Tan Music Man

[martin manning]

So this 192 amp does not take the screen supply from the middle of the reservoir?

[ToneMerc]

So this 192 amp does not take the screen supply from the middle of the reservoir?

AFAIK, it does just additional filter feeding the screens. Also, the screen grid resistors are lower in value ,100-150R.

Modify the sch to reflect the 4x100 mains, totem pole at B3 and 820k bleeder.

TM

[ToneMerc]

I think I have just about a full chassis shot of a MM supply amp, just need to find it.

TM

[martin manning]

So this 192 amp does not take the screen supply from the middle of the reservoir?

AFAIK, it does just additional filter feeding the screens.

Ok, I think I've got it now.

Tony do you have more photos of this amp?

[talbany]

I think I have just about a full chassis shot of a MM supply amp, just need to find it.

TM

Martin/TM
192 is a 1 off so far?. This amp has 100uF on the plates. Out of the 4 that I have seen this is the only one that he has done this in.(could be because it's wired for only 6L's who knows!) If you want to do another supply labeled 192 with 100uf filtered B+1, that would be great however I would not call it his stock MM supply just yet since most of the ones I have seen are only 50uF or until we get more details. I would like to see more shots of a MM wired 6L's before anything is confirmed.

You know Dumble



Thanks for catching the 82K..It was pretty late here.

Tony

[talbany]

So this 192 amp does not take the screen supply from the middle of the reservoir?

AFAIK, it does just additional filter feeding the screens.

Ok, I think I've got it now.

Tony do you have more photos of this amp?

Martin
I think the cap order goes
4x100uF (Series/Parallel) Kyoei Caps=Plate Caps 100uF @ 800V
20uf IC closest to back of the amp=Screen Cap
Radial caps =PI cap
IC to the right of the radial=V2
last one=V1
Thanks for checking the load lines
I am not home so I have no good shots of the PS with me?
Tony

[Aaron]

Cool!
Thanks!
Also do you have any more shots of the amp. Preferably of the front -stack.
I wonder what the Drive and OD mastr value are?

BTW.If this is the Ultrasound amp I heard this amp now resides in Russia

Tony

Hi Tony,
That is the only photo I have.

Thanks,
Aaron

[talbany]

Here is the 192 Power supply from what I can determine from the pics I have
If someone sees something different will be glad to revise
Thanks for all the contributions!

192 PS.jpg

Tony

[pompeiisneaks]

Phil
Thanks for the work!
It's close a few things,
The 40k/10w connection should go to B+1 (Plate Supply) Not the screen supply!
The last dropper should be 2k2 not 22k
The 82K bleeder goes between the 40k resistor and B+3 to gnd (see pic below)
The bleeders across the plate caps should be 270K not 150K
Label the rest of the caps 20uf
label the 150k at the end of the string FET resistor
Also the heater windings are on the bottom.The middle winding is for the bias supply.Maybe we can draw that up at some point


Thanks Phil

Tony

The bleeder to ground should be 820k not 82k.

TM

I was wondering about that. The old schematic had 820k but talbany specifically called out 82k in his comments... now I'm really confused

~Phil

[pompeiisneaks]

I've got the latest with that fix AND I noted I forgot to actually label the 20uF 500V caps, fixed that as well.

DumbleMMPSU.PNG

Edited: Fixed per Charlie's note.

~Phil

[Charlie Wilson]

Phil, the 22k dropping resistor is the one that can be 12k for higher preamp voltages. Thanks for doing the schematic.
CW

[martin manning]

Here is the 192 Power supply from what I can determine from the pics I have

Thanks Tony. The image is very fuzzy (only 27kB). Can you repost at higher resolution?

I don't see the need for balancing resistors on the reservoir caps. The PT and doubler diodes will insure that the voltage is evenly split, and the B+ divider and screen cap balance resistors will drain the voltage when the power is switched off.

[talbany]

Here is the 192 Power supply from what I can determine from the pics I have

Thanks Tony. The image is very fuzzy (only 27kB). Can you repost at higher resolution?

I don't see the need for balancing resistors on the reservoir caps. The PT and doubler diodes will insure that the voltage is evenly split, and the B+ divider and screen cap balance resistors will drain the voltage when the power is switched off.

Martin
Yeah but dont you still have to balance the 2 series caps?.Wish I could see some traces.
Here you go!

Full supply3.jpg

Tony

[martin manning]

Yeah but dont you still have to balance the 2 series caps?.Wish I could see some traces.

I'm sure that's what those 270k's are there for, but I don't think they are doing anything except wasting power. The upper and lower cap pairs will get charged up to peak AC 30 times per second, which is much faster than the RC time constant with the balance resistors. To do this right, though, I think all of the other caps should be stacked to cover transients and power-up without tubes installed. I'd also put a Zener on the FET filter node to protect it.

[ToneMerc]

To do this right, though, I think all of the other caps should be stacked to cover transients and power-up without tubes installed. I'd also put a Zener on the FET filter node to protect it.

Martin, that's not a bad idea. On my very first HV build I used stacked radials across B3 thru B5 because of the high unloaded voltages. That particular amp ran right around 730 on the plates and almost 770V unloaded.

TM