i am fairly confident its installed the correct way round, as i used an IC socket i can refit the old one and the fan comes back on, i am also counting the pins correctly, would you like me to do the test again but this time use pin 8 and not 7?I think that you have IC3 inserted the wrong way round or you are counting pin numbers incorrectly.
The voltage readings make no sense. Pin 4 is the negative 15 volt power rail so I would have expected it to remain at about -15 volts at each of the 4 time that you tested it. (I made a mistake putting pin 7 down as the positive 15 volt power rail I should have said pin 8) This is a link to the BA4560 datasheet so that can confirm the way the pins are numbered. The view of the IC is from above in the datasheet. If you have inserted it the wrong way round you have probably destroyed it as the supply pins would be reversed.
Les.
No I did not by from a reputable supplier, it was an amazon purchase, I did get 10 of them and have tried another with the same results,I have corrected the +15 volt test pin but I have also added two extra test points.
Also try these tests with nothing plugged into the socket.
I have just seen your post #512. The socket is fitted correctly.
For left hand channel.
measure the voltage on the following pins of IC3 with Q16 base emitter junction not shorted and then shorted
Pin 2
Pin 3
IC4 pin 2
Pin 4
Pin 8
For right hand channel.
measure the voltage on the following pins of IC3 with Q42 base emitter junction not shorted and then shorted
Pin 6
Pin 5
IC4 Pin 6
Pin 4
Pin 8
Did you buy the BA4560 from a reputable supplier ? I am wondering if the items supplied could be some other device remarked as BA4560.
Les.
please see post #515 again,From the way you you have shown the results in post #515 I think you may have misunderstood (Or I was not clear enough.) in post #514. I think after taking the readings on pins 2 & 6 of IC4 you have taken the readings on pins 4 and 8 of IC4 rather than IC3.
I think there is a problem with the -15 volt supply to pin 4 of IC3. In previous posts the reading on IC3 pin 4 has been close to zero volts except for the first reading in post #509 when it was close to -15 volts. You need to investigate the cause of this.
The reading of close to + 15 volts on IC3 pin3 / IC4 pin2 indicates that Q16 base emitter junction is open circuit OR it's emitter lead is not connected to zero volts. You also need to investigate this problem.
Les.