[R-390] 390A ramblings

[Flowertime01 at wmconnect.com]

Collin,

Top side first and then the bottom side.

The three filter sections of Z216 are between the two test points.
An open wire in one off the cans will get you. A bad slug in one of the cans 
will get you. There is a lot of circuit in there that you cannot ohm or 
voltmeter check.
However it does disassemble it parts you can test.

I have not read all your input.
Did this receiver use to work for you and just quit?
Or did you receive the receiver as is and now trying to get it working?

Pull the slug rack and check the slugs in Z216.
You can then remove the cans by removing a Philips machine screw in the 
bottom of the slug rack tube.

You are looking for crud in the transformer pins and sockets.

You push the clips on the side of the cans in a bit and the cover will slide 
off.
You then inspect for crud and eyeball the trim caps.
Look at the schematic and test the coil winding for continuity (low ohms).

Put that all back to gather and try it again.

If you do not find a definitive problem on the top side of the RF deck then 
you will need to pull the deck and do some checking under it.

Almost every one has recapped the IF deck. But the RF deck also has a couple 
of the plastic caps that fail. Your deck may still have some old caps that 
need to be replaced.  

Often someone will run a tube to death and char a plate resistor or cathode 
resistor to near death. They change the tube and the receiver works. The 
charred parts get left under the deck. Pull the deck and do some measurements on the 
resistors. Check the continuity of the signal paths for a cold solder joint 
or broken wire. Check your band switch alignment while you have the deck 
removed.

Check for a bad pin in a tube socket. These crack once in a while.


In order the problems are Mostly
Crud in contacts
Bad cap
Charred resistors
Cold solder
Open wire at a solder point.


Roger AI4NI   </HTML>