Phonoland

HI all: I am recapping the 528 amp from a wurlitzer 1800. i am working on building the replacement for the 4 in 1 filter caps. I was sent 8 individual caps for the 2 combo caps. I am not sure which is negative. the common to ground or the 4 terminals (?). The schematic is rather lazy and does not give any indication. I don't want to blow these new caps, any help would be great. Mark

The cans are all chassis negative. Center terminals positive. Nothing exotic here.

Rob/NYC

Mark,
What Rob wrote is common on schematics--if not marked differently--one can safely assume that it is a negative ground system--No harm askin', however, as I more then anyone else, should know better then to "assume"--anything--but, alas, I guess I'll never learn--
Ron Rich

When I had a 1700, it had POSITIVE ground twist prong cans. On the case of the capacitors it actually said, "CAN COM POS". Now I don't know if they switched back to common negative on the 1800, but I had positive grounds on the 1700.

Take a close look at the markings on the can of your 1800 to see if they say, "CAN COM NEG".

Just to avoid any confusion here, this is a completely conventional negative chassis circuit.

I owned a1700 and three 1800's, I can't recall seeing any can-positive caps.. If used in this circuit they would have to be insulated with a cardboard sleeve and mounted on an insulating wafer. The only reason a manufacturer might have used them during a run might have been due to getting a very good deal from the cap maker, or Gov't war surplus.

At any rate, in these amps they are replaced with regular can-neg caps.

Rob

Thanks for the info guys! I hope to have this done and get sound out if it soon. Mark