My AD30H is sick!!!!!!!!!!!!

[Pneumonic]

Hi, all.

I have a single channel AD30H which has come down with a (serious?) problem.

For starters, I get no sound. Slight humming coming out of speakers. Power indicator light doesn't turn on. Fuse checked with meter .... A OK. Neither preamp tube turns on. Rectifier tube powers on as do the two closest power tubes to it. The two power tubes closest to the preamp tubes don't power on however.

I have swapped all tubes with known good ones but to no avail .... same results as noted above.

Anyone have any ideas before I take this baby in?

TIA

[jason41224]

what do you mean by turning on? if they're not getting a light, that's not always an indication that the tube is dead. however, if you swapped all the valves (including the Rectifier) to no avail, i'd say it's tech time.

[a.hun]

Hi, all.

I have a single channel AD30H which has come down with a (serious?) problem.

For starters, I get no sound. Slight humming coming out of speakers. Power indicator light doesn't turn on. Fuse checked with meter .... A OK. Neither preamp tube turns on. Rectifier tube powers on as do the two closest power tubes to it. The two power tubes closest to the preamp tubes don't power on however.

I have swapped all tubes with known good ones but to no avail .... same results as noted above.

Anyone have any ideas before I take this baby in?

TIA

Yeah you can't always tell from glow / no glow if a valve is working or not.

The mains fuse is clearly OK as there is some power getting somewhere. But how about the HT fuse - the one which protects in case of a power valve failure? If that is blown you'll get no sound whatever else you do.

However a bit of hum (even a little) tends to suggest that the power amp is working.
http://www.geofex.com/ampdbug/onlyhiss.htm" onclick="window.open(this.href);return false;
http://www.geofex.com/ampdbug/hum.htm" onclick="window.open(this.href);return false;
Other than valve swapping there isn't really much more you can safely try yourself, so I suspect it is going to take a trip to the amp doc to see you sorted...

Good luck,


Andy.

[Pneumonic]

Thanks guys. I suspect it's tech time.

I only checked the HT fuse, the one labeled "HT Fuse" at the back of the chassis beside the IEC connector. Where is the other fuse?