Lab Series L5 keeps blowing a fuse.

[stonerbox]

OK, first of all, what kind of noise is it? Hum or hiss? Did you notice any change in noise level when tweaking the bias pot?

First of all, try to do a brief bias adjustment, it's describe in one of the service notes above. Just turn the pot CCW Counter Clock Wise (motsols ;-) remove the F21 fuse connect you DMM set to current measuring, let the amp heat up, no signal applied and master volume set to zero. Then adjust bias until you reach 200 mA.
OK, I know your amp has links soldered instead of fuses just like mine, simply cut the wires and install proper fuses (10A).

IF your noise is more like hum, it COULD be in the power supply, i.e. diodes or filter caps (C209, C210). If one or two of the diodes are smoked, you'll probably get a LOT of hum, I mean really annoying amounts. Hum can also appear if you have a fault somewhere in the amp making it draw more current than normally, when the power supply isn't capable of delivering enough power you'll get hum in power supply which then is introduced into the amp and output sound. For that reason, it's a good idea to make the bias adjustment above to see that the amp doesn't draw more than 200 mA.

You can't measure caps with an analog multimeter, you can't even do it on all DMM's (Digital Multi Meter). And even if you have one with the possibility, a measurement will not always tell you about the condition.

Man, you are the greatest!

Its noisy, no any hum at all, but only when I got a guitar plugged into it. A guitar that barley creates any noise in any of my other amps.