Having a new problem with the 19" Insignia that I modified with one of my automatic turn on circuits. That is now completely disconnected so that is not the issue. I was doing some modifications on that circuitry and managed to short something out on the underside of the power board.
Actually found and bought the service manual (who knew it was even available?!) which brought me to the High Voltage Startup Circuit controller chip.
Looking up that chip number- LD7575APS brought me to the attached datasheet. I have marked my voltage readings on the schematic sheet (open in new window to see voltages). I see good VCC (sort of) and good HV and maybe good voltage at the switching frequency pin (1) but variable voltages elsewhere (all are DC voltage measurements). I'm guessing that these are bad and the chip is toasted but there are no suggested voltages on the data sheet or the actual schematic which is almost identical to the data sheet circuit.
If anybody knows what those voltages should be I'd appreciate it. The external MOSFET could also be bad so I'd like to know these voltages first before I just start throwing parts at it.
Also, this is essentially obsolete but I can find replacements marked LD7575 not LD7575A. Any idea how much difference there is? Can't really find out from reading the two data sheets.
Thanks
Actually found and bought the service manual (who knew it was even available?!) which brought me to the High Voltage Startup Circuit controller chip.
Looking up that chip number- LD7575APS brought me to the attached datasheet. I have marked my voltage readings on the schematic sheet (open in new window to see voltages). I see good VCC (sort of) and good HV and maybe good voltage at the switching frequency pin (1) but variable voltages elsewhere (all are DC voltage measurements). I'm guessing that these are bad and the chip is toasted but there are no suggested voltages on the data sheet or the actual schematic which is almost identical to the data sheet circuit.
If anybody knows what those voltages should be I'd appreciate it. The external MOSFET could also be bad so I'd like to know these voltages first before I just start throwing parts at it.
Also, this is essentially obsolete but I can find replacements marked LD7575 not LD7575A. Any idea how much difference there is? Can't really find out from reading the two data sheets.
Thanks
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