Question about Hitachi Televison & Video
I have the same model, P50H401 and it developed the same problem two days ago. This set is 2 1/2 years old in service, being purchased in December 2007. The original manufacture date was October 2007.
The set was turned on and operating at the time and then promptly shut down by itself. The front blue LED power indicator began flashing four times in a loop or cycle.
The flashing LED sequence in this instance points to a problem with one of the following boards: PSU, X-Sus, Y-Sus or SDRs (there are two SDR boards, SDR-U and SDR-D, both are connected off of the Y-Sus board on the left hand side of the frame when rear facing). The set shuts down to prevent further damage to other boards or components.
I could power cycle the set but it would shut down after after a few seconds. Power LED would stay solid, I could hear the PS relays switching, and audio would output through the speakers. Then as the screen was just about to illuminate, the entire set would just shutdown. The blue LED would again go into the 4X flashing sequence.
I could not visually detect any signs of severe component damage on the main PS board. The two large electrolytic capacitors which have been mentioned as problematic in other threads seems fine. The where slightly raised on the top surface, but not blistered or completely blown open.
The only indication of component damage that I could detect visually was on one of the small surface mounted ICs on the SDR-U board.
Through reading other posts on this site, I learned that I was able to remove the suspect SDR-U board and then re-power the set. Doing this proved that the PS, X and Y Sus, and the SDR-D boards where o.k. The PS held, and the lower half of the screen illuminated. (I would only do this for as brief a period as required to determine if the the other boards would function and the screen would illuminate. Do not pro-long operation in this state so as to not cause further damage.)
It was somewhat difficult to locate the correct SDR-U board. My local service rep did not have one in stock, and the Canadian parts distributor was also out of stock. They estimated 10 - 14 business days to order one up from the U.S.A. (Hitachi closed their consumer electronics division in Canada back in 2009.)
By chance, I checked with another service rep in an adjacent town. He had a board for the P55. We did a visual comparison on the two boards and determined that it would be compatable.
The easy part was removing the defective SDR-U board and installing the replacement. The hard part was re-alinging the three ribbon tabs into the respective connectors on the SDR board. Be careful with these ribbons. The other end of each is fused to the plasma panel screen, so if you damage them, your screen is rendered useless.
I initially had the same problems as others have posted with having black or gray lines on the screen when the SDR-U was replaced. After gently adjusting the position of the ribbons as they are seated in the connectors, the lines disappeared. This was a slow and frustrating procedure, but it worked, Be patient.
Posted on Jul 03, 2010
check your sdr boards. you can test them with a multi meter. they are known for going bad. what happens is the two caps by the output go bad on the power supply and they make the sdr boards burn out. you can replace the two caps and save lots of money. then please check out this web page http://www.hometheatershack.com/forums/hitachi/38229-hitachi-p50h401-led-flashes-3-times.html
This web page has info about repairing these. The 4 flashing lights maybe the x sus or the y sus but it's still a good idea to check the sdr boards since its a common failer. I had one tv with a bad sdr board flash 3 time and another set it was flashing 4 times.
Posted on Feb 22, 2011
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