Hi All,
I have a LG 50PS30 in near-mint condition given to me by a colleague in it's original packaging (!). On startup it was black screen, but the LED indicator blinked red then went solid blue. I took it apart and consulted the service manual and found the Va and Vs rails were 200mV or so.
After looking around at troubleshooting tips (I'm new to TV's, all my experience is on communications systems and robotics/mechatronics) I disconnected the Z-Sustain board and fired it up. Picture was dim and discolored (a known side-effect of no sustain, I see) but the rest of the system seems to be working fine.
I started troubleshooting the Z-Sustain board (part # EAX55361501) and found that the +Vs rail is short to ground, with a resistance of about .3 ohm. The +5 rail appears to be fine (150k to ground). If the power bus is disconnected, but the control connector is still installed it whines like hell.
There are no bulgy caps, and no damaged components that I can tell.
There are no board diagrams in the service manual for the Z-Sustain, and as TV is not my "first language" I was hoping there were some in the community that could point me to likely culprits on the board.
I've got a full lab to work with.. digital storage scope, analog HF scope, sig gen couple of fluke multimeters and LC meter, hot air rework etc.. so getting down to swap components is not a concern.
Cheers
KS
I have a LG 50PS30 in near-mint condition given to me by a colleague in it's original packaging (!). On startup it was black screen, but the LED indicator blinked red then went solid blue. I took it apart and consulted the service manual and found the Va and Vs rails were 200mV or so.
After looking around at troubleshooting tips (I'm new to TV's, all my experience is on communications systems and robotics/mechatronics) I disconnected the Z-Sustain board and fired it up. Picture was dim and discolored (a known side-effect of no sustain, I see) but the rest of the system seems to be working fine.
I started troubleshooting the Z-Sustain board (part # EAX55361501) and found that the +Vs rail is short to ground, with a resistance of about .3 ohm. The +5 rail appears to be fine (150k to ground). If the power bus is disconnected, but the control connector is still installed it whines like hell.
There are no bulgy caps, and no damaged components that I can tell.
There are no board diagrams in the service manual for the Z-Sustain, and as TV is not my "first language" I was hoping there were some in the community that could point me to likely culprits on the board.
I've got a full lab to work with.. digital storage scope, analog HF scope, sig gen couple of fluke multimeters and LC meter, hot air rework etc.. so getting down to swap components is not a concern.
Cheers
KS
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