Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ElPedro on May 30, 2016, 02:11:53 pm

Title: Dual rectifier issue
Post by: ElPedro on May 30, 2016, 02:11:53 pm

Have a customer who has a new three channel dual recrifier. Once out of every five or six times the amp is used he has an odd thing happen. I saw it do this once myself on his amp.

He will play for a few minutes, and then the amp acts like it rebooted - it shuts off for a second and then comes back on.  Only on the ht circuit tho, cuz the jewel light stays lit.

I haven't found anything causing the problem yet - although I am suspecting a bad solder joint someplace - or something else that may be affected by heat/expanding/contracting.

Any ideas out there?

Title: Re: Dual rectifier issue
Post by: tubenit on May 30, 2016, 02:44:33 pm

Oscillation can cause the amp to squeal and also to just go silent.  And then when the oscillation stops, the sound can return.  I have had that happen, and replacing the power tubes resolved it.

with respect, Tubenit

Title: Re: Dual rectifier issue
Post by: Ritchie200 on May 30, 2016, 08:23:00 pm

I am guessing that there is an effects loop associated with this channel?  Looking at a schematic (not sure if it was the right one) it looks like the loop is engaged with a relay?  Next time it happens have him cycle in the effects loop.  It could be intermittent relay contacts related to heat/vibration/phases of the moon...  If he is currently using the effects loop when this happens, cycle loop and if no change check jacks for intermittent contact.  That is the only thing I can think of that would cause the amp to go silent if otherwise functioning properly at volume. 

Jim

Title: Re: Dual rectifier issue
Post by: ElPedro on May 31, 2016, 08:14:49 am

Thank you for the tips, guys!

I'm fairly certain its not the tubes in this case, as he has the problem prior to putting in all new tubes, and the problem persists.

I'll check into the effects loop today!