hitachi p50h401 ton or logic controller short

[awyatt2]

anyone here ever had exp with the hitachi logic controller, mine is shorted i unplugged it as ser manual suggests and it will hold on within seconds after it is plugged in the ps shuts down. i would like to be able to do a repair at component level. i don't like board pulling. the diodes and caps check out so it would have to be a chip. i will post pics of the board later today.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

should say tcon not ton a typo i hate laptops!

[simplytrini]

Re: hitachi p50h401 ton or logic controller short

Hi awyatt2, what exactly is the tv doing to assume that the Logic controller is shorted. Are you able to explain the symptoms some more? I worked on a few of these Tv's recently and might be able to help.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

when i remove the connector from power supply the set has sound and the ps stays up if i plug up the logic controller then the ps shuts down. no backlights no pic no sound with everything connected the one that makes the difference is the logic board.if i totally remove the logic board then the ps will shut down with blinking light. about 99% sure the problem lies here.

[cashkennedy]

Re: hitachi p50h401 ton or logic controller short

I would sugest testing the regulators if there are any on the tcon. and try to detect if when its connected there is a short to ground (leave the tv off, but just measure the fuse to ground if there is a fuse on the tcon.)

The only way the tv can run without the tcon, but shut down when it is connected is probably a ground causing it to draw a lot of power.

Granted i would never , never try connecting a tcon while a set is running.

[tom66]

Re: hitachi p50h401 ton or logic controller short

Ceramic caps on T-cons tend to short a lot.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

i didnt connect while running just failed to mention it, i do agree the set will run with it disconnected with sound channel and input, use antenna and dvd to verify, no backlights no display, without tcon this is normal according to ser manual. no regulators, and only a few ceramic smd caps, the lytics pass esr and vom tests. mostly chips on it.

[budm]

Re: hitachi p50h401 ton or logic controller short

http://www.shopjimmy.com/hitachi-fpf...ctrl-board.htm

Are you taking about this logic board? I have never seen T-CON board without some kind of Regulator IC, or switching power supply IC on the board.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

yep and i found the ldo regulator but its not shorted

[simplytrini]

Re: hitachi p50h401 ton or logic controller short

Sorry to possibly sound repetative but is the red light on or is it the blue light on when everything is connected? Let me know

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

blue light, sound no pic or backlight, vcc and vs are missing voltages at ps. the logic or tcon is not the fault. i just replaced it, unplug the wire harness from digital and does the same as unplugging tcon. much farther and it will be the display. i will remove the digital board tomorrow and look for a short there. something is holding the vs and vcc down, and its not the power supply at fault.may also try disconnecting display just to see before i tie any more money in it. a friend had a spare tcon known to work same set so we ruled that out. he didn't have the digital board though,tried his power supply as well. both supplies work in his set.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

the blue light is on until the set kicks off about the time the sound comes up.when it goes off no light at all until you reapply power.

[simplytrini]

Re: hitachi p50h401 ton or logic controller short

ok, not sure if you tried this, unplug the upper and lower s-dr modules from the sustain board (the two longer slim board to the left when looking a the tv from the back they have about 10 buffer chips on each of them). let them hang freely away from the tv and power the set up. if the set powers up and stays on then we know that the sus modules are good. then plug each module (S-dr boards) in one at a time at this time only half the screen should be lighting. If one of the modules are bad it will just shut the tv off again and that should be your issue. This has seem to be a very common issue on this model. I have had 2 exact sets with this issue in the last 2 months. please let me know if this helps. if you have any questions please let me know. take care.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

been there already nothing changed. the cable from the logic to the neptune digital board when unplugged does the same as when i unplugged the logic. i dont know if i'll spend another 100 on it. but i may ride over where i got the logic board and try my digital board in it. it has to either be there or the display. haavent tried to check the digital yet but i did read a couple of surface mt diodes that were very low.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

alright, here is where i am now, the neptune dig main has three diodes bad, one open and 2 shorted they all are marked 5480 a smd diode looks like a rectifier. i cant reference these as the ser manual i have has no parts listing for them. the board designation is dg01 and dg02 and dtp1. any help as to deciphering them. i already emailed cust ser. but don't expect to hear back anytime soon. thanks for the help guys. used to work in a shop on crt days. now i'm learning, dont do it for a living.it is a hobby.
don't care how many times you fix a set, no feeling like throwing the switch and firing it up, working as it should.

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

no help from hitachi, call customer assistance and wait to go thru the automated system,then they refer you to a service center. well no more hitachi's allowed here

[simplytrini]

Re: hitachi p50h401 ton or logic controller short

Did you figure out the components you are looking for? what are the part location numbers of the diodes?

[simplytrini]

Re: hitachi p50h401 ton or logic controller short

Not sure if you have this but it might help.
http://www.fixdevice.com/smanuals/file/36680.html

[awyatt2]

Re: hitachi p50h401 ton or logic controller short

two messages up diode markings and location numbers, think they are schottskys look about 2 amps or so but stilll unsure. the service manual download has no schematics.already got one wit at least partial schematics this one has none. we are trying.

[cadiman]

Re: hitachi p50h401 ton or logic controller short

This p50h401 plasma tv has 99% failure of buffer boards and bad caps on secondary of power supply.

I normally start with these tvs by removing the buffer boards then powering up the tv.

I have seen the buffers take out the y drive and then take out the power supply.

These tvs are harder to troubleshoot than the l/gs and other models.

If the screen lights up when powered on than I would say you are on the right track.