Strange red plating tubes on new build
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Re: Strange red plating tubes on new build
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.
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Re: Strange red plating tubes on new build
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!
Please confirm that you have no ac voltage on pin 5 for us!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Strange red plating tubes on new build
Here is a bias supply for your consideration:
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Re: Strange red plating tubes on new build
Please note the correct install of the diodes in Ten over's bias supply as compared to yours!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Strange red plating tubes on new build
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
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Last edited by Guitarxtc on Mon Nov 01, 2021 11:20 am, edited 1 time in total.
Re: Strange red plating tubes on new build
I will try to reverse diodes, then i have on HT supply diodes wrong wired
Re: Strange red plating tubes on new build
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.
Re: Strange red plating tubes on new build
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 everythingsluckey wrote: ↑Mon Nov 01, 2021 12:10 pmPlease 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.
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Re: Strange red plating tubes on new build
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?
Re: Strange red plating tubes on new build
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 trysluckey wrote: ↑Mon Nov 01, 2021 12:38 pmNothing 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?
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Re: Strange red plating tubes on new build
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-silver with gold band as the tolerance)
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Re: Strange red plating tubes on new build
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.
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.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Strange red plating tubes on new build
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 solderingSoulFetish wrote: ↑Tue Nov 02, 2021 3:38 am 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)
thanks Soulfetish to catch that
Re: Strange red plating tubes on new build
brown/black/gold/goldSoulFetish wrote: ↑Tue Nov 02, 2021 3:38 am 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)
Jack Briggs
Briggs Guitars
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