SS Power Amp ?

[Arn C.]

I have an old power amp that I am refurbishing.  I have no schematic.
signal in goues through a 1.6K resitor then through a 4.7 electrolytic cap.
Should the + be on the input side towards the resistor?

Thanks!
Arn C.

[R.G.]

If I were doing the same job and had no schematic, I would either
(a) turn it on and measure which way the voltage was, + or -, with my multimeter
or
(b) use a non polar (NP) capacitor there
or
(c) use two 2.2uF metalized polyester (not polarized) capacitors instead.

[smoguzbenjamin]

I would do the same as RG stated, but to answer your question Arn The + side of the cap goes to where the signal is coming from, the resistor in this case. So you're correct

[Boofhead]

What RG said is technically correct.  There *is* a correct orientation and without a schematic there's no way to tell except by measurement.  It follows that the + to signal in can't always be right!

[smoguzbenjamin]

Eh? As far as I know that should always work if the signal is really coming from the resistor.... Or am I being naieve again? :mrgreen:

[Arn C.]

Thanks for the info Gents!   I researched a few different power amps and yes, it can be either way + or - .    I saw it both ways in several different schematics.  So, to be on the safe side I will put a non polarized cap.

Thanks again!!!!
Peace!
Arn C.

[Arn C.]

Thanks for the info Gents!   I researched a few different power amps and yes, it can be either way + or - .    I saw it both ways in several different schematics.  So, to be on the safe side I will put a non polarized cap.

Thanks again!!!!
Peace!
Arn C.

[Boofhead]

Or am I being naieve again?

I think you are drawing a general conclusion from a very specific case.   If you have a single supply circuit, like most effects, *and* the circuit is negative ground,  then *usually* the input and output cap have the + to the bulk of the circuit (as this is usually somewhere around +4.5V) and (usually) the other side of the cap is grounded.  As you can see there's a lot of ifs and buts here.  All this can be cut short by saying the + side of the cap has to go to the more postive node of the circuit, however that turns out.

[smoguzbenjamin]

Aha! Sounds logical, why didn't I think of that? Thanks for the explanation