Tov said:
Given the age of the TV (at least 17 years) I can't really justify the
expense. I'm prepared to spend my own time, though, in the hope that
it will be a fairly inexpensive fix, once identified.
It would first be necessary to determine if the power supply was
'self-faulting', or tripping as a result of detecting an over-current
condition on one of its rails. Without experience in the field, this may
prove difficult for you to determine, as sometimes, trip conditions can be a
little bit 'round and round in ever decreasing circles'.
Generally, self-faulting of the power supply is caused by faulty
electrolytic caps - which may be open circuit, short circuit or poor ESR -
short circuit secondary diodes, and occasionally more subtle problems in the
feedback circuitry. Reasons for overload tripping include short circuit HOP
transistor, faulty flyback transformer, faulty HV tuning caps, faulty E-W
modulator circuitry, faulty field output chip, faulty sound output chip, bad
joints in HOP stage and so on. To get any more specific help, you would need
to declare the make and model number, and then someone on here might be able
to point you at particular problems for that TV.
Also, I don't know what your experience level is, but if you are not used to
working with TV sets, and switch mode power supplies in particular, please
be very careful of your personal safety. These power supplies are connected
*directly* to incoming line power, and are potentially lethal, as in able to
cause death.
Arfa