5F6-A Voltages help

[vince76]

hi, guys
I hope you can help me again
I built my bassman and had a noise problem I solved following your indications.
Now I noticed my amp won't break up. Since I've no experience I was thinking It was a characteristic of the amp..This morning, reading a thread I decided to take the voltages and this is what I get

V1
pin1: 223vdc
pin3: 2vdc
pin6: 230vdc

v2
everywhere I touch I have a loud scratch I think better to ask

v3
pin1: 206vdc
pin3: 64vdc
pin6: 200vdc

B+ at pin 8 of GZ34 is 465vdc

I think the wiring is ok but all a little high readings??

thank you,
vincenzo

[vince76]

anyone?

[Garydean]

V1 readings look a bit high.


also

What does your B- read going to the output tubes?

[vince76]

Thanks a lot for your reply Garydean.
What do you mean with:
What does your B- read going to the output tubes?
I'm not an expert, so you have to tell me in less tech word :-)

vincenzo

[vince76]

Ok I measured all voltages, I hope did right
tell me what can i do.
v5(6l6gc)
pin 3: 463
pin 4: 460
pin 5: -41
pin 6: 463
v4(6l6gc)
pin 3: 463
pin 4: 463
pin 5: -41
pin 6: 463
v3
pin1:208
pin2:19 mutes the amp when touch
pin3:64
pin6:200
pin7: 19 mutes the amp when touch
pin 8:62
v2
pin1:165
pin2: 0 and loud buzz
pin3:1.22
pin6:357
pin7:166
pin8:177
v1
pin1:223
pin2:0
pin3:2
pin6:230
pin7: buzz
pin8:2

vincenzo

[Garydean]

your amp is fixed biased so lets look at the negative voltage it has connected to the control grid pin 5. There will be a separate neg power supply of sorts, coming from the secondary of the output transformer and it connects between two 220K resistors that lead to the grids of the 6L6's. Did you include a cermet pot to adjust your output bias? I'd adjust the bias to read
-45 to -50 at pin 5.

[vince76]

Ok, I can see what you are saying.. I have a wire from the PT going on the board and then the two 220K res connected to pin 5 of the two power tubes. I have only the bias pot I don't know if you are talking about this.
However on pin 5 I was reading -41 I think before I misread the MMter
One think I don't understood: the other voltages are right?

thank you for your time, Garydean

[Garydean]

That pot should be the bias adjust. Check pin 5 on the output tubes and turn that pot so the reading gets between -45 and -50, -48 is good. Check the other pin readings on those tubes as well to see a change. Be sure everything is within the limits. Play the amp any better? Any worse? Watch the plates of the 6L6gc for orange or red plating.