Shotgun

[MannyE]

Bob mentioned the members that never come back after a long session of troubleshooting help. That is a pet peeve of mine.
I have worked on machine tools that I'm not familiar with and have contacted the factory service department for some guidance. Sometimes it takes several calls. After fixing the machine I always make one last call to let them know what I found to be the problem. It helps them and I like to thank them. I often filled in on the service tech line when I worked at Bridgeport Machine Tools. Nothing like being appreciated for all the tech advise. Most customers never called back.

BillWojo

Yes that is truly annoying. But around here plenty of folks give back too and that makes the chattel tolerable. Not that I'm able to offer much advice, but those of us who can't teach, donate.

 

[merlynski]

Not discounting those pieces that require so much time spent in dis-assembly to get to the problematic board that not replacing all known culprits before re-assembly (and testing) seems a bit silly.
-Lee

I would call that "Preventive Maintenance" or "upgrading" not shotgunning.

Back in the '80s I worked for a company that made commercial video recording equipment. There was a discrete component switch mode power supply for a portable video recorder that was so notorious for exploding the first time it was powered up on the test fixture that it had a clear lexan safety cover with a power interlock on it. The only way to successfully repair that board was to replace all the semiconductor components at one time, i.e. "shotgun" it. I hated that, but if you did not do it that way you could spend all day on one board and never get it to work.
I have seen some of the best techs on AK recommend replacing all semis on specific power supply boards for similar reasons, though they do recommend measuring all the resistors first, among other things. Shotgunning has its place in the tool box, but not usually first or primary.

 

[xwarp]

I would call that "Preventive Maintenance" or "upgrading" not shotgunning.

The only way to successfully repair that board was to replace all the semiconductor components at one time, i.e. "shotgun" it. I hated that, but if you did not do it that way you could spend all day on one board and never get it to work.
I have seen some of the best techs on AK recommend replacing all semis on specific power supply boards for similar reasons, though they do recommend measuring all the resistors first, among other things. Shotgunning has its place in the tool box, but not usually first or primary.

IMHO, a shotgun repair is a repair that fixed a problem because the person replacing the part, replaced the part along with a hand full of others, getting lucky and correcting the problem without ever understanding or detailing the root cause of failure. That is NOT a technician, but a youtube hack.

Replacing components in your scenario is more reasonable because when a catastrophic failure occurs in a switch mode p.s., it's pretty darn good and components in such circuits can and do suffer life expectancy/loading changes that make them a risk.

 

[mike_p]

Spinroch, you have caused quite a ruckus. Good for you. BTW, you are aware of the "blueprinting" job I have waiting for my MC30s. Would you call that 'shotgunning"?

 

[BillWojo]

mike_p, I would not call that "shotgunning" myself. You have rare and very desirable amps that are filled with ancient components. Even if some of the components test good "today", what about a year from now?
My MC40's were rebuilt with carefully selected components from Jim McShane. I purchased complete rebuild "kits" and AK member NJ Phoenix did the work. He needed the schematics to properly spec the parts depending where in the circuit they belonged.
Long after I'm gone, hopefully someone will be enjoying these as much as I do.
No, "shotgunning" is when a person really isn't sure WTF is wrong and wholesale changes out everything in it's path to try and get it to function normally. Usually done by a technician that knows that he really doesn't know. LOL

BillWojo

 

[spinroch]

Yeah, what BillWojo said. (Zactly)
Mike_p: you should post pics of your system. It’s so nice!

 

[Ray Gianelli]

but even before deciding one way or another, how about re-soldering all joints.
either (before you start - tape down the component side) remove all solder
and resolder, or with flux added, retouch all joints. this is especially true with
kits where the original solderer treated solder like gold (I see this often on
PAS units) and on a few NAD units.


enjoy the music.

Bob, you raise an interesting point about resoldering. Because if the issue is defective solder joints, shotgunning may well fix it even though none of the components are bad. Aside from the waste, it reinforces what most of us feel is a poor practice.

 

[gslikker]

I was happy to aquire some defective stuff where people gave up because of their assumption resoldering would solve problems, but actually they created more.

 

[gadget73]

I'm also onboard with troubleshooting and repairing the problem before swapping parts just to see what happens. I've done that when I ran out of better ideas though. Sometimes it works, sometimes it just eliminates a possible cause.