Mitsubishi LT-55154 *Experienced Tech Help Needed*

[ericbernard]

Hey all-

Been trolling the fourms for a while. I'm working a dreaded "blinking green light" issue on the Mitsu LT-55154. I've been through the other threads and read up on what folks have posted, however I haven't seen any successful resolution. With your help, I'd love to put an end to this nightmare and help others get the same issue solved.

I do have tools available to help identify the issue at my disposal (scope, DMM, etc.).

Symptoms: Blinking green power light on display. No display or audio. Power voltages test fine across PWB and into Main Board. Power on relay operates as it should. No cap buldging, swelling, etc. The board looks physically fine.

Steps taken thus far: Checked all caps on main for noise. Found and replaced two 100uf electrolytics that had marginal signal noise. No change in symptoms. I replaced several other 100uf caps for good measure, no change. Tried to re-load firmware with two different USB drives. Light on drive blinks for hours and hours with no physical change in set behavior. I've traced my voltages against the schematic in the FSM and I just can't seem to nail the culprit down.

Let me know what other information would be helpful and I will get it tested and reply. Guys on eBay are selling the repair service but won't share any information.


TIA

Eric

[R_J]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Have you tried doing the reset procedure? have you got the service manual? If its just the green led blinking it may be that the flash or the microprocessor is corrupt
How are the usb drives formated, they should be fat32, If the flash is corrupt I dought it would update.

[diif]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Any clues here ?

http://techlore.com/article/mitsubis...pair-procedure

[budm]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

So the supply Voltages are OK but how about the command signals Voltages?
Do you have any good clear pictures of what we are dealing with?
Can you upload the service manual for us to look at?

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Have you tried doing the reset procedure? have you got the service manual? If its just the green led blinking it may be that the flash or the microprocessor is corrupt
How are the usb drives formated, they should be fat32, If the flash is corrupt I dought it would update.

RJ- I do have the FSM. I formatted the USB drives to fat32, long format. I have tried the power button for 8 seconds, etc. Also tried volume down and menu to reset video.

Thanks for taking the time to help!

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Any clues here ?

http://techlore.com/article/mitsubis...pair-procedure

Diff,

I found that article on google. The WS series is a rear projection set. I did see if there were any similarities in the sets but they are quite different.

Best,

Eric

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

So the supply Voltages are OK but how about the command signals Voltages?
Do you have any good clear pictures of what we are dealing with?
Can you upload the service manual for us to look at?

Bud,

Thanks for the reply. The FSM is posted in a link above. VCC signals also test within spec. I will try to get a few pictures soon, but the unit is identical to the one in this post https://www.badcaps.net/forum/showthread.php?t=59076

This one has me chasing my tail!

Thanks for the help!

Eric

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Both fuses (AC on PWB and DC on Main) test OKAY.

Symptoms are identical to the other post I shared from the forum!


Eric

[dskall]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Sounds like you've watched this video. https://www.youtube.com/watch?v=KJQB86WPVlk

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Sounds like you've watched this video. https://www.youtube.com/watch?v=KJQB86WPVlk

D-

Yep. I even reached out to the guy who made the video asking him for his $.02 on the issue. He said if the caps were bad they would throw ~1v of hash on the scope set on AC coupling at 1/10 volt. None of my caps did that at all. In fact the ones that I changed had noise in them, nut only a slight amount and they still do with the new ones. I tried to use that as a clue to go back through the circuit but I didn't get anywhere.

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

This is all the noise I saw on the "bad caps"

[dskall]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

The repair for that board also references HDMI not working. Wondering if the problem is tied together?

[ericbernard]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

The repair for that board also references HDMI not working. Wondering if the problem is tied together?

I think it may be related to the HDMI chipset. They do sell the chip on eBay so I thought about giving it a shit. The guys who rebuild them won't touch them if someone else has had an iron on the board. I replaced ALL the 100uf caps...

[diif]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Check any small ceramic capacitors near it for shorts also.

[Michael Long]

Re: Mitsubishi LT-55154 *Experienced Tech Help Needed*

Finally Fixed my Mitsubishi LT-55154. The Failure was identified by Nyjetfan21
so lets be sure to give credit where credit is do. I Reflowed the surface mounted GPU on the Mainboard. The suspect chips are under the heat sinks.
The Rig I used was originally used to reflow GPUs on Laptop Motherboards.