5E3 voltages not right any suggestions?

[leevc5]

B+ off of 5Y3 without other tubes installed is 470 - that seems OK

but
B+ with tubes installed drops to 240? Should be ~360
6V6 pin 8 cathode 48V??? Should be ~20

What might cause this weird voltage stuff?
Have swapped out all the tubes and readings are consistently puzzling.

Also, when power switched on after a couple of seconds there is a pop or click noise. Doesn't continue or repeat, just one time every time powering up.

[PRR]

6V6 G1 voltage??

[sluckey]

What is the voltage on pin 5 of each 6V6? Should be zero.

[leevc5]

What is the voltage on pin 5 of each 6V6? Should be zero.

When measuring pin 5 on each 6V6 starts at ~1.6 and drops tp .5V and stays there.

[sluckey]

Disconnect both coupling caps between the PI plates and 6V6 grids and recheck the voltage on pin 5 of each 6V6.

[leevc5]

6V6 G1 voltage??

where/how do I measure G1 and what is it?

[sluckey]

G1 = pin 5

[leevc5]

Disconnect both coupling caps between the PI plates and 6V6 grids and recheck the voltage on pin 5 of each 6V6.

With coupling caps disconnected from PI still reads .5V but does not start higher and drop down just immediately .5.

[sluckey]

With those two caps still disconnected do the B+ voltage readings go up? And does the pin 8 voltage go down to a more reasonable value?

[leevc5]

With those two caps still disconnected do the B+ voltage readings go up? And does the pin 8 voltage go down to a more reasonable value?

B+ still low ~254 but pin 8 now at 24 which is more in line.

[sluckey]

Reconnect only one of those caps and then recheck pin 8 voltage. If voltage goes up, replace that leaky cap and recheck pin 8 voltage. If still approx. 20 volts, install the other cap. If voltage goes up, replace that leaky cap and recheck pin 8 voltage. If still approx. 20 volts, throw away the leaky cap(s).

With power off, measure resistance between chassis and pin 5 of each 6V6. What have you?

[PRR]

Old build, new build?

i.e. did it work right once or are you first-time smoke-testing?

[leevc5]

Reconnect only one of those caps and then recheck pin 8 voltage. If voltage goes up, replace that leaky cap and recheck pin 8 voltage. If still approx. 20 volts, install the other cap. If voltage goes up, replace that leaky cap and recheck pin 8 voltage. If still approx. 20 volts, throw away the leaky cap(s).

With power off, measure resistance between chassis and pin 5 of each 6V6. What have you?

Thank you for your patience and persistence.
Unfortunately, just took a step backwards. Tried the leaky cap replcement process without success and now with both caps disconnected am back up to 48V @ pin 8?????

[leevc5]

Old build, new build?

i.e. did it work right once or are you first-time smoke-testing?

New build, first time to fire it up.

[sluckey]

OK, so it ain't the caps. What about the resistance check?

[leevc5]

OK, so it ain't the caps. What about the resistance check?

Infinity - Open Loop

[sluckey]

Infinity - Open Loop

You are most likely missing a ground connection to the junction of those two 220K grid resistors. Fix it and things will get a lot better.

If this is a Hoffman board the most likely problem is a missing under board jumper from the junction of those two 220K resistors to the negative terminal of a 16µF filter cap. If using another layout just look.

[leevc5]

Infinity - Open Loop

You are most likely missing a ground connection to the junction of those two 220K grid resistors. Fix it and things will get a lot better.

If this is a Hoffman board the most likely problem is a missing under board jumper from the junction of those two 220K resistors to the negative terminal of a 16µF filter cap. If using another layout just look.

That Dr. Sluckey sir was the problem! 
You got me thru many a 5F1 weirdities and have got me thru my first 5E3 build to success. If there was a Nobel prize for Tweed Amp Troubling Shooting you should certainly win the award.
Thank you one again.

[tubenit]

If there was a Nobel prize for Tweed Amp Troubling Shooting you should certainly win the award.

+1              Sluckey definitely holds the record for correctly trouble shooting my amp builds!

with respect, Tubenit

[Ed_Chambley]

If there was a Nobel prize for Tweed Amp Troubling Shooting you should certainly win the award.

+1              Sluckey definitely holds the record for correctly trouble shooting my amp builds!

with respect, Tubenit

He also holds the record correctly shooting amp builder problems.

[sluckey]

He also holds the record correctly shooting amp builder problems.

I try to treat all equally. Give'm what they ask for. 

[Willabe]

I try to treat all equally. Give'm what they ask for.