CDM2 of Unit #3 repaired

After the uProc and the CD-Player keys are working it was time to have a look at the CDM2. A short test revealed that it was not able to read the TOC or to play tracks. I sometimes had the problem that the TOC failed to read but it was possible to play some tracks. Mostly above certain track the playback failed. In this case, the CDM2 just turned but was not working at all.

The first thing, which is always a good idea is to replace the capacitors. They are responsible for timing and it is better to exchange them first before searching for an issue. This was the first step, in a second I cleaned the optics and checked the flex cable. This often has some broken wires because of the plastic lock that holds the cable down. It is to strong and damages the cable. A replacement can be downloaded in the download section. However, when cleaning the lenses some mistake happened.

There is a small plastic plate on the top of the focus which is just glued onto the thin focus metal bar. During cleaning it got lost and because it was transparent I have not noticed this in a first step. Anyway, I finally came up with a solution and put it back with a double sided tape. The drawback is, that the weight of the optic is now different and not working when in horizontal position since it seems the coil is not strong enough to keep the focus. In a vertical position it is working fine – the weight is than reduced. Since this is the final position in the sound machine I keep it that way.

After the small plastic label is back on everything was working. As a result, the only thing that has to be done was to exchange the capacitors. Highly recommended to make this your first step. There are only a few capacitors and the CDM2 really enjoys good quality parts.

I also calibrated the currency of the laser – the procedure is shown in the video below. In addition to the video I recommend to test several Audio-CDs! Some are easy to read and the currency of the laser can be lower in this case. If you calibrate the laser to this CD it will fail to play other CDs. Usually a test CD from Philips exists but I was not able to get it. Try to find an Audio-CD which is hard to read e.g. requires a higher currency to get played. If you want to play CDRs test them since they often require a higher laser currency. Be careful of what you are doing, you can destroy the laser!

When you bought a Sound Machine check if it has been opened already. If so, control the potentiometer of the laser and if it is on one of the ends move it into the middle position before you start. To increase the laser currency helps to read the disc and hides other issues. Afterwards it seems the CD Player is working fine – which it does – but only for a short time, very soon the laser is gone.

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