Yes there are actually 4 of those, although only 1 is visible in the picture. Which part is the likely culprit, ie, what should I try first?

Given the age of you device I would replace all diodes and the capacitor(s). These components are very cheap.
You can also replace the 4 diodes with one rectifier, this is the same as 4 diodes only more modern.

Make a note (or picture) of the orientation and solder the new components in the same direction.

Rob

There is a bridge rectifier visible in the lower left of the first pic.
A DC power supply will work through that for the time being, until the diodes fry completely and you are left with an open circuit.
You can buy a universal 18v plug-in power supply that will handle all the transformer and DC conversion duties. Harbor Freight sells one for about $25 that comes with a free crappy cordless drill. Just cut the plug off, and solder the leads onto the board after the bridge rectifier.

Rectifiers or diodes very very very seldom are intermittent. They either work or dont.

Yours are the small black pair in pic 1 in the upper left above the transformer.

The large tall black cylinder in the lower left of pic 2 is your filter cap.

"These days known as 1000uF 35V." I concur. You can go larger on either number but smaller is NOT recommended especially on the 35V.

Ebay, radio shack, Mouser ect... should last for at least 10 years of 24/7 use.

Rectifiers for amplifiers consist of 4 diodes never 2.

If they go bad it is possible that they allow current to run the wrong way (short circuit).

I would never leave a old diode in, the cost is minimal.
A bridge rectifier for this device will cost from $2 to $6
The capacitor from $8 to $15

Rob

There are 2 more diodes but they are vertically oriented. You can see the ends of them. In addition to the black filter cap, there is a silver cylinder. The black one is right under diodes and the silver one is right next to it but missing in the pics. Its business end is to the right of the ground screw.

A picture speaks a thousand amps...

Hey it works! The new capacitor is 1/10 the size of the old one - I hope its right. I wasn't sure how the rectifier should be mounted, so I winged it. Got cold solders on the chassis, but theres a common wire to ground separately with a screw. And no more hum! Thanks for all the help.


http://i286.photobucket.com/albums/l...r/IMG_2888.jpg

I'm scared! Ha Ha, glad it works. Yeah I figured the new cap would be a lot smaller. Make sure you have the polarity correct. But it would probably be blown already if it wasn't!

I was definitely scared! As you can see I don't solder things for a living. I avoid it because I usually end up screwing up the project and throwing it away. But this time the force was with me.

I got 2 light bulbs that fit, except when I plug them in, the receiver buzzes louder than ever. Maybe there is another cap I need to attack!