SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

[sugar_ray]

Anyone with suggestions?
Sammy plasma PN42B400

Its got a red standby light on the front bezel ONLY. Solid red no flashing codes! Tv just wont turn on. Something is preventing this from turning on

What I've done.......
Swapped both the Power supply board and Y-sus boards with known good ones.
"No change" with either swap. So can rule out both a bad power supply and bad Y-sus board.That being said, there is NO relay that can be heard either.

My huntch is the digital main board is preventing it from turning on?? Shopjimmy does sell a kit for this board for similar issues

https://www.youtube.com/watch?v=oC4f2Ik8rCI

Ive solved several LCD's and LED's but plasma, as you know, a different animal. I cant imagine a bad logic would put the tv in standby mode?

[Hamie]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

Jumping the power supply on and generating test patterns on the control board would answer your question.

[ReeceyBurger123]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

What a load of kack why not diagnose it properly using bcn to help, listen to what Hamie says

[sugar_ray]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

thanks for the replies gentlemen. not sure if you can elaborate further?
I have taken a "hard drive jumper" and jumped pins 3 & 4 on the control board test block. Still only solid standby with no change in the tv coming on

[maxvalutech]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

You are a bit light on with info such as did you jumper the power board on before looking for test patterns? It would be best to go back to basics and disconnect lead from main board being the one going to power board then jumper ps-on to gnd and vs on to stby which appears to be working then measure all voltages on power board when if no vs and/or va disconnect lead firstly to y side and see if vs comes up on power board then, in need, do same for x side. Also advise what green led on control board is flashing - hopefully once per second. Post your findings.

[sugar_ray]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

Thanks Max sorry for being so vague and thanks for offering advice
When I jumper PS ON and GRND then plug in I will get get a relay click Indicating it was forced on without the digital main in the equation. Then, after powering down, I jumper 3 and 4 at the logic test block. Re-powering up we hope to now generate on screen test patterns. However, I can see the onscreen flicker just for a second but no test patterns on screen at all just black and no screen glow.

Where I'm slightly stumped, and again forgive the fact I'm very much still learning, to this point the only LVD cable removed from logic is the one that feeds the digital main. With only that Lvd removed the green LED logic light will turn on solid for a few seconds after plugging in then turn off shortly after relay is heard. However, if I remove the LVD cables that go from logic to either y or x buffer and conduct the same PS ON - GRND jumper test the logic led light blinks once per second indicating everything ok.

[maxvalutech]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

Yours is an old set being 720p I think and you won't get any picture without screen working so you have to get Vs and Va voltages working - normally around 200v and 65v but see panel sticker. You need to find out if power board will generate these voltages which if they are ok with main disconnected then points to main being the problem by not generating the Vs on voltage. If they don't stay up then by disconnecting in turn y and x from power board you will get an indication of which side has a problem. Off hand the control board seems to be ok.

[Hamie]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

You need to jump;

Ps-on to Gnd

And

Vs-on to 5vstby.

[sugar_ray]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

You need to jump;

Ps-on to Gnd

And

Vs-on to 5vstby.

did this with NO change

[maxvalutech]

Re: SAMMY plasma PN42B400 kicking my butt!! Red standby ONLY

In that case it is your power board not getting the voltage up required by Vs Va and then Vscan on Y main and Ve (erase) on X main. Hence no picture. The flash would indicate that protection circuit is turning set off immediately the Vs on signal is received. Now while both jumpers in place did you disconnect the y feed from power board then turn on and see what happened to vs test point on power board I.e. did vs about 200volts come up and stay. If not did you then disconnect the x main feed similarly and test? Boards that could be bad are the y buffers if your new y main is good and then x main and or its buffers but also the power board itself and we are trying to eliminate boards by testing as above. Basically if with y and x feeds disconnected and power board jumpered on if no vs the power board is at fault. If vs comes up with y side off then that side is at fault and same apples for x side being at fault if vs ok when x disconnected. Also let us see what Hamie thinks .