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Stymied by Nak 480

D

drumbum

Super Member
A couple years back,....I took my working Nakamichi 480 off the shelf after a short hiatus of non use and discovered the idler tire expiration date had arrived.

Been there many times on other decks and ordered a tire from sleazebay.

Tire in hand, and thinking about brittle nylon,....I opt to sneak the tire in w/out removing transport, by loosening three top screws and carefully wedging open.....

Successfully removed and replaced idler mech and tightened everything back up.

NO worky! Set aside till now.

Assuming I somehow got something out of time, I pulled the transport yesterday evening and cleaned and lubed the function cam and various other bits.

Same as before, I only have rewind function. No play, FFW ect. There are also no illumination of buttons when pressed. The head block does rise when turning the cam gear by fingernail.

Does this still sound like a timing issue or the typical for me, a coincidental simultaneous electrical component failure?

Point me in the right direction please.
 
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Your timing is right but the deck doesn't know it because you didn't align the cam pot with the cam. The cam pot(potentiometer) tells the electronics where the cam is, otherwise the deck is blind. When you split the transport you will see a pot with a fork. That fork straddles a flat blade on the cam. When you snap the transport back together these 2 need to be aligned. I think everyone has forgot this small detail at least once so don't feel bad.classic nak pot_zpsintqeswq.jpg
 
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zedex said:
Your timing is right but the deck doesn't know it because you didn't align the cam pot with the cam. The cam pot(potentiometer) tells the electronics where the cam is, otherwise the deck is blind. When you split the transport you will see a pot with a fork. That fork straddles a flat blade on the cam. When you snap the transport back together these 2 need to be aligned. I think everyone has forgot this small detail at least once so don't feel bad.View attachment 3351416
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No, I did that already. lubed it too.

I am missing something.
 
From your description of the problem, what @zedex suggested sounds like the likely culprit so I would go back in and check that cam again. Same thing happened to me working on my ZX-7.....identical symptoms, and I had omitted making sure everything was lined up properly when I put it back together and the fork was indeed not straddling that flat blade. Once I got it all lined up, everything worked like a charm. If you check and it is all aligned as it should be, then take pictures and post them here for us to see what else might be going on. Here's the image that helped me see most clearly how things should line up (thanks @zcarnut):

Cam gear and pot notch.jpg

And yeah, it's a PIA but I applaud your actually pulling the transport out and taking the top plate off entirely, checking your work on the idler tire, and making sure you have put everything back together as it should be. There is that small lever switch on one of the corners that prevents you from recording over a tape that has the tabs removed and if that isn't back in correctly, with the lever in the proper position in relation to the actuator arm, you're not going to get it to work properly either as I recall.....

This video is a bit long and tedious, but I found it ultimately quite helpful, especially when I was trying to see how things looked before I pulled mine apart:


Please do let us know what you find as it will be very useful for others who have to do this job to have all the information possible to avoid making errors, and good luck amigo!

PS - Oh, and there's those small wires that go to the drive motor.....one of mine had broken and I had to solder it back on. That was one of the reasons nothing wanted to work but even after fixing that, with the blade and fork not lined up right it still did not work so I was really frustrated, thinking I'd found the problem because of that broken wire.....
 
Be careful with screws when reassemble transport. All screws should be rotated left first to catch old thread in plastic pillars. You do not want to damage those old plastic.
P.S. And fork misalignment is common mistake when reassemble transport for the first time. I believe we all did this :)
 
Fishead said:
From your description of the problem, what @zedex suggested sounds like the likely culprit so I would go back in and check that cam again. Same thing happened to me working on my ZX-7.....identical symptoms, and I had omitted making sure everything was lined up properly when I put it back together and the fork was indeed not straddling that flat blade. Once I got it all lined up, everything worked like a charm. If you check and it is all aligned as it should be, then take pictures and post them here for us to see what else might be going on. Here's the image that helped me see most clearly how things should line up (thanks @zcarnut):

View attachment 3351811

And yeah, it's a PIA but I applaud your actually pulling the transport out and taking the top plate off entirely, checking your work on the idler tire, and making sure you have put everything back together as it should be. There is that small lever switch on one of the corners that prevents you from recording over a tape that has the tabs removed and if that isn't back in correctly, with the lever in the proper position in relation to the actuator arm, you're not going to get it to work properly either as I recall.....

This video is a bit long and tedious, but I found it ultimately quite helpful, especially when I was trying to see how things looked before I pulled mine apart:


Please do let us know what you find as it will be very useful for others who have to do this job to have all the information possible to avoid making errors, and good luck amigo!

PS - Oh, and there's those small wires that go to the drive motor.....one of mine had broken and I had to solder it back on. That was one of the reasons nothing wanted to work but even after fixing that, with the blade and fork not lined up right it still did not work so I was really frustrated, thinking I'd found the problem because of that broken wire.....
Click to expand...
Yeah,....like I said,.....I did that already.

I honestly think it didn't get out of time the first go around when I loosened the 3 top screws on the long plate with the dogleg,....just enough to get the idler mech out and back in.
....but again the notch was and is aligned correctly on the function gear.

Please quote me so I know I have gotten a response.

I will watch the zx vid.

Thanks.
 
radiokom said:
Be careful with screws when reassemble transport. All screws should be rotated left first to catch old thread in plastic pillars. You do not want to damage those old plastic.
P.S. And fork misalignment is common mistake when reassemble transport for the first time. I believe we all did this :)
Click to expand...
Yeppers,....well aware of the aged plastics and finding threads.

although I did somehow break the cable clip at the record/play switch after I had previously repaired.

Speaking of that switch,...... there is a spring wire (straight w/ an L bend at the end) that was wedged down at the r/p switch that is fastened at the other end under a screw at one of the aluminum plates. I don't remember this wire from the last time I was in the deck. I the wire a ground?
 
Hi @drumbum, any luck at getting things sorted properly? If I remember correctly, that spring acts as a return mechanism for the switch lever. Don't quote me on that though as I'm not 100% sure and we could be talking about different things here....

PS - just checked......WRONG! I was referring to something they call the "Record Protector" so not even close. Sorry. Do you have the service manual for your deck? If not, I can get you one.....
 
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Fishead said:
Hi @drumbum, any luck at getting things sorted properly? If I remember correctly, that spring acts as a return mechanism for the switch lever. Don't quote me on that though as I'm not 100% sure and we could be talking about different things here....
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Not sorted yet. Going to pull apart again and clean the position pot.

Where should the pot be positioned before aligning with cam gear? assuming it is not 360* range.

Re-repaired the r/p switch cable connection with a little plastic welding.
The wire I referenced is a straight wire (spring steel with an L bend at the end) that terminates at the aluminum plate,....not the coil spring that returns the r/p switch.

I was hoping someone would say something along the line of "you just need to momentarily connect a jumper from pin 123 to terminal qrt on conniption motor to reset"

I still don't understand how it screwed up just from gaining a little clearance for idler mech....smh. For the distance moved it doesn't seem possible things got out of time,.....but this event transpired a couple years back and I'm not sure I would remember fine details short of a fire.

lol
 
@drumbum, look at the image in post#4, that's about as much as I can help you with regarding the proper positions of things. The "fork," or "notch" needs to fit directly over that blade, which I'm sure you're getting tired of hearing because you mentioned several times that you checked that and it did. I can't see how anything could be out of whack if those two pieces engage properly because I believe they can only fit together in one position of the wheel and the arm that has that notch/fork. I did mine according to that picture and everything started working properly. Before, I had identical problems to what you described in your first post. Wish I could help more sir.....

Do you have/need the service manual?
 
Fishead said:
@drumbum, look at the image in post#4, that's about as much as I can help you with regarding the proper positions of things. The "fork," or "notch" needs to fit directly over that blade, which I'm sure you're getting tired of hearing because you mentioned several times that you checked that and it did. I can't see how anything could be out of whack if those two pieces engage properly because I believe they can only fit together in one position of the wheel and the arm that has that notch/fork. I did mine according to that picture and everything started working properly. Before, I had identical problems to what you described in your first post. Wish I could help more sir.....

Do you have/need the service manual?
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Yes, I have the service manual......and I absolutely HATE PDF's.
Just got done taking the transport back apart and back together.

Control pot cleaned/lubed with F5.


Cam wheel "S" (for stop position) aligned with plastic indicator,.... control motor fork aligned with vertical portion of cam gear, like every time thus far.

Properly lubed, belts cleaned, no wires pinched, broken or disconnected via bad solder joint.

Have yet to reinstall transport into chassis again.

The service manual points to disconnecting the position motor and resetting cam gear manually.

I predict I will only have rewind and zero/dead function of play and FFD as I have seen nothing that should cause the issue. I do have voltage at the P switch (around 24v).

I need to get it functioning again before I give it fresh belts.
This deck has been aligned and was working fine before tire started slipping.

I'm down to 19 decks, so pretty desperate to get this one back working.
 
I'm starting to feel as insane as a voter,....doing the same thing over and over and expecting a different outcome.

I don't want to take this problem over to the anime ridden site.
 
Maybe you did something to the eject microswitch. There is a series of naks and i cant remember which, that if the stop lamp is burned out. deck wont work. .
 
drumbum said:
There is a lamp that illuminates under the tape counter area.
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It is hard to guide by distance. Nakamichi classic transport needs some knowledge to work with it. If you did something wrong you can fry some fusible resistors, for example. It means, when you measure voltage you can get right value, but under load it does not work (at least I fried one long time ago). And so on.
 
radiokom said:
It is hard to guide by distance. Nakamichi classic transport needs some knowledge to work with it. If you did something wrong you can fry some fusible resistors, for example. It means, when you measure voltage you can get right value, but under load it does not work (at least I fried one long time ago). And so on.
Click to expand...
Hard to convey malfunctions at a distance too. Showing pics of a non working transport rarely helps. I wonder if a vid of it doing nothing would be better.....lol
How can I have rewind,....but nothing else?

This is why I suspect an electrical issue that appeared at the same time I replaced the tire. I am THAT lucky.
 
The 480 doesn't have any well illumination. The only lamp that can barely be seen near the well is for the tape motion sensing lamp on the right side of the transport. And the 480 series is not affected by transport function lamps being burned out. I could be wrong on this one but I don't believe the 480 series mutes when a lamp goes out.
 
nakmandan said:
The 480 doesn't have any well illumination. The only lamp that can barely be seen near the well is for the tape motion sensing lamp on the right side of the transport. And the 480 series is not affected by transport function lamps being burned out. I could be wrong on this one but I don't believe the 480 series mutes when a lamp goes out.
Click to expand...

If I remember right my fried fusible resistor was in function lamp circuit. I measured voltage and got correct voltage. Lamp was OK too, but no light. It was because of fried fusible resistor. But I do not remember it was in 480 or LX-3 because of shortcut of well illumination lamp wires (wires shorted when well was closed) or both.
 
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