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Sony KP41S4U projection TV problem

 
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mikecb1
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PostPosted: Fri May 18, 2007 6:11 pm    Post subject: Sony KP41S4U projection TV problem Reply with quote
I'm trying to fix a Sony KP41S4U projection TV.

Initially completely dead. Found that the 3.15 amp fuse on the -15 volt rail on the PSU board was blown. Fixed that, and now have sound, but no picture. There is video on the AE board, but the RGB drives are all the same, just a single narrow pulse unrelated to programme content. There is a signal called IK fed back to the AE board from the tube drive boards, which I suspect may be disabling the drives, but I don't know what this signal should look like.

Banging my head against the wall on this one, so any ideas/suggestions greatly appreciated.

TIA

Mike
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minnie



Joined: 18 Aug 2005
Posts: 2880
Location: Hell
PostPosted: Sat May 19, 2007 6:46 pm    Post subject: Reply with quote
Does the -15 feed the convergence IC'c?
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cory
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PostPosted: Sun May 20, 2007 6:45 pm    Post subject: Reply with quote
if the 3.15 amp fuse was blown,it probably blew again.most likely caused by bad convergence ic on that pcb.if the board is mounted on the right side,looking from back,vertically.then replace both ics(stk392-010?).
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PostPosted: Mon May 21, 2007 3:27 pm    Post subject: Reply with quote
cory wrote:
if the 3.15 amp fuse was blown,it probably blew again.most likely caused by bad convergence ic on that pcb.if the board is mounted on the right side,looking from back,vertically.then replace both ics(stk392-010?).


Thanks for the suggestions.

However, since posting the original request I've fixed the problem. The red tube is rather tired, and was not giving the correct IK feedback signal to the jungle ic. Without this signal, the RGB drives are inhibited, and the vertical scan is suppressed. I turned up the red screen drive a little, and BINGO the picture popped up. I'm sure the correct fix would be a new tube (£££), but the friend I'm fixing the set for can't afford this, and is very happy with the set as it is.

Regards

Mike
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