I dearly love my Panasonic 42" plasma TV, TH42PZ85U. It is getting old, and I've resurrected it once, but this time it is putting up a fight. I have the service manual with schematics. Usually when this set has a problem, the On indicator LED flashes a code. This time the entire set is just dead. No clicks, no hum, no nuttin.
I was out of town for one night and severe storms were predicted, so I unplugged the set. When I returned and plugged it in - nothing. This says to me that due to inrush or static buildup or something, something on the primary side of the ps popped. All five physical fuses test good.
The isolated standby power supply is making a nicely regulated 5.07 Vdc, but AC for it comes from before the AC mains DPST relay. Everything else is down. Neither the mains relay nor the PFC pre-charge relay pull in.
The power supply board is two-sided, all PTH on top and all SMT on the botton. The big power transistors and rectifiers are PTH parts on the bottom side, bent parallel to the board and mounted on a heat spreader almost the size of the board. This makes replacing the entire board assembly easy, but it is almost impossible to rework the SMT. There are no visible problems with any topside component.
The service manual is a 67 MB PDF file, so I cannot upload it to the site. I picked it up in 2014, probably from electrotanya, but I don't have a link.
Any ideas? Is this a known thing?
Thanks.
ak
I was out of town for one night and severe storms were predicted, so I unplugged the set. When I returned and plugged it in - nothing. This says to me that due to inrush or static buildup or something, something on the primary side of the ps popped. All five physical fuses test good.
The isolated standby power supply is making a nicely regulated 5.07 Vdc, but AC for it comes from before the AC mains DPST relay. Everything else is down. Neither the mains relay nor the PFC pre-charge relay pull in.
The power supply board is two-sided, all PTH on top and all SMT on the botton. The big power transistors and rectifiers are PTH parts on the bottom side, bent parallel to the board and mounted on a heat spreader almost the size of the board. This makes replacing the entire board assembly easy, but it is almost impossible to rework the SMT. There are no visible problems with any topside component.
The service manual is a 67 MB PDF file, so I cannot upload it to the site. I picked it up in 2014, probably from electrotanya, but I don't have a link.
Any ideas? Is this a known thing?
Thanks.
ak
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