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Philips DPTV305 dead with loud chirping

M

Mike

Jan 1, 1970
0
I ran into one of these with a loud chirp-chirp of an over-loaded power
supply.
I took it apart and looked at the main board, and i seen where the fluid had
leaked all over it. not real bad, but it was pretty evident. so like i do
every other board, i removed it, and sprayed it down with hot water and
baked it at 175-200F for about two hours.

then let it cool down, and i checked the HOT and HV out transistors, and
they are fine.

hooked it all back up, and it still chirps. i checked all secondary diodes
and capacitors on the power supply and they are fine. ESR is fine. however
the main input filter cap on the module was bubbled up, so i replaced all 3
470uf at 200v caps. to make sure. they ESR checked fine, but that didnt mean
anything.

Still chirps. I removed plug 1516 that feeds power to the STK convergence
amplifier, it still chirped. so something has shorted somewhere in the main
HV/sweep/power supply module where the fluid leaked. didnt leak anywhere
else, no residue left behind.

any ideas? or am i stuck replacing the entire sweep/power module?
 
M

Mike

Jan 1, 1970
0
nevermind. i figured it out. i found a 330ohm short on the 130V HV supply
line. well 130v into 330ohm load, well ya know, anyway.... thats why it
chirped.

but heres the kicker: there is a hidden board beneith the flyback
transformer that you dont see. its actually a little circuit that drives the
flyback. so instead of having a HOT and all that good shit, you got a little
FET driver board like in a tesla coil or something.

wel turns out some fluid got on the supply rail inside that board, and
shorted out the fets. so i changed the fets and resoldered that board, and
cleaned off all the fluid and arc residue. and will see what it does. if it
blows the fets again, i can get the flyback/driver combo for like $60 bucks.
it comes in one peice.
 
P

Paige D'Winter

Jan 1, 1970
0
nevermind. i figured it out. i found a 330ohm short on the 130V HV supply
line. well 130v into 330ohm load, well ya know, anyway.... thats why it
chirped.

but heres the kicker: there is a hidden board beneith the flyback
transformer that you dont see. its actually a little circuit that drives the
flyback. so instead of having a HOT and all that good shit, you got a little
FET driver board like in a tesla coil or something.

wel turns out some fluid got on the supply rail inside that board, and
shorted out the fets. so i changed the fets and resoldered that board, and
cleaned off all the fluid and arc residue. and will see what it does. if it
blows the fets again, i can get the flyback/driver combo for like $60 bucks.
it comes in one peice.










- Show quoted text -

what a sad pathetic troll loser wanker.
 
P

PeterD

Jan 1, 1970
0
what a sad pathetic troll loser wanker.

Enough about you, with you it is always you, you, you... How about
anyone else?
 
I am not even mentioning the assholes. Forget them.

What you need is a HVG, NAP's new term for a flyback, and yest the
HVOTs are included. You are working on an HDTV. In this case there is
no H drive to the flyback at all, it runs whatever frequency it feels
like. There is very little else to it. You put in the 130 volts, out
come 30KV and 10KV or whatever.

This system does use ractive scanning for the yokes, but HV is totally
seperate, and brother it is really seperat in these sets. It regulates
itself, the only reason for HV feedback and ABL is for the geometry
correction and shutdown.

The thing that irks me, is how the hell did coolant get into it ?

JURB
 
P

Paige D'Winter

Jan 1, 1970
0
I am not even mentioning the assholes. Forget them.

What you need is a HVG, NAP's new term for a flyback, and yest the
HVOTs are included. You are working on an HDTV. In this case there is
no H drive to the flyback at all, it runs whatever frequency it feels
like. There is very little else to it. You put in the 130 volts, out
come 30KV and 10KV or whatever.

This system does use ractive scanning for the yokes, but HV is totally
seperate, and brother it is really seperat in these sets. It regulates
itself, the only reason for HV feedback and ABL is for the geometry
correction and shutdown.

The thing that irks me, is how the hell did coolant get into it ?

JURB

u sound real mean u need jesus in ur heart
u need to get a life becuz u r a lonely sad pathetic loser social
reject.
 
M

Mike

Jan 1, 1970
0
im assuming the gasket is bad in the CRT. i see a fluid stain on the red CRT
toward the top. ill figure that out later.


right now, after reaplcing the shorted transistors in the HV driver board on
the flyback, the set quit chirping. it fires up, but still dead. no video,
sound, or anything. im assuming since theres no output on the fly, it goes
into shutdown. probably becuase the TEA driver IC is fried. so im going to
have to order the entire HVG :)
 
M

Mike

Jan 1, 1970
0
the coolant was all over the board, so i twas a pretty good leak. not a bad
one, but not a very nice one either...
 
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