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" wrote in message
om...
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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