3 Prong Conversion On Solid State Amp and advice on Output Transistors?

[Jecarroll7]

Picked up an Ovation 6442 solid state from 1970 without a grounded plug.

I've done a bunch of conversions on tube amps, but this my first on a solid state.

I got the amp running, but can't find a schematic.

It looks like I could do the 3 prong conversion without any modification, but thought I'd better check here for thoughts on this.

Also, I'd like to reduce the "air, it's not a hum" at the speaker at idle with controls zeroed out. I've done a cap job and cleaned the grounds, could it be old output transistors? It's using the original RCA 40411s. Quite usable as is, I'd describe it as a notch above noticeable. Seems an acoustic amp should be a tad bit quieter.

Thanks in advance guys.

[Tom Phillips]

...I've done a bunch of conversions on tube amps, but this my first on a solid state. I got the amp running, but can't find a schematic. It looks like I could do the 3 prong conversion without any modification, but thought I'd better check here for thoughts on this...

The function of the earth ground and the methodology for installing it is the same for any electrical device that has exposed parts that could become "hot" (voltage wise) if there were a malfunction internally. Therefore, it does not matter weather your amp is a tube or solid state unit. Follow the basic code to give the ground wire it's own dedicated and super secure connection to the chassis and make sure the switch and the fuse are in the hot side conductor or switch both hot sides if you are in a part of the world that uses 220V / 240V wall plug service . (Your profile doesn't list where you are. That info is useful to people responding to your posts)
Cheers,
Tom

PS: The transformer bolt is NOT a proper connection for the earth ground.

[gbono]

I don't have a schematic for your amp but you might try replacing the transistors in the input/preamp section first. If you have a scope you can verify where the noise originates.

Does the amp have a polarity switch on the primary side of the PT? If so I suggest disabling it.

[J M Fahey]

If it's barely audible as you mention, I would leave it as is.
Hiss is a fact of Life.
Now if it were loud buzzing, humming, crackling, that would be someting else.
And 40411 are KILLER transistors, keep them unless actually shorted.

[Jecarroll7]

Conversion went smooth. No polarity switch to worry about but I did replace the circuit breaker on the common side with a fuse on the hot side, and grounded it well to the chassis. As for the "air" at idle, going to take the advise and leave it alone.

Thanks for all the help and advice on this.