I'm trying to fix a B&O CD player that uses the Philips CDM2/10 mechanism.
I had got it nearly working perfectly but some CDs still didn't play correctly as if the error correction wasn't working correctly. I took it apart again and lubricated the radial arm, again, and also cleaned the motor windings which looked very tarnished. When I put it back together and ran the test mode, it wouldn't pass any of the tests. Not even the one that confirmed the ribbon cable from laser to servo board was connected correctly. It had always passed this test.
After investigation I found the power supply lead from the decoder board to the servo board was incorrect once plugged into the servo board. But, only when plugged in.
The decoder provides power through a lead with a 5 pin plug at each end. The pins should be;
Pin 1 +9.5v
Pin 2 +5v
Pin 3 ground
Pin 4 -6v
Pin 5 -9.5v
This is what comes from the decoder board when measured on the board itself and I also get those readings when measured at the 5 pin connector before connecting it to the servo board. But, and this is what my problem is, when I connect the plug to the servo board and take a reading direct from the plug, the -9.5v becomes +6v. All other pins read correct. The decoder board is still giving -9.5v as it should do.
The 6v then goes to places the -9.5v should go, i.e. it doesn't lose any significant voltage on its journey around the board.
The problem exists if the servo board is connected to the CDM2/10 module or not.
What's happening? If the voltage changed from -9.5v to 6v somewhere on the servo board I'd be checking all components it goes through. But, at the plug before it even gets starts on its journey through the board?
I had got it nearly working perfectly but some CDs still didn't play correctly as if the error correction wasn't working correctly. I took it apart again and lubricated the radial arm, again, and also cleaned the motor windings which looked very tarnished. When I put it back together and ran the test mode, it wouldn't pass any of the tests. Not even the one that confirmed the ribbon cable from laser to servo board was connected correctly. It had always passed this test.
After investigation I found the power supply lead from the decoder board to the servo board was incorrect once plugged into the servo board. But, only when plugged in.
The decoder provides power through a lead with a 5 pin plug at each end. The pins should be;
Pin 1 +9.5v
Pin 2 +5v
Pin 3 ground
Pin 4 -6v
Pin 5 -9.5v
This is what comes from the decoder board when measured on the board itself and I also get those readings when measured at the 5 pin connector before connecting it to the servo board. But, and this is what my problem is, when I connect the plug to the servo board and take a reading direct from the plug, the -9.5v becomes +6v. All other pins read correct. The decoder board is still giving -9.5v as it should do.
The 6v then goes to places the -9.5v should go, i.e. it doesn't lose any significant voltage on its journey around the board.
The problem exists if the servo board is connected to the CDM2/10 module or not.
What's happening? If the voltage changed from -9.5v to 6v somewhere on the servo board I'd be checking all components it goes through. But, at the plug before it even gets starts on its journey through the board?