Re: Proscan PS56670 / Chassis CTC195 Issues

From: Art (plotsligt_at_comcast.net)
Date: 08/18/04 

Date: Tue, 17 Aug 2004 20:57:48 -0400

Convergence power supply problem, probable pincushion problems, and a
defective tuner assemnbly. Convergence power supply and tuner are available
as assemblies from an RCA Parts Supplier. Pincushion may be just a diode and
cap in the pcc circuitry, common failure. Very probable not an E_Prom or
data related problem. Tuner should have a part number wither inked on it or
afixed to a white paper adhesive tag. Convergence power supply probably can
be ordered by description with the correct CTC169XXX numbers.
"Andy" <rowlandmcc@comcast.net> wrote in message
news:76f40757.0408171626.129d3f45@posting.google.com...
> I bought my Proscan 56" RPTV (model PS56670LG1, Chassis PTK195CP or
> CTC195C) back in 1997. Within 6 months, I was experiencing
> intermittent picture quality issues, such as the picture going to all
> snow, and the audio making loud hissing/crackling sounds. Each
> "event" would last approximately 1 minute, then the picture would
> return to normal. I made the faulty assumption that I simply had
> reception issues with my cable, and did not pursue a problem within
> the TV itself. As a result, the problem has escalated into other
> areas of the chassis. The picture is now very fuzzy, the convergence
> is way out, and the picture is bowed at the top and bottom of the
> screen.
>
> I am not a TV repairman, I'm an Engineer, but I used to repair TV's on
> the side while I was in college, so I have a fundamental understanding
> of electronic repair. I have the Chipper Check II system (ver 1.83a)
> [which, by the way, is not displaying properly on my 1 year old
> computer running XP - TCE says I have my fonts set incorrectly, but
> every possible font size doesn't remedy the issue.] Chipper Check was
> able to read the Main EEPROM without problem, the PIP Tuner EEPROM
> without problem and supposedly, the Digicon EEPROM without
> problem-although the Digicon EEPROM came back with all FF's in each
> parameter.
>
> Also, during the I2C check, Chipper Check was able to communicate with
> all components except it came back with the message: "Convergence
> Module did NOT respond on the Run bus." [It also came back with the
> message: "YPrPb Processor, U22303, did NOT respond on the Run bus."
> But, I'm not certain that my chassis has the YPrPb Processor
> installed--I was unable to find it.]
>
> From reading the many comments on this site regarding the CTC195
> chassis, I measured the output voltage of the Convergence Power Supply
> at the connector (J19701) and discovered the voltages were not as
> published. The voltages at each pin were approximately 17 volts to
> the ground pin (pin 3). I then pulled the Convergence Power Supply
> connector and it did not effect the picture. I plugged the power
> supply connector back in and the picture jumped a little bit, but did
> nothing more.
>
> I don't know if the voltage errors are a result of some failure in the
> convergence power supply, or the convergence module or both. I have a
> copy of the "Basic Service Data" First Edition - First Printing dated
> 1997. This was published long before the historical issues with this
> chassis become known, so I have none of the Service Bulletins and
> Service Kits later made available.
>
> I've noticed that many of you have extensive experience with this
> chassis, and also that many of you have a great passion for your work,
> so I'd love to hear your recommendations for repairing this TV.
>
> Thank you,
>
> Andy McClellan

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