Nakamichi 700
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OscarEmmy
VHFSE Originator/Blogger
Here's my old thread on the 700 II - I imagine the 700 is very similar.
http://www.audiokarma.org/forums/showthread.php?t=149902
http://www.audiokarma.org/forums/showthread.php?t=149902
I've always wanted a 700 
Seems to me that everything I've read about them is that they are a real bear to work on!
Hopefully others with some experience will chime in. Bet Fred Longworth would know...
That said, if it were me, I sure would put forth my best effort into getting it back into top shape
Seems to me that everything I've read about them is that they are a real bear to work on!
Hopefully others with some experience will chime in. Bet Fred Longworth would know...
That said, if it were me, I sure would put forth my best effort into getting it back into top shape
Fred Longworth
audio fanatic
The 700 is moving into the realm where lack of replacement parts may put up serious obstacles to a full restoration. That said, here's what you should do to your 700:
(1) Treat all user-operated switches and controls with Caig DeoxIT. Treat all internal switches with DeoxIT as well. Also treat plug-in edge connectors.
(2) Lube motor(s) with Teflon-based lubricant. Lube capstan with machine oil.
(3) Replace all belts.
(4) At the very least, resurface all tires and treat with rubber rejuvenator. If a tire has a concave face from wear and shrinkage, replace it.
(5) Thoroughly clean head assembly and treat pinch roller with rubber rejuvenator.
(6) Check for warped/cracked plastic parts in tape drive. Warped/cracked plastic parts can be the largest pain in the fanny as far as a full restoration.
Hope this is useful.
Fred
(1) Treat all user-operated switches and controls with Caig DeoxIT. Treat all internal switches with DeoxIT as well. Also treat plug-in edge connectors.
(2) Lube motor(s) with Teflon-based lubricant. Lube capstan with machine oil.
(3) Replace all belts.
(4) At the very least, resurface all tires and treat with rubber rejuvenator. If a tire has a concave face from wear and shrinkage, replace it.
(5) Thoroughly clean head assembly and treat pinch roller with rubber rejuvenator.
(6) Check for warped/cracked plastic parts in tape drive. Warped/cracked plastic parts can be the largest pain in the fanny as far as a full restoration.
Hope this is useful.
Fred
OscarEmmy
VHFSE Originator/Blogger
And make sure the memory switch isn't depressed (stops the tape at 0000 setting even if that's half way through the tape - this can easily catch you out!)
Buzz may also be a dirty contact inside - if you open it up, there is a large PCB inside that is a push fit into a linear socket...if there is oxidation or some other break in contact, one channel can drop out and generate a buzz and a flickering VU meter (exactly what mine did before a good cleaning). Now it operates perfectly. You can tell if this is the issue by pushing gently on the edge of the board during record or playback and seeing if the fault disappears. That was how I found the problem, anyway.
Nakdoc
nakamichi spoken here
As a playback deck they are fabulous. As a recorder, it doesn't take much to get better performance. I love the deck for its history and substantial construction. I repaired one last year that needed new belts. Belt kits on eBay from Marrs communications will solve that problem. All the plug in board edge connectors will need retensioning to cure the buzz.
Hi,
Generally not but it totally depends on how much it has been used. Nak heads are known for long life. I have never seen a Nak with worn out heads but they probably exist. Buyer beware. Ping the seller and ask.
Sparky
Mr. Pleasant
New Member
Hi, hope someone can answer my dumb question.
I bought a Nakamichi 700 from eBay that was advertised as 100% functional. When it arrived, it had two problems: first, one channel would drop out and hum during playback, and that channel's VU meter would only go about halfway to its peak reading. I removed the back panel, and the circuit board beneath the flywheel assembly was super dusty, so I sprayed it clean. I also disengaged and cleaned the edge connecters, as suggested in this thread. When I reinserted the edge connecters and played a cassette, both channels played back perfectly at full volume, and both VU meters worked perfectly. So I fixed that problem.
The second problem is that, once I insert a cassette and it starts playing, the deck locks into "play" mode and won't stop. Hitting "stop" or "pause" repeatedly will sometimes stop playback for a split second, but not long enough to eject the cassette. The only way to eject is to power off. I'm asssumimg I need to remove the silver front panel and clean/DeOx the play/stop/ff/rewind switches? Or does this sound like some sort of microprocessor/logic board failure? I'd appreciate any tips on how to fix this switch problem.
Finally, I'm assuming that removing the silver front panel is the only way to access the heads and pinch roller and capstan for cleaning?
I bought a Nakamichi 700 from eBay that was advertised as 100% functional. When it arrived, it had two problems: first, one channel would drop out and hum during playback, and that channel's VU meter would only go about halfway to its peak reading. I removed the back panel, and the circuit board beneath the flywheel assembly was super dusty, so I sprayed it clean. I also disengaged and cleaned the edge connecters, as suggested in this thread. When I reinserted the edge connecters and played a cassette, both channels played back perfectly at full volume, and both VU meters worked perfectly. So I fixed that problem.
The second problem is that, once I insert a cassette and it starts playing, the deck locks into "play" mode and won't stop. Hitting "stop" or "pause" repeatedly will sometimes stop playback for a split second, but not long enough to eject the cassette. The only way to eject is to power off. I'm asssumimg I need to remove the silver front panel and clean/DeOx the play/stop/ff/rewind switches? Or does this sound like some sort of microprocessor/logic board failure? I'd appreciate any tips on how to fix this switch problem.
Finally, I'm assuming that removing the silver front panel is the only way to access the heads and pinch roller and capstan for cleaning?
cleverdick
Active Member
Don't tackle this without the service manual.
Tarnished edge connectors are a common problem. The transport switches are touch-sensitive, so there are no switch contacts per se to clean.
The permanent play condition is likely due to a failed electrolytic somewhere. Look particularly at the shut-off sensor and detector circuits.
Potentially a very good machine, but doesn't erase high-coercivity tapes at LF too well, due to its very small erase head.
Tarnished edge connectors are a common problem. The transport switches are touch-sensitive, so there are no switch contacts per se to clean.
The permanent play condition is likely due to a failed electrolytic somewhere. Look particularly at the shut-off sensor and detector circuits.
Potentially a very good machine, but doesn't erase high-coercivity tapes at LF too well, due to its very small erase head.
Mr. Pleasant
New Member
Thanks for the reply. Looking inside the machine you can see that the original capacitors have never been replaced, and I was afraid that, as with any 40+ year old piece of equipment, they will have to be replaced. I'll get a service manual and see what I can figure out.
This is my favourite tape deck. It sounds very natural and uncoloured. I've had to fix 2 of them. In case anyone reads this in the future here are some repair tips.
1. Loose connectors with circuit boards. This is nortorious with the 600 & 700, 700II. It will cause hum, weird behaviours, sound in one channel only, motor working intermittently. All sorts of electrical gremlins. To fix i used green paint tape. Double them up cut into strips. Tape them to the backside of the connector to give it a snug fit when it slides into the harness.
2. To clean rollers and head just pull out the tape cover in front of the machine. You dont have to disassemble anything. Close the tape cover frame and hit play or rw ff. You can now access the heads and rollers.
3. You can clean the play motor quite easily. The hardest part is removing the motor but because im super smart i didn't do that lol. Find the screw along the body casing in the motor. My screw was facing towards the side of the machine. I drilled a hole on the metal frame so i can get a screw driver through to loosen the screw. Worked like a charm. Once off, you can remove the back cover if the motor and everything will silde out. There's a grey plastic cover for the wires. Just remove it and disassemble the motor. It is held together with plastic clips. I broke one and had to use glue to hold the cap in place so be careful. Clean the contact surface and spindle with alcohol. Oil the metal surfaces that have contact points with the shell. If this motor gets stuck the play will not engage and it will make grinding noises. Try rotating the belt to hear if it squeeks first but always good to clean it out.
4. If the ff or rw is weak you can increase the tension. Remove the 4 screws at the corner of the woodbox. Remove the 2 screws that holds the plastic cover next to rca jack. Now lift the deck out of the box. Behind the two big round metal wheel pulleys are the plastic pulleys for the play and rewind. Two little screws hold them to the spindle. It is better to remove the metal pulleys first. Remove the two screws holding the metal bar to the pulley. Note which direction is up with marker. Note which pulley goes in first when you put it back. Two springs are going to fall out. Now loosen the 2 tiny screws on the play pulley. Then push it in towards the front of the deck a couple of millimeters to increase the tension. Do the same to the rewind pulley. Put the metal pulleys back.
That's all for now.
Cheers
1. Loose connectors with circuit boards. This is nortorious with the 600 & 700, 700II. It will cause hum, weird behaviours, sound in one channel only, motor working intermittently. All sorts of electrical gremlins. To fix i used green paint tape. Double them up cut into strips. Tape them to the backside of the connector to give it a snug fit when it slides into the harness.
2. To clean rollers and head just pull out the tape cover in front of the machine. You dont have to disassemble anything. Close the tape cover frame and hit play or rw ff. You can now access the heads and rollers.
3. You can clean the play motor quite easily. The hardest part is removing the motor but because im super smart i didn't do that lol. Find the screw along the body casing in the motor. My screw was facing towards the side of the machine. I drilled a hole on the metal frame so i can get a screw driver through to loosen the screw. Worked like a charm. Once off, you can remove the back cover if the motor and everything will silde out. There's a grey plastic cover for the wires. Just remove it and disassemble the motor. It is held together with plastic clips. I broke one and had to use glue to hold the cap in place so be careful. Clean the contact surface and spindle with alcohol. Oil the metal surfaces that have contact points with the shell. If this motor gets stuck the play will not engage and it will make grinding noises. Try rotating the belt to hear if it squeeks first but always good to clean it out.
4. If the ff or rw is weak you can increase the tension. Remove the 4 screws at the corner of the woodbox. Remove the 2 screws that holds the plastic cover next to rca jack. Now lift the deck out of the box. Behind the two big round metal wheel pulleys are the plastic pulleys for the play and rewind. Two little screws hold them to the spindle. It is better to remove the metal pulleys first. Remove the two screws holding the metal bar to the pulley. Note which direction is up with marker. Note which pulley goes in first when you put it back. Two springs are going to fall out. Now loosen the 2 tiny screws on the play pulley. Then push it in towards the front of the deck a couple of millimeters to increase the tension. Do the same to the rewind pulley. Put the metal pulleys back.
That's all for now.
Cheers
Last edited:
MRL_Audio
RIP 2022
Thanks for taking time to post that. As an owner of 2 700's I appreciate all the help and guidance I can get.
