Use the Nakamichi MB-1S as a single disk player

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Because the multi-disk mechanism is not very reliable, I like to modify the circuit of the Nakamichi MB-1S seven disks bank system CD player so it will act as a Single disk player.
The mechanism is regulary jamming during the initialisation fase at power on and gives an ERROR on the display. How can I disable this function so there is no more initialisation fase and the player should use always the same tray.

The player sounds very good. I added a Trichord Xtal oscillator with a LCAUDIO separate power supply. The mechanism is repaired twice but stays unreliable.
Thanks.
JP
 
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Hi JP,
Thanks for directing me to your thread.

The transport is not unreliable, it appears as though your service is unfortunetly. :(

I have repaired many, but don't have the manual right now. The DAC section was extremely good.

The seven disc player did have a problem with grease on the belts. Timing and laser head lead length was important, as was the gear timing. I did many but they were reliable after service. Yours should be.

I'll bet they haven't replaced a belt, or there is a grease / timing issue.

-Chris
 
Thank for your help.
I'll look for cleaning the belt.

The unit jams at startup when it is placed in level position.
Lifting the front side about one inch prevents mostly the jam during startup.

Is it possible to modify the unit so there is no music bank initialisation and only one tray. So I'll use the unit as a single disk player.

I have the service manual for the MB-1S.

Kind regards.
JP
 
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Hi JP,
Is it possible to modify the unit so there is no music bank initialisation and only one tray. So I'll use the unit as a single disk player.
1. Ill advised.
2. Un necessary. The CPU needs to initialize the transport and do inventory.

Fix the problem, don't create new ones. It was designed this way for a reason.

-Chris ;)
 
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Hi ocaukrell,
No, just my memories. I had the complete set of manuals.

I didn't think much of them when I first saw them. They originally had a problem with customers firing the disc in wrong. They brought out a new program (new cpu chip) that actually gave the tray a shake on the way in to center the disc. :D Problem solved. Sad that you can't even trust a human to insert a disc correctly. :rolleyes:

The SF-90 head gave a pretty good RF pattern. The transport was reliable. Most of it is pretty flexible as you take it apart. I changed a lot of belts for slightly thicker ones in the early days. Those were the only faults with them.

-Chris
 
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Hi JP,
Sorry, I don't off hand. My supplier went out of business years ago. What we did was to get a belt the same circumference, but increased the cross sectional thickness. Most parts jobbers should have an assortment that you can choose from. In my case, we went from an "SBS" (square belt small) size to an "SBM" (square belt medium) size. I don't know if your general suppliers use the same system of describing belts.

-Chris
 
NAK MB Sorting Mech Problem

Had the same problem myself with the sorting trays constantly jamming. Contacted the UK Nak service agent and ended up spending over £90 on an (alleged) repair. They had it for weeks and in the end claimed it was a software fault. After getting it back and using it for about 5 months the same problem returned. Not wishing to throw more money at it I removed all the trays except for position 1 and that was 3 years ago and, touch wood, I've had no further problems.
 
jpfastre said:


I have the combined service manual for the NAK mb-1s, mb2s and mb-3s.
Perhaps the music bank mechanism is identical. ( Mr. Anatech ?)
Eventually I can send it by email.

Kind regards and thank you all your help. I'll try to repair my Mb-1s


HI JP do you still have the service manual in e mailable form? On reflection I might see if I can replace the belt on my MB2s and put the trays in and see it sorts the problem. Regards Tim
 
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Hi Tim,
Those MB things are the same. The problem normally occurred when a CD was not placed entirely flat in the tray. The software change caused the tray to jog back and forth to shake the CD into the tray. We called it the "shaky - shaky" mod. The CPU was replaced.

I have seen this fault when the CD player was not sitting flat. Also, the belts must be in good condition. Clean the pulleys when you replace the belts. Also check that something has not got "dry" and sticks the mechanism. Lastly, hair. It gets everywhere and you must pull that stuff out. People with cats suffer the most from this.

-Chris
 
anatech said:
Hi Tim,
Those MB things are the same. The problem normally occurred when a CD was not placed entirely flat in the tray. The software change caused the tray to jog back and forth to shake the CD into the tray. We called it the "shaky - shaky" mod. The CPU was replaced.

I have seen this fault when the CD player was not sitting flat. Also, the belts must be in good condition. Clean the pulleys when you replace the belts. Also check that something has not got "dry" and sticks the mechanism. Lastly, hair. It gets everywhere and you must pull that stuff out. People with cats suffer the most from this.

-Chris


Chris

Thanks. The model I have came with the "shaky shaky" mod. I think the service agent didn't have a clue what they were doing as they were really concentrating on the in car entertainment sector. I suspect the problem with mine was a dry mechanism combined with a defective belt. Don't think its hair as i'm bald as a badger:scratch1:
JP is looking to email me the service manual. Will let you know how I get on.
 
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