RCA Tv Chassis TX825

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northern1
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RCA Tv Chassis TX825

Post by northern1 » Sun Jun 06, 2010 7:34 am

Does anyone by chance, have a copy of the schematic available to download?
Trouble shooting the power supply on this little 13 inch ac/dc tv. It still has a very nice picture when it starts up. Looking for the cross reference replacement part number for 198752 if that is the problem.
Any help greatly appreciated.
TIA

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Janitor Tzap
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Re: RCA Tv Chassis TX825

Post by Janitor Tzap » Sun Jun 06, 2010 4:57 pm

Is this a transistor?
The case style TO-92?

If that is the case style.
Then it is a NTE 123AP T-NPN, Si, AF/RF Amp Driver.
Note: check the the leads.
It should be: (E)miter (B)ase (C)ollector
Image


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northern1
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Re: RCA Tv Chassis TX825

Post by northern1 » Mon Jun 07, 2010 7:08 am

Thanks for the reply Janitor..
the E/C leads are reversed from your image, but possible this would be the replacement.

The number on the tranasistor is RCA 3214.
From what I could find online, without the schematic or paper work, 198752 apppears to be the correct part number.

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Janitor Tzap
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Re: RCA Tv Chassis TX825

Post by Janitor Tzap » Mon Jun 07, 2010 2:57 pm

I checked the other part number you gave.

That shows a cross to a NTE 287.
Here's the PDF Data sheet.
http://www.nteinc.com/specs/200to299/pdf/nte287.pdf
I think that is closer match.


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northern1
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Re: RCA Tv Chassis TX825

Post by northern1 » Mon Jun 07, 2010 3:49 pm

thank you very much!

Robert Reed
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Re: RCA Tv Chassis TX825

Post by Robert Reed » Mon Jun 07, 2010 4:45 pm

Northern 1
Don't get bent out of shape about an exact replacement for TP15. As long as it is specced at >200 volts, >200 ma and rated at several watts - you are OK and any NPN will work. I recently replaced TP15 in My RCA and used a Motorola MJE 340. Why? Because it met the specs (and exceeded) and I had one on hand. This is in a small flat pack package and rated at >10 watts dissipation. I would not recommend a TO-92 package as your just asking for trouble here. I tried one in the first replacement and even though it worked, the temperature was way to hi, then replaced it with the MJE unit.Unless you operate your TV in the refrigerator, there is no TO-92 that I know of that will work on a long term basis. I have included a schematic on the circuit portion you are working with. Ignore the notations, they are not mine. Heres what I measured:
TP15 Collector - Plus 130 V 1/2 wave 60Hz (active); 145 v 1/2 wave 60 Hz (inactive)
TP15 Base - Plus 12 volts almost pure DC (always)
TP15 Emitter -Plus 11.5 (active):13.5 VDC Biased off
When TV is in standby mode, TP15 supplies the memory with 11.5 VDC. When TV is in the 'ON' mode the normal 13.5 volt supply takes over and reverse biases the TP15 emitter effectively shutting the transistor off. Good luck with your repair.

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