sys.entropy
New Member
I purchased a used MCD301 at quite a deal because the top trim and cover had some pretty big scratches in them. Upon receipt, everything powered up, ran fine for a day or two, then the disc tray stopped coming out smoothly, then stopped working almost entirely. Now, this being a buyer beware world, I hold no ill will against the seller. In all likelihood, this issue just started when I received the unit. So, after a little research, and some thought, I determined that the problem was the belts.
Since I really didn't feel like having my new toy out for repair for weeks or longer, and didn't really like shelling out any more cash to anyone (just finished building my first real two channel system), I decided to take on the repair myself. After a quick call to Mcintosh, I had a new set of belts on order as well as a new trim piece and a new top cover.
Since I had some difficulty getting any information online on this repair, I figured I'd share it here.
Here is the top of the MCD301, there are eight (8) screws holding the top cover, six (6) on top, and two (2) on the rear. No real trick to removing the top cover.
Removing the top cover reveals the transport, PCBs, etc.. Yes, the transport is stamped Denon, yes, it's based on a Denon production transport. I am not going to get into the debate of is it a special Mc transport or a standard Denon transport. But, I will say that there is a Denon service manual has a breakdown that is identical to the transport found in the MCD301. Having the breakdown helped. There are only six (6) screws holding the transport cover down. They are located on three sides of the transport, the fourth side is held on by tabs. This means, to remove the cover, you have to slightly lift one side, and then pull the cover to the right to remove. Be careful removing the cable hold downs.
Once the transport cover is removed, we easily see the inner workings of the transport. This is where I pulled the unit, powered up, and pressed the open/close button. With a little manual help, the tray did open, revealing the belt assembly.
It is necessary to remove the large pulley to replace the belt. There is nothing complicated about this. The large pulley is retained by a very small snap ring. This pops off with a fine flat screwdriver. The smaller pulley is held in with a unique disc with a slit in it. This disc has to be removed to to get to the belt. This is also easily removed with a little finesse. Be careful when removing. I got the feeling that this plastic disc could be brittle and won't give too much. Just flex the disc enough to pop one edge out of the groove on the pulley shaft, rotate the disc, and it will spiral off easily.
So, with both belts free. It was easy to replace the secondary (on the left) belt. To replace the primary (right) belt I needed to remove the motor assembly. No big trick to this either. There are three fixed position screws holding the motor to the transport chassis. 
Pop the motor off, swap the belt, and do everything in reverse. All in all, not knowing what I was doing, the whole job took about 45 minutes. I could probably do it in 30 now. The design allows belt service to be pretty easy. With the transport back together, I replaced the trim piece and put the new cover on, and we're back to mint!
While it may be intimidating to tear into a piece of electronic equipment costing several thousand dollars, with plenty of research, I felt this was a pretty straightforward repair. Just go slow, be careful, look at everything twice before taking anything apart.
-John
Since I really didn't feel like having my new toy out for repair for weeks or longer, and didn't really like shelling out any more cash to anyone (just finished building my first real two channel system), I decided to take on the repair myself. After a quick call to Mcintosh, I had a new set of belts on order as well as a new trim piece and a new top cover.
Since I had some difficulty getting any information online on this repair, I figured I'd share it here.
Here is the top of the MCD301, there are eight (8) screws holding the top cover, six (6) on top, and two (2) on the rear. No real trick to removing the top cover.
Once the transport cover is removed, we easily see the inner workings of the transport. This is where I pulled the unit, powered up, and pressed the open/close button. With a little manual help, the tray did open, revealing the belt assembly.
While it may be intimidating to tear into a piece of electronic equipment costing several thousand dollars, with plenty of research, I felt this was a pretty straightforward repair. Just go slow, be careful, look at everything twice before taking anything apart.
-John
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