Silly rocket volume output question

[yalesmith]

The red wire is going to ground. it feels like i am running like 10 watts or something...it gets loud but way as close or near the Liverpool or Express.

[M Fowler]

Make sure your cap stack is wired correct I can't tell if the wire from pin 8 is going to the 40-47uf pair.

[JazzGuitarGimp]

13.6V on all the control grids (pin 2) doesn't make sense to me either, the junction of R17 and R18 are tied to GND....... this is so annoying to me, these are the things that drives me crazy.

I'm probably just being silly (or suspicious) but if you haven't already, maybe you should measure the voltage at the R17 / R18 junction, just to make sure the GND connection is secure. But, it also strikes me as odd that the plates would be 5.15V higher than the cathodes, which would cause red-plating. All of your voltage measurements are DC, and measured while the amp is idle, correct? Is there a possibility the amp is oscillating?

[yalesmith]

I will look into the voltages at the junctions when I get home but do you think there any chance the ot is bad?

[JazzGuitarGimp]

I will look into the voltages at the junctions when I get home but do you think there any chance the ot is bad?

If there is not an inordinate amount of distortion, the PT is probably not suspect, except for this: Is the primary impedance of the OT correct for the build? I would expect to get about 35W out of four EL85's, and at your HT of 275V, the maximum OT Z wants to be no more than about 3.4K.

(edit): Actually, I just looked at the BOM and I see there is a note for the OT that says "Use the 5.2K primary", so I have two more comments:

1. I would expect about 23 Watts from this arrangement.

2. It sounds like the OT has a multi-tapped primary, so make sure you're using the 5.2K primary.

[yalesmith]

The OT is a Dynaco A470 reproduction made by triode electronics and the taps are 4.3k. The ultralinear taps are not being used. I wonder if i should try the UL taps....


http://www.triodeel.com/pdf/a470sdiag.pdf

[keewee]

Looks like a cold solder joint on c5 pot side but cant tell whats going on the other end of c5 looks burnt. Id jumper the tone circuit to test. also check solder joints under the board.