Sanyo Plasma DP50741-01 On/Off problem

[seandog6101]

Hi my name is Sean I am new to this forum and would greatly appreciate any help I can get on this. From the start, one day i was watching TV then it shut off. Tried turning it back on and clicked (green led came on) then 2 seconds later click (green led turned off).

I have done a lot of research and pulled out my muti-meter and started testing what i could. The one thing I knew for sure are my fuses were good....
I searched for everything i could poke at and checked all caps look far any signs of swelling or burnt connectors or anything. If you took one look at my tv it looks great.

So what i thought was the problem was my PSB so i replaced it...no luck
Then i found something funny in my main board (no voltage at the audio 13v star thing.) so i replaced it ....no luck

A few things i have done for self diagnosis are start unplugging and every time i unplug check to see if it stays on longer. only when i unplug both left and right boards the tv stays on for about 7 seconds but does not and will not stay on at all.

One question i have does my tv have a bulb? and will this cause my problem?

I am not giving up on my tv if anyone can point me in the right direction or can tell me whats wrong that would be great.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

I just had a quick look at the SJ website to see what boards this has since you don't have a picture of the complete setup.

It's a Panasonic panel and driver boards. On the left you have 2 buffer boards known as SU(upper), SD (lower) driven by the SC (y-sustain).

On the right you have ths SS ( x-sustain ) which I suspect is board number TNPA5072 rev AE ? I know that board fails shorted in the Panasonic models and i suspect why the TV shuts down straight away when connected and with it disconnected stays on longer.

On the TNPA5072 there should be a connector which the PSU is connected, SS11. disconnect the power cable and measure resistance across TPVSUS and gnd pin, you may find this shorted.

On this board Q001,002,021,022 can go short but these boards are fairly cheap to buy if it has failed.

I'd do the same and check on the SC board TNPA5063AB at SC2 for short as well across those 2 pins.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

Thank you for getting back to me I checked my x Sustain tnpa5072 ae board and I tested the connector that comes from the powe supply (TPVSUS). On the power supply they are vsus, gnd, and +15Vc I get 0.000 between vsus and ground. And OL between +15Vc and ground. And OL between +15vc and vsus.
Then I checked my ysus TNPA5063 AB and tested connector SC2 and I don't get continuity and the ohms jump around

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

So on the connector at the SS, SS11 0 ohms tpvsus -gnd, just as I suspected. Looks like just that board to start with, no shorts anywhere else so replace the SS.

I guess you can't return the boards you don't need although I did stumble across a post about those mainboards playing up causing constant restarts.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

This seller has been good for me so far. He has plenty of these which generally means they'll be from damage in transit TVs.

he did confirm with me that's where most of his parts come from when asked a while back.

http://www.ebay.com/itm/SANYO-DP5071...item2c71718d8c

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

Thank you for the quick response I bought the board as listed
will see if that's my proble hopefully its just that one and not my ysus with two buffer boards.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

DEEP BREATH......That did not fix it.....im about ready to do some target practice. I received the new xsus board and installed it and the same symptom's. I checked and tripple checked and the tpvsus to gnd and the old board doesnt have any continuity and the new board does. So i know that was a problem but the tv still does not turn on. So far i have replace the power board main board and xsus board what else can i check, or what can still be wrong.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

DEEP BREATH......That did not fix it.....im about ready to do some target practice. I received the new xsus board and installed it and the same symptom's. I checked and tripple checked and the tpvsus to gnd and the old board doesnt have any continuity and the new board does. So i know that was a problem but the tv still does not turn on. So far i have replace the power board main board and xsus board what else can i check, or what can still be wrong.

Hang on I'm confused, in post 3 you said you had 0 ohms across vsus-gnd on the original SS board and in post 4 I repeated that you had 0 ohms at SS11 across vsus-gnd.

Now if I read your latest post, you say on the old SS you have no continuity across that point so the short is now gone? On the new board you have , so is that shorted?

The SC could have been damaged too, but boy , not many parts left to replace.

sorry it did not work, disappointed myself really it failed to fix it.

I guess you tried putting both mainboards in with the new SS just in case the replacement main was faulty?

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

Yes I read that too and didn't understand myself, I ment 0 ohms as = nothing. Not the actuall number. I'm sorry for confusing you and myself. On the old board xsus the ohms between tpvsus and -gnd is OL. And on the new board it is 0.000 ohms.
And don't worry one bit I'm not blaming you at all I really do appreciate your help.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

I'm sorry I just remembered I don't know which one is new or old but I just swapped them out and no change even tho clearly the boards are reading differently.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

usually there'll be a black stamp on the board from payless or most sellers of parts. It is important I guess to know which was which for two reasons, one for fault finding, two so you can send it back if you got a dud.

anyway 0.000 displayed in ohms range = short circuit & O.L means the resistance is outside the range set on the meter.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

Ok so the new board is definitely in and the old board is definitely bad befor I had to disconnect the ysus and xsus board inorder for it to stay on a little longer (6seconds compaired to 2) so what on my ysus board can I test ? I still do not see any cosmetic damage to anything on the board and the SC2 vsus to -gnd reads 31K ohms.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

31k sounds wrong, measure it then lift a probe for a sec or two then put it back on and see if it's consistant. then try with the probes reversed.

I'd expect a few hundred k ohms or higher

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

Maybe check out Sc3 for short too, there's 3 pins, not sure if 2 are gnd, the board is double sided. That's the energy recovery cct that connects to the SS.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

It is 30kohms if black is on gnd and red on vsus and if I switch them it reads 2.9kohms

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

If I put my DMM on continuity SC2 reads OL.. on SC3 there are three pins the one closest to the top of the board ill call pin 1. Pin 1 is bottom ground it has continuity when I touch the heat sink and solder around screw holes(I have the board out). Pins 2&3 are measuring the same they have continuity on the metal spacers the the buffer boards ground too and the power coming in from vsus.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

bump

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

Sorry, been busy .

I think the SC is bad too.

If you're 100% certain of the readings 30k and 2.9k, it's bad. I trust your meter is autoranging?

What you should expect there as a ballpark figure is 300k initially but the cct charges and then it will jump in to Megohms, expect 2-3Mohms across the vsus input SC2.

AS for the 3 pins at SC3, I'll refer to them as they are in cct and on the board there should be a tiny 1 & 5 screenprinted for the outer most pins.

1 = gnd, 3,5 feed Q441, expect resistance 60-80k across 1 and either of the 3 or 5.

[seandog6101]

Re: Sanyo Plasma DP50741-01 On/Off problem

Do I need to replace the sc only or do I need to replace the two buffer boards that it attaches to.

[tw2005]

Re: Sanyo Plasma DP50741-01 On/Off problem

Do I need to replace the sc only or do I need to replace the two buffer boards that it attaches to.

They'll need to be resistance checked prior to re-use.