Setting Bias in W1700 jukebox Amplifier

[mauro]

Hi all, my second post here in the group.
I've just finished rebuilding a 524 amplifier from a model 1700 and would like to put the amplifier back into service but I'm wondering how to set up the bias in this amp or whether it's critical to do so. I have many Wurlitzer manuals but for the 1700 only have amp schematic and parts list. The jukebox is not mine so I'd like to set it up before I return it.
Procedure would be very much appreciated,
Thanks, Mauro

[robnyc]

Mauro, Wurlitzer used only cathode bias in the output stages. There is no adjustment. The only other internal adjustment was for the drive on the AGC which later in the stereo amps became a sort of limited cathode bias adjustment on the reactance tube (AGC). The purpose was to even out the attenuation curve in that tube. Here, it made little audible difference with a normal tube.

On your amp it appears to be an interstage gain trimmer. Just set it for the best gain with undistorted sound. It can't do any damage at any setting.

RobNYC

[mauro]

Hi Rob,
Thanks for confirming what i was thinking.
I always really appreciate your input to my inquiries.
Cheers,
Mauro