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Customer of mine brought in the above mixer in for repairs, he had told me that he has to switch the unit on and off a few times then the unit will work.
I had a few units like this before and found that changing the caps on the power supply will sort the problem out.
I went ahead to check the power supply caps and found a few that were bad. I replaced all the caps both on primary and secondary side. I also went ahead and changed the crystal for the display.
On power up the unit switched on but the LCD display was black as per link.
https://www.diyaudio.com/forums/attachment.php?attachmentid=801681&d=1576229537
I have checked all voltages without a load and the voltages are all correct.
Now here is my problem with supply connected to rest of mixer. the 3,5,8 volts are all fine the problem is now with the +- 12 volts. the +12volts goes down to about 7 volts and the -12 goes up to about -16 volts.
I have found that when I discount the board that has the serial port on it the + 12volts(which is now 7V) comes up to +9 volts.
Customer of mine brought in the above mixer in for repairs, he had told me that he has to switch the unit on and off a few times then the unit will work.
I had a few units like this before and found that changing the caps on the power supply will sort the problem out.
I went ahead to check the power supply caps and found a few that were bad. I replaced all the caps both on primary and secondary side. I also went ahead and changed the crystal for the display.
On power up the unit switched on but the LCD display was black as per link.
https://www.diyaudio.com/forums/attachment.php?attachmentid=801681&d=1576229537
I have checked all voltages without a load and the voltages are all correct.
Now here is my problem with supply connected to rest of mixer. the 3,5,8 volts are all fine the problem is now with the +- 12 volts. the +12volts goes down to about 7 volts and the -12 goes up to about -16 volts.
I have found that when I discount the board that has the serial port on it the + 12volts(which is now 7V) comes up to +9 volts.
