[ke5yum]

Good morning all

I've been working on the 321 lately and am having some success.

Work done so far: replaced paper caps, replaced 2 section electrolytic, replaced one resistor, replaced power cord.

All voltages are good and I have good reception with a long wire antenna, though the sound is a garbled. I am pleased with the recepton, and I listened to several stations last night. However ...

I have volume with no volume control, if that makes sense. When the radio starts working, volume appears to be at a preset level with no change as I turn the knob. A slight twitst of the knob yields a little more volume but only for a moment. I feel that I have a dirty or bad on/off/volume control switch. Question: Can I spray contact cleaner into the switch without causing damage? I really don't want to take that thing apart! From what I have read on the Phorum, a bad switch can cause poor reception.

Thanks,
Terry

[klondike98]

Spritzing the volume control with contact cleaner should not cause damage (power must be disconnected and you must let it dry before reconnecting power). Wear safety glasses though since the spray can shoot back at you after hitting the volume control. Don't want any casualties! Work the volume control back and forth after spraying to give it the best chance to clean the wiper arm on the volume pot.

[morzh]

if cleaning does not help, measure the resistance between ends of the pot and then between the wiper and each end while rotating. Note the wiper in the center and at both ends values.
Compare to the value in the sch.

In fact I would do this before cleaning. Maybe in the current condition the cleaning won't help.

[ke5yum]

I followed Morzh's advise and measured the resistance. 500 mohm with the volume closed and 3 ohms (or so) with the volume full open. I will verify when I my new schematic arrives. The copy I got from Nostalgia air was not that clear.

[morzh]

What is end-to-end value, this is even more important, as it will tell you if the resistive element is open. If it is also 500 Mohm, this is bad.

[ke5yum]

I measured the end to end value, and it reads 0. End to end value while rotatating the pot is also 0. When I measure the other two connections, I get 550 ohms with the volume closed; 0 when the volume is full open; about 220 with the volume about half way.

A friend of mine says that the pot is bad.

Terry

[codefox1]

Yup, if end to end resistance is infinite (I think that is what you are saying,) there is a break and the pot is bad.

[ke5yum]

Good morning, all

The pot was bad, so I bought a new one from AES. It has the round shaft as compared with the flat sided original shaft, but other than that, it will work just fine. I was thinking about using a dremel tool to grind a flat side on the new shaft. Has anyone done that? Or do I need to make the hole in the knob larger to receive the round shaft.

Terry

[vinzer]

I would grind a new flat spot on it just go slow so it doesn't get to hot.

I have done that before worked for me.

[ke5yum]

Good morning, all

An update with some questions:

I installed the new switch after shaping the shaft with a file to make the knob fit. The switch works like a charm, and I now have a working radio that receives well all along the band. Installing it was much easier than I thought it would be.

Does anyone have a dial cord installation diagram for this unit?

Also, what the correct size dial light? Did the original look like a night light bulb?

Thanks, Terry

[klondike98]

Terry,
According to this post http://www.antiqueradios.com/forums/view...1&t=199506 , I believe the 42-321 chassis and the 42-PT-4 chassis are the same. If that's the case here's a dial string diagram for the 42-PT-4.

[Image: https://dl.dropboxusercontent.com/u/5462...string.jpg]

IF that's not the case I also have a hand drawn dial string diagram for a 42-322 that I restored that "might" give you some ideas if its at all similar to the 321.

[Image: https://dl.dropboxusercontent.com/u/5462...string.jpg]
Hope that helps.

[ke5yum]

Thanks Klondike98. This is what I need.