"ac" wrote in message
...
OK, I have uploaded a bit more of the diagram to the same address, I have
the complete diagram, it came with the TV.
http://www.photo-it.com/3375.jpg
You are right, from pin 9 it goes through a small posistor PTC2 then
through
2 resistors and into the bridge rectifier. I have ordered a couple of
S2000AF's, and the TDA4601 and will also replace the caps.
I will test the 2 resistors, can I check that PTC2 is working ok ? do you
just check that it is not shorted ? What is it for any how ?
Some one else also told me to remove PTC1 that the degauss is connected
to.
Thanks again ,
Perhaps I should have pointed out that if you're not familiar with servicing
switch mode power supplies then it's advisable to take extreme care, even
when disconnected from the mains, as some of the larger capacitors can stay
charged up with circa 300v for a quite a lengthy period, and are therefore
capable of giving a serious electric-shock.
In this case C100 has a couple of bleed resistors across it, but I must
emphasise once again you should still be very careful. whilst I don't mind
offering advice, if you have any doubts concerning your ability or issues of
safety, then I would strongly recommend that you leave it to a qualified
technician to carry out the repair for you.
I shouldn't think that you would find any problems with R153/4 the fuseable
resistors, the little blue positor can cause intermittent start-up or
destruction of the control chip, but they don't often give problems [like
the earlier white ones] however they can/do often suffer from dry joints.
The MELF means that it's a metal film resistor which will probably be OK,
however high value resistors in power supplies are 'always' worth checking
as routine, as in some circumstances open circuit ones can cause the
immediate destruction of all those nice new components you to took all that
time and trouble to replace!
I think it's highly unlikely that PTC1will cause the the destruction of the
bridge rectifier and output transistor, normal symptoms are patches of
colour on the screen plus mains fuse blowing, if you're uncertain it won't
hurt to leave out during testing, usually when they're defective in the
majority of cases, shaking it will produce a rattling noise inside.
Adam
As you don't show the complete circuit it's difficult to see where the
[pin
nine] start-up voltage derives from, presumably from an arm of the
bridge
rectifier via a resistor/s, or a small positor which can all cause
problems.
I don't have a circuit diagram to hand, but could probably dig one out
tomorrow, however it would be on the left-hand side of the diagram if
you
trace back from pin nine of the 4601.