Help with Traynor YBA200
I recently purchased a 1st gen YBA200 from GC. I bought it online from a GC in California and had it shipped to my local GC. So I tested it out and it didn’t seem as powerful as I thought it would. After a few weeks I plugged it in at my house and it was horribly distorted and weak. Figured maybe it had weak tubes.
Anyway, I opened it up to take a look at it. I found resistor R64 and R66 were blown out. So the outer tubes weren’t working properly.
So my question is, is this a symptom of the autobias circuit failing? Or is it caused by something else?
I know that the gen 2 switched to a fixed bias system. How hard is it to switch to a fixed bias system? Or is there a way to upgrade the autobias circuit to make it more reliable? What is the issue that makes the autobias circuit garbage?
Before anyone says it, I’m well aware that the capacitors can hold deadly voltage. All precautions will be taken while working on it. I have a background in industrial electrical maintenance.
ETA: The power tubes were switched to Ruby KT88’s. From what I gathered the originals were Sovtek 6550’s. If the previous owner didn’t use a matched quad, would that cause those resistors to blow?