Operadio pia125

[Catfishfry]

I have an Operadio PIA125, it has 7 tubes, 2 5u4-g, 4 6l6-g, & 1 6sn7-gt.
The Badge on the front say's 200 watts. its a Mono amp, and it has a 7 pin
octal type plug. I would like to keep it vintage and was wondering where i could find a Field Coil Speaker for it that would restore it to original. I'm not shure what it was ever plugged into, just that it was used in a church at one time. The schematic calls for a 5000 ohm Field coil and 8 ohm speaker,
I don't know what kind of speaker it needs to be or where to find those old plugs.
Any advice would be greatly appreciated.

[Catfishfry]

I wonder why no one tried to help me? odd.....Well, I found & Bought the original speaker from the Same guy I got the Amp from, will run it through the Variac as soon as it arrives. Sometimes, you gotta help yourself.

[Prairie Dawg]

If you think using a variac is going to help you reform the electrolytics, it won't. The rectifiers won't do a thing until they get up to about 75 volts and then they'll hit it with the B+. You could maybe do this trick by using diodes for your slow ramp up. For the most part attempting to reform 70 year old electrolytics is not likely to be profitable.

[Gtr_tech]

Don't even try to save the original filter caps.....they are well beyond their useful life. There is only 4 sections, so just replace them with individual caps (disconnect the originals from the circuit).

As far as the tag on the chassis that says "200 watts", that just means the chassis *uses* 200w off the AC line. Actual output power for something that uses 4 6L6g's cathode biased would be somewhere around 40-50w depending on plate voltage.

You'd be wise to replace the cathode resistor and bypass cap for the output section as the cap is wasted and the resistor has likely drifted way off value.

Actually....if it were me I'd replace *all* the resistors. Anything that old will have drifted values or just plain open resistors all over the place.