Had this PS43D490 43" Plasma Tv here by Samsung. Fault is relay clicking and set wont power up. First thing I checked was the Vs output to ground with my meter in diode mode and well Vs is shorted to ground so thats the problem right there I dont think the Psu works with its power outputs grounded. I checked this as its common on these for something to short Vs to ground.
I unplugged the Sustain boards connector and the short on the Psu went away so the fault is on one of the Sus boards. This set uses combined ERC so the recovery circuit on the sustain boards is chained between the Y and Xmain so if one is bad both will show up as failed and in some cases if one fails it can actually kill the other so both need to be checked properly.
As the Xmain gets its power from the Ymain I unplugged the Xmain and then checked the Vs input on the Ymain to ground and its not shorted so the Xmain is failed. Surely enough with the Xmain unplugged from the Ymain its Vs input is still shorted so the Xmain is the issue.
This set is super cheap and uses the Smd type power fets for the Sus output, while this will work fine if you cool the fets properly they get hot and Sammy didnt bother heat sinking them so I guess they just get too hot and fail.
The failed parts are under the Pcb and have a PN of RJP30H1 there are 4 of these connected to the sus output they also have a smd diode next to them which will show up as S/C with the bad fets in circuit but if you remove the fets the diodes are fine. All 4 fets were S/C so I changed them all.
After replacing them the Vs input of the Xmain is not longer shorted to ground so its safe to test the board now. Before I reinstalled it I added a thermal pad from all the fets to the chassis to help them cool I also did this to the Sus output fets on the Ymain as they also commonly fail so hopefully should last a little longer.
After getting it back together it works great too bad they cheaped out on these Plasmas as they have potential to last a long time, decent image quality tbh and not a lick of MD, hope this helps someone
I unplugged the Sustain boards connector and the short on the Psu went away so the fault is on one of the Sus boards. This set uses combined ERC so the recovery circuit on the sustain boards is chained between the Y and Xmain so if one is bad both will show up as failed and in some cases if one fails it can actually kill the other so both need to be checked properly.
As the Xmain gets its power from the Ymain I unplugged the Xmain and then checked the Vs input on the Ymain to ground and its not shorted so the Xmain is failed. Surely enough with the Xmain unplugged from the Ymain its Vs input is still shorted so the Xmain is the issue.
This set is super cheap and uses the Smd type power fets for the Sus output, while this will work fine if you cool the fets properly they get hot and Sammy didnt bother heat sinking them so I guess they just get too hot and fail.
The failed parts are under the Pcb and have a PN of RJP30H1 there are 4 of these connected to the sus output they also have a smd diode next to them which will show up as S/C with the bad fets in circuit but if you remove the fets the diodes are fine. All 4 fets were S/C so I changed them all.
After replacing them the Vs input of the Xmain is not longer shorted to ground so its safe to test the board now. Before I reinstalled it I added a thermal pad from all the fets to the chassis to help them cool I also did this to the Sus output fets on the Ymain as they also commonly fail so hopefully should last a little longer.
After getting it back together it works great too bad they cheaped out on these Plasmas as they have potential to last a long time, decent image quality tbh and not a lick of MD, hope this helps someone
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