black screen magnavox 42mf231d/37

[fhorta]

hello to all,

this plasma tv was only 2 1/2 years. started by blacking out half the screen. it worked normally again for days and would black out half the screen again. finally one day heard cracking sound and burned smell and screen went completely black.

took it in for free diagnosis. of course they only tell you limitd information if any if you choose not to repair it. one of the shops said it was the y sus and if he was replacing the y sus he would also want to replace upper and lower buffers.

other shop said it was the sustainer pc board assembly. thought i would get second oppinion see if they matched.

question: are these parts (y sus and sustainer pc board) the same thing?

i have no experience in tv repairs or electronics period. i feel confident i can open the back of the tv. could these parts be replaced bya novice or would one have to hire a technician, period. where can i find these parts. lastly, would failure of these parts warrant the black screen.

i read on other post similar problem but not exactly. tv screen did not go black completely.

i appreciate any feed back i can get. thank you soo much.

[retiredcaps]

Re: black screen magnavox 42mf231d/37

i have no experience in tv repairs or electronics period. i feel confident i can open the back of the tv. could these parts be replaced bya novice or would one have to hire a technician, period. where can i find these parts. lastly, would failure of these parts warrant the black screen.

Wizard and PlainBill are the experts in this area.

I have zero hands on experience in repairing plasmas, but after following this forum for the last 6 months, I have come to the conclusion it is not a trivial exercise for a number of reasons.

1) Lack of good documentation like schematics or troubleshooting books.

2) Plasma "repairs" seem to be a lot of board swapping versus component level repair (like changing out transistors or capacitors).

3) The cost for replacement boards can easily be 1/2 the cost of a brand new 42 inch plasma TV. Boards from ebay may or may not work (and sometimes without warranty).

4) Plasma TVs have very high voltages. This could be dangerous for people not familar with electronics.

I'm not trying to discourage you from DIY. In fact, I wish you all the best and luck in repairing this, but I'm just trying to set your expectations properly. Hopefully, it will be as simple as an open fuse or bloated capacitor.

With that, I'm sure people here will want to see clear focused pictures of your boards.

[fhorta]

Re: black screen magnavox 42mf231d/37

thanks for the reply. plain bill and or wizard; is it possible that y sus goes out without the upper or lower buffer going out first. asking beacuse one of the techs said he would replace upper, lower buffer and y sus. other tech said its only the y sus. reading other posts i understanding that its when buffers have gone bad then the y sus goes bad. just wondering if possible that y sus can go bad alone witout buffers being damaged. thanks again.

[Wizard]

Re: black screen magnavox 42mf231d/37

YSUS board have fuses on them, if one of them blown, that means it died along with the upper buffer board because of kept using the TV with fault.

And yes boards cost pretty penny.

Cheers, Wizard

[PlainBill]

Re: black screen magnavox 42mf231d/37

I just repaired one of these. Here's the scoop.

First of all, yes, the sustain board is also known as the Y-Sustain board. The initial problem was one of the Y-buffers. When a buffer shorts it usually takes out the Y-sustain. The usual recommendation is to replace both Y-buffers and the Y-Sustain.

Here is a more extensive discussion from an expert.

Mechanically, this is not terrifically difficult. If you have the skills to tune up a car, or replace the motherboard in a computer, you can do the mechanical part yourself. There are electrical adjustments to be made. Wizard may know if this is usually necessary on rebuilt boards. I would assume it is. The actual adjustment is relatively easy, it's the equipment that would cost a lot. Assuming you could find a qualified technician to do that part, here are the other items you would need.

Y-Sustain LJ92-01200A, BN96-02033A

Upper Y Buffer LJ41-02760A LJ92-01202A

Lower Y buffer LJ41-02761A LJ92-01203A

The best deal would appear to be from this eBay auction. They will repair your Y-Sustain for $62 and test both buffers. They have replacement buffers available.

The bottom line if both buffers are bad would be about $250 + the cost of adjusting the Y-Sustain. I don't recommend the repair.

PlainBill

[fhorta]

Re: black screen magnavox 42mf231d/37

thank you plain bill and wizard. i will give it a shot and order parts and replace myself. we'll see how it goes. thanks again.

[mbates14]

Re: black screen magnavox 42mf231d/37

you can get the buffers for the toshiba 50HP66 as they are VERY cheap compared to the notorious fail buffers. You can pick up a buffer for a 50HP66 which is a PDP50X3 for roughly 30 bucks. which provides all 6 chips to repair one samsung buffer.

the chip numbers are not exact, BUT i decided to bite the bullet, and swap out the ICs from the 50HP66 buffers onto the philips buffer, and it worked. So that means they are electrically compatible, i guess the 50hp66 buffers probably handle slightly more current which is why the IC numbers arnt the same, but they are VERY close.

[matteau31]

Re: black screen magnavox 42mf231d/37

Does any have issues with tv screen going blank after being on for a few but you can still hear sound? Do I need to check resistance on everyone of the boards on my plasma in order to find the bad board or cap etc?

[PlainBill]

Re: black screen magnavox 42mf231d/37

Does any have issues with tv screen going blank after being on for a few but you can still hear sound? Do I need to check resistance on everyone of the boards on my plasma in order to find the bad board or cap etc?

on for a few

Few what? Hours, minutes, seconds? And is this a Magnavox 42MF231D/37?

Probably starting with the voltages out of the power supply would be best.

PlainBill

[matteau31]

Re: black screen magnavox 42mf231d/37

Thanks, do I need a special voltmeter to test the power supply? I was talking with a TV repair tech and she said the same thing. I bet my TV got a power surge from the energy company. Do you use UPS or expensive surge protector for your TV?

[matteau31]

Re: black screen magnavox 42mf231d/37

TV screen goes back on all ports after 30-60+ minutes.

[mrosenberg42]

Re: black screen magnavox 42mf231d/37

you can get the buffers for the toshiba 50HP66 as they are VERY cheap compared to the notorious fail buffers. You can pick up a buffer for a 50HP66 which is a PDP50X3 for roughly 30 bucks. which provides all 6 chips to repair one samsung buffer.

the chip numbers are not exact, BUT i decided to bite the bullet, and swap out the ICs from the 50HP66 buffers onto the philips buffer, and it worked. So that means they are electrically compatible, i guess the 50hp66 buffers probably handle slightly more current which is why the IC numbers arnt the same, but they are VERY close.

Where did you get the idea that these buffer chips are compatible between the magnavox and the toshiba? Thats a ballsy move unless you had the chip numbers with the data sheets to prove that they in fact were compatible.

What exactly is the buffer chip make and part # for the Toshiba buffer?

You must have some good desoldering equipment or are very skilled. The pitch on these chips is pretty tight. I wouldn't be as worried about getting them soldered in as much as damaging the good chip from the desoldering process. Although chip quik can be a techs best friend.

[mbates14]

Re: black screen magnavox 42mf231d/37

Yup its a ballsy move. But thats my nature, you dont learn unless you blow something up.

and in this case, it worked.

Removing the IC is challenging. First you have to remove all the heatsinks off of the bufferboard on the magnovox ones.

Then you must razor blade all of the silicon surrounding the pins, off.

Then you must build a heatshield out of aluminum foil or something of the like, to protect all plastic connectors on the board. Exposing only the chip area. This avoids direct exposure of the hot air gun heat from the plastics so they dont melt and deform.

Then you preheat the board with some hot air, then take a hot air pencil to each chip and remove each one. This may take some time on each chip to keep the heat applied before it will remove. Not only are the pins soldered down, but there is a solder pad directly underneath each buffer IC that solders down as well.... Clean the excess solder left behind when the IC comes off, and remove all silicon residue and remains.

Presto. Oh and you need some thermal adhesive to put the heatsinks back onto the buffers. I just used 2 sided thermal tape. They do sell thermal adhesive compound, you must scrap all the old off the heatsinks.

You do the same thing for the toshiba buffers, but there are no heatsinks. just a thermal pad that presses against the panel backplate.

[PlainBill]

Re: black screen magnavox 42mf231d/37

Thanks, do I need a special voltmeter to test the power supply? I was talking with a TV repair tech and she said the same thing. I bet my TV got a power surge from the energy company. Do you use UPS or expensive surge protector for your TV?

I use a 3 1/2 digit $25 DMM. If you are doing this professionally a $200 Fluke DMM would be more appropriate.

What I would suggest is studying the power supply carefully. There are several cables running to the small signal board (directly below the power supply). It is unlikely those voltages would be bad. There are also large bundled cables running to the Y-Sustain (left side as viewed from behind) and X-Sustain (right side) cards. The power supply cables are marked with the voltages (Va, Vs, etc), the values for those voltages are on a white label on the back of the plasma panel. Work carefully, some of these voltages are as high as 200 VDC. Once you have identified the locations, turn on the TV and verify the voltages are correct. Repeat when the TV goes dark and see if one or more of the voltages are wrong.

If the voltages are all correct, there is a possibility that one of the sustain cards is responsible. Turn the TV off, let it cool down, then turn it back on and try to cause the failure by heating one of the sustain cards with a hair dryer. Repeat with the other card. If one of the cards is heat sensitive, replace it.

PlainBill

[matteau31]

Re: black screen magnavox 42mf231d/37

Yeah the tv screen goes back after tv heats up and works if I power tv off for 5-10+ minutes.

[beeg]

Re: black screen magnavox 42mf231d/37

I just repaired one of these. Here's the scoop.

First of all, yes, the sustain board is also known as the Y-Sustain board. The initial problem was one of the Y-buffers. When a buffer shorts it usually takes out the Y-sustain. The usual recommendation is to replace both Y-buffers and the Y-Sustain.

Here is a more extensive discussion from an expert.

Mechanically, this is not terrifically difficult. If you have the skills to tune up a car, or replace the motherboard in a computer, you can do the mechanical part yourself. There are electrical adjustments to be made. Wizard may know if this is usually necessary on rebuilt boards. I would assume it is. The actual adjustment is relatively easy, it's the equipment that would cost a lot. Assuming you could find a qualified technician to do that part, here are the other items you would need.

Y-Sustain LJ92-01200A, BN96-02033A

Upper Y Buffer LJ41-02760A LJ92-01202A

Lower Y buffer LJ41-02761A LJ92-01203A

The best deal would appear to be from this eBay auction. They will repair your Y-Sustain for $62 and test both buffers. They have replacement buffers available.

The bottom line if both buffers are bad would be about $250 + the cost of adjusting the Y-Sustain. I don't recommend the repair.

PlainBill

PlainBill,
Thanks for the detailed parts, vendor and servicing advice. But what I think is your greatest contribution is you parting message "Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic. "