Help with Gibson Skylark ga-5t Crestline

[ndimm]

Hey All,

First time on for so let me apologize for any misakes in advance.

I got this amp in 1975 when I bought my first guitar. It had a torn speaker so seller threw it in for free. Total price for guitar and amp-15.00$. I brought it home and put it in closet and forgot about it. A few months ago I was cleaning my Dads basement and guess what I found. Thanks for being a packrat Dad. I put in speaker from a Vox Valvtonix 30 and fired her up. Everything worked but had a slight hum. After a few sessions of pushing it hard it developed a buzz at various positions on volume control. Shortly after that buzz got louder and would only be quiet at 12:00. Next time I turned it on loud buzzing in all positions. You can still hear guitar faintly under buzzing. I am gonna do cap job, remove death cap, change to grounded power cord and upgrade speaker. While searching how to wire in new cord I noticed my PT has extra white wire from left side that goes to ground. Photos I have seen of other amps do not have this wire. Can someone fill me in on what this means and best way wire in cord. Any advice would be greatly appriciated.

Thanks

[vexorgtr]

Sorry to be late to answer. I had one of these fixed for me by Brunswick Amplifier. http://www.brunswickamplifier.com John may answer you if you email him.

[8417]

That extra wire going to ground is for the faraday shield between the primary and secondary of the power transformer.

 

Digging through my schematic collection- the later version of the Crestline (the one with the Sprague network) shows the shield on the schematic.

 

The earlier version (no Sprague network) does not show the shield.