Nakamichi 600 Cassette deck Complete Restoration

Akaudiotech

Member
Joined
Feb 25, 2023
Messages
34
Points
18
Location
Coimbatore, Tamil Nadu
Hello guys. No need an introduction to this beautiful sounding machine. I don't remember exactly but it must have been more than ten years, I bought this machine from a friend of mine in an (knowingly) "as-it-is" condition. Actually this is my first Nakamichi deck. I bought this for the fascination of its name and excellent sound quality. Unfortunately, my luck was like that, the machine stopped its working (partially) few weeks later. My expectation was a Jaguar! But I got Plymouth (that too from tinkering workshop). Ok let’s come to the story. At the time of purchase, I wasn't too keen on it due to its condition. And, within a short period (after its silence) I had taken it and put into a box and keep shelved. Some years later slowly I got interest in fixing the deck and back it to life. But the main problem is that the overall condition is as follows when I bought this machine.

1. No original record/playback head. Someone had replaced with dyny or something else.

2. Broken reel hubs (Tires are now crumbled)

3. Mechanism switches 2 out of 6 were broken.

4. Calibration plastic alignment sticks 4 out of 12 to be replaced.

5. Pressure roller was in bad shape.

Later.., Right channel not working within few weeks.

Following that, I started collecting replacement parts one by one over the years. Now I have got all the necessary parts accordingly and am about to start the restoration work. Obviously, I am not sure that I will complete the work. But I will try doing my best. Also, I am hopping the HFV members can help make better to this deck.

Fine, let’s start with right channel issue.
 

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Hello guys. No need an introduction to this beautiful sounding machine. I don't remember exactly but it must have been more than ten years, I bought this machine from a friend of mine in an (knowingly) "as-it-is" condition. Actually this is my first Nakamichi deck. I bought this for the fascination of its name and excellent sound quality. Unfortunately, my luck was like that, the machine stopped its working (partially) few weeks later. My expectation was a Jaguar! But I got Plymouth (that too from tinkering workshop). Ok let’s come to the story. At the time of purchase, I wasn't too keen on it due to its condition. And, within a short period (after its silence) I had taken it and put into a box and keep shelved. Some years later slowly I got interest in fixing the deck and back it to life. But the main problem is that the overall condition is as follows when I bought this machine.

1. No original record/playback head. Someone had replaced with dyny or something else.

2. Broken reel hubs (Tires are now crumbled)

3. Mechanism switches 2 out of 6 were broken.

4. Calibration plastic alignment sticks 4 out of 12 to be replaced.

5. Pressure roller was in bad shape.

Later.., Right channel not working within few weeks.

Following that, I started collecting replacement parts one by one over the years. Now I have got all the necessary parts accordingly and am about to start the restoration work. Obviously, I am not sure that I will complete the work. But I will try doing my best. Also, I am hopping the HFV members can help make better to this deck.

Fine, let’s start with right channel issue.
My good wishes for your work. You have already procured the necessary parts and hope you will succeed in repairing your loved Nakamichi deck. Our lovely forum has many talented DIY guys and they will help you. However your endeavour to breath in a new life to this analogue sound machine in an era of digital technology is praiseworthy. Thanks again from the end of an analogue lover.
Regards
 
My good wishes for your work. You have already procured the necessary parts and hope you will succeed in repairing your loved Nakamichi deck. Our lovely forum has many talented DIY guys and they will help you. However your endeavour to breath in a new life to this analogue sound machine in an era of digital technology is praiseworthy. Thanks again from the end of an analogue lover.
Regards
Thank you very much 🤝for your encouraging words and wishes. Definitely I believe I'll complete.
 
Update - One

Initially, I followed the basic instruction of cleaning (i.e., Record switch, intermittent connectors). But there was no improvement. Then, I found the problem in Line amp section was that the output transistor 2sa733 was short and the coupling capacitor 1.5uf (but the service manual says 4.7uf) degraded. I’ve swapped the transistor 2sa733 to Ksa992 and 2sc945 to Ksc1845 (for complementary) as well as the capacitor. Now the problem fixed.
 

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Update - One

Initially, I followed the basic instruction of cleaning (i.e., Record switch, intermittent connectors). But there was no improvement. Then, I found the problem in Line amp section was that the output transistor 2sa733 was short and the coupling capacitor 1.5uf (but the service manual says 4.7uf) degraded. I’ve swapped the transistor 2sa733 to Ksa992 and 2sc945 to Ksc1845 (for complementary) as well as the capacitor. Now the problem fixed.
That is a great work.
 
Update - Three

Completely Recapped in main board, Dolby circuit and shutoff pcb.

The capacitors that I've replaced with Panasonic FR/FM/FC Series and Nichicon UKW/UVZ and Rubycon YXJ (for PS stage). For line level changed with Nichicon FG and Elna Silmic II.
 

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Excellent job.I have a Dragon,and am wanting to replace the head and also get it serviced.Do you know anyone who can do it?
Hi, thanks for your appreciation. Which one you're looking for in playback or record head? If its PB head (4 track 4 channel) highly rare to see one for sale. For service technician, I don`t know other than Mr.Umesh who have all necessary calibration tools and equipment. Because dragon needs more capability.
 
Update-4

The mechanism has been Completely overhauled. Replaced Pinch roller, Capstan belt, Reel hub(s) with new tire, Rec/Play head (used one) as well as two function keys. For lubrication purpose synthetic grease (Ptfe) and oil are used.
 

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A few alignment done., Head height, take-up & back tension torque, Tape path aligned properly. After many years I did see the tape moving. 😊

 

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Update-5

Friends, Sorry for the late reply. Due to a long business trip I couldn't keep up with work (no need to say reason since no one was expecting the update 😜) Anyway, Playback level calibration completed. Head height then Speed calibration aligned with two different tapes 3000Hz and 3150hz.
 

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Playback level aligned. Azimuth level calibrated with 10khx and 12.5khx tapes
 

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Dalby level and Playback frequency response calibration.
 

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