SAMSUNG LE32C450 not booting

[shrad]

Hi all,

I have a samsung LE32C450 which is not booting

I fixed all or part of the PSU by replacing the FAN7530 and the hybrid IC, and everything seems OK as all the voltages are OK, backlight is working and the TV sets itself ON when using the remote

After being set out of standby, the TV doesn't boot as there is no menu or sound

The red LED blinks to the remote commands though, after the LED has blinked 5 times

Resetting the EEPROM did nothing

I read it might be a TL431 which would be bad but the PSU seems fine now...

Would anyone be able to help me?

[tom66]

Re: SAMSUNG LE32C450 not booting

Do you have good 12V at both ends of the fuse on the t-con board?
Don't rely on the melody start up sound. It is an option that the user can turn off in the setup menu. Also, selecting a source with no image can be difficult.

[shrad]

Re: SAMSUNG LE32C450 not booting

The T-CON fuse is not open, I checked it

I may have to re check for the 12V at the T-CON ribbon, but I recall having measured some 5V and 3V3 paths at the ribbon test points underneath the board

Are there known scenarios anyone could describe me so I'd be able to work more than 5 minutes before having to ask again?

I'm into TV repair since that one, so I still have to learn a bit, even if I have repaired much things for years... so I have to learn a bit

[tom66]

Re: SAMSUNG LE32C450 not booting

To confirm T-con function, check AVDD, VGL (or VOFFE), VGH (or VONE) on t-con board.

[shrad]

Re: SAMSUNG LE32C450 not booting

Would it be the same signals as at the other side of the ribbon? I'd like to avoid dismantling the T-CON and creating bonding faults at the LCD

If I can measure this at the mainboard side, it would be nice

As the TV seems to get out of standby and remote commands make the LED blink, I fear the T-CON may have died for some reason... fingers crossed...

[tom66]

Re: SAMSUNG LE32C450 not booting

Does this TV have a separate t-con board? Pictures please.

[shrad]

Re: SAMSUNG LE32C450 not booting

hi

the T-CON has no voltage on the VPANEL line (I guess this is the 12V line as it has 4 via and is 3mm wide)

the main board is this one: http://www.duycom.com/wp-content/upl...N94-04175J.jpg

the T-CON is separate... I guess I'll have to check the different regulators I can find on the board...

I fear the main board is toasted but everything tells me there is something to find

The TV set was working nice, then took more and more time to power itself on, up to an hour before the set was ON

This makes me think about a bad capacitor or solder joint, or even a faulty regulator which has to heat before it works

As I had to replace the PFC buck it may have been caused from excessive ripple... I'll have to trace the regulators, but it may be tricky on a 4 layer board like this...

[shrad]

Re: SAMSUNG LE32C450 not booting

EDIT: just checked the P MOS feeding the T-CON, it tests OK and sees the 12V supply, and the command transistor of the MOS seems OK so I guess the CPU just doesn't send the command

Does it need to boot for the remote indicator to light when commands are sent? I think not, but it is strange that the CPU seems to heat just a bit over ambiant so it's draining power... I should harness the scope but there could still be thing to try

If you know of any scenario I could ckeck, I'd be happy

Anyway, I'm going to visit some shops next week and maybe I'll find a spare TV of the same model if I'm not able to repair it