Re: Hitachi 55HDT52 - VCEGO/VSAGO ON for 2 seconds
Remove the upper and lower buffer boards from the Y sustain.carefully. Unplug it from the wall for 20 minutes or so OR unplug and replug CN68 flat wire to the logic board.
Then, without the buffer boards in, but with the Y sus properly connected to the X and thus the Main, power up. You should be able to see Vc and Vs on the pins going into the Y sus (yellow flat cable top of board). If you do, and if it stays up, ie, no self protect mode, start checking those buffer boards.
The TV is going...
Dennis H
Member
Last Activity: 08-09-2023, 08:05 PM
Joined: 12-23-2012
Location: W. Lafayette, IN
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Re: Hitachi 55HDT52 no picture, no audio
I decided to try the buffer chip repair and ordered the $11 chip. Just got it so hopefully this weekend I'll have a chance to replace it. I'll post back with results... hopefully good ones
Rack, I just noticed your in Cedar Lake, small world!...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Yes, actually those are great in that they confirm the source of the bits and pieces of info I had so far, add some more info, and seem to lend support to or validate the trouble shooting path I/we've followed. The blown IC (buffer) fits it all perfectly now.
Thank you!!Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Yes I did try with just the upper, but she still when into protect mode.
That's part of the reason I wondered about the cause...
I'ts hard to tell, but there may be a very minute cut or mark in the same ic on the lower board the had the screwy outputs.Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
I've tried to indicate which component's had what readings to support the thoughts that IC M810 is bad..., C878 is dead short, and C888,890,892 (blue caps) are showing low resistance both ways.
Think we are getting somewhere
...
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Re: Hitachi 55HTD52 Sound, but no picture
Tom, I was thinking about it,the three blue caps that show low resistance are all on the lower sdr and are all the lower cap of the three pairs that go to the three outputs. Looks like they are all on a group ground, so I thought maybe if one was jacked it could cause my readings for the other two to show the same?? maybe, maybe not?? The thinking a little further, the buffer chip (ic) that is showing the screwy non-uniform (Different from the other 11) is the lower chip of the middle pair...so I was wondering if it were shorted, could it...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
yes, did that too, three of them show about 200ohms in both directions...the others are open one way and about 800-1000 ohms in the other direction... So I assume at least the three are bad..
Any change I can just replace these guys and solve the mystery?Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Oh and is that a burned spot I see on the back side of the board, last picture almost directly up from the 2008 date. Its right under a chip and it looks like one of the pin holes may be burned... what do you think?Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
I checked both buffer boards (out of the TV) with the meter to try and see if I could find any issues (my logic being that with 6 buffer chips on each board, I should be able to get the same resistance from the corresponding pin points).
I did find one chip that did not respond like the rest.
There are 3 output plugs on each buffer board, and two chips going to each output.
The orientation on the boards is the same for all 12 chips so I found that if I placed my...Leave a comment:
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Re: Hitachi 55HDT52 no picture, no audio
Yes, somehow I transposed the HDT to HTD in my thread, but we seem to have the same model accept my failure was no picture, but sound worked.
I initially had no Vs and Va, but after doing the check Rack linked to, I was able to verify that the power supply was indeed working (this was done with the Y sus disconnected.
I was then able to trace the problem further past the Ysus to the upper and lower buffer boards. With the Y sus in and connected but with both buffer boards removed, and the logic board reset out of...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
The meter is a vintage Simpson 260series 7P. It's old but seems to work fairly well.
Ok, I dis connected the plug between the two buffer boards and we're back to showing Vs and Va.
I get the same voltage number whether I ground on the chassis or the gnd pins at the appropriate plug.
so current status;
all boards plugged in with the exception of jumper plug between buffer boards.
In this state, I still have my sound (always had sound), no screen glow, Do have correct...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Ok, chips haven't failed like that, at least not yet.
So, I powered it all down, unplugged and re installed the buffer boards and seated everything carefully. Powered it back up and I still show my Vs and Va out the main and all the way over to the plug on the Y sus board. ...but no picture, and no glow.
And, The heat sinks on the X sus board all have some degree of warmth to them and the main board heat sinks are nice and warm. The Y board heat sinks are the least warm, and at least one does not seem to have any...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
I'll check the screen in a couple of hours when it's good and dark to make sure, but generally speaking, I don't think I'm getting any glow
Although, right now, without the buffer's in, I shouldn't get any should I?Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Those buffer chips confuse me, I see what looks like a molded indention in one corner (I assume this is the spot they would burn out and show a failure??) but then they all seem to have an almost irregular kind of circular mark in another corner, again, not sure if this shows up in the photo's.
Changing the CAPS would be pretty easy, but I suspect I won't be able to change out the buffer chips if they are toasted, right? On the other hand, if it is possible, I think I found a source for the correct part number...Leave a comment:
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Re: Hitachi 55HTD52 Sound, but no picture
Yes, Here are some pictures, overall looking at the back.
The Y board is on the Left,
Main Pwr in the middle (has the two larger CAPS on it)
Logic board is smaller and to the left of Main board
Xsus is to the far right
The upper and lower buffer boards mount to the far LEFT outside of the Y sus board (they are in a seperate close up)
Vs and Va go from the Main power board over to the X sus board which then send them over to the Y sus board.
Both the X and Y board's...Leave a comment:
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Hitachi 55HTD52 Sound, but no picture
Hello, I am hoping You all might be able to help steer me in the right direction with this old Boat anchor of a TV. First a little background:
We bought the TV new in late 2005 and it has been hanging in the same spot on the wall ever since working fine until a couple of months ago when upon turning the TV on one day, it never showed a picture (sound was ok and it seemed as though all the commands etc worked even though I got absolutely noting on the screen). I did not notice any pops, noises, or other prior to the issue, and it had worked fine the night before. Although the TV... -
Re: Is this 55" Hitachi a good buy? (lines on screen)
Wow, This is great thread, glad I found it! I too have a 55HDT52 Hitachi, actually paid that crazy money and bought it new back in late 2005. It had been fine until the picture went black. Mine was the whole screen, could not see anything anywhere, but sound was/is perfect and it would change channels and controls worked etc, just couldn't see any display.
Like Matt I do want to fix it and I finally did get around to pulling the 140lb monster off the wall for a looksie. It had been on the same wall since we bought...Leave a comment:
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