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General amp health checks

Started by nosaj, May 21, 2015, 09:13:26 PM

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Does anyone have a generic checklist they do when checking the health of a solid state or a tube amp?



No, but it shouldn't be hard to make one.

Does it power up?  Does it make sound?  Does it pass signal?  Does it sound OK?  Is it hummy?  Or otherwise noisy? Speaker sound OK?

Bang on the top with your fist while it is running.  Does it make any noise when you hit it?  If it does, something is loose.  COuld be a screw, could be a solder joint, etc.  Does the cabinet or chassis buzz, rattle, or vibrate?

Play a guitar or other music through it.  Do all the controls function as they should?  Volume controls make it smoothly louder and softer?  Tone controls smoothly alter the tone as expected?  Got reverb?  Make some reverb sound and turn the control up and down, does the reverb follow?  Got trem?  Does the speed control work all through its range?  Does the intensity control work?  And are any of the controls noisy or scratchy when turned?

Do channel switching or other feature switching work?  Does it have a footswitch?  Does that work?

Tubes? Tap on each, any microphonic?  Do the heaters light up in all of them? Tubes have clear glass except for that black/mirror looking area on them - usually on the end, but also could be on the side.  If the edge of that black area has turned gray or white, then the tube vacuum has failed. White inside a tube means it is bad.

Basically we have looked it over to see if everything works.

Inside the amp, we can check the bias on the tubes.  You would need to know how to do that and have the equipment for the task.  Many solid state amps have a bias adjustment too, though it works in a different way.  If it is way out of whack, the amp either will run hot and overheat, or it runs cold and has too much crossover distortion.  Again, you'd need to know how to check that and correct any thing needing it.

Is the hardware tight?  Are the jack nuts snug?  Are the pot shaft nuts snug?  Are the mounting bolts for transformers and stuff tight?  If the circuit boards have screws in the corners, are they snug?

This is all basic checkout, I probably forgot to mention something obvious, but someone will point that out if so.