UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Superstar 6900N V6

SiriusHardware · 24th May 2020, 6:54 pm

I think any and all observations regarding this chassis are interesting and will eventually add up to a useful repository of information about the set.

Pin 4 on the microphone socket goes to an ADC input (AN7, pin 50 of the microprocessor) which measures any resistance which appears between pin 4 and ground.

If it sees 47K to ground, that's the 'Up' button pressed, if it sees 100K, that's 'Dn' and if it sees 150K that's 'SQ'. Between pin 4 and the microprocessor ADC input there is a 1K resistor (R608) which should limit the current into or out of pin 4 if it is inadvertently connected to something it should not be.

Anyway, at the moment we are still chasing that transmitter problem.

24th May 2020, 6:54 pm	#95
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Superstar 6900N V6 - Fault with SSB mode I think any and all observations regarding this chassis are interesting and will eventually add up to a useful repository of information about the set. Pin 4 on the microphone socket goes to an ADC input (AN7, pin 50 of the microprocessor) which measures any resistance which appears between pin 4 and ground. If it sees 47K to ground, that's the 'Up' button pressed, if it sees 100K, that's 'Dn' and if it sees 150K that's 'SQ'. Between pin 4 and the microprocessor ADC input there is a 1K resistor (R608) which should limit the current into or out of pin 4 if it is inadvertently connected to something it should not be. Anyway, at the moment we are still chasing that transmitter problem.