harsh buzzing, power drop when signal is applied
Posted: Thu Jan 20, 2011 1:28 am
i have a PP 2xel84 guitar amp, PCB construction, and when i hit notes hard, or even not so hard, there is a nasty buzz, and a partial volume drop/ complete volume drop, that usually recovers in a second 2. its been doing this for awhile now. if i bang on the amp or wiggle tubes, it seems like it has a very temporary remedy effect...
the problem is intermittant too, but when it is doing it, it is bad. i played with dropping line voltages with a variac, and that doesn't seem to have an effect either.
i have ruled out any and all tubes.
so at this juncture i'm thinking bad solder somewhere, but based on my description, can anyone narrow down which part of the circuit/tube socket may be suspect? i examined the PCB, and lots of it looks like cold/inadequate solder to me. it is a rather complicated circuit(Orange Tiny Terror), and the PCB looks impossible to remove without lots of surgery due to PCB-mounted jacks and pots...schematic was unavailable at last query....
last, but probably most significant fact: this amp never had a problem, until i removed the transformers to paint them due to mounting corrosion on the bells....but i have looked at my resolders and they really seem solid.
cheers
pic of the suspect-looking solder:
the problem is intermittant too, but when it is doing it, it is bad. i played with dropping line voltages with a variac, and that doesn't seem to have an effect either.
i have ruled out any and all tubes.
so at this juncture i'm thinking bad solder somewhere, but based on my description, can anyone narrow down which part of the circuit/tube socket may be suspect? i examined the PCB, and lots of it looks like cold/inadequate solder to me. it is a rather complicated circuit(Orange Tiny Terror), and the PCB looks impossible to remove without lots of surgery due to PCB-mounted jacks and pots...schematic was unavailable at last query....
last, but probably most significant fact: this amp never had a problem, until i removed the transformers to paint them due to mounting corrosion on the bells....but i have looked at my resolders and they really seem solid.
cheers
pic of the suspect-looking solder: