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Philips 28pt4503/15 (MD1.2E AA) Help!

 
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Lefteris
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PostPosted: Fri Mar 21, 2008 1:55 pm    Post subject: Philips 28pt4503/15 (MD1.2E AA) Help! Reply with quote

Hello,
First, sorry for my English if i do mistakes from now on...

This TV set is not mine, a friend gave to me for free, because he couldn't fix it.
He told me that he replaced the original LOT with HR-8116, but with no luck...

TV set was at protection mode (hick-up) with led flashing. I opened it and
C2433 (1,5nF/2KV) has burnt. I changed it with a 1,5nF/3KV capacitor, soldered
some dry-joints in Large Signal Panel and checked some LOT related components
(resistors/diodes).

Now when turning on, for 5 secs i hear tic-tic sound then i take black picture
with some blurry "ghost" colors, but with good sound from channels. The tic-tic
sound come from crt panel and i see from back, near G2 pin, a little "lightening".
If i adjust the LOT (Focus/Screen), tv screen goes white and flashing quickly,
adjust more has result to goes in stand-by and start-up with more tic-tic...

I enter in SDM Mode but no led blinking for error codes... I suspect two transistors
near C2433 which burnt, T7410 (BF819) and T7421 (BU1506DX). How can i check
these with multimeter?

Anything else to check it...

Thank you for your time,
Lefteris, Athens (Greece).
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Lefteris
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PostPosted: Sat Mar 22, 2008 3:33 pm    Post subject: Philips 28pt4503/15 (MD1.2E AA) Help! Reply with quote

Hello again,

I replaced BF819 and BU1506DX with BU1508DX, but nothing...

What else should i check?

In the store told me that maybe it's diode problem, but where...
in the high-voltage or in the power supply circuit?
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PostPosted: Mon Mar 24, 2008 11:53 am    Post subject: Reply with quote

do you check voltage on suply and RGB
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Lefteris
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PostPosted: Mon Mar 24, 2008 7:03 pm    Post subject: Reply with quote

Thanks for your reply,

Big Capacitor: 375V
Next Capacitor: 132V

In high-voltage:
L1 (VOS): 185V
L6 (VFRAME): 20V

RGB (if you mean in crt panel):
both 210V in collector of transistors...
*(measures in scart-mode without scart plug-in, black screen)

**For "ghost" colors that i said earlier, it's more than a blur (no focus) rainbow,
which is all over the screen, with picture of channel very very blur (hard-visible to see).
Sorry for my poor english, i don't know how to explain better.
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Lefteris
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PostPosted: Wed Mar 26, 2008 1:04 am    Post subject: Reply with quote

I don't know if it's very important (for my problem i mean), but i found in the SSP, a missing smd transistor (7693), which terminated in pin25(=0V) of the μP (7600). It's like removed and not dropped, but i'm not sure... I soldered some dry-joints in the SSP and i saw it.

Sould i continue to search in the SSP or this is a waste of time?
I'm not an expert with tv repairs and i need some help here, please... Crying or Very sad
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