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 Post subject: Re: RCA 1965 Solid State Phonograph Circuit Question
PostPosted: Apr Wed 10, 2019 4:58 pm 
Member

Joined: May Sat 06, 2006 4:03 am
Posts: 3400
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
Your cartridge is not crystal; it's ceramic. Unlikely any of the three are bad. On solid state phonographs of that era I replace all the electrolytics. You need to try another input. Also, the "grounds" should be correct.

Bill J.

Need to read slower and attentive; mentioned things already stated.


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 Post subject: Re: RCA 1965 Solid State Phonograph Circuit Question
PostPosted: Apr Wed 10, 2019 9:52 pm 
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Joined: Jul Sun 08, 2018 10:41 pm
Posts: 10
Tim, Bill, you're right. It's an Astatic 348, ceramic.

I'll back down the voltage on the signal generator and try again. I'll also look at C6 and C8 and the nearby resistors.

When you say another input Bill, what do you mean?


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 Post subject: Re: RCA 1965 Solid State Phonograph Circuit Question
PostPosted: Apr Thu 11, 2019 12:37 am 
Member

Joined: May Sat 06, 2006 4:03 am
Posts: 3400
Location: ZIP 23831 South of Richmond, VA 25 miles down the pike.
You can input from a radio. I've for years have used leads to a transistor radio speaker output with clips attached. I even use the headphone output of my laptop. Any source of audio will do.

Bill J.


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 Post subject: Re: RCA 1965 Solid State Phonograph Circuit Question
PostPosted: May Wed 01, 2019 10:58 pm 
New Member

Joined: Jul Sun 08, 2018 10:41 pm
Posts: 10
Update:

First, thanks for all the help and input. I wouldn't have gotten this far without you.

As mentioned, all the electrolytic and paper caps were replaced and I replaced a few out of range resistors.
I traced the ground to be sure that was correct.
I was able to get a clean signal and scope reading through the first caps C6 and C8 and the first two transistors, SE4002.
It was between X2 and X3 that the sine wave distorted.
I then removed some transistors to test.

Could you take a look and let me know if, with these transistor test numbers, you see a problem?

X2 2N406 Ge PNP

b/c .201
b/e .210
reverse c/b and e/b open open
e/c open
c/e open
hfe 70

X3 40022 Ge PNP

b/c .129
b/e .132
reverse c/b and e/b open open
e/c 1.863
c/e open
hfe 90


X6 40022 Ge PNP

b/c .129
b/e .131
reverse c/b and e/b open open
e/c 1.517
c/e open
hfe 114


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