Is this 55" Hitachi a good buy? (lines on screen)

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Oh, I see it! That IC has a hole in it... wow. Usually they just go on their own accord. If something was real bad, the TV wouldn't power up at all, or all the ICs would be dead.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I was surprised to see it too. It makes diagnosing things a whole lot easier. I have opted to try to change out the IC instead of the board. I got the old one off with minimal problems, now I'm just waiting on the new one in the mail...

I'm going to be as careful as possible and triple check my work before plugging the TV, but what if I screw up my soldering job? Is it possible it could damage other boards or even the panel when I turn it on?

[Th3_uN1Qu3]

Re: Is this 55" Hitachi a good buy? (lines on screen)

How did you manage to remove that epoxy? Or was it something softer.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Soft silicone I think, i just used a razor. But when encounter epoxy usually 200c from the heat gun and a razor blade will do it. What is this soft glue for? keeping the legs from lifting?

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I was surprised to see it too. It makes diagnosing things a whole lot easier. I have opted to try to change out the IC instead of the board. I got the old one off with minimal problems, now I'm just waiting on the new one in the mail...

I'm going to be as careful as possible and triple check my work before plugging the TV, but what if I screw up my soldering job? Is it possible it could damage other boards or even the panel when I turn it on?

If you short lines together, you'll likely damage your new buffer IC, but that should be where the damage stops.

The panel is essentially glass and wires. It's very difficult to break it electrically.

How did you manage to remove that epoxy? Or was it something softer.

It just peels off. It's HV insulating epoxy. Because each of those rows are energised with -200V/+400V relative to common depending on the current state of the sustain waveform. I had one buffer with a rather toasty insect (a small fly) between some of the pins. It didn't end well for the insect -OR- the buffer but luckily the part was cheap.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I wasn't planning on replacing the glue, but I am thinking twice now... Is there anything I could buy locally at a home improvement store? Will these ICs get too warm for hot glue?

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I wasn't planning on replacing the glue, but I am thinking twice now... Is there anything I could buy locally at a home improvement store? Will these ICs get too warm for hot glue?

Hot glue isn't great but it should be an acceptable substitute.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Ok, and what about the "big cap" you talked about in earlier posts? Is it on the power board? They all physically look good, but I haven't put my meter on them yet.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

If they haven't bulged on this set they're OK. I think the failure on this is simply a random event.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I think these ICs are just kind of crappy. There are lots of people on ebay offering repair service for this board for $80-$100 so, I guess the problem is wide spread.

Surprisingly this beast has no fans although I think it has room for some. If I get it working I think I might add some. Is there 12v anywhere on the psu I could tap into?

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

More than likely 12V for audio or main board you could run a fan off. Most Panasonics use fans for reliability. Disappointing that Hitachi wouldn't use some, especially if it's an older plasma (much higher power consumption)

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

490 watt max, 393 average. I guess it could be worse for a 2007 55" plasma.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Well, for comparison, a 2006 NEC 50 incher (that I fixed) drew close to 550W full white and about half that average.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I just ran the tv with the bottom buffer board out and the bottom half of the TV was black as expected but the top half still had the even odd problem. Is this to be expected or do I have more problems?

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

I had the same issue with a Panasonic plasma. Something didn't sync up right when the bottom was out, and I only got an interlaced picture on the top half.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Great, thank you.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Oh, I forgot to mention the 550W NEC had two fans. One for the combined Y-sus/Z-sus (all in one board with massive hybrid module), and one for the PSU.

So I think Hitachi were just cutting costs by not including a fan, and it might have lead to buffer failure. You can also install heatsinks on the buffer ICs, Panasonic does this a lot.

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

What would I use to attach the heat sinks? The epoxy would make it hard to get good contact with the chip.

[tom66]

Re: Is this 55" Hitachi a good buy? (lines on screen)

Thermal adhesive. (Adhesive which is a good thermal conductor.)

[mattpd]

Re: Is this 55" Hitachi a good buy? (lines on screen)

15 heat sinks and thermal plaster for less than $5. Thank you ebay. Just think of how cheap hitachi could get them. Weird they didn't include them in a $3,000 TV.