Can bad filter caps cause a short curcuit?

[bluesguitar]

I bought a '66 Twin Reverb. I used a current limiter when first firing it up. Everything was fine when turning on the power. The limiter bulb shown brightly then dimmed, which is an indication of no short. However, when I took it off standby there was a loud hum, like a constant buzz and the limiter light remained bright. I tried it a second time, and after a few seconds the buzz stopped, and the bulb dimmed, but after ten seconds it began again, and the bulb lit brightly in sync with the sound. The buzzing (hum) sounds like a classic case of old, dried up filter caps, which on visual inspection confirm their age. This is the first time I have encountered this problem first hand. My question is- would bad filter caps cause a short curcuit? Why would my current limiter indicate a short circuit in unison with the hum?

[Firestorm]

A bad filter cap can draw a lot of current; for all intents and purposes, at least a partial short. The fact that the amp exhibits the problem after the standby is closed suggests the problem is downstream of the main filter. A tube short is a possibility, even the OT. But I'd start by replacing the caps.

[JazzGuitarGimp]

I suspect that even if the filter caps were to fail open, the light would shine brightly, because you're basically running the power amp full bore, with a 120Hz input.

[Aurora]

'lytics can indeed be a dead short, but then there should be no sound.....

[tubeswell]

I bought a '66 Twin Reverb. I used a current limiter when first firing it up. Everything was fine when turning on the power. The limiter bulb shown brightly then dimmed, which is an indication of no short. However, when I took it off standby there was a loud hum, like a constant buzz and the limiter light remained bright. I tried it a second time, and after a few seconds the buzz stopped, and the bulb dimmed, but after ten seconds it began again, and the bulb lit brightly in sync with the sound. The buzzing (hum) sounds like a classic case of old, dried up filter caps, which on visual inspection confirm their age. This is the first time I have encountered this problem first hand. My question is- would bad filter caps cause a short curcuit? Why would my current limiter indicate a short circuit in unison with the hum?

All of those symptoms you describe point to filter caps methinks

[bluesguitar]

A bad filter cap can draw a lot of current; for all intents and purposes, at least a partial short. The fact that the amp exhibits the problem after the standby is closed suggests the problem is downstream of the main filter. A tube short is a possibility, even the OT. But I'd start by replacing the caps.

Thanks for the heads-up on a possible tube short. I replaced all preamp tubes with known good ones to see if it would make a difference. Sure enough. There was no hum and the current limiter detected no shorts. All is well! I will replace the filter caps, and rock on with my new amp. Thanks.

[vibratoking]

Cool. Glad you got it going. Another case of, "have you checked the tubes"