15-05-2015, 05:22 PM
So if the hiss is present at minimum volume, then that's an amplifier problem. Forget about anything before the volume control.
The fault might be a faulty transistor, but it's impossible to say for sure. Check by substitution, starting with VT4 (OC71) first. Sometimes, carbon composition resistors go noisy. Again, check by substitution.
The AGC cap is C21 (8uF). If it is leaking, that could reduce the gain. If it is open-circuit, it could cause distortion.
The fault might be a faulty transistor, but it's impossible to say for sure. Check by substitution, starting with VT4 (OC71) first. Sometimes, carbon composition resistors go noisy. Again, check by substitution.
The AGC cap is C21 (8uF). If it is leaking, that could reduce the gain. If it is open-circuit, it could cause distortion.
