Hello everyone,

I obtained a Sams for my Magnavox U44 (http://www.audiokarma.org/forums/showthread.php?t=187889) and dropped the chassis last night. Everything looked pretty clean except for two areas:

Someone did work to the horizontal AFC network, which is one of those all-in-one pc chips that look like a wide orange-drop cap with 5 leads (forgive me - I don't know the proper name for these.) They must have used a pretty hot iron, as heat blackened the board and cooked the insulation on a couple of wires. My question is: is there a good source for these chips, or are they made of unobtanium? Also, was there a reason other than convenience that the resistors and caps were integrated into the single chip?

Second, the silicone rectifier diode for the low voltage was replaced, and the tech thought it better to mount it on the opposite side of the chassis where it can be easily accessed. My question is: is the current placement of the rectifier in the circuit kosher, or should I move it back to where it originally was? (see image below)

That location for the silicon diode should work. However, it does increase the potential between the secondary and the transformer core. As long as it's within the isolation rating it should be o.k. Since it's only a 160Volts more I would expect it to be o.k. But, who knows?

If you have the values for the AFC filter I think you'll have to make your own unless you find a parts chassis. Maybe someone else knows a source.

John Y.

Hello everyone,


Someone did work to the horizontal AFC network, which is one of those all-in-one pc chips that look like a wide orange-drop cap with 5 leads (forgive me - I don't know the proper name for these.) They must have used a pretty hot iron, as heat blackened the board and cooked the insulation on a couple of wires. My question is: is there a good source for these chips, or are they made of unobtanium? Also, was there a reason other than convenience that the resistors and caps were integrated into the single chip?


They are called "Couplates" - Centralab and Sprague made replacement units. As John said, most folks replace them with the discrete components now that they are unobtainable.

Cheers,

Found this site on the internet - check it out! k5mo.com/reference.html

Thanks so much guys for the info!