IR receiver punking out on my XBR

[Findm-Keepm]

Yes, there is one in series with the data, but the 5V STBY has a 47 ohm pullup resistor in series - needed to bring the collector of the IrDa output to Vcc. When the transistor is on, this resistor drops some of the 5V, as the collector (output of the IrDa Sensor)is at 0.5V or so to ground. Works like any other Open Collector logic output.

With CMOS/MOSFET outputs, the RGs(ON) is sufficient to drop the voltage, and no pull up or pull down resistor is needed. A clue that my IrDa sensor was CMOS was the packaging - a carbon impregnated ESD safe bag.

OP/50s - can you measure the 5V STBY voltage? It can be telling - low, and it could be a leaky zener, and that could decrease the sensitivity of the IrDa sensor. With no signal (no remote command), the voltage at the IrDa should be a solid 5V, with a command signal, it should drop some.

[fifties]

Findm, gonna dig into it now, and will report back.

Update; OK, here are scans of the top and bottom of the board. With my 72 Y.O. eyes I'm not sure where to measure for 5 volts, and then what component would I be looking to replace?
Also, would it be OK to operate the TV with this board removed?

[zeno]

There is a pretty massive IC there with a clock so I would say
it needs the board. More than remote going on I would say....
Try e-bay for a part out. May take some time but a better chance
than most. Also watch for free sets on Craigs list. A parts set
is a nice thing to have.......

BTW never mess with the light box/engine on any of these type sets.
You will soon be holding a knife to your throat ! Even the best techs
in the Boston area only changed things at board level & still had troubles.

best luck
73 Zeno
LFOD !