Tools to Troubleshoot an Old Tube Amp???

[Tonefish]

If you want to try to go trace down a problem with an old tube amp and the schematic, do you need a capacitance meter or maybe better yet, an LCR meter?

[phsyconoodler]

A good working knowledge of amp circuits and basic electronics tools are all you need.A DVOM is mandatory.Capacitance meters are useful,but not necessary.There are certain capacitors in an amp that get changed regardless of what a capacitance meter tells you.And unless you invest in an expensive one,they can be off as much as 10-20%.
You need to know a cathode from a plate,from a grid,from a filament.That knowledge is the key to fixing an old amp.That and a healthy respect for electricity.It can kill you if you don't know what you are doing.Even when it's unplugged,a capacitor can hold enough of a charge to stop your heart.

[Tonefish]

A good working knowledge of amp circuits and basic electronics tools are all you need.A DVOM is mandatory.Capacitance meters are useful,but not necessary.There are certain capacitors in an amp that get changed regardless of what a capacitance meter tells you.And unless you invest in an expensive one,they can be off as much as 10-20%.
You need to know a cathode from a plate,from a grid,from a filament.That knowledge is the key to fixing an old amp.That and a healthy respect for electricity.It can kill you if you don't know what you are doing.Even when it's unplugged,a capacitor can hold enough of a charge to stop your heart.

Thanks psyconoodler. I understand about the electrolytics, tube parts, and the safety aspects (thanks), but if I'm chasing down a section of the circuit that has caps, can a DVM tell me a cap is ok?

[paulg]

One of the all time best troubleshooting techniques is outlined in "The Tube Amp Book" by Aspen Pitman. It's a chapter by Jack Darr. Basically, you start at the power tube pin connections and work you way back to the first gain stage. Works great and makes very busy looking amps easy to understand. You really must read it! good luck

[phsyconoodler]

Yes a DVOM can tell you if a cap is good,but there are lots of other ways to determine that.Are the controls scratchy even when you've cleaned them or even replaced them?That is good indication a coupling cap is leaky.If you are talking about an old '50's amp,then the filter capacitors are likely long overdue for replacement.Any electrolytic in the amp is.
If you have a specific problem in mind,why don't you share it with us?
you generally lift the grounded end of caps out of the circuit,turn the amp on and measure for DC leakage past the cap.It is designed to pass AC voltage and block DC.

[Groovey Records]

Book, Bell. and Candle its magic in there