Help identifying ST 70 mod

Hi all,

I'm new to the Dynaco and tube world, and could use some help identifying this modification to an ST 70.  I've done a fair bit of searching on this forum and elsewhere, but haven't found a lot of details.

It looks like one of the older VTA driver boards, but there are some transistors on the underside and some other things going on that I don't understand.

Are there downloadable instructions or schematics that I could access for the older board?

I would post pictures, but since I'm a brand-new forum member, it looks like I can't do that for 7 days.

I've just purchased this unit and it is en-route, so I don't have it for physical inspection or testing yet.

Thanks for any insight you can share!

-David

I'll come back and post pics when my 'probationary' period is over. :-)

crosseyed-cricket wrote:Hi all,

I'm new to the Dynaco and tube world, and could use some help identifying this modification to an ST 70.  I've done a fair bit of searching on this forum and elsewhere, but haven't found a lot of details.

It looks like one of the older VTA driver boards, but there are some transistors on the underside and some other things going on that I don't understand.

Are there downloadable instructions or schematics that I could access for the older board?

I would post pictures, but since I'm a brand-new forum member, it looks like I can't do that for 7 days.

I've just purchased this unit and it is en-route, so I don't have it for physical inspection or testing yet.

Thanks for any insight you can share!

-David

There have been any number of driver boards over the years, some of which were quite impressive in terms of capturing auto-bias and voltage regulation. As you note, when you are able to send pictures, that will help.

Thanks, Peter. I've enjoyed reading and learning on this forum so far....looking forward to more.