Re: CTC197 typical FBT symptom but FB rings ok

Seen this happen on numerous occasions, the ringer can not subject the LOPT to sufficient voltage and current to test for arc over or isulation breakdown. BTW seen so many RCA LOPT that are defective that almost any time the h-output device is blown the LOPT is changd also. That is if a viable replacmentg transformer is actually available.
"Michael" <noreply@nospam> wrote in message news:a8d1b$47263c75$d8fea177$24646@xxxxxxxxxxxx
RCA F35676MB, CTC197CD, ser 649560677, mfr Dec 1996.

Have you had one of the CTC197 FBT failures where a ring test shows good but
the flyback is shorting or arcing internally only under full power?

This set has the "four strikes you're out" symptoms of a bad FBT reported in
this group in the past.

Power supply seems okay - in standby have 144 V, plus the lower voltages and
regulation appears good. When the power is turned on, the 144 drops to
about 100 V each time the set trys to fire up, then returns to 144 or so
back at standby.

In previous postings this symptom has been diagnosed as a faulty flyback and
most reported that changing the transformer fixed the problem. However,
this flyback rings good, and the yoke winding also show no apparent fault.
The HOT is okay.

I'm wondering if the CTC197 problems with the FBTs that were repaired by
replacement in the past were confirmed with a ring tester, or if the
failures showed up only when the HV comes up, as it might be in this case.

Michael (C.E.T.)



.

Relevant Pages

  • Re: grundig flyback problem
    ... Grundig themselves, to have your Grundig set properly serviced. ... I have the problems of my tv esp the flyback, ... Why this LOPT, just can resist for very2 a short time before that leak ... flyback make sound tick tick tick tick from the flyback, ...
    (sci.electronics.repair)
  • Re: Blown HOT in Sony KVT-29SZ1
    ... Replace the H-transistor, but do not solder the collector terminal - route ... If this arrangement fails to develop a voltage across the LOPT ... Caution - examine the flyback tuning caps first - the current limiting lamp ...
    (sci.electronics.repair)
  • Re: Blown HOT in Sony KVT-29SZ1
    ... Also resolder theconnections of the LOPT, H-Driver Transformer, and Driver ... Seen way too many of their sets with funky solder conections ... Caution - examine the flyback tuning caps first - the current limiting ... lamp won't protect the transistor from excessive flyback if it fires up!!! ...
    (sci.electronics.repair)
  • grundig flyback problem
    ... I have the problems of my tv esp the flyback, ... Why this LOPT, just can resist for very2 a short time before that leak ... flyback make sound tick tick tick tick from the flyback, ...
    (sci.electronics.repair)
  • Re: Sony KV 32S36 Vertical Line then to a point suggestions?
    ... Fuse resistor in power supply, both switching transistors with original SONY ... Possible LOPT is bad, check it with a ringer before ... Suspect the flyback transformer itself. ...
    (sci.electronics.repair)