30-11-2013, 07:56 PM
The first port of call for a gain fault is the red/black capacitor C22 and C10.
For distorted loud audio C27 first then C21.
For tinny or weak audio C23 and C25.
You will be able to see that C22 and C10 keep the power to the receiver part of the set clean of AC and leakage of the received signal. Any signal lost here does not get to the detector diode.
C21 will make the DC voltages on TR4 bad and part of the audio will get distorter off so that it never gets to the speaker and this will make the set sound awful. C27 will cause buzzing and screeching that can be intermittent or constant that gets worse as the battery ages.
C23 and C25 stop the audio from getting onto the resistors that have to be there to regulate the voltages on TR4 and TR5 the effect of one of these going faulty will start with poor bass and get worse. Faults with these capacitors will be amplified by the transistors.
Most of the buzzing will be from power cables close by and once the gain of the receiver part of the set is restored it should be drowned out by the stations you listen to.
For distorted loud audio C27 first then C21.
For tinny or weak audio C23 and C25.
You will be able to see that C22 and C10 keep the power to the receiver part of the set clean of AC and leakage of the received signal. Any signal lost here does not get to the detector diode.
C21 will make the DC voltages on TR4 bad and part of the audio will get distorter off so that it never gets to the speaker and this will make the set sound awful. C27 will cause buzzing and screeching that can be intermittent or constant that gets worse as the battery ages.
C23 and C25 stop the audio from getting onto the resistors that have to be there to regulate the voltages on TR4 and TR5 the effect of one of these going faulty will start with poor bass and get worse. Faults with these capacitors will be amplified by the transistors.
Most of the buzzing will be from power cables close by and once the gain of the receiver part of the set is restored it should be drowned out by the stations you listen to.
