CTC169 INTERMITTENT PROBLEM!
 

Hello Group!
Have two similar CTC169 chassis in the shop. Both showing similar
failure. One, when turned on will play perfect for up to 1/2 hour then
go into shut down and will keep trying to turn back on. If you catch it

in the "on" position you can power it down. If left unplugged for a
while, it will do the same thing all over again.
The second unit will never start up completely. Just stays on for a few
seconds - when raster starts to come up you can tell there is no
vertical deflection - then immediate shut down. The 8pin vert. IC
seems to be ok.
On both units the TEA2261 seems fine. Proper Voltages on pins 15 & 16.
Have replaced a couple caps here and there on both - but no
improvement yet. Do not have schematic for 169 here. Can anyone
point us in the right direction please?
T.I.A.
Jim

CTC169 INTERMITTENT PROBLEM!
 

On Thu, 08 Jul 2004 18:10:58 GMT, wrote:

Hello Group!
Have two similar CTC169 chassis in the shop.

CTC168/169 have many quirks that u need to be aware but they're very
reliable and good design for it's time. Service manual is needed so
we can tell you what parts that can be a problem for you and helps you
to make sense of it.

Both showing similar
failure.

Not what I see from your descriptions:

One, when turned on will play perfect for up to 1/2 hour then
go into shut down and will keep trying to turn back on. If you catch it
in the "on" position you can power it down. If left unplugged for a
while, it will do the same thing all over again.

Classic SMPS caps will cause this and over voltage B+ (four of them in
hot side, two needed to be from RCA (15uF and 39uF if it is 47uF,
change this to 39uF, I always use 100V except 470uF stays at 35V) and
diode going bad (CR4118). This diode is very sneaky, doesn't take
long to change just to be sure and this can casue all kinds of
problems from, playing dead, intermittent power problems all the way
to black and white picture. Yes I saw all of this! Check the
voltage, should be appox 12V to 13V in standby, in run mode appox 13V,
occasionally see 14Vish. Anything less or b&w, swap that diode!

The second unit will never start up completely. Just stays on for a few
seconds - when raster starts to come up you can tell there is no
vertical deflection - then immediate shut down. The 8pin vert. IC
seems to be ok.

Vertical generation in this chassis is unique! It needs both vertical
pulses (from jungle IC) and horizontal pulses and cut to size via
zeners, (horizontal pulses is from one of flyback pin via circuit
network). These two pulses, using R/C circuits developed two ramp
waveforms, one for 60hz rate, one 15.7KHz rate then both fed to the op
amp IC (LM311) it comes out looking like vague vertical waveform
chopped up at 15.7KHz feeding to gate of SCR transistor in the circuit
with vertical yoke winding powered directly from the isolated winding
on the flyback transformer, oh yes, another winding wound on that
horizontal driver transformer too.

Yet this nutty vertical generation works!?

Ok, this is very umcommon for vertical problem. I can count two on my
fingers that I have seen among 50 CTC169'ers. It pays to have scope
and change both 1N4148 diodes for the pulses from anywhere else to
this vertical area. I had one happen to me. No, very rarely ever
vertical circuit to fail the surronding this area caused the problem.

On both units the TEA2261 seems fine. Proper Voltages on pins 15 & 16.
Have replaced a couple caps here and there on both - but no
improvement yet. Do not have schematic for 169 here. Can anyone
point us in the right direction please?
T.I.A.
Jim

TEA2261 is a SMPS controller IC for the power FET, if the FET is
blown, must change: CR4122, all four caps, this IC, maybe a resistor
and exact FET from RCA don't sub. Or you will get call backs! For
any reason after working on SMPS, must adjust to 143 +/- 5V in standby
using this unsealed pot in the hot side using plastic adjusting tool.
Once in awhile, I would still get poor voltage after this rebuild
where I use another set of two diodes in that hot side, again from
RCA.

Another common fault is pincushion failure, the small capacitor
plastic block can be swollen, (C4402 in parallel with diode CR4402,
change both, and always put the bead back on new diode in same place.

ESR meter is good in rest of chassis, but please don't bother testing
any of four caps in that SMPS, just change them.

Cheers,

Wizard

I hope you have the required isolation transformer while working on
open TVs.

CTC169 INTERMITTENT PROBLEM!
 

?? Have you tried the 15Vdc supply diode? #164589 was the original part.
Also the caps in the regulated supply, near the regulator control ic, have a
way of failing causing all kinds of aggravation.
wrote in message
...
Hello Group!
Have two similar CTC169 chassis in the shop. Both showing similar
failure. One, when turned on will play perfect for up to 1/2 hour then
go into shut down and will keep trying to turn back on. If you catch it

in the "on" position you can power it down. If left unplugged for a
while, it will do the same thing all over again.
The second unit will never start up completely. Just stays on for a few
seconds - when raster starts to come up you can tell there is no
vertical deflection - then immediate shut down. The 8pin vert. IC
seems to be ok.
On both units the TEA2261 seems fine. Proper Voltages on pins 15 & 16.
Have replaced a couple caps here and there on both - but no
improvement yet. Do not have schematic for 169 here. Can anyone
point us in the right direction please?
T.I.A.
Jim