jmartin7221 wrote:yeah it's the older model with the tube rectifier. thanks for all the help guys seriously.

That's not a rectifier. It's the driver tube.

so what exactly is the main purpose of this tube, it always seems that i've read that this is a rectifier tube.

i got tired of waiting for this guy to come by and look at my amp so i changed all my tubes and the fuse. now it's powering up in standby but as soon as i switch off standby it hums really loud and shuts down. this shit is killing me, my backup amp is only 50 watts and just can't compete.

Do you have a multimeter?

not here at the house, but not sure i'd know exactly where to check if i did.

jmartin7221 wrote:i got tired of waiting for this guy to come by and look at my amp so i changed all my tubes and the fuse. now it's powering up in standby but as soon as i switch off standby it hums really loud and shuts down. this shit is killing me, my backup amp is only 50 watts and just can't compete.

Try this. with the amp cold and off, take amp off stand by (so the amp would be active if powered up).

Turn on the power. If it fails after it warms up you might have a bias problem. Take all the tubes out and try again. If no fuse blows then you most likely have a bias problem. Check the bias supply for about -55 volts at the grids.

If it hums and fails immediately you have a probable short. The most likely cause, and I'd bet a fifth of Ardbeg 10yr on this, is one of the two back EMF diodes on the plates of the power tubes. One may be shorted. They are connected from pin 3 to ground on two of the four tubes. D7 and D8 are black cylinders, about the size of a raisin and may be tapered at one end. If you can find them just cut one lead of each if you don't have an ohm meter to check them. If the amp then works, replace each one with MR250-5 types.

You can then send me the whiskey.

If it still fails, check the other diodes and filter caps as well for a problem in the power supply.

Schematic

I might also check D9 and D10 by the power supply while you're there. I'll just take a shot of Ardeberg if this is the fault though.

Rodabod wrote:I might also check D9 and D10 by the power supply while you're there. I'll just take a shot of Ardeberg if this is the fault though.

Yep. And the caps C44-C45 as well. voltage doublers are hard on electrolytics.

jmartin7221 wrote:my backup amp is only 50 watts and just can't compete.

You need an HD130 to keep up? How fukkin loud does your drummer play?

Anyway, Here's to playin loud through tubes and ear plugs. Shots all around (sips though, it is single malt after all).

Skol!

what i meant was it couldn't keep up with the musicman. it gets too dirty before i can get the kind of volume i'm looking for.