Magnavox 50 mf231d37

[ljintexas]

Re: Magnavox 50 mf231d37

Well I don't have squat in this set..$65 all in with scan board. If it needs a logic board I will be at $100..not bad at all. Most important, I have learned quite a bit about Sammy Plasmas. Ordered a meter that can check ESR in circuit.

[budm]

Re: Magnavox 50 mf231d37

"Ordered a meter that can check ESR in circuit." I would not check the caps that are still in the circuits, they should be removed and tested off the board.

[ljintexas]

Re: Magnavox 50 mf231d37

Cleaned all ribbons and sockets, replace E Buffer Board..still has the same issue. I am going to order a logic board..

[MagicSmoke]

Re: Magnavox 50 mf231d37

It has sparklies in the black region now.

Can you post a pic of what its doing now. Black w/sparklies is usually not a good sign. Look carefully at the ribbon directly under where the line is for any kind of damage to that ribbon or chip.

Check the pads on the ribbon itself to see if they are still bonded to cable. Any dark area or holes in ribbon is not good.

[ljintexas]

Re: Magnavox 50 mf231d37

The ribbon looks good..however the IC is loose from the heat sink..not bonded with heat transfer paste like most of the others. There are a few that are not stuck with paste..that area is one of them.

[ljintexas]

Re: Magnavox 50 mf231d37

I already ordered logic board..$20 with shipping..worst case I will have a whole set's worth of boards for a Sammy 50" plasma..Someone will need them sooner or later.

[MagicSmoke]

Re: Magnavox 50 mf231d37

Is the paste a glue like substance or is it greasy? Those chips have to be heatsinked when set is on or instant panel damage can occur. Don't run the set with the cover removed.

The cover strip should have foam pads on it to help press chips to frame.

[ljintexas]

Re: Magnavox 50 mf231d37

White thermal paste. Aluminum angle actually forces them to contact heatsink.

[ljintexas]

Re: Magnavox 50 mf231d37

isn't there a way to put the panel in test mode to see if it is, in fact the panel?

[ljintexas]

Re: Magnavox 50 mf231d37

Well, I followed Tom's instructions..disconnected lvds cable and shorted pins 3 and 4 on logic board..when turned on, all I get is a white screen as in picture. The line is still visible and that section is a brighter white than the rest of the panel. It did not change colors or go through any series of screens as I think it is supposed to. Does this mean logic board is toast?

[MagicSmoke]

Re: Magnavox 50 mf231d37

The complete screen is on now? no dark areas where line was? Did you reinstall the aluminum strip before powering it on.

If complete panel is on then logic is bad. It should be showing test colors and patterns.

The line on screen in pics looks like burn in from running the set with that area dark. Once you get test patterns and full function there should be a screen cleaner in the menu to help clear it up.

[ljintexas]

Re: Magnavox 50 mf231d37

Complete panel is on. All solid white. No test colors or patterns. Yes the heat sink strip is in place..Its a piece of heavy wall aluminum angle with dimples to keep it aligned. I have a logic board on it's way. I have been using a phillips remote with it that seems to have full functionality menu wise and all. Will screen cleaner be in th emenu when I am in test mode with 3&4 jumpered and no lvds cable? I could not get a menu in test mode with remote. Maybe because logic board is bad?
Thanks for your help MS

[MagicSmoke]

Re: Magnavox 50 mf231d37

The screen cleaner/image cleaner or sometimes called white screen is in the regular menu. mainboard will have to be connected and everything working for access.

[ljintexas]

Re: Magnavox 50 mf231d37

Well replaced logic board..no joy...going back to try panel test again..with new logic board.

[ljintexas]

Re: Magnavox 50 mf231d37

Is it possible that used logic board is also bad? I get exactly same results with 3&4 jumpered without lvds cable..complete white screen with no test patterns.

[ljintexas]

Re: Magnavox 50 mf231d37

As a basic trouble shooting method, since new logic board did the same as old, I unplugged the harness that powers the lower buffer boards..It appears that they are working(passing signal or the lack of it evenly to the panel) from the pics..so that makes me think the issue here must be what is feeding it the signal to pass on to the panel. Also measured all PS and X/Y voltages. All four are measuring within one volt of spec on the label. Notice in the pics, the blue in the lower right corner as well as in one pic the vertical lines to the far left are almost gone.
I am starting to think that my new logic board is bad. It came from TriState Modules. Anybody have any history with them?

Thanks to all.

LJ

[MagicSmoke]

Re: Magnavox 50 mf231d37

Since the picture is different from what you started with I would say you got a bad logic board.

If you re-install the original one and the screen behaves like it did at first, then replacement is definitely bad.

Also when reconnecting any wires or LVDS cables it's best to wait at least 10 min to let the capacitors bleed off any stored voltage.

[ljintexas]

Re: Magnavox 50 mf231d37

To be clear...new logic board did not produce results any different from original logic board. The latest pics are with buffer boards harness disconnected. I will RMA logic board and get a new one. I usually wait 10-15 min before powering back up for just that reason.
I think new logic board is bad. I should get the test sequence and patterns. Voltages stated on panel label are right on the money..+/- 1 volt.

[ljintexas]

Re: Magnavox 50 mf231d37

I should not have to disconnect X sustain board to perform self test, correct?

[ljintexas]

Re: Magnavox 50 mf231d37

I have a couple of questions. I noticed that there are two versions of this logic board..one ending in "A" and one ending in "B". If original is an "A" and replacement is a "B", could that be the issue? Also, could the issue be related to the main board? I am wondering as the only time the whole screen is lit is when LVDS from main board is disconnected.