The first thing I liked to repair for Markus’s machine was the CDM2. The disc was not spinning and has not shown any signs of life. To avoid any possibilities of using a failed decoder board I was using my “modified” CD150 which has the connectors outside the case ready to be used with a CD unit for a better testing.
First I replaced all capacitors which is always a good idea although it was obvious that this alone will not solve the issues. Since the disc was not spinning I located an issue with the drivers for the hall motor. The output of the CPU was fine but it seems the OpAmps failed to drive the motor. Since it is a CDM2/10 the electronic contains another panel with a JRC4556D. There another OpAmp JRC4560D On the CDM2 panel itself. I was too lacy to check which one failed so I replaced both and CD is now spinning.
However, the electronic still failed to read there TOC and I noticed the focus of the laser unit does not do anything and the demo mode fails to focus in the first step. I checked the COU output for focus and noticed the CPU is working. This leads me directly to the focus drive – the OpAmp 6104, a L272MB. The fusable resistors 3318 and 3140 are both broken and got replaced. However this does not solve the issue so I replaced the L272MB OpAmp and thankfully the CDM2 was back working. At least with the CD150.
Before putting the CDM2 back in to the machine I checked the voltages and the negative voltages were missing. It comes down to another usable resistor 3484 on the power supply panel. Replacing it brought all the voltages back.
But the CDM2 failed again. The decoder board was not working and switching off the CD-Player resulted into a movement of the laser head to its top position. That only means one thing, the power supply has another issue and still presents some voltages when it shouldn’t be. After controlling the components inside the mute circuit (I cannot express how I hate this circuit) the transistor 7478 has shown some unusual values. After replacing it everything was fine now, except that the decoder panel still has some issues.
