Nakamichi repairing/ servicing professional in India

[TD150]

If you have already messed the head alignments, you need to try adjust it to the optimum listenable setting.

 

[allanmatters112]

It's hard to say if it was replaced . It's a Japanese one as I am aware of the brand NEC . It reads as (the transistor with the heat sink ) NEC C1096 Beneath it L108A

 

[TD150]

The transistor is sure a replaced one. As the original is 2SC1096 and this one is C1096 made by NEC. Though the specification is same, but the new ones become very hold though they can withstand uptown 150 Deg cent temperature.

Check the solder pads of the transistor you will be able to make out whether they are replaced ones.

 

[allanmatters112]

Yes it's replaced . The solder marks are more shiny than the other ones on the board . I tried blowing the transistor continously while in playback mode . The heat from the heat sink reduced completely and the deck played for longer time as I was blowing air on the transistor. It eventually stopped as every time I touch the heat sink the solder might be getting lose on the board so I guess it needs a resolder .

 

[allanmatters112]

I think you are correct. Fwd Rew seem to work flawlessly no matter how hot the transistor gets .but in play mode once the heat sink is HOT it stops playing and the auto shut down comes in play . Auto shutdown is working fine . The pinch roller are 60-70%used . I should have cleaned it . So as I was blowing directly cool air on the transistor the deck seemed to play for longer time . The middle leg of the transistor seems like the solder is not touching the green part of the board . The green part is. Worn out from all around and it's basically soldered to the wood of the PCB. I don't know how and who did such a thing>( only the middle leg )

Also the white substance which u should apply between transistor and heat sink is like not even there . It's like 5 % . That's important to dissipate heat

I kept blowing the transistor while in playback mode, seems to last longer in play . But still testing for more accurate results

 

[TD150]

You may solder the transistor leg to the connecting component (with a short piece of wire) so that the line track is maintained and the transistor is well connected in the circuit. This will also ensure the transistor leg if it is getting disconnected due to such damaged PCB pads solder joint when getting heated up.

 

[allanmatters112]

Ok .How important is the middle leg transistor in terms of solder . I tried resoldering the middle leg but it all wood around it the green circuit around the transistor in the PCB is all worn out .I will try your suggestion. I resolrdered the other two outter legs and then tested . I played the tape for a while then tried twisting the transistor with the heat sink, it stopped playing . Only rewind works now, fwd does not work . Shook it again and it tried to play but stopped . Now its not playing again . Need to check that solder again. Will try your suggestion. Thank you very much so far . Appreciate it

 

[TD150]

Those two transistors Q407 and Q408 are power transistors and provide +12vdc supply to the deck motors. It is a circuit to step down the +24vdc supply to +12vdc supply from the other part of the deck to provide for the motors. If any of the legs of these transistors is disconnected then the +22vdc supply gets disconnected from the motors. Since for the rewind it requires +24vdc the function is unaffected and working wereas play & ffw will not work.

 

[allanmatters112]

Thank you for the information. Sorry for the extra questions s . Thanks

 

[allanmatters112]

Update on the problem found.

Iam 99% sure it's the control motor (reel motor)
So here's what happened . I resoldered the Q407 legs (all 3 again ) especially the middle one as the circuit line was bit worn out (so I just made it better as in one time I resoldered the middle leg and the fwd play dint work as the solder on the middle leg was not touching the circuit line ) .
So the transistor is intact soldered well now

Turns out that was not the problem , no matter how hot that NEC transistor gets its not really causing any interruption.
The issue is with the control motor . It has dead spots inside . Remember that vertical free play I spoke about (the shaft ). The motor shaft is lose in the vertical direction(I.e when the player is kept upside up normally like default position . For you to understand the position just how u regularly keep your player the shaft is lose vertically .
So as soon as the cassette stops . I try to play it again or fwd it again or rew it again the motor shaft does not move . I push the shaft with my finger then press play or fwd or rwd it turns instantly .

The motor is pretty much gone for a toss . I read a similar article here though its a different nakamichi model but issue is same as what I am facing on my nakamichi . Check it out http://www.tapeheads.net/showthread.php?p=767057#post767057

It's recommended to change the motor in such cases .
The motor can stop at any time sometimes after 2 mins or 1 min or 6 min or 10 min . Because its become weak . ( I have tested it and found these random times it runs and stops )

What do u think ? I will not focus on fixing the play head and azimuth alignment now as the motor needs to be looked at first . Do you think I can get a motor from lamington road if I take the sample?? Or can this motor be opened and fixed ?

Lots of new problem s keep coming . I really want to fix this unit and enjoy the sound .
Took a video

 

[TD150]

Ok no need to tamper with the alignment of heads at this stage.
Regarding the motor, if you are sure it is giving problems. There is a shop in lamington road (I don't recollect the name) it is near to the bridge. When you pass below the bridge (from the railway station) to go to lamington road it is on the first right turn. You will see lot of such motors in their display rack (which you can see from outside from the road). Some seems to be new, some salvaged from old units & some repaired. You may find your motor model there or else could get the existing one repaired. However I have no experience of such repair nor have any affiliation to the shop. You may try it on your own risk.

 

[allanmatters112]

Ok thanks for your help . I will take out the motor test it with a 9 volt adaptor see if it dies suddenly

 

[TD150]

If you happen to go to lamington road, do me a favour, I am looking for a replacement lamp for the play button/ switch glow lamp. It is 24vdc 20mA rating, just see if you can find any shop having it.

 

[allanmatters112]

I am pretty sure it's the motor . Because even after I switch off the deck , let it cool down (transistor) and then switch it on the motor does not engage unless I give it s nudge on the motor shaft

 

[allanmatters112]

If you happen to go to lamington road, do me a favour, I am looking for a replacement lamp for the play button/ switch glow lamp. It is 24vdc 20mA rating, just see if you can find any shop having it.

Sure i will check it out and let you know once I make a trip . Now the stressful taking out of the motor . Screws are like located in the toughest place

 

[allanmatters112]

So my reel motor died completely as I kept forcing it to work even though the shaft was lose (probably worn bearings ) which I am not sure can be fixed ) I managed to take out the motor carefully
I have another deck with two motors . One is capstan motor reading 12v DC and other is a reel motor but nothing mentioned in volts etc on the back or side .
Do we just have to find a 12v dc motor as a replacement or do we need to look at other technical info also on the new motor for appropriate matching ?

 

[TD150]

I have no idea about interchanging the motors from different decks. But the main thing to remember is though the other motors rate 12vdc, it is the rpm which needs to be accurate for the reel motor spin the hub reels and the cassette speed may vary. Thus this will have to be set and taken care off.

I would say get the motor to someone who could repair it. Should not be a bit task.

 

[allanmatters112]

I have no idea about interchanging the motors from different decks. But the main thing to remember is though the other motors rate 12vdc, it is the rpm which needs to be accurate for the reel motor spin the hub reels and the cassette speed may vary. Thus this will have to be set and taken care off.

I would say get the motor to someone who could repair it. Should not be a bit task.

These motors cannot be repaired . I opened the entire 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 terminal of the old motor (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 Rew became forward and forward became rew . And when I hit play the motor was trying to play cassette from the opposite side ( which is 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 . The rwd and fwd was working in the correct direction . But play was not working . How ever if I connect the negative terminal of the motor (add a third wire from the negative terminal if 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 .(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, same issue although they can work well . Now my mind is exhausted so I guess tomorrow 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.

 

[TD150]

You need to do R&D for a accurate motor. I would still say repair the existing motor, it can be done with new spares.

 

[allanmatters112]

Got my Yamaha AVR and Sansui 717 serviced by them. They are good at their work. Only issue is, you will have to carry the equipment to them and pick it up as well. They do most of the highend brands

@mshifi I'd really like to know the address of this place as my nakamichi needs thorough looking at . Iam trying to fix the reel motor but there are also other issue s . My record function actually does not record anything even thought there is input being received. Rec lamp needs looking at and I am unable to adjust azimuth for clear playback .( Tried all possible ways slowly steadily)

I would greatly appreciate if you could share the address of this place with me as it's not there on their website and the number does not work . I sent a request with my phone number but no one has called me back

Do let me know if you can help . I reside in Mumbai Western line
Regards
Allan

@TD150 I found an exact same motor but can't seem to get it to work . Even the old moto is not responding. I opened the old motor . The brushes were all bent inside and carbon is like breaking into powder .
I think the best option is to give it to a trained tech so that all other transistors and capacitors which are also faulty can be changed once and for all . I have at least dine half the job replacing belts and idler tire . Do you know where this service centre is ? The link in which you mentioned in your comment