Hitachi P50TP01U A Buffer board blown

[Moggy]

Just need some basic advice please. This 50" TV has a blown lower buffer board. ND60200-0047. 3 ICs look damaged/burnt.

I have tested the Y-SUS board, no obvious shorts.

Am I likely to need to replace both buffer boards, and is it likely to have caused problem on the Y-SUS board.

Thank you Stuart

[freakaftr8]

Re: Hitachi P50TP01U A Buffer board blown

These boards blow buffers in series. I would advise replacing the whole board. Sometimes it can damage the other buffer board. It may work for a bit but can go. Sometimes you get lucky. Blown buffer board can damage a few discrete components on the ysus. Try disconnecting the bad buffer board and power up tv. Do you have half a picture? It will be dark but the panel should light up.

if it doesn't or it looks funky on the screen then take a clear picture of the Y sustain board and I will show you the discrete components that are known to go bad.

if the buffer board destroyed the components on the ysus board replacing the buffer board will cause it to fail right away so you need to be careful with that.

Take a clear pic of the ysus and

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

Hya, thankyou for your help. Just what I needed. I put the boards back, and just the lower buffer which looks ok. Powered up and here are the pictures as requested.

[Alastair E]

Re: Hitachi P50TP01U A Buffer board blown

Looks like there's issues with either the Y-SUS and or the bottom buffer board too.....

On the set I did, I had a half picture--that was perfect, but it was my bottom buffer that had failed

Buffers for these sets are horrendously expensive--at least they were when I looked for one a little while back, I ended up re-chipping the one I had.....

The chips for the buffers ain't cheap either, cheapest I found was £11 each.....

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

OK, sh ysus boards seem to be cheap, there are 3 def blown on the buffer board, pair from china about £70-00, Said I wouldnt repair anymore tvs, stick to vintage hifi. Ok thanks for the info. The glue around the edges it that a heat conducting goo. Also not geared up to remove replace these chips.

[Alastair E]

Re: Hitachi P50TP01U A Buffer board blown

OK, sh ysus boards seem to be cheap, there are 3 def blown on the buffer board, pair from china about £70-00, Said I wouldnt repair anymore tvs, stick to vintage hifi. Ok thanks for the info. The glue around the edges it that a heat conducting goo. Also not geared up to remove replace these chips.

The glue on the chip pins is silicone of some type, I used my finger-nail to scrape it off, get as much off as you can....

I used a paint-stripper hot-air gun to remove the chips, they have a pad underneath thats soldered too, so just cutting the pins off the chip wont work.....

Wrap the board in tinfoil--except the chip you intend to remove, heat at a distance of 3-4" or so full heat, and keep the heatgun on the move, until the solder melts--(test by dabbing with some fresh on the IC pins), Takes about 3-4 minutes in real time to get hot enough. (Seems like forever when you're doing it)
Heat for a little while longer, then very carefully--but with no force at all--flip the chip up....
Easier and much more fun to play with the likes of EL34 and its friends innit!

Ive done TV sets on and off for years, but hate all this new crap, Give me a Philips G8 anyday!

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

I have used similar techniques to what you have mentioned. Thought is wouldn't be high tech enough. Perhaps I should try a YSUS board, see if I get half a good picture, I think its the spending lots of money and having a duf tv at the end.

[Alastair E]

Re: Hitachi P50TP01U A Buffer board blown

If its your set,--then maybe worth doing...

If someone elses,--then maybe not. These sets never seem to have a particularly good/bright picture, seems to be faded washed out--even when working well--They are a good few years old now too....

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

Ok, food for thought, it was going to be ours, but not desperate. If they are that bad perhaps put on ebay for spares or repair faulty. I doesn't stand me in any money

[freakaftr8]

Re: Hitachi P50TP01U A Buffer board blown

Check 3 pin voltage regulators cx31 at top of board near heat sync and another one like it at the bottom there most likely shorted. Also there may be another smaller smd style transistor at the bottom near the regulator shorted as well. I'm almost guaranteed or shorted looking at the bottom buffer board in the output showing up on the screen. This particular model tv will still show a perfect bottom if the top buffer is not connected.

[Shinju]

Re: Hitachi P50TP01U A Buffer board blown

So I have the Hitachi P50V701 and yours looks damn near identical to mine on the interior.


Could you do me a solid? With your bottom buffer connected could you get VA/VS readings for me? WIth mine the bottom buffer is blown and the top is fine the picture comes up on the top half but my VA/VS voltages are WAY higher then they should.


Just curious as to what yours are in the similar state as mine is.

Thanks!

Oh and these buffers are NOT CHEAP!

(My Thread)

https://www.badcaps.net/forum/showthread.php?t=41736

[aaronwt6]

Re: Hitachi P50TP01U A Buffer board blown

On a different subject not related to the YSUS and buffer problem -- Are the two large capacitors on the upper right of the power supply bulged or is it just the picture making them look that way? They look bad at a glance.

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

They do look bulged, I removed and tested with a ESR meter and checked fine, but I thought the same.

[Moggy]

Re: Hitachi P50TP01U A Buffer board blown

freakaftr8 thanks for the reply, have been off for a few days, which board are you referring to, I can't see these parts on the ysus board.

[freakaftr8]

Re: Hitachi P50TP01U A Buffer board blown

Yes the ysus board. Right at the top and bottom of the connect for the buffers you will see 3 pin transistors on the board. One on the top and one on the bottom. Top is called cx31
Bottom cx-- something to the liking. See if they are shorted. They are very small.