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 Post subject: RCA K60 No Reception
PostPosted: Apr Mon 06, 2020 7:56 pm 
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Joined: Apr Sun 05, 2020 10:57 pm
Posts: 2
Hello... I have an RCA-Victor K60 that suddenly stopped receiving. The audio section is still good, as I can plug something into the TV or Phono input and it sounds great. But on any of the broadcast bands, including standard AM, I just get static across the whole dial like there's nothing on the air.

A little history... I got the radio and it had a bad tube, which I replaced, and it worked (I don't remember which one). Then within a few months it developed a hum, so I replaced all the caps, and the hum was gone. It was good for about a year. Then one day it stopped receiving. Now keep in mind I know just enough to be dangerous... I can read a schematic and replace parts but I don't understand most of the theory behind what's going on. I do own a tube tester, although it's not able to test the 6SF5. But since that's in the audio section, I figure that one is OK. The others test good.

I read some of the other posts about K60's and started testing resistors (clipping one lead of course so I get a proper value). I found that R1 had an abnormally high value; it's supposed to be 1M-ohm but it was reading more like 8M-ohms, and it is located in the RF area. I replaced it but still no luck. Everything else I tested was fairly close to spec; I replaced a few others that were close but not within the 10-15% rule of thumb.

(note... I tried to post a link to a schematic for the K60 but was told it was too spammy to post)

What I'm wondering is if the receiver needs adjustment. There are quite a few adjustment pots on this thing and I have no idea how to adjust them properly; I've not found any literature describing what they do or how to adjust them properly. I do have an oscilloscope if that helps; it seems like some of these are oscillators and may need to be set to a specific value?

Any/all ideas appreciated.

Dave Lennie
Peoria, IL


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Mon 06, 2020 8:29 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 12741
Location: Mountains of Mourne. Ireland.
Never attempt to align a radio/receiver that is not working.

12-pages of Service information can be found in...
RCA-Service-Data-1938-1942-C.pdf
pdf-page-548
chassis RC-415, RC-415-A and RC-415-B

direct download here... 70.5MB
https://www.americanradiohistory.com/AR ... 1942-C.pdf
from: https://www.americanradiohistory.com/RC ... ervice.htm

Greg.


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Mon 06, 2020 8:32 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 12741
Location: Mountains of Mourne. Ireland.
Here is the LO (local oscillator) test explained... :)


Use a second radio switched on at moderate volume and tuned to somewhere around 1200kHz to 1400kHz (top end of the AM broadcast band). You don't have to be tuned to a station.

This is your listening device.

Switch on your "silent" radio (RCA K-60) and hold it next (very close) to the second (working) radio.
Tune up and down the band on your silent radio, and you should hear a squeal/whistle at some point on the working radio. This will confirm (to some degree) that the oscillator (AM Osc. Coil) in your silent radio is running (working).

Greg.


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Mon 06, 2020 8:37 pm 
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Joined: Jan Tue 31, 2012 1:55 am
Posts: 12741
Location: Mountains of Mourne. Ireland.
You shouldn't be clipping leads to test components... :shock:
Unsolder them.

Resistors can be quickly measured in-circuit - - - if you see something "funny" lift one leg and remeasure.


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Tue 07, 2020 5:12 pm 
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Joined: Jun Sun 03, 2012 12:40 am
Posts: 1715
Location: Cromwell, Connecticut
How about the simple approach. Maybe just another bad tube. They can and do go bad.

_________________
Tony

People may not remember how fast you did a job, but they will remember how well you did it.


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Tue 07, 2020 5:30 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 6368
Location: Near Brandon, Iowa
Tbone wrote:
How about the simple approach. Maybe just another bad tube. They can and do go bad.


"I do own a tube tester, although it's not able to test the 6SF5. But since that's in the audio section, I figure that one is OK. The others test good."

My "take" on the above statement is that the OP tested all of the tubes except for the 6SF5 after the set stopped working this most recent time. But that's somewhat of an inference on my part. If the tubes weren't really all re-tested in this last go-round, I agree that they are a good first thing to check. Might as well clear out the low-hanging fruit.


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Tue 07, 2020 5:34 pm 
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Joined: Apr Sun 05, 2020 10:57 pm
Posts: 2
I'll go through the tubes again just to be sure, and take a look at the documentation posted above (thank you!) and try the local oscillator test. Does the test radio also need to be a tube unit or could it be a transistor radio?


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 Post subject: Re: RCA K60 No Reception
PostPosted: Apr Tue 07, 2020 6:47 pm 
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Joined: Jan Mon 16, 2012 4:15 pm
Posts: 6368
Location: Near Brandon, Iowa
wdln wrote:
I'll go through the tubes again just to be sure, and take a look at the documentation posted above (thank you!) and try the local oscillator test. Does the test radio also need to be a tube unit or could it be a transistor radio?

Transistor set will work fine as a "detector". In fact, due to its small physical size and built-in ferrite antenna, it is probably much better than using a second tube radio.


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