Samsung samsung fpt5084x/xaa power supply isues!

[Shinju]

Hey all!

I have been sitting on this one for almost 6 months now, this panel works but takes quite a few self power cycles to come on. When it does this self on and off the plasma display is primed up when it comes on then you here a click and off, then a click click on.

After the panel has been on and playing and warmed up it will turn on and off fine no issues. BUT if I unplug it for any amount of time it will go back and do the on off on off deal again. Same issue if I leave it plugged in and try turning it on well after its been on and playing.

There is NO issues with the picture it is very clear/sharp and looks great when working.

Trouble Shooting:

I have checked both the VA/VS voltages they are with in spec when the unit is on and playing.

I have visually inspected the PS board for bad cold soldier joints, I couldn't see any (but that doesn't mean I didn't miss em too).

I have replaced 5 2200 10v caps, 1 1500 35v cap (by accident I used a 2200 25v) and 1 1000 10v. Still the same self power cycle issue happens.


I am at my witts end on this power supply, they are stupid expensive and I would like to see about getting this one working before giving up and just swapping it out with one that was fixed/replaced.

also does anyone have a schematics for the power supply BN44-00175A ?

Here are some closes ups of the PS, I don't think it could be anything else but who knows!

thanks in advance!

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Ahhhh, No love for Shin!?

/bump

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Could a bad Logic board or a mainboard cause the panel to self power cycle?

I am not sure if a bad Y or X board would be the culprit, but my luck it will be the most expensive piece to fix

[mmartell]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Did you try hitting the power supply with some heat from a hair dryer and induce or allevieate the symptoms ?

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

I was about to do that when the Element in the Hairdryer took a poop, I was watching a movie on it last night and was turning it on and off when it was at peak warmth and it was coming on and off just fine.

I have to hit the store and get a new dryer so I will report back.

I bought a repair kit from CTVR and this is what the tech told me to try, Should I disconnect everything just the PS or should I what he told me with all the boards connected?

"See if you can manually activate the board (PS_ON to GND and VS_ON to +5V) and if it does the same strange behavior."

Thanks!

[mmartell]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Let it cool down so you are having trouble with it then spray it down with some heat with everything connected.

[tw2005]

Re: Samsung samsung fpt5084x/xaa power supply isues!

If the caps are fine could very well be dry joints on some of the heatsinked FETs. I've struck that on another Samsung of the 2007 era but I have no knowledge with these.

symptoms do sound similar and with thatone I did would stay on for random amounts of time, was dry joints and heat related but they can blow up with that issue too. I tried flexing my board whilst on and it induced the fault. That was as PS50C91HD from memory, boards completely different to yours though.

certainly nothing lost by reflowing everything that's heatsinked.

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

If the caps are fine could very well be dry joints on some of the heatsinked FETs. I've struck that on another Samsung of the 2007 era but I have no knowledge with these.

symptoms do sound similar and with thatone I did would stay on for random amounts of time, was dry joints and heat related but they can blow up with that issue too. I tried flexing my board whilst on and it induced the fault. That was as PS50C91HD from memory, boards completely different to yours though.

certainly nothing lost by reflowing everything that's heatsinked.

I might just do that, I knew I should have grabbed the other BN44-00175A PS that was working fine on a panel that had a bad display heh!

this one is silly, just yesterday after being unplugged for 2-3 day's I plugged it in and turned it on and BAM Samsung chime and turned right on.

[tw2005]

Re: Samsung samsung fpt5084x/xaa power supply isues!

I might just do that, I knew I should have grabbed the other BN44-00175A PS that was working fine on a panel that had a bad display heh!

this one is silly, just yesterday after being unplugged for 2-3 day's I plugged it in and turned it on and BAM Samsung chime and turned right on.

there is another post if you search the board number, sounds similar issues. not sure if it will help except I saw there was mention of a low standby voltage. you'd have to read it.

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Just wanted to follow up with everyone on this, So after doing some major troubleshooting and swapping out and testing other power supplies and mainboards from compatible Sammy Panels who shared the same plugs.


Forcing the power supply to stay on the voltages were spot on perfect for VA/VS and others.


I found out and tracked it down to the mainboard not sending back the 5v to the PS, The cause was the CPU and from the looks of it someone tried to reflow it at one point. If Pressed on the CPU sink or used a hair dryer the panel would fire up fine.


So mainboard replacement, seems to be common problem with these when they heat up around the CPU They sag pretty bad. Guess I will need to put a support under it.


Anyway thought I would share what I found incase it might be useful for anyone who runs into a similar problem.

[mmartell]

Re: Samsung samsung fpt5084x/xaa power supply isues!

Ok good thanks for the follow up.

[Shinju]

Re: Samsung samsung fpt5084x/xaa power supply isues!

One last follow up, panel is up and running 100% after a new heart transplant (mainboard).

Looks amazing, VA/VS voltages stable and with in spec.

Call this one fixed.