TH-P42VT30 - 6 blinks

[Telefixer]

Hi All.

I've got a 42ST30Z. It's a New Zealand model. When I first got it, it was dead. I replaced the mains fuse and two chopper transistors on the P board. As the SN board was shorted, I found dead IGBTs so I did the normal check for a burnt screen and damaged buffer boards before I then changed the usual IGBTs and their diodes. Turned it on, and hello 6 flashes, 8 if I disconnect the flat control cable SN20.
Very pleased with myself when I found one of the little driver ICs, IC501 and 502, had a shorted output. Replaced them, still 6 blinks!
(SN board is SC plus SD and SU on one board)

I do have a 50VT30 to compare it with, BUT, has anyone come across this before? I'd love to know what you found. If I fix it I'll be posting. i must be close!
Cheers

[tw2005]

Re: TH-P42VT30 - 6 blinks

Hi All.

I've got a 42ST30Z. It's a New Zealand model. When I first got it, it was dead. I replaced the mains fuse and two chopper transistors on the P board. As the SN board was shorted, I found dead IGBTs so I did the normal check for a burnt screen and damaged buffer boards before I then changed the usual IGBTs and their diodes. Turned it on, and hello 6 flashes, 8 if I disconnect the flat control cable SN20.
Very pleased with myself when I found one of the little driver ICs, IC501 and 502, had a shorted output. Replaced them, still 6 blinks!
(SN board is SC plus SD and SU on one board)

I do have a 50VT30 to compare it with, BUT, has anyone come across this before? I'd love to know what you found. If I fix it I'll be posting. i must be close!
Cheers

If the driver was shot then good chance the npn/pnp driver transistor was also shot and you would also check the gate resistors too.

What pins were shorted on the driver IC? What transistors were replaced?

[syaoran123]

Re: TH-P42VT30 - 6 blinks

http://alpengeist-tvrepair.blogspot....330-board.html

[Telefixer]

Re: TH-P42VT30 - 6 blinks

Thanks TW2005 - Replaced IC502, as pin 7 (output) weas shorted. Checked Q531 that it drives, lifting two legs, and it measured okay. Resistors measured okay, but I might just replace the double transistor Q531 anyway.
The transistors I replaced were the normal Q401 etc and Q421 etc IGBTs.
I note that usually there's only one or two of these IGBTs shorted, but I think it's a good idea to replace them as a set, 'cos you don't know how close they got to going also.

syaoran123 - Good stuff there two thanks, I'll check out the extra transistor that blew for you giving you 6 blinks.
Thanks for the help guys - I'll post more when I have more - be mon or tues I think

[syaoran123]

Re: TH-P42VT30 - 6 blinks

6 blinks could also be a bad soldering of the driver IC. May need to check the pin connections and/or check for bridges etc.