Nakamichi TD-500 and TD-700 "worm gear" part

[zedex]

Those 3 wires with the fuses are positive. You might as well cut off that 4 prong plug unless you have the other half that plugs into it.There is no ground wire. Ground goes from battery negative to the rear ground lug on the deck. I believe the other wire, looks like tan in your picture is probably for power antenna .
When you power up your deck, insert tape. The deck should FF, rew, then play to take up any possible tape slack. Thats how the td 700 works anyways.

I cant tell by your picture if the teeth are damaged though. If some are missing you have problems.

 

[brianjrealto]

I think this unit has had after market work done to it. The wires seem to be extended or something. I'm uncertain where I would want the wires to go from the battery to the harness. There are four prongs in the harness. Also, I think the teeth on that wheel are damaged as well. Here are some pics:

you need to get the wiring straghtened out. the new fuses holders are ok. but here is a link to get a free Nakamichi owners manual for this unit. It looks like the TD-500 seeing that there is only one pinch roller. the black square box in the wirings is the noise suppresser for engine noise.

Here's the link that should help. just sign up for free and you can downlaod the PDF of the original Nak owners manual with a wiring diagran. That should help alot..

http://www.hifiengine.com/library/nakamichi/td-500.shtml

I was correct- the yellow/red are the hot leads to tie together and run to the positive battery terminal. a seperate wire for the negative lead can connect to any screw on the back of the unit and run that to the negative of the battery. although your unit previously had different colored wires used for leads from the original wires. you can still see the originals and work from there to connect it correctly.

the worm gear that breaks is the small white gear connected to the black wheel gear in the photos you took. from the angle of the photos, I can't tell if any teeth are broken off of the white worm gear.

BUT, the unit can still work and play tapes even if a tooth or two are broken off from the gear.

Nakdoc is another member here on AK and he repairs these car stereo units and other Nak home decks. he knows his stuff. He told me that the worm gear can still work if a tooth or two are broken. but when 3 teeth are broken, that's when it won't function and needs replacement.

If I were you, I would still do a test on the unit for playing tapes after getting the wiring diagram and connecting to the car battery. at least you will know if you can possibly have a little bit of time in analog heaven and hear how truly awesome these car stereos are. If it plays tapes now then breaks down the road, you at least know how good they can sound in a good car stereo setup. You will then want to get it fixed and be willing to wait for a gear like the rest of us!

If it deosn't work...I would recommend an Alpine cassette deck from the early 90's. Look for the one's with a HLTAC tape head that have the "6 cube" lighted preset buttons. the later 90's models sound aweful. I had an Alpine, but can't remember the model number. I got it for about $60 on Ebay.

Here is a listing as an example of the face plate style too look for with the "6 cube" lighted buttons on an alpine you can usally find cheap.

http://www.ebay.com/itm/ALPINE-7280...=&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

The Nak 500 sounds light years better than any alpine. thought, Alpine makes solid units that play tapes OK. The Alpine was too brash IMHO. But will get you through until the Nak can get up and running.

 

[Oliade677]

Thanks for all of the help. I'll snip the harness off and attempt to supply power tonight. The housing has some rust, but the interior looks pretty solid. I don't see any water damage or corrosion inside. Will update later tonight once I've had some time to fiddle with it. I also have a 10 disc changer that I'd like to determine the functionality of.

 

[Oliade677]

Ok, tested it out tonight. It powers on and runs through some cycle over and over. I gotta assume the tape-deck portion is not functional, as it sounds like it is stuck. I'm hesitant to put a cassette in as I don't want it to jam. I did notice that only the top portion of the tape deck door is visible. I don't know if the bottom can tuck away or what, but I don't see it.

I intertwined all of the cables with fuses and connected them to the positive of my battery. There was a really thick cable jutting out of the bolt on the back of the deck, so I connected the negative to that. Was pretty excited to see it power on, but I'm not surprised that it is having issues. It's pretty rough!

 

[Oliade677]

Well, scratch that. I placed a tape into the deck while it was disconnected. I can't get it to eject, but it does play, rewind, and fast forward. There is a fairly loud hum coming from the deck, but the functions seem to work fine. Gotta figure out what's wrong with the load/eject function next.

 

[brianjrealto]

Well, scratch that. I placed a tape into the deck while it was disconnected. I can't get it to eject, but it does play, rewind, and fast forward. There is a fairly loud hum coming from the deck, but the functions seem to work fine. Gotta figure out what's wrong with the load/eject function next.

So, when you connected to the battery terminals and fired it up, the tape loaded played, RW and FF....but wouldn't eject?

If this is the case, you have either bad belts, broken gear or both.

even though the tape is stuck insde, remove the top cover of the unit again and get a better look at the worm gear. In your original post with pictures, the first picture you posted is a close up of area to look at. From the photo, the worm gear is to the right of the black wheel gear. It's what moves the black wheel gear. You can't miss it. It's just that the worm gear is perpendicular to the wheel gear and very small. From the photo, I can barely see some teeth.

Not sure what the HUM noise is about. Maybe it's the motor spinning, but with bad belts.

I think your worm gear may be in good shape, but you probably just have very old belts. These units have about 3 rubber drive belts inside, if memory serves me right.

Also, these Nak car stereo units are more than 20 years old from production. If yours was stored for a long period of time, belts become no good very fast when they just sit. The worst thing for vintage car stereo cassette players of any brand is to sit around for years without use. The belts dry out fast and stretch easily from sitting.

Look inside again, visually inspect the worm gear very good and let all of us know. If your visual inspection of the gear has all the teeth, you've probably just got bad belts.

Do a search on AudioKarma for a NakDoc and contact him... He repairs these units for alot of us and is very helpful. If all you needs is belts, your cost from him would be about $100 or so for all new belts.

 

[Oliade677]

Before I inserted the tape, I was able to move the loading mechanism freely. It felt pretty loose, so I loaded the cassette manually while the unit was disconnected. The play functions are working, but I can't get the cassette to eject through either the eject/load mechanism or manually. It looks like there is an arm holding the cassette in place.

 

[brianjrealto]

Before I inserted the tape, I was able to move the loading mechanism freely. It felt pretty loose, so I loaded the cassette manually while the unit was disconnected. The play functions are working, but I can't get the cassette to eject through either the eject/load mechanism or manually. It looks like there is an arm holding the cassette in place.

I would have rather you tried to load it when powered up. Not sure if the tape will eject now.

Again, remove the top cover and inspect the worm gear. if it won't eject, that may be the problem. Not for sure though until we get better feedback on how the gear teeth appear...

 

[mossfred]

These car machines from Nak are very special, akin to having a CR7 in your car, no other brand comes anywhere close at any price and they deserve to be saved!!
Nakdoc should be able to help you out with it.
Fred

 

[brianjrealto]

Good News to those reading this thread having problems with their TD-500 or TD-700 car stereos...

NakDoc has found someone to make new worm gears for these units, bonus is that the new gears are made of brass instead of plastic...

He tested one of the new gears in a unit and it seems to work great..

Mine are in line for new gears that he has bought to get all our Nak's up and running...

I'll post when I get my units back to let everyone know of the results!!

 

[jdurbin1]

sweet!

John