Obscure Guild Maverick Amp (7591's) VERY low volume/not working.

[bbrownsbrick1]

Hello everyone.
I just purchased a guild maverick (guitar version) tube amp circa 72' on eBay. The description said it was working. When I got it I plug in, and the volume was VERY low to say the least (maybe putting out 1/8th of a watt). I opened it up and wasnt surprised it was all original (although the mustard caps are in there). First thing I did was check the plate voltage on the power tubes. VERY LOW!
I was getting 27 volts on each of the two plates.
The plate current was also at zero.
First thing I did was order new filter caps as those should be replaced anyway.
Then I notice that the reverb tube keeps flickering "blue lightning" (some kind of inter-tube shock). I removed the tube completely and its still putting out 1/8th of a watt volume. The reverb is working on the amp as quiet as it may be.
Does this sound like filter caps to you guys? I cant find a schematic for this thing if my life depended on it (found the bass version but it was impossible to read). I am thinking of giving up and taking it to a tech. Any thoughts on what it might be?
Thanks so much

[Gtr_tech]

Sounds like rectifier(s) to me. There's 2 diodes and a 10 ohm 10w resistor before the plate supply caps. Check there.

[bbrownsbrick1]

I was getting a hunch it was the rectifier as well. The two diodes look like theyre doing fine visually, and due to not having a schematic i was wondering what diodes i should replace them with (really dumb question i know). I measured the ohms of the 10 watt resistor and there isnt much driftage. I will post pics, wheres a good place to get diodes? im used to working with amps that have tube rectification. thanks

[bbrownsbrick1]

switch rectifiers, still no luck

Ok, I changed out the rectifier diodes to 1n4005's, the 10 ohm resistor read fine so no need to change, and the problem still persists. i will attach some pics below of the diodes i switched out as well as the guts

[52 Bill]

I'll ask the dumb question here, what is the voltage reading at the first filter cap?

[bbrownsbrick1]

I'm going to get an endless amount of junk for this...

but i have yet to successfully read high voltage without blowing an ohmmeter up. I am not a tech, just a musician. I do understand high voltages and discharge all caps before i get into one of my amps. I have replaced filter caps in many amps that seemed to be having some trouble without reading voltages with success and fully understand that i have not been doing everything the right way. please help me if you can.

[52 Bill]

Then how did you get the reading from the output tube plates?

I don't know what meter you have, but just be sure that it is set to DC volts, can safely read the amount of voltage that you expect to find in the circuit and that your leads are in good condition.

Set the meter to read DC volts, set the range for the highest voltage that you think you will be measuring. Take the black lead and ground it to the chassis. I often just stick the lead through one of the mounting holes and let the weight of the lead itself put pressure on the metal contact point.

Take the red lead and touch it to the various points in the circuit that you want to measure.