[Geoff]

According to this image I found after a Google search there is a tube shield on the right-hand side near the transformer.

[Image: http://45honcho.com/yahoo_site_admin/a**...170006.JPG]

I recently acquired a 90B and it was missing the shield on the right. How critical is that shield?

Thanks,
Geoff

[tab10672]

Acording to the schematic (bottom of page 7) this shield was added as a change in production placed between the 47 and 80 tube so I guess it would depend on the tube lineup or production run of your set if it needs or ever had it.

http://www.nostalgiaair.org/PagesByModel...013881.pdf

[rghines1]

Be interesting to put a scope on the audio output to be sure it's not oscillating at ultrasonic frequencies or higher that would be inaudible.

Potential risk of capacitive coupling between the two 27 tubes and audio output stage.

[Geoff]

Mine is the type with the single 47 tube and the chassis does have the holder for that shield.

- Geoff