Nakamichi 480 control motor stops responding

[allanmatters]

Hi all ,

I recently picked up a non working nakamichi 480 for 119 usd . I know I got looted completely and the risk I took on buying it without hearing it play as the tape wouldn't turn as I hit play fwd or rwd .

So I brought it home . Ordered all the belts
Here is what I changed.
1-capstan belt (as it was slipping at times)
2- idler tire
3-autoshut down mechanism belt
.
The deck started working after fixing all these things. I heard it for the first time .
It dint sound really clear like in all the reviews I read . Right channel was muffled and lower than the left . (Played a maxell type 1 normal bais) it even slit the tape at one point of time I don't know how

Problems
The control motor
It does not turn most of the time when I hit play fwd Rew. It seems lose (there is a Freeplay in the vertical direction)
So sometimes when I push it with my finger from the top (the motor shaft )the shaft engages the tire idler and reels , it spins instantly and the tape plays) but not for long .just a minute

Alignment has to be done as the sound is not clear and muffled on one side .

Now I did come across a thread on tape heads here http://www.tapeheads.net/archive/index.php/t-40311.html

I think my motor too might be overused .
Will I be able to fix the motor ?. I suspect the shaft is gone from the inside . If I can open it up and fix it I wouldn't mind . I am looking for a permanent fix .
Appreciate your help

Regards
Allan

 

[allanmatters]

So I was thinking of taking out the motor . But discovered something down the line . The shaft of the motor is lose vertically so I took a pair of tweezers which had an L shaped tip, pressed it on the shaft pole not the head of the shaft . And pressed play then fwd then rewind while I pressed the shaft downwards with the tweezers . It worked well for long and always responded to any functions.

So I guess I need to find a way to keep the shaft pressed downwards as then only it runs properly for longer time without interrupted random stops

 

[revox-b77]

Sounds like the bearings in the motor are shot.

 

[allanmatters]

Sounds like the bearings in the motor are shot.

So can the bearings be fixed ?

 

[allanmatters]

Double post

 

[allanmatters]

I opened the old motor and saw the inside . Basically it's life is over(the bush was like expired and unrepairable)

I had taken out a 12v dc motor from another deck .. Had success but some complications at the same time . So basically there are two brown capacitors connected at the terminals of the old motor outside (plus one more inside the motor ). I took it out (only the two capacitor s on the outside terminal) and connected it to the new motor in the same way and then to the chassis just like the original installation . Connected the + and - correctly on the new motor . Assembled the chassis and entire tape deck with all springs and screws . It worked . But in the opposite direction . So here Rewind became forward and forward became rewind . And when I hit play the motor was trying to play the cassette from the opposite side ( which is the wrong direction as it's not an auto reverse deck ).

So I checked my connections everything was right . I interchanged the plus minus connection on the motor (just out of curiosity) . And the rwd and fwd was working in the correct direction . But play was not working(the motor would not turn for play ) . How ever if I connect the negative terminal of the motor (add a third wire from the negative terminal of the motor ) to the chassis and hit play the cassette plays in the correct direction with no problem at all . But when I hit stop the motor was still running unless I disconnected that extra 3rd wire from the chassis .(3rd extra negative wire form motor )


Been trying to figure out or understand the logic for the past 7 hours . . I even tried 2 different motor s not just one . Now my mind is exhausted so I guess tomorrow i will start fresh again

It's the same thing . I guess even if I buy a new one, it would still result in this confusion.

Does anyone know why I am doing wrong ?

Appreciate it

 

[allanmatters]

Since I put back the system my cam also is inaccurate . I guess I should not have turned anything(cam wheel ) while the set was disassembled
Now the fwd play and rewind don't work. I managed to set the stop at the pointer correctly "S" on the big wheel with the help of the service manual . But cannot seem to get the remaining markings PY and R and F to sit at the correct point when the desired function is pressed

 

[avionic]

Is the Hunters Club still in business in Al Manama ? One of the best tasting steaks I've ever had. Back in spring/summer of 1993. I was at Al Khobar supporting OSW.

You probably need to find another 480 parts unit with the correct motor/cam timing position.I suppose the service manual isn't much help.

 

[allanmatters]

I am not sure if it's still there . However I will try and look for it and update . 1993 huh . That's a long time.

 

[allanmatters]

Thing is the cam arm was working fine until I disassembled it . I was putting in a new control motor for a more permanent fix . As the old one kept dying allot and I didn't want to do the deoxit method on that .

The new motor does not turn when play is pressed . It only turns when rewd is pressed and when the fwd function is pressed .

The old motor is dead .. no response at all .
I think I may have screwed up the cam assembly as I disassembled and assembled the chassis .
. I don't need to get another 480 frankly speaking as the system was working . Only issue was the control motor and after changing that the cam is messed up . I have a feeling . .
So far replacement of the tire idler and capstan belts and auto mechanism belts have been successfully . Now I am stuck on this step

 

[allanmatters]

Actually I've come to understand that cam will behave properly if the correct motor is fixed . I tried two motors from different deck ( one had a nice long shaft like the original ) but both did not work right . Only rwd fwd worked . When I hit play the new motor would not turn and the cam wouldn't even lift the play head up neither would it play .
How difficult are these motors to match when buying . I know it's definitely a 12v that's about it