subman
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Nov 23, 2015, 9:55 PM
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Pioneer 50 SCAN B ASSY Board how to determine bad ICs?
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This is for a Pioneer Plasma TV PDP-506PU. When I turn on the media receiver it has the ON(blue), STANDBY(red), and REC(orange) LEDs on solid. When I turn on the TV panel only the STANDBY(red) LED is on solid and there is no picture. A previous Tech looked at the TV and said there was a problem with the 50 SCAN B Assy. I have entered the TV service mode with the remote control. The bottom half of the screen powers on fine and you can see the TV window saying the TV is starting. The top half of the screen is powered, but there is no picture and has a green haze (pixels randomly on) which fits the tech's diagnosis. I am trying to isolate the IC chip(s) on the 50 SCAN B Assy to replace, but there is no visible sign (pinholes) of a blown IC and when I do a resistance (ohm) check between the VH and GNDH contacts on the board there is no short detected. I have tried the methods on how to trouble shoot the IC issues on the Shop Jimmy.com YouTube videos, but I am still confused. Having the top half of the screen be powered and have no image points to there is something wrong with the 50 SCAN B Assy, but then not having any short circuits on the IC signal pins and ground would point to there not being any bad ICs. What else is there on a 50 SCAN B Assy or am I not checking the resistance correctly? Also when I disconnect the 50 SCAN B Assy from the 50 Y Drive Assy and power the up the TV the STANDBY(red) LED blinks three times. If I reconnect the 50 SCAN B Assy to the 50 Y Drive Assy and then disconnect the 50 SCAN A Assy and power the up the TV the STANDBY(red) LED blinks four times. Do these LED codes indicate something else? I think all things point to there being a problem with the high side 50 SCAN B Assy but then the traditional methods of locating where the problem is on the 50 SCAN B Assy board itself don’t seem to indicate there is anything wrong(?). Thank you for any help.
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