Spectrum ll Tech Questions

[flythair]

Hello to the Sunn Forum Community,

First post here with a plea for tech help.

I have a 1967 Spectrum ll that has had a new power cord installed. The aux. outlet & ground switch were by-passed. I think there is a neon power-on lamp built into the on-off switch. There is now an unused terminal on the on-off switch. When I check the switch, only the two terminals that have wires connected show continuity in either position. I have the schematic but I still cannot figure out if there is a wire missing that will allow the lamp to work. Help?

The schematic also shows the yellow wire 16 ohm tap on the output transformer connected to what I assume to be the negative feedback circuit, between the 680R1w and the 1k1w/750pf. On my amp, the yellow OT wire just dead-ends on a terminal block. Did a jumper wire get missed at the factory?

What does the Contour control actually do?

Are both of the inputs the same? 

The schematic is posted at Schematic Heaven under Post '70s Amps.

Thanks in advance!

Scott

[mckinnon audio]

  Hi there,I've wired all my Sunn's this way:Middle terminal on A.C. sw. is power in,the bottom terminal,closest to the chassis is the other side of the internal neon,so it goes to the neutral (white wire ) and the top terminal,closest to you is the hot to the trans.Most of the time a red wire comes from the bottom terminal of the sw.(neon),just connect this to the neut.(white) wire.Also I disconnect the Ground/polarity sw. and the 2 prong A.C. outlet in the back of the amp.Just a note,I always wire mine switch first,then fuse holder on the hot (black) side.This way you can shut off the amp to change the fuse,much safer.The downside is,if you blow a fuse,the neon stays lit because of the internal connection in the sw.Hope this is of some help,good luck Mel.  P.S. sounds like someone took your feedback loop resistors out of the loop!!