Mitsubishi LT-40148 Blinking Green Light

[iFixStuff]

I was given this tv and it was dead. I repaired many parts on the power board and now I get the relay clicking but no power to inverters. 12v is present where it should be, no 5 volts and all fuses on the power board and main board are ok. Green blinking LED (non stop) when you plug it in. Nothing happens when you push the power button, the reset button functions as it should. Appears it is stuck thinking it's in reboot mode. I can't find any help from the mitsubishi site as I have the only model listed without a firmware update. I'm about ready to turn this into trash, but I know somebody has been in this same situation and may have suggestions. I know an easy solution is to buy a board thats working, but that's too dang easy and I can't teach myself buy spending money when I'd rather eat BBQ!

[budm]

Re: Mitsubishi LT-40148 Blinking Green Light

You can start by uploading good clear pictures of the whole backside of the TV so we can see how all the boards are connected together, and then good clear straight shot of the power supply board for now to see what we are dealing with.

[iFixStuff]

Re: Mitsubishi LT-40148 Blinking Green Light

Thanks, loading a few up. The Model # LT-40148

[keats11]

Re: Mitsubishi LT-40148 Blinking Green Light

Its most likely a bad main board. The green blinking LED according to Mitsubishi means that its trying to boot.

[budm]

Re: Mitsubishi LT-40148 Blinking Green Light

Please list the pin name and Voltage reading on each pin of the connector PA and PB of the power supply board.
Pictures provided by shopjimmy.

[iFixStuff]

Re: Mitsubishi LT-40148 Blinking Green Light

PA:
Dimming 0.0
Bk Lght on/off 0.0
Inv Short. 3.2
Inv Relay. 0.0
Panel Pwr. 0.0
Gnd. Gnd
Pnl 12v Short. 0.2
AC off. 0.0
Main Relay. 3.6

PB
VA. 22.8
VA. 22.8
Gnd. Gnd
Gnd. Gnd
Panel vcc. 1.0
Panel vcc. 1.0
Gnd. Gnd
Gnd. Gnd
12v sl 12.0
12v sl. 12.0
Gnd. Gnd
Gnd. Gnd
Gnd. Gnd

All tested on dc with ground set on chassis.
I have a low to medium level of skill but understand the basics and bought a Oscilliscope a few days ago to help me figure things out better.
Thank you all for your time.

[fzabkar]

Re: Mitsubishi LT-40148 Blinking Green Light

Service manual:

[budm]

Re: Mitsubishi LT-40148 Blinking Green Light

I need to download the service manual to see what the normal Voltage of the 'AC OFF' pis should be. I believe it is the same as 'AC DET' as used in other TV manufacturer and is normally HIGH (>2VDC) for normal.
Right now the main board is not sending lots of command signals.

[iFixStuff]

Re: Mitsubishi LT-40148 Blinking Green Light

Thank you very much for the link, just what I needed.