dead CTC203
 

We inherited an RCA F32668 TV (CTC203CA6 chassis), vintage Jan 2001.
But as Dr. McCoy on Star Trek used to say, "It's dead, Jim."

On opening the unit, I found and replaced the blown chassis fuse. On
plugging the set back in, saw bright white sparks from the vicinity of
the fuse. Quickly (too late?) powered off, found that the leads had
melted off the RT14201 thermistor. Tried to power the set back on w/o
the thermistor (based on previous advice that as part of the degauss
circuit, don't really need it), but the TV is still dead.

When the set is plugged in there is line voltage across the fuse, and
about 2 volts across the open thermistor leads.

Thanks in advice for any advice anyone can offer.

Lots of common problems with the CTC 203 chassis. The thermistor
is what blew the fuse. Make sure the large cement power resistor isn't
bad. Did the fuse go again? Check standby voltages, & does the T.V.
"squeak" at plug in? It should. Repair the horizontal drive coil, & post
your findings. Was the unit dead, or just no video first, before it went?
Does it try to startup three times? If so likely flyback. Rono.



"Big Al" wrote in message
oups.com...
We inherited an RCA F32668 TV (CTC203CA6 chassis), vintage Jan 2001.
But as Dr. McCoy on Star Trek used to say, "It's dead, Jim."

On opening the unit, I found and replaced the blown chassis fuse. On
plugging the set back in, saw bright white sparks from the vicinity of
the fuse. Quickly (too late?) powered off, found that the leads had
melted off the RT14201 thermistor. Tried to power the set back on w/o
the thermistor (based on previous advice that as part of the degauss
circuit, don't really need it), but the TV is still dead.

When the set is plugged in there is line voltage across the fuse, and
about 2 volts across the open thermistor leads.

Thanks in advice for any advice anyone can offer.

You need to troubleshoot the switch mode power supply first to verify
that standby voltages are all good. Then troubleshoot the system
control through the horizontal startup and power supply run voltages.

Just some standard tv troubleshooting for starters.

On Tue, 20 Sep 2005 00:08:59 -0230, "Rono" wrote:

Lots of common problems with the CTC 203 chassis. The thermistor
is what blew the fuse. Make sure the large cement power resistor isn't
bad. Did the fuse go again? Check standby voltages, & does the T.V.
"squeak" at plug in? It should. Repair the horizontal drive coil, & post
your findings. Was the unit dead, or just no video first, before it went?
Does it try to startup three times? If so likely flyback. Rono.


Not this one, If the fuse is popped, and one answer: caused by chain
reaction all the way back to this hotglue on the L14401. When glue
broke the solder on L14401 coil, corrupting the horizontal signal to
base of the horizontal transistor (T14401), now blown, the power
supply tries to drive short circuit through this to ground.
Wheeeeeeeee! POP! 3 transistors & one resistor fries, finally fuse
went up in a flash.

Not too bad to do, just get correct parts and remove that STUPID (aka
money-maker) glue off the L14401 coil (remove coil and clean all glue
off, dig out glue of that tiny hole for L14401's lead, reinstall new
parts and coil, solder. Done.

Cheers, Wizard


"Big Al" wrote in message
roups.com...
We inherited an RCA F32668 TV (CTC203CA6 chassis), vintage Jan 2001.
But as Dr. McCoy on Star Trek used to say, "It's dead, Jim."

On opening the unit, I found and replaced the blown chassis fuse. On
plugging the set back in, saw bright white sparks from the vicinity of
the fuse. Quickly (too late?) powered off, found that the leads had
melted off the RT14201 thermistor. Tried to power the set back on w/o
the thermistor (based on previous advice that as part of the degauss
circuit, don't really need it), but the TV is still dead.

When the set is plugged in there is line voltage across the fuse, and
about 2 volts across the open thermistor leads.

Thanks in advice for any advice anyone can offer.

Also glue around the two crystals near the LA7612 IC and the very
common flyback failure causing a shorted output.