CTC187

[Krystonjd]

I have a CTC187 that blew Diode for B+ in turn damaged caps on that line. It
also blew the 10 uf 63v cap burned a resistor and damaged the STK730-010. I
can't find anything else damaged but the B+ will skyrocket over 300v if power
is put to it. Obviously I'm missing something in the reg circuit but I cant
find it. I did change T4101 also. any help would be appreciated.

 

[Jason D.]

On 26 Mar 2004 03:53:59 GMT, krystonjd@aol.com (Krystonjd) wrote:

I have a CTC187 that blew Diode for B+ in turn damaged caps on that line. It
also blew the 10 uf 63v cap burned a resistor and damaged the STK730-010. I
can't find anything else damaged but the B+ will skyrocket over 300v if power
is put to it. Obviously I'm missing something in the reg circuit but I cant
find it. I did change T4101 also. any help would be appreciated.

The feedback winding is internal to T4101, keep your mind on the SMPS
primary side circuit, checking carefully on resistors, capacitors
(both types) etc.

Data sheets on STK 730-xxx in PDF format is available to help you
understand the circuit better especially that feedback area.

Also, the if there is shorted loads, IC will overshoot because the
feedback winding isn't pumping enough voltage to bring STK 730 into
regulation mode and blow up. Check the horizontal transistor! Take
care that double check on those diodes, they can be sneaky espcially
with RCA.

If in doubt, check everything in that power supply with meter.
Sometimes you get lucky.

Cheers,

Wizard

 

[Art]

Alo check the soldering on the SMPS, Horiz Driver Transformer, and LOPT. As
well as the ground reference points at the tuner and other shields.
"Jason D." <jpero@sympatico.ca> wrote in message
news:4063abf5.11765681@news1.on.sympatico.ca...

On 26 Mar 2004 03:53:59 GMT, krystonjd@aol.com (Krystonjd) wrote:

I have a CTC187 that blew Diode for B+ in turn damaged caps on that line.
It
also blew the 10 uf 63v cap burned a resistor and damaged the STK730-010.
I
can't find anything else damaged but the B+ will skyrocket over 300v if
power
is put to it. Obviously I'm missing something in the reg circuit but I
cant
find it. I did change T4101 also. any help would be appreciated.

The feedback winding is internal to T4101, keep your mind on the SMPS
primary side circuit, checking carefully on resistors, capacitors
(both types) etc.

Data sheets on STK 730-xxx in PDF format is available to help you
understand the circuit better especially that feedback area.

Also, the if there is shorted loads, IC will overshoot because the
feedback winding isn't pumping enough voltage to bring STK 730 into
regulation mode and blow up. Check the horizontal transistor! Take
care that double check on those diodes, they can be sneaky espcially
with RCA.

If in doubt, check everything in that power supply with meter.
Sometimes you get lucky.

Cheers,

Wizard

 

[john]

Whilst in there change that 47 mfd very close to HOT.
kip


--
"Watch the return E-Mail addy its false"
"Jason D." <jpero@sympatico.ca> wrote in message
news:4063abf5.11765681@news1.on.sympatico.ca...

On 26 Mar 2004 03:53:59 GMT, krystonjd@aol.com (Krystonjd) wrote:

I have a CTC187 that blew Diode for B+ in turn damaged caps on that line.
It
also blew the 10 uf 63v cap burned a resistor and damaged the STK730-010.
I
can't find anything else damaged but the B+ will skyrocket over 300v if
power
is put to it. Obviously I'm missing something in the reg circuit but I
cant
find it. I did change T4101 also. any help would be appreciated.

The feedback winding is internal to T4101, keep your mind on the SMPS
primary side circuit, checking carefully on resistors, capacitors
(both types) etc.

Data sheets on STK 730-xxx in PDF format is available to help you
understand the circuit better especially that feedback area.

Also, the if there is shorted loads, IC will overshoot because the
feedback winding isn't pumping enough voltage to bring STK 730 into
regulation mode and blow up. Check the horizontal transistor! Take
care that double check on those diodes, they can be sneaky espcially
with RCA.

If in doubt, check everything in that power supply with meter.
Sometimes you get lucky.

Cheers,

Wizard