Nakamichi 582Z

[NakTech]

Hello all,
I have got a 582Z today. It is in very good shape for such an old machine. It was packed very nicely with good padding and it arrived safe and sound. This is the first unit I am getting with all functions in working condition. Thanks a lot to Rahul, Bangalore for giving it to me.

If I were a layman, the deck worked sufficiently well right out of the box. It plays and records. It does not eat my tapes. But as usual, I will not be completely happy unless the deck performs to factory specks and no nak will do it unless they are constantly pampered. So I have decided to rebuild it completely. It will take some time because I have limited time available per day to do it and the belts have to be procured.

I am thinking of posting the details of the work done. It will be useful for me to learn from the experienced hands here as well as it may help someone to improve their naks.

 

[Sandesh]

Post some pics. And is this Rahul the dealer from Mysore?

 

[NakTech]

Yes he is Rahul from Mysore. He is very professional in his dealing. Gave me all the pictures I had asked for and also sent me a video showing the present working condition. Once it was sent he followed up with the courier and me continuously till it reached.

Going ahead I am posting the first part of restoration.

The first thing to do is to evaluate the unit in dept. So I played a music tape (not a good one, I have kept some tapes only for this kind of tests). Checked the basic transport operations. Connected a headphone and checked all the level controls. (Not the cal pots) The controls and switches didn't give any cracking noise while operated. This is good news.
But when the internal cal tones were switched on, I see that they are off in level. Both 400Hz and 15KHz are off by several dB.

https://imageshack.com/i/neq4aetj
https://imageshack.com/i/nedko60j

I decided to attend to it later. I also find that there is some lose connection in the headphone socket. I may replace the socket itself later with a good one.
The next thing to do is to play a tape with 1KHz (or any other mid frequency tone) at a lower level. -20 to -10 will do. If you hear a steady, clean tone, it is good. But in my case I hear periodic fluctuation. This is because of imperfections in the tape travel. Even dirt in the tape path can cause this.

So I opened up the door. There was considerable amount of dirt. Due to long years of usage and someone had over lubricated it in the past the dirt is stuck. The rollers are glassy and has some marks on them. I'm not sure if I have to replace them now, only after cleaning the rest of the parts it can be decided. There is also some rust on the flywheel. This could be the main reason for the fluctuation I hear in the tone. When the belt run over it there will be slight deviation in speed of the capstan. So I removed the transport out for a complete rebuild. While removing I find that the right bottom side plastic post which holds the transport was broken. Someone had glued it with Super glue, but it had come off. There is better way of fixing this. It can be done when it is put together back again.

https://imageshack.com/i/mrkprbj
https://imageshack.com/i/mucplxj

After removing the cassette holder assy it was found that the the felt in the back tension arm has dissipated to oblivion. In all classic transport this happens. The original felt deteriorate and become powder. Then they fall all over inside. I need to do some DIY solution to this.

https://imageshack.com/i/n1wljuj

But I need the parts to be clean first. Unless they are all spik and span clean, I won't feel like working. So the mechanism goes to parts.

https://imageshack.com/i/mugoew8j
https://imageshack.com/i/nlnmufj
https://imageshack.com/i/msmav3j
https://imageshack.com/i/nm9g7ij

And some parts are cleaned.

https://imageshack.com/i/nskclvj

A lot more parts yet to be cleaned.

https://imageshack.com/i/np558qj

As you can see, this is going to take some time to finish as I can work only a limited hours per day on this. I will keep taking pictures and add them. Once it comes to the stage of something worth mentioning. I will right. I need to get the 3mm retaining ring for the eject piston. It was fully rusted. Will search in the market. So until next time......TC all nakers...

 

[Selvin]

Hi.. You are a real Nakamichi Operation Doctor only....:clapping:

Interesting and eager to see the singing....

 

[Selvin]

Now we got a nice technical person for Nakamichi decks.

Insinakdoc please share all your restoring experience with us... It will helpful all of us.

 

[reubensm]

From the description, looks like the deck has had some serious running, has seen some DIY hands and has also been stored for a considerable period. Fluctuation on the 1Khz tone could also probably be due to minute slippage of the tape passing under those glossy pinches. Rust on the flywheel, gosh the deck may have been in storage for atleast 2-3 years+. The calibration variances at different level thresholds is an interesting case and will require some indepth scruitiny. I would start with the level control itself and work backwards, perhaps its some calibration presets that have been turned or some caps performing below par, in the bargain. Looking forward to hearing about the diagnosis and remedies.

 

[NakTech]

Hello Friends,
Thank you so much for your support and responses. Adding some more photos.
Before cleaning
https://imageshack.com/i/ncx0lvj
https://imageshack.com/i/mrkjsij

Flywheel rust
https://imageshack.com/i/nsscoej

After some sanding with very fine emery paper the rust was removed. There is discoloration but the rust stopped leaving any mark on the emery paper and surface is now smooth and free of uneven rust formation.
https://imageshack.com/i/mv19v1j

Cleaning and putting the transport back together.
https://imageshack.com/i/mvhp3vrj
https://imageshack.com/i/nr4onsj
https://imageshack.com/i/mu0fzaj
https://imageshack.com/i/nsnl21j
https://imageshack.com/i/mrccm9wj
https://imageshack.com/i/mvm04h2j

The tension arm felt was replaced with a small piece of felt cut out of a polishing wheel I had. This was the closest material I could find to the original. It works perfectly. Note that the felt has to be cut in such a way that it should only touch the bottom part of the supply reel hub.

https://imageshack.com/i/mv19d2j

Restoring the rollers took a lot of time. I washed them first in water. Then too, the brown color and the glaze remained. So the rolled was assembled back on to its arm. Then I got super fine abrasive sheet (2000 grit) from polishing shop. Kept this sheet flat on the table and rolled the pinch roller over the paper while pressing the roller down. If you attempt this make sure that the roller rotates freely even when it is pressed. The movement should be gentle straight lines back and forth. As the roller is rolling over the paper, it doesn't remove much of rubber. But this is the only way because, if the paper rubs against stationary roller, it will go out of shape. Rolling will remove the surface non-uniformity and dirt beautifully. So after a lot of rolling I got it very clean. All the lines and cracks disappeared and the surface became soft as new. You have to do it slowly and patiently. This is what I have got.

https://imageshack.com/i/nrmoxgj
https://imageshack.com/i/mrj8avaj

The next step is to adjust the guide heights. For doing this in the proper way, an M-300 gauge or an exact replica WHS-300 (what I have is required).

https://imageshack.com/i/nsyre2j
https://imageshack.com/i/nma1yyj
https://imageshack.com/i/nmu9xkj

The purpose of this alignment is to have the guides and the rollers in the exact position where the tape would be when they travel across the head. Improper alignment will cause miss tracking and in worse cases, the tape edges will be chewed.

Once this is done, it is time to mount the head block in place and adjust PB and Rec head tilt. The tilt is to make sure that the head surface is exactly parallel to the tape surface when it comes in contact with the tape. This is required for even pressure of the tape on the head in both L and R channels.
Miss alignment of tilt can cause unequal freq response between L and R, Tape skewing and non uniform head wear in the long run. The tilt is also called as Zenith.
The top screw in the head block adjusts tilt. The bottom one is used for track height. The height is only approximate setting for now because it require the height alignment tape and we need to monitor the audio while doing it.

Once the tilt is adjusted, the center pulley has to be inserted so that while aligning the height later, the tilt setting won't go wrong.

https://imageshack.com/i/nmho0vj
https://imageshack.com/i/mrqzpsj

The next thing to do is the head stroke setting. This determine how much the head penetrate into the cassette during play and record. This is a standard form DIN and Philips. The gauge is precision machined to these standards.

https://imageshack.com/i/muhl1uj
https://imageshack.com/i/nskagmj

It is almost time to put the work so far to test. So only the power section of the transport is connected. The leaf switch which was on the door holder assy has to be closed by putting a light rubber band around it. Also the ground connection has to be given to the cam drive motor with a wire(I made one with clips on both sides). This connection is required now because the transport is kept outside.

The first thing is to ensure that the tape path is correct and the restored rollers are behaving properly. I have a DIY cut open tape, which is a wild imitation of the Nak mirror tape. That one is loaded and I set it to play. :yahoo::yahoo::yahoo:
The tape runs rock steady.
https://imageshack.com/i/n121g5j

Now I can confidently use my alignment tapes for the remaining work.

But before that I need to do some work I had kept pending. First to fix the broken post in the right bottom. A 15mm M3 machine screw, a 10mm brass spacer and a washer is used for this job.

https://imageshack.com/i/n685vcaj
https://imageshack.com/i/nlpf81j

The next is to fix the soft eject. The feel of the eject was unlike my other naks. On inspection I found that rubber piston inside the vacuum pipe was torn. Someone who serviced this before was brut enough to pull it out without pressing the eject lever. This is the only way it can get torn. Because it is full of grease, no glue will stick on it. I need to wash it thoroughly first.
I am out of energy today. So I will continue this tomorrow.....
Thanks for reading...

 

[balajeem]

though this is not related to Nakamichi 582Z, this is about Nakamichi alias Rahul - It's a pleasure to deal with this youngster, got a tuner from him recently, it's in immaculate condition - very professional in the dealing.

sorry to have taken off the topic a bit.

 

[NakTech]

Going further ...

The eject piston was fixed with a rubber part removed from a 2mL syringe. This is very crude, but it works. I would like to have the original replacement for this. If anyone has a part machine with classic transport and can spare this part, please PM me. Until I get one, the DIY solution will work.

https://imageshack.com/i/mssy0xj

Now its time to put the rest of the parts together.

https://imageshack.com/i/n1ludnj
https://imageshack.com/i/nl4ydlj
https://imageshack.com/i/npwmttj

Once the transport was back in the chassis, I tool the service manual and decided to go in the right order. First the head height, then the azimuth. I did not use the 1K intra track tape for height, but the tapes from Louis (from Spain). I will use the other tapes only after one round of calibration is completed with these.

The next thing to do was to set the speed with the 3KHz tape. But I found it tough. In the closest I got is with the frequency varying between 2994Hz to 3012 Hz. This is due to flutter (Bad capstan belt - it is very hard and thin. The new belts may take more than a month to come).

https://imageshack.com/i/nrd64qj

The next step...to calibrate the internal tone Osc..

I found that the levels were only slightly off in 400Hz (83mV instead of 90mV), but the 15KHz was a lot more off (15mV instead of 9mV). I corrected both, but this unit don't have the L/R balance setting in the tone OSC like in the dragon. But both channels were very close (only 1 mV difference) So I left it as such.

Now I was sure that the difference I saw in the first test is caused by some problem in metering section. In the manual also the next step was to check the meters.
Here is my setup.

https://imageshack.com/i/mrosgwj

At this stage something really funny happened. As mentioned in the manual I fed 400Hz from T100 and adjusted VR102. But nothing happened. I was very confused and tried the next set VR103. Then also nothing happened. I started wondering if these presets are not doing what they are supposed to do what exactly are they doing???

After some time I figured it out. There are 2 numbers of VR102 on the board. VR103 is also written as 102. The VR104 is written as 103. There rest were correct. I'm still very suspicious about this. I have reported this to my Guru to confirm this. But this revelation put be right back on track. In no time external tone, internal 400 and 15K levels were calibrated. This explains the difference we have noticed in the beginning. The previous technician also would have got it confused and he could not get it right.

Needless to say, with the meters going wrong, the rest of the calibration also would be off.

https://imageshack.com/i/ns9z7cj
https://imageshack.com/i/nmy3paj
https://imageshack.com/i/npwlixj
https://imageshack.com/i/ncnf7zj

Once the meters were done the 400Hz Playback level also was set easily. At this stage I could not resist the urge to put some music and play. It played beautifully. But there are issues. One is the flutter. It is noticeable in the HF. I will post some videos in you tube. But I am unsure how it will translate when you listen to it due to the compression.

https://www.youtube.com/watch?v=hECefNkhCmA

The other thing I have noticed is the transients in the meter. They actually don't seem to exist in the audio. This needs to be investigated. Anybody has seen this before? But do not try to relate the transient problem with the youtube video. The video seems non sync. The meter is in time when it actually play here. I think the video frame rate or something like that messed it up. Please ignore the video and listen to the sound part alone. Actually the HF sustain and fertility is lacking in this one. The CR3 and the DR3 play (Both belt drives) it properly.

When the level go very low, Dolby is pumping the audio too much. This is miss tracking. May be this is happening continuously, but not audible when the level is more. This pumping effect doesn't happen in any of my other naks.

Without resolving the PB, it is not possible to calibrate the Rec section. So this is take a long time. I have not yet ordered the belts.

 

[Selvin]

in the video the deck sounding so nice. Which album. Nice vocal who is the artist?

 

[NakTech]

@ Selvin, Glad to know that someone is listening. This song is called "Could this be love" by a Female Group from the early 90's called "Seduction". It is from an Album called "Nothing matters without Love". I have this album, but what you are hearing is from a Thomsun compilation tape called "Find a way to my heart"
It would have been an amazing gift to present to loved ones. But alas...now only mp3s to be seen everywhere. Girlfriends would not have tape decks to listen to mix tapes. Ironies of Kaliyuga....What else to say.


Going back to the deck...

The flutter part is very difficult to notice unless you have heard the song without it. Ignorance is a bliss in this case. Now that I know it is there, I won't be satisfied till I eliminate it.

In the meanwhile listen to Lead me on - Eric Clapton. Amazing feel. It is recorded from the line out via my DSLR's mic input. So I don't know if the response is as good as the previous one. But this time the video is good and the meters are in sync. You may notice the sudden jumps in the meter. It crosses +7 sometimes. But there is nothing in audio that loud. I am unsure if the 582Z meter response itself is like that or this unit is extra sensitive to HF transients. As I have mentioned earlier, at low levels there is pumping in the dolby part. I suspect if this has something to do with the strange meter response too.

https://www.youtube.com/watch?v=k2JPdySF4YY

It would be great if someone who has/had a 582Z could confirm this.

 

[NakTech]

Waiting for the belts from Marrs. In the mean while doing some beautification. The lamps in the transport had irregular brightness. Only 2 of them were the original 12V types. The rest were low voltage ones with added series resistor for current limiting. due to aging these low voltage types had their leads almost burnt out. With the slightest touch, the bulb got separated from the leads. I replaced all of them with white LEDs with series resistors. 5mm LEDs fit precisely in place and the caps on the buttons contain them well. The lights are looking very good now. It takes less current than the lamps and doesn't heat at all.
Yet to figure out the dolby part