RCA CTC203CA6 squeals

L

Lenny

Guest
This 32" set squeals when plugged into AC power. There is no response
when pressing the power button, which leads me to believe that the
standby supplies such as the +12V and +5V are not working. I'm not too
familiar with the 203 power supply and having no schematic for this
set only makes it all the more difficult. Are the standby supplies
derived from like a 135V source which is operating all the time, or
some other method? I plan to start out by ESR'ing all the caps in the
SMPS but in the interim has anyone seen this problem on this chassis,
or would you perhaps be able to point me in the right direction?
Thanks, Lenny Stein, Barlen Electronics.
 
Start by removing the shorted HOT. Then remove the coil on the base of the
hot and remove all the glue and completely clean the leads before soldering
it back in. Replace the HOT and the set will likely be repaired.

Do not forget to do a good check of the board for any other suspect solder
connections.

David

"Lenny" <captainvideo462002@yahoo.com> wrote in message
news:d980bc2c.0403201717.79a9eb4f@posting.google.com...
This 32" set squeals when plugged into AC power. There is no response
when pressing the power button, which leads me to believe that the
standby supplies such as the +12V and +5V are not working. I'm not too
familiar with the 203 power supply and having no schematic for this
set only makes it all the more difficult. Are the standby supplies
derived from like a 135V source which is operating all the time, or
some other method? I plan to start out by ESR'ing all the caps in the
SMPS but in the interim has anyone seen this problem on this chassis,
or would you perhaps be able to point me in the right direction?
Thanks, Lenny Stein, Barlen Electronics.
Click to expand...
 
On Sat, 20 Mar 2004 20:25:11 -0500, "David" <dkuhajda@locl.net.spam>
wrote:

Start by removing the shorted HOT. Then remove the coil on the base of the
hot and remove all the glue and completely clean the leads before soldering
it back in. Replace the HOT and the set will likely be repaired.

Do not forget to do a good check of the board for any other suspect solder
connections.

David

"Lenny" <captainvideo462002@yahoo.com> wrote in message
news:d980bc2c.0403201717.79a9eb4f@posting.google.com...
This 32" set squeals when plugged into AC power. There is no response
Click to expand...
Correct David, The location of HOT is Q14401 (may be Q4401 on PCB),
that coil (or inductor whatever) is at L14401 (also may be L4401).

This also applies to:

CTC185, ATC113 and CTC203.

On both ATC113 and CTC203 can also be totally dead (blown power supply
caused by left on too long squealling because of shorted HOT), another
symptom also be either intermittent or no picture (loses HV & heaters)
with working audio. All caused by that blasted GLUE on that little
inductor L14401. Power supply is same on both, always replace all
three transistors & resistor if power supply is blown.

You can see this solder flaw easily with ohm-meter across that
inductor, reads open or as low as 30 ohms, probe the pads indirectly
not on the coil's pads itself. If you have a strong magnifer that
solder break is visible and is very tiny right on the inductor lead,
always same spot.

About the solder issues, that's is much true especially those plated
brass gromments, many of them had solder that won't touch it, dry up
remaining solder and buff it up with pink eraser or rod eraser that
can remove oxide off a old penny, that will remove the gromment's
oxidation. Also useful on component leads that wouldn't take solder.
Not just ctc203, afflicts all chassis old and new.

Cheers,

Wizard

PS: ATC113 had glue on that coil.
PSS: Key to this success with no callback is not just remove inductor
and glue, clear that one tiny hole too, that hole is glue filled.
PSSS: I once had a ctc203 with blown HOT, it was gassy tube because
tried another chassis on as testing for another reason.
Finally PSSSS: Take care, some of CTC203 flybacks had pinhole that
arcs to ground, sometimes can take out a HOT that instant. SNAP!
Squeal.
 
Thanks very much everyone for the tips. I plan on getting back into
this one next week. Lenny.

jpero@sympatico.ca (Jason D.) wrote in message news:<405d175c.18045356@news1.on.sympatico.ca>...
On Sat, 20 Mar 2004 20:25:11 -0500, "David" <dkuhajda@locl.net.spam
wrote:

Start by removing the shorted HOT. Then remove the coil on the base of the
hot and remove all the glue and completely clean the leads before soldering
it back in. Replace the HOT and the set will likely be repaired.

Do not forget to do a good check of the board for any other suspect solder
connections.

David

"Lenny" <captainvideo462002@yahoo.com> wrote in message
news:d980bc2c.0403201717.79a9eb4f@posting.google.com...
This 32" set squeals when plugged into AC power. There is no response

Correct David, The location of HOT is Q14401 (may be Q4401 on PCB),
that coil (or inductor whatever) is at L14401 (also may be L4401).

This also applies to:

CTC185, ATC113 and CTC203.

On both ATC113 and CTC203 can also be totally dead (blown power supply
caused by left on too long squealling because of shorted HOT), another
symptom also be either intermittent or no picture (loses HV & heaters)
with working audio. All caused by that blasted GLUE on that little
inductor L14401. Power supply is same on both, always replace all
three transistors & resistor if power supply is blown.

You can see this solder flaw easily with ohm-meter across that
inductor, reads open or as low as 30 ohms, probe the pads indirectly
not on the coil's pads itself. If you have a strong magnifer that
solder break is visible and is very tiny right on the inductor lead,
always same spot.

About the solder issues, that's is much true especially those plated
brass gromments, many of them had solder that won't touch it, dry up
remaining solder and buff it up with pink eraser or rod eraser that
can remove oxide off a old penny, that will remove the gromment's
oxidation. Also useful on component leads that wouldn't take solder.
Not just ctc203, afflicts all chassis old and new.

Cheers,

Wizard

PS: ATC113 had glue on that coil.
PSS: Key to this success with no callback is not just remove inductor
and glue, clear that one tiny hole too, that hole is glue filled.
PSSS: I once had a ctc203 with blown HOT, it was gassy tube because
tried another chassis on as testing for another reason.
Finally PSSSS: Take care, some of CTC203 flybacks had pinhole that
arcs to ground, sometimes can take out a HOT that instant. SNAP!
Squeal.
Click to expand...
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top