maxent MX-50HPT51 Plasma no picture

[ntehicks]

I will start by saying I haven't worked on many plasma TV's. In fact I have only worked on one in the last 5 years. I was given the task by one of my neighbors to look at a Maxent 50" plasma TV.
I plug the tv in and I hear a couple relays click and the amber light is lit. The screen comes on with a static picture but it slowly fades to just a warm glow, no more static. And after a few seconds the green light comes on. at this point if you try to push the power button or any button for that matter the buttons do nothing. even though I say the picture has static there is no sound whatsoever.
I did a search for this brand and didn't find anything. most of the boards in the tv are samsung. I am not sure where to start. Thank you for any help you can give.

[drpj23]

Re: maxent MX-50HPT51 Plasma no picture

So flashing amber light --> snow to glow --> green light (does the tv go off or the glow remain?)

Regardless, check the voltages coming out of the psu.

Does menu or input do anything during and after snow?

[Loozer]

Re: maxent MX-50HPT51 Plasma no picture

Does menu or input do anything during and after snow?

Hey Im also in the beginning stage of fixing plasma tvs. I have a 55" Samsung model hp-S5053. I got it and it was your typical black screen of death. After i opened it up i noticed 3 bad capacitors that i've just replaced. This time when i plugged it in and it powered up it made the start up sound but the screen was static/snow with a few vertical lines goin up and down the entire screen mainly on the right side. Also i have no display at all. No menu. No Input. Not even a hint that the buttons are even doing anything for that matter. Ive read into it but nobody seems to have this problem exactly. Ive check all the plugs, caps, and ribbons making sure they are all secure and perfectly placed. Would a new power-supply board fix it? Or T-Con board? Im so frustrated right now. Any advice would be greatly appreciated. Ive attached a photo to hopefully give you a better understanding.(The darker areas are like black static and the lines are light grey static) Thanks in advance.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

So flashing amber light --> snow to glow --> green light (does the tv go off or the glow remain?)

Regardless, check the voltages coming out of the psu.

Does menu or input do anything during and after snow?

The amber light is solid right as I plug in the tv to power and relays click. then after about 10 seconds the amber goes green. there is no sound, no menu. the buttons do nothing including turning the tv off. in order to turn the tv off you have to unplug the tv.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

That makes me suspect the main board but have you tried giving it a source with sound?

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

I have tested and this is what I got from the power supply
vset 190
vs 198
ve 106
vScan -160
va 75

the sticker on the screen is vset 190 vs 198 ve 105 vscan -185 va 75

other voltages
d5v is reading 18 I would think this should be 5 volts
vg is 27
a12v is reading 25 I would think this should be 12 volts
vamp is 25
vt is 43
d3v3 is reading 17 once again I would think this should be 3 volts
5vsb is reading 20 and I would think it should be 5 volts.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

Something is wrong with vscan and with your lower voltages. Your meter is likely the fault for the lower voltages.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

the lady that gave me this tv to see if I could fix it told me that they just had the power supply replaced. she said it worked great for about 3 months and then it stopped working.
what should I test next or should I just throw out the TV.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

If D5V were 18V then something would likely go bang; can you test your meter on a 1.5V battery to see if it reads correctly.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

My meter is a Fluke 383 I would think it would be a half way decent meter. do you have a recomendation for a good meter.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

I assume 83-III? That's not a bad meter at all (one of the best); but I cannot believe 18V on the D5V. Please do the 1.5V battery test.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

ok I tested a 1.5v AA with the meter and I get 1.5 I also tested a 9v with the meter and I got 9.4 for a brand new 9v which is correct. I am enclosing a picture of the test site. I am using the gnd as my ground.
and these are the voltages that I am testing now with the tv plugged in and green power light on.
vset 197
vs 198
ve 122
vscan -93
va 77
d5v 21
vg 30
a12v 28
vamp 27
vt 47
d3v3 22
5vsb 24

seems the voltages are going all over the place. also there is 5 heatsinks on this board and only one of them is getting hot. the rest are cold.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

Where are you grounding your negative lead? There's either a really bad problem with the PSU (18V would make output caps go pop) or a measurement error.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

If I disconnect the board on the right it is labeled Drive X-Main I un plug the big white power connecter all voltages test as they should. is there a way to trouble shoot this board or should I just replace the entire board.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

so I purchased a new X-Main board. still not fixed. voltages on the powersupply are normal when I just have the X-main board plugged in. when I plug in the y-sustain board the power supply voltages go crazy and are all over the place. when i plug in the tv the light is amber and then turns green I hear 2 relay clicks but that is as far as it goes. I wish there was som kind of step by step on troubleshooting plasma tv's.
the power button does not work to turn on or off.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

I doubt the board is causing your problem. Your meter is probably picking up the electrical noise from the TV. Does moving the meter change the measurement?

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

what I have noticed on the power supply there is 6 heatsinks. 5 of them stay cold and one of them gets pretty hot. could it be that a part on the power supply is shorting and causing this. the power supply has correct voltage mesurments when x-main and Ysus are not plugged into it. but as soon as I connect these boards the power supply voltages are all over the place. I move my leads around and still get the same results.

[tom66]

Re: maxent MX-50HPT51 Plasma no picture

Which heatsink gets hot?

Careful with touching heatsinks, they are sometimes live! That is, connected to one half AC. In US, that's only 60V AC so just a nasty shock, but elsewhere it can prove more dangerous. You can touch the heatsinks as soon as the unit is unplugged though.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture

I have posted a picture of the heatsink that is getting warm. all others do not get warm on this board.

[ntehicks]

Re: maxent MX-50HPT51 Plasma no picture no sound

ok so not sure if I should replace the Y board or replace the power supply. what I am getting is when I plug the tv in I hear a couple clicks of the relays. the amber light is lit. the screen looks great for about 2 seconds with snow. then the snow goes away and it has just a light glow to the screen about 25 seconds the amber light turns green. I have tested voltages on the power board with the Y board disconnected and all voltages on the power supply are what they should be. but when I plug in the Y board those voltages are all higher and fluctuate. I have tried to put an input to the tv and I get no sound. I am going to look for a main board and see if that fixes the issue. if you have any suggestions I am willing to try anything. thanks.