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Old 01-10-2019, 05:32 PM   #1
CuriousJohn
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Join Date: Dec 2018
City & State: Britain
My Country: Great Britain
Line Voltage: 230VAC 50HZ
I'm a: Hobbyist Tech
Posts: 21
Default Bush idlcd26tv22hd 17PW15-8 issue

Hi folks, I hope somebody out there can clue me up on this 17PW15-8 i have been reading lots of threads on it and already repaired the STBY 5v as obtained this set dead. Its an older tv now but still tidy and the audio is nice has big speakers compared to modern tvs.

Anyway, as I said repaired this psu 5v STBY and had it running for a day noticed a bit of whine fromthe TV on the day it was running but thinking it was from cold cathode inverter thought about stripping it down to check prob should have oplayed with turning it down to see but the next day poweredthe set to the mains first thing and sure there was a pop, thought did I really just hear that... Standby light on would not power up..

The set will not come out of stby now and when mains is applied the 33v 12v
and 24v comes up for a second during the test but then off leaving just STBY 5v and 3.3v. Cant see any obvious damage and already applied a repair kit replacing the following caps:

C801
C901
C892
C817
C877
C878

Before it went pop the day after I repaired the STBY 5v the psu was working fine even when disconnected and forced on all outputs where good. Today not so good, the primary will not come on and stay on connected to mb or not.

Now wondering what has gone on with it where did that pop come from, IC802 seems ok it has vcc 11.13v, Q803 drain sits at 331v and gate is 0 all way to pin 7 of IC802 so obv not coming on some reason? Vcc1 and Vcc2 are present with IC828 also having 13v on its ip and 11.27v on its output with 10v fed back to adjust via the resistors dropping by roughly 1.25 from 11.27 to 10 volts as a LM317 is supposed to behave. Mainboard is pulling pl803 pin 6 to ground when power button is pressed.

The weird and annoying thing i noted was that the the 33v + 12v on pl803 and 24v on other outputs only come up intermittently at start when mains is applied during the self test, something like 1 in 5 times sometimes less or more so obv something is wrong I hate intermittent faults.

Does anybody here have any ideas about where to look next also i cant find the source of Vcc1 or what value VF main should be it is coming into IC828 as 13v with PSU in standby...

I admit this is a complex psu any help appreciated.

Last edited by CuriousJohn; 01-10-2019 at 05:40 PM..
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