Univox bass head question

[Bob-I]

A friend found an old Univox bass head. It had very low volume, conversation level so he brought it to me for troubleshooting. Simple fix, the impedance selector was toast, melted plastic all over it so I removed it and hard wired the speaker out. I'll replace the selector later but I have a question.

The power ground is floating. All power grounds are connected to the - of the first filter cap, nothing to the chassis except the death cap. I'll replace the power cord with a grounded cord, but should I ground the power supply to the chassis?

Notice the black leads going to the cap. They're daisy chained throughout the chassis, the cathodes and PT as well as the other filters.



http://schematicheaven.com/bargainbi...ox1050bass.pdf

The filter caps look solid, not the standard paper caps found in most 70's amps so I believe they'll be fine. The chassis is clean and other than the typical clean and retension sockets, reflow solder joints it doesn't need much. It was already re-tubed to try to fix the volume problem.

I think it was a great buy for $75.

[Enzo]

You sure the circuits are not grounded to the chassis at the jacks? Is there an open circuit when measuring resistance between chassis and this floating ground?

[Bob-I]

You sure the circuits are not grounded to the chassis at the jacks? Is there an open circuit when measuring resistance between chassis and this floating ground?

Yes, the controls and signal grounds are grounded at the jacks. The power supply is floating.

[Enzo]

There is an open reading between chassis and power common?

It has to be referenced to signal ground somehow.

REgardless, if it works, why mess with it?

[Bob-I]

There is an open reading between chassis and power common?

It has to be referenced to signal ground somehow.

Good point. I just checked and there is a star ground to the cathodes. Thx.

REgardless, if it works, why mess with it?

Because this amp has a 2 pronged plug and death cap. Even though it works I'm not leaving that!!

[Enzo]

Grounding the chassis to the mains is a separate issue from grounding the power supply within. You can ground the chassis to the mains without changing the internal supplies.