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- Most embarrassing moment: When the Chinese clone works better
than the original.
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
On 14/12/2015 18:02, Cydrome Leader wrote:
N_Cook <diverse@tcp.co.uk> 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.
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....
N_Cook <diverse@tcp.co.uk> 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.
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 youAnyone 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....
Anyone care to share their experience on the correct approach to
troubleshooting?
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).
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
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 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.
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.
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.
That often works. If possiable after working on a problem for a while, as"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.