Why am I having to replace transistors T1 and T2 for second time?
Is it possible that the spec of the replacement BC640 that I bought from RS Components is a problem? Vceo max =80V. Can this be too low?
In the RS Catalog there are two current ratings for BC640; 1A and 500mA. I bought the 500mA device. From what I can see in their datasheets Vceo max is 80V for both.
The voltage I measure (loudspeaker not connected) across the VM100 power rails is 81.5V!
I have already posted this question last week but I get no reply. Is there another method I can use to request help from Velleman?