Hitachi P50H401 DEAD with blue dight on

[ajshoe]

Have a Hitachi P50h401 that seems to power up. red indicator goes to solid blue. no display, fans come on for 1 second, checked all voltages, disconnected upper and lower buffer boards, went thru diagnostic flowchart, and getting nowhere. power supply looks good, Buffer boards check out (ohmed). ysus bad ?? has anyone have any experience with these sets ???

[ajshoe]

Re: Hitachi P50H401 DEAD with blue dight on

after more thorough testing = both SDR boards are bad. have 4 buffer chips on upper and 4 buffer chips on lower board bad. ysus board checks out good on conn CN32. Got set with brand new power supply board - somebody must have replaced it and then gave up.
does anyone know if P50h401A SDR boards will work in my set ?? My SDR boards have 8 buffer chips - P50H401A SDR boards only have 6 buffer chips.

ordered some new P50H401 SDR boards (chinese) - let u know

[Shane711]

Re: Hitachi P50H401 DEAD with blue dight on

How do you test the buffer/SDR Boards?

[kca]

Re: Hitachi P50H401 DEAD with blue dight on

Did you ever get your Hitachi P50H401 up and working, ajshoe? I have one similar and am on the verge of fixing it. It has the solid blue light you spoke of, power, voltages are all correct up through the CN32 connector, and I know both of the SDR boards are bad.

I am wondering if you know how to test the YSUS board in a full, comprehensive manner.


Here is a post i made a few days ago. I'm hoping you might be able to comment on it and provide some insight based on your experience. Thanks.

I've been working on a Hitachi P50H401 for a couple of weeks now, learning from this site and other forums as well as I have progressed. I'd really like to get some quality, detailed advice before I plug back in new SDR boards to help ensure that I won't lose them when power is applied.

Here is my current scenario:

1) The two 3300uf caps were swollen, so I replaced them both.
2) The two SDR boards (U and D) were both clearly damaged.
3) I disconnected both SDR's and connected a video source. It now goes from red to solid blue on the front panel and stays that way. The sound is perfectly fine, but there is (of course) no picture as the SDR's are unconnected to the YSUS board.
4) I can change channels (as evidenced by the sound of various channels changing) with the DirecTV remote and can change the volume with the Hitachi remote.

I have checked, double, and triple-checked all of the voltages involved.
PSU is fine.
PSU to XSUS is fine (via connector CN23)
XSUS to YSUS is fine (via connector CN22)
YSUS from XSUS is fine (via connector CN32)


My focus is now on the YSUS Board (and, in particular, the two connectors that lead out from the left side to the SDR's):

THIS is the current crux of the matter. I tested all 25 pins on the lower left connector that comes out of the YSUS board (and ultimately leads into the SDR-D), and ALSO the 25 pins on the YSUS upper left connector (that leads, ultimately, to the SDR-U).

I assumed that I would find exact voltage matches because both of these connectors are labeled exactly the same on the circuit board itself. That turned out to be the case, the voltages do match, EXCEPT for pin #8 and pin #21 (counting up from the bottom) on the LOWER LEFT CONNECTOR ONLY. Those two read 0.00

All of the upper left connector pins had readable voltages, including its pin #8 (-24.5v) and pin #21 (-51.8v).


Note: On both the lower and upper, pin #8 is labeled as DA2 on the circuit board, and pin #21 is labeled as DA1.


All of this leads to a rather simple question I hope can be answered. Does the fact that I get the two 0.00 readings on the lower left connector mean that this particular YSUS board is entirely defective and must be replaced?

{Or, can I repair it in some way? Or, as is my hope, these two 0.00 readings will NOT prevent the SDR-D board, or the tv in general, from working properly when I connect it?}

It seems very odd to me that the upper left YSUS connector has readings at pins #8 and #21 and the lower left YSUS one does not.

Please feel free to reply in as detailed and as exacting manner as you'd like. I am into this pretty deep, as you can see, and I want to get it right before risking $120+ on the SDR U and D's.

Thanks in advance for your replies.