Power/Standby switch Q - '74 Super Lead 100 mk2

Marshall Amp Discussion

Moderators: pompeiisneaks, Colossal

Post Reply
funkgang49
Posts: 130
Joined: Sun Mar 25, 2012 4:36 pm
Location: Northern New Jersey

Power/Standby switch Q - '74 Super Lead 100 mk2

Post by funkgang49 »

*Re-posted in Technical Discussion Forum.

A friend dropped off a Super Lead 100 mk2 for me to work on - replace & install new electrolytics, new power tubes (matched quad JJ El-34's), and re-bias.

Also he had an issue with the old power & standby switches: the amp had developed an intermittent drop out of volume when playing the amp and noticed that when putting the amp into Standby mode the volume would briefly return to normal before shutting off completely. Unfortunately he disconnected the wire hookups prior to bringing the amp to me for service.

I ordered new switches and have proceeded to hook them up to what seems to me to be in proper fashion but it seems a bit odd and not according to any clear layout that I can find. There is no wire/color code legend on the power transformer. The transformers appear to have been replaced at some point and are not original.
The White Lead from the power cord connects to the switch first as opposed to the Mains fuse. The Yellow wire from the Power switch connects to the Mains fuse then Black wire runs through the twisted bundle to the Board turret which is connected via Purple wire to the Red wire back through the twisted bundle to the Power transformer.
The Black negative wire also connects to the power switch and when switch is turned on is connected to the Orange wire which feeds the transformer.

This will be the first Marshall that I have worked on and any clarification & assistance would be greatly appreciated.

[img:1280:720]https://s25.postimg.org/cbvt128pb/007.jpg[/img]
[img:1280:720]https://s25.postimg.org/6q9dx080f/010.jpg[/img]
Post Reply