Strange red plating tubes on new build

[Firestorm]

So that's 4.365 watts. Kind of the textbook definition of biased too cold, certainly not red plate territory. BTW, -30 VDC bias voltage doesn't seem right for that reading. I'd think the tubes would be pulling way more current.

[Stevem]

Yes, I agree, I would think that with -30 on pin 5 that even halfway decent tubes would be idling at 18 to 20 ma.

Please confirm that you have no ac voltage on pin 5 for us!

[Guitarxtc]

Pull out your outputs, set your meter for ac volts and read what you have on pin 5 of either tube, do you have AC volts showing up there?

varies from 2 to 20 AC millivolts

[Ten Over]

Here is a bias supply for your consideration:

[Stevem]

Please note the correct install of the diodes in Ten over's bias supply as compared to yours!

[Guitarxtc]

Please note the correct install of the diodes in Ten over's bias supply as compared to yours!

have a look at photo please,left side is output to tubes,right side is ground and middle wires are from PT,diodes are Fast avalanshe sinterglass by269, can some diodes type make this kind of problems? i didn' draw correctly in first post

image0 (1).jpeg

[Guitarxtc]

I will try to reverse diodes, then i have on HT supply diodes wrong wired

[sluckey]

I will try to reverse diodes, then i have on HT supply diodes wrong wired

Please don't. Your diodes are wired correctly and your voltage measurements support that fact.

Your schematic drawing was incorrect, but that was just an error on paper.

You still need a resistor in series with the pot to prevent being able to adjust the bias voltage to zero.

[Guitarxtc]

I will try to reverse diodes, then i have on HT supply diodes wrong wired

Please don't. Your diodes are wired correctly and your voltage measurements support that fact.

Your schematic drawing was incorrect, but that was just an error on paper.

You still need a resistor in series with the pot to prevent being able to adjust the bias voltage to zero.

I am testing everything,and to me diodes seems solder ok, i rewired bias supply like Ten Over drawn for me and i have range from -26 to -47 negative volts but small current draw on tubes like before. suspecting wrong diodes type, will try 1n4007...dont' know what else can be because i changed everything

[sluckey]

i rewired bias supply like Ten Over drawn for me and i have range from -26 to -47 negative volts but small current draw on tubes like before. suspecting wrong diodes type, will try 1n4007...dont' know what else can be because i changed everything

Nothing wrong with the BY269 diodes. Changing them to 1N4007 will do nothing. I suspect that all tubes that have been plugged into this amp are now defective due to redplating caused by improper bias setting. I really believe that a fresh set of EL34s will fix this problem ***IF*** everything else is wired correctly. You do have pin 1 connected to pin 8, right?

[Guitarxtc]

i rewired bias supply like Ten Over drawn for me and i have range from -26 to -47 negative volts but small current draw on tubes like before. suspecting wrong diodes type, will try 1n4007...dont' know what else can be because i changed everything

Nothing wrong with the BY269 diodes. Changing them to 1N4007 will do nothing. I suspect that all tubes that have been plugged into this amp are now defective due to redplating caused by improper bias setting. I really believe that a fresh set of EL34s will fix this problem ***IF*** everything else is wired correctly. You do have pin 1 connected to pin 8, right?

Yes pin 1 and 8 are connected to 1ohm resistor and then to ground,tried directly to ground and is the same, will order new el34 pair and try

[SoulFetish]

Dude, you are measuring across a 0.1 Ω resistor. I suspect that when you install proper 1 Ω resistors in place of those, it will all make more sense

(brown-black-silver with gold band as the tolerance)

[Stevem]

GOOD catch soulfetish!!!
I did not zoom in enough to see that, but you are 100% correct, the OP has .1 ohm resistors where 1 ohm should be off of those output cathodes!!
It's very likely that every pair of output tubes he has had in there are fully shot!

This is a classic example of why folks new to the amp building thing even if you have built 50 stomp boxes before should not attempt to build anything more more then Fender Champ, or a Gibson GA-5.

If you F up one of these even big time atleast you have not lost much Dollar wise in major parts!

Guitarxtc, just chalk it up to a life lesson, don't get down about and keep moving forward now like you are.

[Guitarxtc]

Dude, you are measuring across a 0.1 Ω resistor. I suspect that when you install proper 1 Ω resistors in place of those, it will all make more sense

(brown-black-silver with gold band as the tolerance)

OMG resistors actually are 0.2Ω, on bag was drawn 1Ω 5w from my supplier but they are not...is my fault that i did not measure before soldering

thanks Soulfetish to catch that

[jabguit]

Dude, you are measuring across a 0.1 Ω resistor. I suspect that when you install proper 1 Ω resistors in place of those, it will all make more sense

(brown-black-silver with gold band as the tolerance)

brown/black/gold/gold