Westinghouse H886K21

[Electronic M]

Too little of the schematic is shown to fully evaluate it's purpose, but it's value is likely critical. See that gold band on the end?...That signifies a 5% tolerance resistor. Most resistors in most TVs were 10%, or 20% tolerance. %5 resistors usually cost more and typically were not specified by engineering unless needed. You can make a series set of resistors if you need, but you probably want to check that it measures within 5% of the design value. If it is off a bit more it should not kill the set, but AGC may not set or react right...If you have signal and no more flicker that would confirm the resistor.


Speaking of resistors I've seen ones in series with the HV lead develop internal arcing...They may or may not test fine with 9V from your multi-meter, but at 10-30KV will arc and make RF noise that the set can tune and feed back to the picture and sound.

AGC stages especially non-keyed ones often had long time constant RC circuits with large value paper caps and or resistors.

[FrankieKat]

Originally Posted by Electronic M

Too little of the schematic is shown to fully evaluate it's purpose, but it's value is likely critical. See that gold band on the end?...That signifies a 5% tolerance resistor. Most resistors in most TVs were 10%, or 20% tolerance. %5 resistors usually cost more and typically were not specified by engineering unless needed. You can make a series set of resistors if you need, but you probably want to check that it measures within 5% of the design value. If it is off a bit more it should not kill the set, but AGC may not set or react right...If you have signal and no more flicker that would confirm the resistor.

Speaking of resistors I've seen ones in series with the HV lead develop internal arcing...They may or may not test fine with 9V from your multi-meter, but at 10-30KV will arc and make RF noise that the set can tune and feed back to the picture and sound.

AGC stages especially non-keyed ones often had long time constant RC circuits with large value paper caps and or resistors.

Got it. The parts list doesn't call out a tolerance on that resistor specifically, but of course makes sense to replace with as close to correct value as possible. I'll see what I can come up with.

Attaching a larger version of the relevant schematic (really hard to get these legible and stay under the upload file size limit!)

FK