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-   -   nakamichi mb-2 disc loading problem (http://www.diyaudio.com/forums/digital-source/198326-nakamichi-mb-2-disc-loading-problem.html)

deafdumband50 11th October 2011 08:47 PM

nakamichi mb-2 disc loading problem
 
Hi. I'm new to this.
I have an early 90's Nakamichi MB-2 multi-disc cd player. When I load a cd it goes in fine but when I press play the drawer just opens back up and slides back out. I don't think it spins at all during that time. I'd appreciate any help I can get to fix this. thanks

stephensank 12th October 2011 02:36 AM

If we are talking about an MB-2, and not an MB-2s, the first thing to check is whether or not the second stage of loading is happening fully. To check, you need to remove the top cover & observe what happens when you load a disc. Whether you hit play or not, once the drawer is closed fully, the second step is for the laser/transport mech to be lifted up under the cd until the cd is clamped & free to spin. If you aren't sure, just turn off power as soon as the mech stops doing anything & try spinning the cd with your finger. Should spin free & level, securely clamped by the magnetic clamper on top of it to the platter of the transport mech.
If this checks out, power up again, load a disc & see if, after cd is clamped, the disc spins within five seconds or so of clamping. If not, try re-loading & see if it starts spinning once you give it a clockwise spin with your finger. If yes, the platter motor needs work or replacement. If not, you may have a fairly rare case of a bad Sony KSS-210A laser.

deafdumband50 12th October 2011 06:37 PM

Thanks!
 
very helpful info. Thanks a lot! I do have a Japan made MB-2, not the MB-2s. I also failed to mention that the unit was taken in for repair for the same problem years ago. They replaced a small part but I can't remember what it was. If it was the laser then I'm wondering if the laser is good and the connection is bad. I think you sent me on the right track though. I just have to figure out what to remove to access the laser and it's wires.

stephensank 13th October 2011 02:44 AM

Usually the only thing the MB-1/2/3, aka CDPlayer1/2/3, need is belts, primarily the main loading belt, i.e., tray belt. You can greatly extend the life of that tray belt by reducing the tension of the roller-ended leaf spring that catches the tray at the very back end of the tray guide rail. This spring roller holds the tray fully closed to counter some play in the drive mech, and the tension is excessive, causing premature belt slip. There are two other belts, both of which require removal of the entire mech from the unt to access. One drives the laser/transport up & down, and the other moves the changer trays unit up & down.

deafdumband50 14th October 2011 02:15 AM

Great - I'll look at the belts too. It might take a while because a friend has the unit and he's out of town for a week, but we'll work on it. Thanks.

cchean 5th June 2013 07:40 AM

My CD player 2 has developed a similar problem. It does not show the common symptoms of sticky drawer or worn belts. However, it is not loading disc #3. I opened up the cover and I was able to narrow down the problem. When loading discs, whenever I try to load disc #3 the tray will not go all the way into the magazine. About 1/4" will stick out and I can hear the motor spinning until it gives up and the drawer opens again. Sometimes an "err" message will appear on the display. If I help and push the tray into the magazine with a toothpick or a small screwdriver, then it will work as normal. But when disc #3 is unloaded and loaded again the same problem will arise. I noticed that if I load 5 discs, instead of 6, leaving the #3 slot empty will do the trick. Is there a cure for this or should I replace the whole magazine? Any input is appreciated. Thanks.

deafdumband50 16th June 2013 07:37 AM

sorry for the delay
 
I actually never did look into this unit. I just donated it to a friend's fix-it-later collection and he hasn't opened it up yet. I'm completely guessing here, but if everything works except for #3 maybe there's a problem with the belt that moves the tray unit vertically, or whatever mechanisms that belt drives, when it's trying to load #3. I don't know if there's a tension adjustment for that, but if that's been ruled out, then maybe something is worn or broken on the magazine for that position. Sorry if this info is useless. I just haven't removed the changer mechanism to see those other belts that stephensank was referring to, so I don't know what's there.

vphifi 1st May 2015 04:41 AM

My CD player opens the tray ok, but when it closes, it only pulls the loading tray and leave behind the main drawer. Please help on how to fix this issue.

stephensank 1st May 2015 08:32 PM

Assuming there is no (unlikely) serious mechanical damage, the only way this can happen is if there is no or almost no tension remaining in the above-mentioned roller-ended leaf spring, which could cause the drawer to start coming out before the tray plate comes completely forward into the drawer.
The drawer does not get directly driven, but rather gets driven by the tray plate "mover". If you turn off power, in your malfunctioning unit, as tray gets halfway inward from fully open position, you will see a metal bar engaging the right front corner of the plate. It's this operator bar that is what's driven by the loading drive. When unloading, as it hits the point where tray is fully to front of drawer, a metal claw swings up around a metal peg on side of drawer, locking it to tray drive. If the drawer moves forward before tray fully inserts, claw does not lock to drawer, so it can push drawer out, but not pull it back in. Other than roller spring not holding drawer for full tray insertion, the one other fault could be something in drawer tracks blocking full insertion of tray.
If, when unloading, it's clear that tray is fully forward in drawer, with circle in tray centered all around in circular drawer opening, then damage may have happened to the locking claw mech, but I have never seen this happen, as it's all solid metal & would be very hard to damage.


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