AA764 Vibro Champ build Low output

[bruisedreed]

Ok. Let me preface this by saying this IS my first amp build, but NOT my first electronics build. I consider myself of average or slightly above average intelligence. That said- I am a little confused here. I built an AA764 vibro champ and went thru some of the normal first build problems. I emerged victorious. Kinda.... Here is my dilemma. I had to rewire, test, rewire, test and so forth to nail down some problems with my first run through, and finally got the amp singing. I still have several issues that I will need a little help with. I am getting sound now and it seems to be what I would expect. Once you get the volume to around 1:00 you get some nice breakup, quite a bit once the thing is dimed, but VERY low output. Almost enough that when it is clean you can't hear it. I know I have something off here, but I can't figure out what it is. The other thing is the vibrato. I get nothing out of it. I need a few suggestions I guess. I used the Triode Electronics schematic. Tubes are known to be good. The voltages are as follows: (all voltages measured in DC grounded to the chassis.)

40-20-20-20 Filter Cap- Node 1-459 Node 2-456 Node 3-418

5Y3- pin 8- 458v
pin 2-(primary PT)460v
6v6- pin 3 (OT primary) 414
pin 8 .35v
12ax7 pin 1-257v
pin 3-2.12
pin 6-258v
pin 8-2.11v

By the way I did beef up the Caps to a 500v rating, so I am still in tolerance and SHOULD not blow anything up...Yet. I know there are some really hot voltages here, but it is a little perplexing. From the start they have looked like that. I tried to give all info that may be helpful. Any suggestions will be welcomed. Thanks in advance for your help.

[Structo]

I hope you mean .035v on pin 8.

Why don't you post some pictures and a link to your schematic.

[passfan]

Looking at the schematic double check your cathode resistors and make sure they are 1500 , 47 , and 450 ohm and not kilo ohm. Your bass pot should have an open lug and be wired as a variable resistor wiper to one side. It sounds like your losing gain and it should be easy to find in such a simple circuit. Check B+ voltages at all tubes as somethings not getting power or mis biased or shunting signal to ground. Swap tubes out first with known good ones.

[Firestorm]

Pin 8 of the 6V6 should be 20-25 volts. If it really is .35V, you'll cook that tube in no time. If you're getting low output, I don't think you're hearing "breakup" with the amp dimed. That preamp in that amp won't hardly distort at all so maybe the distortion is a symptom of the problem. Check the wiring on the second triode of the 12AX7 and make sure the 47R, 1K5, cap, feedback and tremolo connections are all in the right places.