Two A12's not working...PLEASE HELP!!!
Posted: Fri Sep 25, 2009 7:09 pmI have checked both multiple times and all the components are in the right places.
I made the same mistake with both of them, I didn't realize it until I had finished both. I didn't install the mill-max receptacles for the SC25. I soldered the SC25 to both of the PCB's.
When I first finished them both I check the voltage readings for the SC25 and both pin 3 and pin 5 had acceptable readings. so I raised the trim pots so that U1 could be +18v and -18v. The first one raised to 18v, positive and negative. but on the second one only the negative would reach 18v. The + would only get no more than 17.03.
When I powered them both up everything seemed fine, until I hook them up.
One was not passing a signal and all I could hear is was very low hissing.
The second one made a high pitch screeching sound.
And on both of them U4 became extremely hot.
I pulled both op-amps out and put in the mill-max receptacles and then put in the SC25's.
Now on one of them I am getting different readings on U1 Pin 3 and 5.
A few times both pins have showed around 14: -14.5 thru -14.6 and + 14.5 thru + 14.75 and other times I will get a reading of + 02.0 thru + 03.2 and the red LED will begin flashing at some point while power is turned on. If the I/O's are connected I hear a pop that corresponds with the flashing of the LED. And the output transformer gradually heats up, but not as hot as heat sink U4.
The second A12 I get acceptable readings at U1 when the trim pots are turned to their lowest levels. When I attempt to raise the trim pots to +18v and -18v the red LED begins to flash.
I don't know if I caused something to malfunction when I hooked them up while the SC25's were soldered on or not. I do know that all components are in the right places. There are no solder bridges. I don't know what to do. If anyone could help it would be greatly appreciated.
I made the same mistake with both of them, I didn't realize it until I had finished both. I didn't install the mill-max receptacles for the SC25. I soldered the SC25 to both of the PCB's.
When I first finished them both I check the voltage readings for the SC25 and both pin 3 and pin 5 had acceptable readings. so I raised the trim pots so that U1 could be +18v and -18v. The first one raised to 18v, positive and negative. but on the second one only the negative would reach 18v. The + would only get no more than 17.03.
When I powered them both up everything seemed fine, until I hook them up.
One was not passing a signal and all I could hear is was very low hissing.
The second one made a high pitch screeching sound.
And on both of them U4 became extremely hot.
I pulled both op-amps out and put in the mill-max receptacles and then put in the SC25's.
Now on one of them I am getting different readings on U1 Pin 3 and 5.
A few times both pins have showed around 14: -14.5 thru -14.6 and + 14.5 thru + 14.75 and other times I will get a reading of + 02.0 thru + 03.2 and the red LED will begin flashing at some point while power is turned on. If the I/O's are connected I hear a pop that corresponds with the flashing of the LED. And the output transformer gradually heats up, but not as hot as heat sink U4.
The second A12 I get acceptable readings at U1 when the trim pots are turned to their lowest levels. When I attempt to raise the trim pots to +18v and -18v the red LED begins to flash.
I don't know if I caused something to malfunction when I hooked them up while the SC25's were soldered on or not. I do know that all components are in the right places. There are no solder bridges. I don't know what to do. If anyone could help it would be greatly appreciated.