17-10-2018, 08:47 AM
I think the base voltage is a clue to what is wrong, Mike.
A silicon transistor requires ~700mV between base and emitter to conduct so, based on the voltages shown in the schematic, the emitter voltage should be ~0.4V.
In your case it obviously can't be higher than 0V!
As far as I can see at the moment, there are only two possibilities: either there is a short from emitter to ground - C27 s/c possibly - or there is insufficient bias current to fully turn T6 on - so perhaps R15 has gone (very) high?
A silicon transistor requires ~700mV between base and emitter to conduct so, based on the voltages shown in the schematic, the emitter voltage should be ~0.4V.
In your case it obviously can't be higher than 0V!
As far as I can see at the moment, there are only two possibilities: either there is a short from emitter to ground - C27 s/c possibly - or there is insufficient bias current to fully turn T6 on - so perhaps R15 has gone (very) high?
