/12/2015 12:24, Ken wrote:
Phil Allison wrote:
Cursitor Doom wrote:


Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....



** Troubleshooting is like a maze, there are many starting points and
blind alleys to negotiate on your the way to the goal.

Unfamiliar equipment requires a more cautious approach than familiar
items.

Always observe the fault carefully *before* starting disassembly and
find out what functions work and what do not.

Owner's descriptions are often misleading or fail to mention
important issues, but you still need to find out what prompted that
description.

Bench tests need to simulate actual use or worst case use, but beware
of simulating abuse.

When stuck on a problem, take a break and start over a day or so
later.




.... Phil


"When stuck on a problem, take a break and start over a day or so
later." I cannot tell you how many problems I solved while doing that.
Sometimes getting just getting away from the problem allows clearer
thought.



Posting a query to some "social media" may not ellicit the solution but
some suggesting will often set you thinking in a different train. Its so
easy to decide in your own mind that the problem must be in some
particular narrow area and you totally overlook a completely valid
alternative area.

Most important, assume nothing. As soon as you think you know what is wrong, it is impossible not to ignore contrary evidence.

I work with some engineers who are good designers because they keep their brain fixed on the goal and work through every obstacle. They THINK they are also good troubleshooters but they are wrong, obstinately frustratingly wrong, for the same reason. They KNOW what is wrong too early, and nothing shakes their belief.

Second. When anybody tells you the symptoms, listen. When they tell you why, STOP! Don't listen. It will probably be theoretically impossible, and then you end up doubting the symptoms. Sorry but this is especially a problem with techs and mechanics. They observe correctly but theorize contrary to the laws of physics, so you need to stop listening when they get to that point.

On 12/15/2015 4:17 AM, Mark Zacharias wrote:
This thread, to me, represents the best of what newsgroups like this are
for.

1. The aforementioned "assume nothing". (probably should have been ALL
CAPS)

2. Correlate stated or observed malfunction with:
a.) Visual inspection and yes, often smell checks.
b.) Power supply checks.
c.) Again, check for mechanically intermittent connections.

3. Don't assume too much from DC voltage checks with a multimeter. A
'scope can often give you the best "eyes" into what the circuit is
actually doing.

Nevertheless, a good multimeter can give really great information
interpreting voltage drops, finding leaky or shorted nodes, bias issues,
etc.

Too many people just start off re-capping for example, assuming this
fixes almost everything. I'm sick to death of hearing this from
customers who have been on the internet.

Another thread here, I see...

Mark Z.

Capacitors?

ducking

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced
are fine, but the rest are marginal at best and make all sorts of errors
creep in that would take hours to find otherwise.

/ducking

While we are in there we check resistors on
collectors/emitters/plates/cathodes as they often drift out of value.
However those we only change if off more than 10%

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."

"John Robertson" wrote in message
...
Capacitors?

ducking

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced are
fine, but the rest are marginal at best and make all sorts of errors creep
in that would take hours to find otherwise.



It all depends on the cost and how much later down time you want to take a
chance on.

At work we had a 200 HP motor drive control that quit and we called in a
factory repair man. He determined that 2 large diodes ( arund 600 volt and
100 amp or so) were bad. AS this was a 3 phase unit , there were 3 diodes.
I told him to replace the 3 rd one as it may have had some stress on it and
may fail later. He said he would but it was $ 50 for the diode. I told
him that at what we were paying him and the ammount of production it would
cost that $ 50 was nothing worth even thinking about.

"Ken" wrote in message ...

"When stuck on a problem, take a break and start over a day or so
later." I cannot tell you how many problems I solved while doing that.
Sometimes getting just getting away from the problem allows clearer
thought.


That often works. If possiable after working on a problem for a while, as
someone else to take a look at it. Don't even tell him what you have done
or checked.

I found that it is beter for me when asked for help to not even listen to
what others have checked. It does pay to listen to see what parts they may
have changed out. Then check those parts to make sure they are good and
installed correctly.

I have done two things that rate as my worst boners. First was a problem
with a SCR temperature controler. Thought I had repaired it, but when
turning on the power it would blow a fuse. Did that 3 times and I just
could not understand it. The next fuse I installed, I checked it and it was
bad. Turned out when I checked the parts bin that half of the new ones were
bad.

Another one was when I replaced a part that came with about 20 feet of 5
wire cable of about # 20 wire. I used the old wire to pull the new wire
through the conduit. Some how I got distracted for a while and then when I
connected the wires, I had forgotten to cut off the old wire. That ment I
connected one end of the old wire back up and the other end was not
connected to anything. I asked someone else to see what it was that I had
done wrong as I knew it must be something simple that I over looked. He
took one look in the junction box and asked why there was so much wire in
it. Then found out what I had did wrong.

On Tuesday, December 15, 2015 at 7:37:47 AM UTC-8, John Robertson wrote:

Capacitors?

Back in the old days, McIntosh used to have clinics where owners could have their equipment restored up to specifications for free. I remember watching them start by routinely replacing all of the cathode bypass electrolytics; they would then check and replace the tubes, as neceeary. They rarely had to go farther (but would if required).

On Mon, 14 Dec 2015 14:05:17 -0000 (UTC), Cursitor Doom
wrote:

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....

There is no correct approach. There are only approaches that work
under specific circumstances. Like the universal solution to all
problems, and the answer to all questions (42), the correct approach
are only useful after you found the solution.

1. That which you know to be functional, beyond any need of checking,
is usually the problem.

2. Solutions found after midnight are best forgotten as they are
likely to be the product of temporary insanity.

3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

4. While it is theoretically possible to work on two problems at one
time, it is much easier to fix problems in the order they appear. I
like to fix the little things first.

5. Nothing is considered fixed until after it is cleaned. If you
can't fix it, at least make it look like it's been fixed.

6. Approximately half the disassembly videos on YouTube are wrong,
useless, dangerous, or out of focus.

7. For a good collection of counterfeit parts, just buy them on eBay.

8. Your most valuable tool is a visual inspection, often with a
magnifying glass. This helps identify exploded, incinerated, or
overheated components. It also shows where the previous repairs were
performed, a sure sign of problems to come.

9. Always ignore the symptoms and theories of the customer. They're
often misleading and will usually waste your time chasing down false
theories. Test the unit yourself to confirm the symptoms. I often
find a very different set of problems or that the buzzwords in the
original description were misused.

10. Fix everything that you find, even if the customer hasn't
complained about it. If it's wrong, even slightly, they'll be back to
complain and you might end up fixing it for free.

11. Take photographs of before and after. Treat is as if it were
evidence in a lawsuit or insurance investigation. I also take a photo
of the insides of the customers laptop, and use it for wallpaper on
their desktop. The reactions are "interesting" and help fortify my
exorbitant rates. The photos also help when I can't recall how to put
it back together.

12. Never do what cannot be undone. For computahs, make an image
backup of the hard disk both before and after the repair. Image
backup programs are now very fast and Terabyte USB 3.0 hard disk
drives are cheap.

13. No repair is complete without a culprit. The first step to doing
a repair is to blame someone or something. This is an important part
of the repair as most customers are worried that they may have done
something wrong (such as buying a piece of junk). By blaming someone
else, this eases their guilty conscience.

14. Never let the customer see you reading the instruction manual.
They will immediately suspect that you don't know what you're doing.

15. Beware of spare parts left over after reassembly.

More later. I'm late (as usual).

--
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 Tue, 15 Dec 2015 07:37:42 -0800, John Robertson wrote:

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time.

Does it, though? I mean, you could save even more time by just running
all the caps through an ESR meter test and just replacing those that
fail. Given how fragile some of those old PCB traces can be, I'd only
want to replace the caps that really way out of spec.

On 12/15/2015 10:16 AM, Cursitor Doom wrote:
On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson wrote:

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time.

Does it, though? I mean, you could save even more time by just running
all the caps through an ESR meter test and just replacing those that
fail. Given how fragile some of those old PCB traces can be, I'd only
want to replace the caps that really way out of spec.


Um, we use temperature controlled soldering irons and the traces on most
of our arcade grade games stand several soldering cycles...

The Bob Parker design ESR meter (which we've been selling since 1999)
doesn't handle small value caps (under 10UFD) very well, and on the
monitors a bunch are 4.7ufd or less.

There are only about fifteen caps in the average monitor, and it takes
about an hour to pull the chassis, replace the caps, do the ring/LOPT
test, check the fuse, reinstall and start the burn-in process. Then it
goes away for five to ten years.

Amps can be worse, particularly early stereo tube amps where all the
parts are connected on standoffs - those can take three to five hours to
recap. They don't come back for ten to twenty years after a recap and
resistor check (tubes too of course).

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 Tuesday, December 15, 2015 at 1:18:52 PM UTC-5, Cursitor Doom wrote:
On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson wrote:

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time.

Does it, though? I mean, you could save even more time by just running
all the caps through an ESR meter test and just replacing those that
fail. Given how fragile some of those old PCB traces can be, I'd only
want to replace the caps that really way out of spec.

I used to do a local vendor's arcade monitors, and I can tell you that a cap that might pass an ESR test may destroy the vertical output on power up when left to sit in an unheated warehouse a week or so during it's route rotation.

I always recapped arcade monitors because of the wild temp extremes they would often see.

Jeff Liebermann wrote:


3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

Oh wow! This one is up there with Murphy's law!

And, unless you are the manufacturer of said device, much of the above will
never be available.

Jon

Ken wrote:
Phil Allison wrote:
Cursitor Doom wrote:


Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.

Perhaps we can assemble a list of golden rules....



** Troubleshooting is like a maze, there are many starting points and
blind alleys to negotiate on your the way to the goal.

Unfamiliar equipment requires a more cautious approach than familiar
items.

Always observe the fault carefully *before* starting disassembly and
find out what functions work and what do not.

Owner's descriptions are often misleading or fail to mention
important issues, but you still need to find out what prompted that
description.

Bench tests need to simulate actual use or worst case use, but beware
of simulating abuse.

When stuck on a problem, take a break and start over a day or so
later.




.... Phil


"When stuck on a problem, take a break and start over a day or so
later." I cannot tell you how many problems I solved while doing that.
Sometimes getting just getting away from the problem allows clearer
thought.

I've stared at well written service manuals (these actually exist, but
tend to be old) that just made no sense until the next day, or after a
break. Not a fan of touching service manuals with diry hands either.

Tim R wrote:
Most important, assume nothing. As soon as you think you know what is wrong, it is impossible not to ignore contrary evidence.

I work with some engineers who are good designers because they keep their brain fixed on the goal and work through every obstacle. They THINK they are also good troubleshooters but they are wrong, obstinately frustratingly wrong, for the same reason. They KNOW what is wrong too early, and nothing shakes their belief.

Second. When anybody tells you the symptoms, listen. When they tell you why, STOP! Don't listen. It will probably be theoretically impossible, and then you end up doubting the symptoms. Sorry but this is especially a problem with techs and mechanics. They observe correctly but theorize contrary to the laws of physics, so you need to stop listening when they get to that point.

I helps to try to figure out what a device should do when it is working.
Extracting this information is sometimes really hard when people are
fixating on what's broken and keep talking in circles.

"Cydrome Leader" wrote in message
...
I helps to try to figure out what a device should do when it is working.
Extracting this information is sometimes really hard when people are
fixating on what's broken and keep talking in circles.

I got a call at the plant I worked at from an equipment operator. When I
got there he said an indicator light would not come on. He had changed
bulbs and even swappend a glowing one with the one that would not come on to
show me it was not the bulb.

I asked him about the equipment as I did not know anything about it. He
said he presses one button and a light comes on , then he presses the second
button and another light comes on, but now the second light would not come
on. As this was just in a control room and the equipment could be located
anywhere in the plant I asked him several times about the equipment and all
I could get out of him was he just pressse the buttons and the lights should
come. He did not seem to know where the equipment was, just the indicator
lights..

On Tue, 15 Dec 2015 15:49:13 -0600, Jon Elson
wrote:

Jeff Liebermann wrote:

3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

Oh wow! This one is up there with Murphy's law!

And, unless you are the manufacturer of said device, much of the above will
never be available.

Gallons of coffee are available at your local supermarket.

I practice what I preach. If really want something to work, I buy 3
of them, and cannibalize one or two for parts to make one of them
work. I also buy or download the manuals:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html
Notice that there are three HP8620C sweep generators, and three
SSI/Wavetek 3000b service monitors in the photo.

If the schematics once existed, they will eventually appear on
someones web pile. The sellers of manuals seem to be very good at
obtaining obscure manuals. I've posed schematics for some of the
stuff I've helped design on my web pile. Much more difficult are
schematics with voltages and waveforms. That used to be standard
practice until about the 1970's, but has lost favor probably because
it requires the schematics to be printed in color.

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

"Cydrome Leader" wrote in message
...

I've stared at well written service manuals (these actually exist, but
tend to be old) that just made no sense until the next day, or after a
break. Not a fan of touching service manuals with diry hands either.

Where I worked we had a copy machine in the shop and I would usually copy
the important pages of the service manual to take with me. Usually had them
already copied in a book I kept so I could fine the important pages quick
and took a copy of that with me.

The electrical blue prints for much of the wiring and some equipment was on
a computer and we had a large plotter so could run off what we needed to
take with us.
Sometimes I would make notes on the copies and leave them in the electrical
cabinet, or just write inside the cabinet with a marking pen.

On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson
wrote:

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced
are fine, but the rest are marginal at best and make all sorts of errors
creep in that would take hours to find otherwise.

http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html
I also do pre-emptive replacements on caps. Worse, if I find a cap
that is bulging or fails an ESR test, I replace *ALL* the caps that
are the same brand and value. Also, if I find a string of parallel
caps, and one is bad, I automatically assume that all of them are
either bad, or will soon fail. That may seem extreme, but I spend
more time extracting and replacing motherboards boards than I do
fixing them. It's easier and cheaper to replace everything that is
suspicious, than to deal with returns, rework, complaining customers,
reputation issues, etc. If the customer returns with the same
problem, but from a different cap, I have to do the rework for free,
which wipes all my profit from the initial repair. Do it right and do
it all the first time.

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg


--
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 2:47, Jeff Liebermann wrote:
On Tue, 15 Dec 2015 07:37:42 -0800, John Robertson
wrote:

I must confess we do replace almost all electrolytic caps that are more
than about 30 years old in our vintage game monitors and amplifiers
(video/pinball/jukebox) as this saves a tremendous amount of
troubleshooting time. It is true that perhaps 60% of the caps replaced
are fine, but the rest are marginal at best and make all sorts of errors
creep in that would take hours to find otherwise.

http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html
I also do pre-emptive replacements on caps. Worse, if I find a cap
that is bulging or fails an ESR test, I replace *ALL* the caps that
are the same brand and value. Also, if I find a string of parallel
caps, and one is bad, I automatically assume that all of them are
either bad, or will soon fail. That may seem extreme, but I spend
more time extracting and replacing motherboards boards than I do
fixing them. It's easier and cheaper to replace everything that is
suspicious, than to deal with returns, rework, complaining customers,
reputation issues, etc. If the customer returns with the same
problem, but from a different cap, I have to do the rework for free,
which wipes all my profit from the initial repair. Do it right and do
it all the first time.

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg


A blue one with a headache.

On Wed, 16 Dec 2015 03:27:36 +0100, Sjouke Burry
wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

A blue one with a headache.

The "bad-caps" is in the URL, so that's rather obvious. However,
that's the result, not the problem. The cause is quite obvious once
you see it. I posted the picture previously and Phil Allison caught
the problem almost instantly. I didn't.



--
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 Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

Either the (out of focus) black capacitors are installed backwards
or the board is mis-labled with the "+" signs.

Jonesy
--
Marvin L Jones | Marvin | W3DHJ.net | linux
38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

On 16 Dec 2015 03:21:01 GMT, Allodoxaphobia
wrote:

On Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

Either the (out of focus) black capacitors are installed backwards
or the board is mis-labled with the "+" signs.
Jonesy

Yep, you got it. Electrolytic capacitors are identified by a wide
stripe on the negative end. To make it easy to hand insert
electrolytics, the PCB is usually silk screen with a wide white area
around the corresponding negative wire. Usually, except for this find
Dell motherboard, that marks the positive lead instead with a wide
white area. To their credit, they added "+" marks, which I missed.
Having replace plenty caps on boards where the negative terminal is
marked, I didn't think to look for the "+" sign, and so installed it
backwards. The computer actually ran for a day or so, before it
started acting funny and blew the tops open. I initially thought I
had a batch of bad caps, so I replaced them a 2nd time, inserting them
backwards again. I knew I was in trouble when the caps got rather
warm. In desperation, I posted the photo to this newsgroup and got an
instant response. Only then did I notice that the PCB silk screen
markings were backwards.

Like I said, it pays to pay attention when re-capping.



--
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:

However, it also helps to pay attention. Do you see a problem here?
?http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg?


85C?

On 12/15/2015 6:43 PM, Jeff Liebermann wrote:
On Wed, 16 Dec 2015 03:27:36 +0100, Sjouke Burry
wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

A blue one with a headache.

The "bad-caps" is in the URL, so that's rather obvious. However,
that's the result, not the problem. The cause is quite obvious once
you see it. I posted the picture previously and Phil Allison caught
the problem almost instantly. I didn't.




Do you mean where someone mixed 85C caps (that failed) with 105C caps,
that look OK?

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 12/15/2015 8:08 PM, Jeff Liebermann wrote:
On 16 Dec 2015 03:21:01 GMT, Allodoxaphobia
wrote:

On Tue, 15 Dec 2015 17:47:13 -0800, Jeff Liebermann wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

Either the (out of focus) black capacitors are installed backwards
or the board is mis-labled with the "+" signs.
Jonesy

Yep, you got it. Electrolytic capacitors are identified by a wide
stripe on the negative end. To make it easy to hand insert
electrolytics, the PCB is usually silk screen with a wide white area
around the corresponding negative wire. Usually, except for this find
Dell motherboard, that marks the positive lead instead with a wide
white area. To their credit, they added "+" marks, which I missed.
Having replace plenty caps on boards where the negative terminal is
marked, I didn't think to look for the "+" sign, and so installed it
backwards. The computer actually ran for a day or so, before it
started acting funny and blew the tops open. I initially thought I
had a batch of bad caps, so I replaced them a 2nd time, inserting them
backwards again. I knew I was in trouble when the caps got rather
warm. In desperation, I posted the photo to this newsgroup and got an
instant response. Only then did I notice that the PCB silk screen
markings were backwards.

Like I said, it pays to pay attention when re-capping.




Oh...that was too obvious. Missed it!

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."

"Does it, though? I mean, you could save even more time by just running all the caps through an ESR meter test and just replacing those that fail. Given how fragile some of those old PCB traces can be, I'd only want to replace the caps that really way out of spec. "

Not so much that, but the ones that matter. For example you could draw a graph of the dissipation of a vertical deflection IC (or transistors for that matter)against the ESR of the boost cap. Usually 100 - 330 uF in value these boost the Vcc to the ouptu stage during retrace. When the cap ESR rises the output circuit operates in linear mode longer to try and compensate. Usually, its dissipation is quite a bit higher before you see anything on the screen like a compression at the top or a foldover. It over heats and burns out and about 80 % of the time the tech finds it with a foldover after replacing the IC or transistors.

So there are CERTAIN ones you want to just replace or at least check. But things are out there with hundreds of caps and it might be impractical to change them all.

And another thing, I would highly recommend getting the unit working properly before recapping. Then, recap in steps, rechecking proper operation in between every one.

Maybe some people are lucky, but I have been where Murphy's law was strictly enforced. And Murphy himself told me "You make your own luck". (the story of Murphy is something I will post eventually but it belongs in another place)

In article ,
Jeff Liebermann wrote:

However, it also helps to pay attention. Do you see a problem here?
http://802.11junk.com/jeffl/crud/GX520-bad-caps.jpg

A blue one with a headache.

The "bad-caps" is in the URL, so that's rather obvious. However,
that's the result, not the problem. The cause is quite obvious once
you see it. I posted the picture previously and Phil Allison caught
the problem almost instantly. I didn't.

Are *all* *four* of those large caps installed backwards?!?

Yah. Amazing you didn't have a chassis full of oily linguine there.

Jeff Liebermann wrote:

On Tue, 15 Dec 2015 15:49:13 -0600, Jon Elson
wrote:

Jeff Liebermann wrote:

3. Things go better if you have a schematic, gallon of coffee, a
working unit to compare, and a parts unit to cannibalize.

Oh wow! This one is up there with Murphy's law!

And, unless you are the manufacturer of said device, much of the above
will never be available.

Gallons of coffee are available at your local supermarket.

I know where to find coffee, although I don't drink it.


I practice what I preach. If really want something to work, I buy 3
of them, and cannibalize one or two for parts to make one of them
work. I also buy or download the manuals:
http://802.11junk.com/jeffl/pics/home/slides/BL-shop5.html
Notice that there are three HP8620C sweep generators, and three
SSI/Wavetek 3000b service monitors in the photo.

Manuals for test gear are usually available. But, for a lot of consumer
gear, automotive modules and industrial gear, they may NOT be! That can be
a real headache.

Old CNC control gear used to have fabulous manuals, with a theory manual
three times as big as the schematics.

But, on later gear, you were lucky to get drawings of the cables, some
configuration charts, and that was ALL that was ever allowed outside the
factory. So, you had to reverse engineer how a lot of stuff worked to
figure out what was wrong with it.

A woking unit to compare to is REALLY a huge help, when available.

Jon

"Cursitor Doom" wrote in message ...

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.


2. If at first you don't succeed, destroy any evidence that you even tried!


3. Try Percussive maintenance first. If it works after you bang it, it has
intermitant connections, or components.


Shaun

"Cursitor Doom" wrote in message ...

Anyone care to share their experience on the correct approach to
troubleshooting? I'll kick off by suggesting:

1. Assume nothing.


Check all user accessible parts and power components, like transistors and
Diodes.
After the visual check of the components for burnt parts or over heated
parts and a smell test; I would flip the board over and inspect all the
solder joints usually with a magnifying lens and and check for cold or
fractured solder joints. When I'd find one I usually remove the old solder
with a solder sucker or wick and then re-solder the joint making sure the
component lead gets lots of heat during the solder process and I use real
solder. Parts or the board around components that got hot often had bad
solder joints from heating and cooling.

Shaun - serious post.