07-21-2014, 02:08 PM
Any scope will do, even a theoretically existing dismal one with 1kHz bandwidth 
1. short input, mesaure voltages, confirm the E voltages always being equal to B volages -minus 0.7V (more or less), with or without load.
2. Run scope, put input signal in so the output signal does not get cliped, if unbearable, lower volume to comfortable level (does not matter really), rotate the trimpot to set the idle until the crossover step goes away fully. If possible measure the power supply current in either plus or minus, and note the change between the beginning of adjustment (set the pot to the minimum current position) and the final current where the crossover disapeares. The difference is your output idle. See if this times half the supply looks reasonable as dissipated power. Could be up to 2-3W per tansstor.
1. short input, mesaure voltages, confirm the E voltages always being equal to B volages -minus 0.7V (more or less), with or without load.
2. Run scope, put input signal in so the output signal does not get cliped, if unbearable, lower volume to comfortable level (does not matter really), rotate the trimpot to set the idle until the crossover step goes away fully. If possible measure the power supply current in either plus or minus, and note the change between the beginning of adjustment (set the pot to the minimum current position) and the final current where the crossover disapeares. The difference is your output idle. See if this times half the supply looks reasonable as dissipated power. Could be up to 2-3W per tansstor.
