Repairing a Hitachi 55HDS69 plasma - no picture, or sound

[khnitz]

I got this TV from a friend who said the original problem was that it had no picture, but sound, and would take several tries to power up until it finally stopped powering on at all. The TV sat in storage from some years (it's a 2006 model) until now - since they are moving to a new home, they didn't want to bring this with.

So, having repaired a bunch of home electronics items over the years, I thought I'd take a gamble on this one.

The TV completes its power-up cycle with no error LEDs lit. The front LEDs will complete the power up cycle and show a solid Blue LED, before eventually showing only an Orange LED for no signal. I tried feeding a signal into the TV and cycling through the inputs (there's no display, so I have to make a best guess of it), but no luck on getting a picture or sound.

None of the 'lytics looked stressed, but I replaced the 2 main ones on the Power Supply board (390uF, 450V), just in case. This made no difference. Also, unplugging the power supply board to check at the connector for Va, Vs and Vcc showed no voltage there, either - I checked this when the Blue status LED was solid on the front of the TV. Again, none of the error LEDs are lit after they complete their power-up cycle.

So, I'm rolling the dice on a new power supply board. I'll post my results when it arrives and I test it out (maybe by the end of this week). I'm posting my efforts and findings here, to hopefully help someone else down the road, too.

[Hamie]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

I wouldn't buy a power supply.
Sounds more like a sustain board problem, control board or even mainboard.

You'll need to upload pictures of all the boards.

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Some more detail, when I unplugged the connector circled in red in the attached image, there was no voltage (0.2V or less) on any of the pins of the connector on the power supply board. This was measured after the power-up routine was completed (no error LEDs lit on the control board, and solid Blue status LED on the front of the TV).

[R_J]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

I would suspect the buffer boards and possibly the ysus also, try unpluging the buffer boards from the ysus and see if the vs stays on.
I have worked on a 55hdt79 with the same symtom, the upper buffer and the ysus were bad.

[Treydogg77]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

RJ,

Would you send me a copy of the service manual that your attachment above came out of?

Thank you,

[R_J]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

That was a Hitachi service bulletin, not from the manual. You can download the manual from here

[Treydogg77]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Thanks RJ!

Trey W
Boone, NC

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

So, as was pointed out here, the new power supply board did not resolve the issue with this TV.

So, on to the buffer boards, as was suggested.

I removed the lower one, first, and powered the TV on - the upper 1/2 of the screen lit up!

So, the next step will be to find a buffer board (or a repair service) and install that and see if I can get this all fixed

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Also, in checking the buffer IC caps on that lower board, 3 of them read shorts across, them. The board is now being sent off for repair.

[ReeceyBurger123]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

More than likely the top buffer Ic is short its normally the top one that blows as its the first one to be addressed, over time it fatigues due to heat and age and eventually shorts. As the bottom half of the screen works the Ysus is probably ok as it addresses the buffers sequentially so if the Ysus was short it would have blown the bottom buffer as it would load the bottom set next if the top buffer isnt present. Replace the top buffer and enjoy the tv

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

I removed the upper buffer board to check for any shorts across the buffer IC caps, and there were none.

Again, to clarify my symptoms: there was no video or audio when the TV was turned on - I would get the solid blue LED on the front. With the lower buffer board removed, the upper half of the screen would come on. And, on the lower buffer board, 3 of the buffer IC caps measured shorts across them. So, my lower buffer board (ND60200-0034) is out for repair, and I'll post how things are working when I get it back and installed.

Given that it seems to be a time+heat issue with these failing, I'm wondering if I should install a couple of small PC fans inside the TV and mount them atop the buffer IC boards to help with cooling. Thoughts?

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

I received the lower Y-buffer board back and installed it - and I now have picture and sound! But...

There are horizontal lines missing (evenly spaced across the whole height of the screen):


Thoughts? Would this mean the Y-SUS board also needs repair?

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

To keep the repairs aligned with the symptoms for future users searching for solutions, I decided to create a new thread to cover this "missing lines behavior" here:
https://www.badcaps.net/forum/showth...418#post585418

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Tinypic swapped the images on the original link. Here is a picture of the missing lines:

[ReeceyBurger123]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Checked that all cables are in ? Are the pixels that are in the blank rows illuminated at all ? Sounds to me like a control board issue.

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

I did go back and re-check all the connections to the y-buffer-IC boards and the Y-Sus board - those seem good.

It's weird how the missing lines are so evenly spaced, too. Yeah, it seems like something in the addressing is off.

[Vengeance]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Did you ever get it fixed? This is exactly what just happened to mine. Picture went out while watching tv but there was still sound. I knew not to waste money on a power board if the sound still works. Did the test with just upper buffer in and then lower buffer in to find the lower was bad. Replaced the lower buffer and there were the evenly spaced black lines through the whole screen. The weird thing is there weren't evenly spaced black lines when it was working with just the top buffer in, now after installing the replacement bottom board the evenly spaced black lines are still there with just the top board in. After a while of double and triple checking everything, the ICs on the bottom board burned out again. My guess would be it's the Y sustain burning it out. Can anyone confirm or give me a better guess? Could the Y sustain also be causing the evenly spaced black lines?

[khnitz]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Unfortunately, no, I didn't get it fixed (never resolved the horizontal lines). Shortly after my last post in this thread I took a new job out of state and in preparing for the move I sold this TV to someone else to try and repair.

[nicholas1110]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

Hello,

The buffer boards fail on this model due to caps on the power supply. I think they are 3300uf if memory Serves correct. They will be buldged Alittle bit. Hope this helps.

[Vengeance]

Re: Repairing a Hitachi 55HDS69 plasma - no picture, or sound

There aren't any bulging caps. That's the first thing I check. The caps are 450v 390uf, and 100v 2400uf. I would think the boards burn up from too much power, and that bad caps supply less power, not more. I don't have an esr meter but was thinking of making a diy one. How do you know what the esr reading should be?