Transplant Of Parts Done In This Very Complicated NAKAMICHI Cassette Deck C1
This is a Cassette Deck brought to me by a new customer, referred by a techie friend. I learnt that this was bought by the customer from another involved in second sales of antique items. The customer paid a good amount for owning this piece just for the love of it, because of its special features. This set had the uniqueness of using two capstan wheels and pinch rollers; one for pulling the tape and another to push it down for collection. It had three motors, one for turning the capstan wheels, one for play wheels and another for loading the head mechanism unit.
Both wheels had their own sensors underneath. I am providing only a few snaps of the mechanism in order to cut short the length of the article. Those of you, who are interested in knowing the very complicated working system of the Deck, can see the following link and download the user/service manual here:
https://www.hifiengine.com/manual_library/nakamichi/cr-1.shtml (You may have to register and log in)
The complaint mentioned by the customer was that the deck get switched off after a few minutes of play or half way through. The set had gone through a few techie hands and after their futile attempts, it finally reached my table, by which time several months had passed. The last man who disassembled the mechanism forgot to put a plate lever inside while reassembling for return. The customer also brought a similar mechanism, which provided an option to replace parts if and found necessary, along with the ‘got out’ plate. So, I dismantled that also to know where the lever was located. Now let us have look at the connected pictures:
The last picture above is the azimuth adjustment mechanism, typical for Nakamichi sets. With a rotary switch provided on the panel, we can manually adjust the head to perfect sound output. The lever that I had to put back is marked with two arrows on the fourth picture above and in the last but one.
First I put the lever in its correct place and reassembled the mechanism, cleaning and lubricating every part. The Service Manual specified that there was no need for any llubrication. But dust and corrosion had set in necessissating the need for it. I used a large sack thread stitching needle and inserted a cloth piece inside the capstan wheels and cleaned it using IPA. It brought out a lot of blackish dirts.
After cleaning and lubricating all the connectors that come from the mechanism, I fixed these in the proper places and applied power and played a cassette. Yes, the player stopped playing after about half. Sometimes immediately afer running. So, I checked the wave forms generated by the sensors and found these to be normal while running the mechanism without a cassette and with the cassette.
So, I knew that the problem was related to some mechanical issues. I removed the mechanism from the deck and dismantled the play wheels, upon which the reason got revealed. There was a round plastic lock with a spring under the play wheel and that had developed crack. So, I put a replacement from the other mechanism, which was kept in a totally dismantled condition anticipating such eventuality. Then reassembled the mechanism and once again ran the tape. This time full tape was played. Both A and B played very well. I loaded a few cassettes of different lengths. C45 and C60. I did not have C90 or C120.
Though the output was not good enouch as per my standard, I stopped working on this set after resolving only the complaint that was reported. I requested the customer to take it home and use it for a month to make that the mechanism was working very well, after which we could think of setting right the minor electronic problems, including change of all electrolytic capacitors. (Unfortunately, in my excitement of finding the true fault, I forgot to click snaps! My apologies!) But it is there in the Service Manual, under the exploded view.
Though I have written as though the work was finished soon, in practice I had to spend several hours, days and weeks and dismantled the mechanism at-least five times in order to pin point the trouble maker. Anyhow, mission accomplished with aplomb and great satisfaction added to the bag. The customer was very, very happy that he paid me a bonus too after a couple of weeks! Here was a customer, who appreciated the strains and efforts that I put and rewarded me well! Such customers are rare to see nowadays!
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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