u73 identification and help

[Michael Tibes]

Afaik the U73 and the different verisons were built by TAB. The Reverb listing shows the TAB logo in the bottom right corner, your faceplates look different though, the labeling on the switch looks different and there's no logo. The pcb inside looks like TAB again. I guess that supports the theory that it it might have been a one-offf, maybe a development sample? The 'typical' U73 / U73b I've seen all look like the pic in rock soderstrom's first post. I guess that's how they were built for the radio / TV stations. But there were also versions for mastering / vinyl cutting, going along with a varicom. I've never seen any of those, not even pictures. It might make sense not to have release controls on the U73b for that, since the varicom takes care of that. But the control voltage needs to bw accessible at the pinout for the varicom to work...

It would be interesting to see a schematic, maybe you're in the mood to reverse it?

 

[ben@timberlakeaudio]

Yes, the markings on the faceplate are all stencil painted without engraving.

There are 8 diodes instead of the 3 in the u73 or u73b. 5 of them are somehow involved in the sidechain rectification stage.

I guess I will have to reverse it and create a diagram, at least enough to get it up and running.

 

[Dark1]

>>There are 8 diodes instead of the 3 in the u73 or u73b.

Yes, all the U73a photos I have seen had this (bridge?) diode arrangement. It seems to be rather different from regular U73/U73b. It would be very interesting to see the schematic, please make one! It would be easiest to print-out a U73 schematic and spot/draw only changes, some parts may be identical...