As best I can remember the TC-630 has only one belt that goes to the motor pulley and one belt that goes from one of the reel tables to the counter. The rest is done by rubber drive wheels.

Your problem is most certainly the rubber drive wheel that drives the capstain as to why it goes real slow/stops at the 1 7/8 ips speed. Also if it is running too fast the motor run capacitor will need to be replaced and must be one of the exact same value as the one installed in order to kep proper speed. If you have an older 8 track player with a 120 Vac motor it will more than likely have the proper value capacitor.

One I had did just that and I replaced the motor capacitor. Problem solved. I never did fix the rubber wheel issue as I did not know what to do then except tighten the spring some. This product should work on the rubber wheel if it has no cracks or flat spots on it

http://www.reelprosoundguys.com/RestoreKit.html

You will want to use that on all the rubber parts as well as to clean the rubber off the motor pulleys where the rubber drive wheels contact.

About a third of the capstan idler wheels on Sony reel-to-reels of that vintage can be chemically restored. The other two-thirds have either gone hard and brittle or soft and gooey, and rubber restorer or rubber rejuvenator will not cure this reliably.

In this case the idler must be rebuilt with fresh rubber. Terry's Rubber Rollers can do this for you.

In addition to the above, in a majority of cases, the pivot bearing that the idler wheel swings back and forth on (not the bearing it turns on) is full of gummed-up grease, and this prevents the idler from properly contacting both driving and driven surfaces. ZEP45 can loosen this grease, but the true fix involves removing as much as the old grease as possible, then then relubing with light grease or simply running unlubed.

Fred
repairing audio gear since the Pleistocene

That pivot bearing is indeed a real pain. I had one that was so "stuck" that I resorted to heat from a propane torch. Mind you, very gentle heat but it worked. Then, I used lacquer thinner to remove the gummed up grease.

The TC-630/630D really sounds great when working properly. But I have had MOST of them fail the motor run capacitor. Symptom is slow, labored running and a warm motor. Value is 1.5 uFD AC capacitor if I remember. Another issue is the heads. Since it has pressure pads, the heads are often worn a lot. So, if you find one without significant head wear, you have a winner...

Hello... a noob here... I'm glad I found this forum. I too have a TC630 with many of the problems discussed regarding motor/belts/drives etc. I have gone thru most of the maintainance proceedures including finding an appropriate drive belt and lubing all the pulleys. My capstain rotates very free and takes about a minute to stop rotating. All the speeds work, rewinds, and ff ok... UNLESS there is a tape in place. With a tape the unit plays for 8-10 seconds then gradually slows to a stop. I have noticed that motor pulley and area beneath it on the chassis is quite hot for the short period of time its been running.
From the responses on this post it appears that I have a motor cap problem.... Oh, I have not yet completely pulled the chassis from the enclosure. So I have not actually oiled/lubed the motor... Could that (among othed things )be a solution? And if I need to replace the cap(s) are they available and from where. Any info is appreciated. Thanks! Rulemaker

Yes the motor run capacitor is bad. Do not run the unit any more until that capacitor is replaced.

Thanks Tube Radio.... ok, where do I geta replacement? Thanks.

For sure, Tube is right, the motor run capacitor. I tried a quick search of Mouser and was not able to find something that is exactly like what Sony used back in 1969 when the TC-630 was manufactured.

I suspect you could use a film capacitor. They come in larger values today than back in the 60s. Since it needs an AC rating, I would at least double the voltage. So, I would think that a 630 VDC cap would work. But you want to stay close to the original value. I believe that the domestic model used a 1.5 uFD single section capacitor. I do think that the export model used a dual section with 1.5 and 2.0 uFD sections. I would wait for the engineers on this site to weigh in on the answer though if you have time.

I have been down this road several times and what you have described fits the diagnosis exactly. I would bet that the motor spins freely but a lubrication may be in order. The grease in these machines is over 40 years old and I a sure Sony didn't expect us to continue using the machines for this long time! (I believe the motor is oiled, not greased)

You may find a ceiling fan motor run cap at a store like Home Depot or other store. I have seen them but remember to use the correct value. You don't want to increase the value...

I agree there. One possible source of the correct capacitor is an 8 track player that has an AC motor in it.

On p. 957 of the current Mouser catalog is this--

5989-630V1.5-F

This is a miniaturized 1.5uF 630 VDC capacitor rated at 250 VAC. It's about 1-1/4" wide, 1.0" tall, and 3/4" thick. The maker is Cornell Dubilier. For 1.0, 1.8 or 2.2uF, simply change the suffix. It may not be able to handle the current, though. About $5.00.

A better choice may be this from p. 962, a device made by Epcos--

871-B32674D6155K

This is also 1.5uF. It is somewhat larger, but costs less because it is not miniaturized, like the one listed first. It has a higher current capacity. For 1.0uF change the suffix to 6105K, and for 2.2uF change it to 6225K. About $2.50.

Fred

Thanks for the info.... I am game to try to replace the cap. I have pulled the chassis and the motor reads 1.5 - 2.0 uF. I need to know where the blasted motor run cap is located on the chassis.... I have the service manual pdf, but have not tried to trace it down.... any help in identifying where the suspect cap is located is appreciated . Thanks!

( I am mechanically proficient, not electronically...!)

Hi again.... I just looked at the wiring diagram via the pdf, and if Im not mistaken the cap is referenced as "C654"... Is that correct, ........ anyone???? Thanks

Original motor run caps are usually located in metal cans (that look like small beer cans), and the cans are usually quite close to the motor(s) themselves. They are often mounted in brackets.

When replacing a cylindrical capacitor with one that looks like a small pillow with leads coming out of one side (a great many film caps look like this), I will often install a terminal strip to mount the cap on.

Fred
owner
Classic Audio Repair

Thanks, Fred.... I did some further inspection and found what I think is the motor cap. It is cylindrical about 1" x 2" with a plastic cover over the wire terminals.
It reads:

1.5uF + 10-5 %
250WV AC
Towa Japan
117 034
8901

It is connected to the motor via a black and a green wire
Is this the suspect cap? Thanks

Yup!

Fred
Owner
Classic Audio Repair

Hello,

I don't mean to detract, but does anyone know what the built-in amp on the TC-630 sounds like through better speakers? I find that the stock speakers sound rather harsh and mid-rangy and I was wondering if anyone had insight as to whether this poor sound quality is due to the speakers themselves or to the amp. I ask because I was hoping to use my half broken tc-630 as a home stereo system (the tape section has all kinds of motor problems that I can't afford to fix) and I'm wondering if it would be worth it to buy better quality speakers for it.

Thanks!

I would certainly agree that the original speakers that came with the TC-630 leave a lot to be desired. You can hook the amplifier section to modern speakers. It is most likely less than 10 watts per channel so take that into consideration. You actually have nothing to loose by doing that. Try it, let us know. I always had mine connected to my amplifier. This deck when serviced and working properly sounds great. The only complaint that I have is tape hiss which was normal "back in the day". But I would rather hear tape hiss as long as I was getting crisp highs.

OK... I got the new motor cap installed (thanks, Fred) and it solved the slow run problem.... The unit works ...records/playback just fine. There is now a noisy idler pulley on the faster play positions ( 7 1/2 and 3 3/4 ips). This is the pulley that drives the flywheel and also simultaneously contacts the motor drive. I have tried different lubrications, spring tensions etc and nothing seems to quiet this down. It turns perfecly free and is very quiet at the slowest speed setting. There is no problem with the 'flywheel' bearing/shaft.
Any ideas as to how to quiet this down? Thanks.

If you can wait about a week and a half, I have some used TC-630 parts and may have something you need. Just shoot a PM in about 10 days if you are interested... (I am in Australia right now and the parts are on the east coast of the US. Far, far away...)

The rubber on the idler wheel is hardened. You can search for a rubber restore kit and that may fix it.

I just resurrected a post CBC, tc 630d. I was going through its functions, and noticed that it seemed to be playing a little slow. I stood it upright, and the motor slowed quite significantly. I was planning on using this machine to do live recordings. This inaccuracy in the speed worries me. I am no electronics expert, but I have built an SET amp kit, and do have a soldering station. Is this most likely a rubber roller issue? Sounds like a bad cap would make the motor run faster. I did see some restoring kits on ebay with a couple belts and a roller.

thanks for any suggestions

G