200S Sunn

[Valvehead]

Cheers dude...going to fire it up tonight .

[Valvehead]

Ok... new Sovtek 5ar4 and here's the latest circuit with voltages .

[Valvehead]

Point A and B went up ??

[Greg Robinson]

Did you fit backup silicon diodes on the rectifier socket like I recommended? If so I wonder if you've made a wiring error that's leaving the silicon diodes to do the rectification on their own with the tube rectifier disabled. They should be in series with the tube rectifier plates so that it's still functional. Post a picture of the rectifier socket with added diodes so we can check your wiring.

Also, unless you note down your wall voltage when making voltage measurements they're not directly comparable. It's fairly common in many areas for voltages to vary by 10% (or even 20% at the extreme) over the course of a day depending on things like amount of local domestic solar and the current insolation/shading, any local industry activity, and people out at work or at home cooking/airconditioning/etc.

[The Dude]

Point A and B went up ??

Node "B" should be clamped to whatever the value of your added zeners is. So, what zeners did you use and does the voltage on the node equal your total zener value?

[Valvehead]

Did you fit backup silicon diodes on the rectifier socket like I recommended? If so I wonder if you've made a wiring error that's leaving the silicon diodes to do the rectification on their own with the tube rectifier disabled. They should be in series with the tube rectifier plates so that it's still functional. Post a picture of the rectifier socket with added diodes so we can check your wiring.

Also, unless you note down your wall voltage when making voltage measurements they're not directly comparable. It's fairly common in many areas for voltages to vary by 10% (or even 20% at the extreme) over the course of a day depending on things like amount of local domestic solar and the current insolation/shading, any local industry activity, and people out at work or at home cooking/airconditioning/etc.

I think i found this wiring on a Dynaco ? site . should i redo it like the posted Fender schematic shows ??

[Valvehead]

Node "B" should be clamped to whatever the value of your added zeners is. So, what zeners did you use and does the voltage on the node equal your total zener value?

from post #81

"The 11.73mA at 440V means just over 5W dissipation in the zeners, so 3x150V 3W zeners in series should be just about perfect, and land close to 440V."

[Greg Robinson]

I think i found this wiring on a Dynaco ? site . should i redo it like the posted Fender schematic shows ??

The wiring in your picture is correct (remembering that your B+ comes from pin 8 and not pin 2), though of course you should be using diodes rated for more voltage than 1N4007's, or use 2-3x 1N4007's in series for adequate reverse voltage rating. Is that how you've wired it?

Node "B" should be clamped to whatever the value of your added zeners is. So, what zeners did you use and does the voltage on the node equal your total zener value?

The zeners are only intended to clamp under no-load conditions to protect the filter caps from overvoltage if the tubes aren't fitted or during startup when their heaters are cold, so everything's working just fine.

[Valvehead]

The wiring in your picture is correct (remembering that your B+ comes from pin 8 and not pin 2), though of course you should be using diodes rated for more voltage than 1N4007's, or use 2-3x 1N4007's in series for adequate reverse voltage rating. Is that how you've wired it? "

yes, its wired exactly like the pic. i can add 4007s or i might have some R3000 in my bin

[The Dude]

I would use the doubled up 1N4007 simply for the higher current capability.

[Valvehead]

Doubled the 4007 on the rect. .... amp has 561v at A ...465v at B .... 341v at C . Sounds good..working great

[Valvehead]

Amp has been out on the road , working perfect. Thanks boys !