Oliver Bias circuit

[drewl]

So I'm rebuilding this old Oliver G150, and it seems like a mixture of models.
The power tranny looks like it's for a tube recitified model, when this one uses diodes.
There was no bias tap, so they installed a little 6v-120v transformer inside.

Think I should remove it, and just tap off the high voltage winding for the bias circuit like the tube rectified models do?

I can alsways switch it back if there's a problem, but it just seems "messy" with this extra tranny inside.


Oh, and the reverb driver is a 6DR7 I asked previously, it's what's used in other models.





http://www.pmillett.com/file_downloads/oliver_amps.pdf

[soundguruman]

So I'm rebuilding this old Oliver G150, and it seems like a mixture of models.
The power tranny looks like it's for a tube recitified model, when this one uses diodes.
There was no bias tap, so they installed a little 6v-120v transformer inside.

Think I should remove it, and just tap off the high voltage winding for the bias circuit like the tube rectified models do?

I can alsways switch it back if there's a problem, but it just seems "messy" with this extra tranny inside.


Oh, and the reverb driver is a 6DR7 I asked previously, it's what's used in other models.



You think you know more than the person who designed it? I don't think so.
Sure you can tap off to supply bias, but what was the reason for doing it in the first place?

http://www.pmillett.com/file_downloads/oliver_amps.pdf

You think you know more than the person who designed it? I don't think so.
Sure you can tap off to supply bias, but what was the reason for doing it that way in the first place?

[drewl]

You think you know more than the person who designed it? I don't think so.
Sure you can tap off to supply bias, but what was the reason for doing it that way in the first place?

Yes, Yes I do.
After a few decades of repairing these 50 yr old designs, I've seen what works and what doesn't.
Not positive it came from the factory this way, or maybe they ran out of the correct tranny that day, or seeing how they didn't sell too many of these it could very well be possible they used whatever they had lying around to get the order out the door.

As I've heard in many places I've worked over the years, including military subcontractors "when in doubt, ship it out"

[J M Fahey]

Does the PT have a center tapped HV secondary?
If so, you can attenuate that voltage down to what's needed with a couple resistors.
What's made in most Olivers shown in the .PDF.
If only a single secondary, bridge rectified, you can't do that directly.
Which one is yours?