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

[jpfastre]

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

[anatech]

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

[jpfastre]

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

[anatech]

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

[ocaukrell]

Sorry to hijack but,
Anatech, do you have info/service manuals for the nak mb-4s ?
Ta...

[anatech]

Hi ocaukrell,
Had ..........

Standard music bank assembly, Sanyo SF-90 head variant.

-Chris

[ocaukrell]

DOH !

Don't spose you any info on MB's at all ?
Servicing or whatever ?

[anatech]

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. Problem solved. Sad that you can't even trust a human to insert a disc correctly.

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

[ocaukrell]

Interesting, Mine is of the vintage that does the shake.
Always liked that idea.
As you say though, how hard is to put a round object in a round hole ?

Surley you could scan your head for me

Of the few that I've worked on (MB changers car and home) they've only needed a mech belt.

Thanks, I'll go back to lurking now and let the OP get back to their thread

[anatech]

Hi ocaukrell,
Okay, use a thicker mechanism belt than stock. They wil stay out longer. Too bad it missed the "shakey - shakey" mod. I always wondered if there was extra wear on the stacker mechanism.

-Chris