CTC5 Pickup!

[timmy]

Originally Posted by Davala

Tube doesn't look tired

So what does the crt show on a tester ?

[Davala]

Originally Posted by timmy

So what does the crt show on a tester ?

Good question, my crt tester burned out testing a gassy tube. I'm looking now for a new one.

EDIT: I just purchased a sencore CR70.
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Matt Davala

[Davala]

I tested the 21AXP22A and it tested near new on all 3 guns. Looks like the power switch caught fire not too long after the CRT was replaced.

What do you guys do when you come across previous repairs that don't match schematics? Luckily for me I'm referencing both the sams and RCA CTC5N service manuals and they both match each other. I'm not sure exactly what the tech was thinking with some of these repairs.

Here are two of the previous repair botches. Only one of the waxed caps on top was replaced and it should have been a .01 and I found an early orange drop replacement of .0047! C108 on the sams

Underneath they really changed the contrast circuit. I tried to draw out what they did and compared it with the sams. Both the sams and RCA service data match. I thought the contrast control might have been replaced with a different value pot but its 500ohms like it should be.

I do plan to put the contrast control circuit back the way it should be.

Check out that power switch failure and fire! Thats a volume/brightness/on-off combo switch. The brightness and volume still work thank goodness. I have the power switch wires shorted. Any ideas how to replace just the on off switch?

I have currently recapped the entire top. Started on the underneath of the chassis this evening.

Hopefully I'll have this up and running in the not too distant future!
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Matt Davala

[Davala]

The resistor parallel with the cap looks like a 620 ohm but I measured 82 ohm. Not sure why they reworked the circuit and added a 25 MFD electrolytic on the wiper of the contrast pot to ground. And they grounded the other end of the pot when it should have been left floating.... A mystery.

That cap and resistor shouldn't even be there and that wire should be wrapped or soldered on a lug to pin 1 of the 12BY7.

[Davala]

showing the 25MFD cap mod they did