Sony TC-730 quick STOP function not working properly

[SongHuJung]

I just pulled my boxed-up Sony TC-730 tape deck out of the closet after having it sit there for about 20 years. I bought it in Japan in 1972 and it had been in good shape before I stored it away. It's a great deck, with Auto-Reverse and Bi-Directional Recording, and it has a first rate built-in amplifier.

Amazingly, I "fired it up" yesterday and it plays fine. (I did first thoroughly clean the heads, capstan, and pinch roller with alcohol and Q-tips.) However, there is one problem. When I put it in either fast forward ("FF") or rewind ("REW") -- using the two silver buttons above the right VU meter-- and then hit the "STOP" button, the tape reels do not "stop on a dime", like they are suppose to, maintaining tape tension against the rollers and heads. Instead, the reels slow down like brakes are being gradually applied and when they stop the tape no longer has tension against the rollers and heads, a definite tape slack being visible at the rollers and heads. As an expedient solution, I can gently turn the reel with my finger several inches so that the slack is taken up and the tape is back to being tight against the rollers and heads, as seen in the first photo below.

The problem is that if I hit any of the movement buttons -- be it "FF, "REW", "FWD", or "REV" -- with tape slack being present and the reels start to move, the slackened tape will get caught on the inside of a reel and be "eaten" by winding itself around the inside side of the reel. You can see that in the second photo below, where "eaten" tape is visible under the plastic of the reel. l then have to gently coax it out and try to smooth out the crinkingly. (If I didn't stop the machine immediately, it would be disastrous for much of the tape.) The problem has happened several times already and I need to discover the root cause.

Since the deck is not maintaining proper tension of the tape when I hit the "STOP" button, that seems to me to indicate that some mechanism or part is not moving in to place when it suppose to and causing the reels to come to a quick halt, maintaining tape tension against the rollers. (There are some YouTube videos that show this proper quick stop function on a TC-730.) Other than this issue, the deck works and plays fine. The audio quality is terrific, even after all these years.

What do you think? Would this more likely be a problem with the reels themselves, perhaps some deteriorated rubber bands or whatever attachment to them that is suppose to cause the quick stop effect; or is it more likely a lubrication problem down around the capstan area? Thought I'd ask for any suggestions, or see if someone else has already had this problem and fixed it, before I take the deck apart to look inside for any clues.

 

[vitorzoom]

I think it's a brake problem. Simply remove the front cover and observe the action of the brakes on the inner reels. They may be dirty or worn.

 

[SongHuJung]

Thanks, vitorzoom.

I'll give that a try and post results here. Looks like I can remove the front cover by simply removing the front screws and knobs.

 

[Awesomeaudio]

You'll also need to remove the slide pins that the head cover slides onto. These too hold the fascia down along with the various visible screws and knobs.
I would also guess that the felt brake liners are either glazed or worn.
I too have one that needs doing but haven't had a chance to as yet.

 

[SongHuJung]

OK, I finished the "brake job" on my TC-730. Deck is now working correctly. The deck no longer gradually slows to a stop, spooling out tape slack below the rollers and heads when I hit the STOP button. It now once again has the proper quick stop functionality and maintains tape tension against the rollers and heads when I hit STOP, and does so for all 4 types of movements -- FF, RWD, FWD, and REV.

A few lessons learned:
(1) I did not have to replace the pads on the brake shoes. I simply scraped the overly smoothed surface of the felt pads with an Exacto blade, removing the slickness and bringing the underlying felt back to the surface, much like it probably was many years ago. (Note: I found an online video by a person who had removed the pads and glued some new wool felt material onto the brake shoes. He did not get optimum results. I would recommend not doing that and instead try first to revitalize the original pads.) In photo 1, you can see a felt pad that I managed to "scrape" back to near its original condition.

(2) I used Isopropyl alcohol and Q tips to thoroughly clean the circumference of the black plastic on the reel table, where the brake shoe presses against it. That black plastic initially looked clean and smooth to the naked eye. (See photo 2.) However, it definitely was not. Scrubbing it forcefully with the alcohol and Q tip resulted in the Q tip becoming very dirty. Also, once done you could see and feel the cleanliness of the black plastic, as if it were brand new. By placing the pad against the black plastic and applying a bit of pressure, I could feel the improved grab.

One more point: Before starting this brake job, I had downloaded a pdf of the Sony TC-730 Service Manual (at hifiengine). It did not tell or show how to replace or rejuvenate brake pads. However, in Section 3-1-12 it did show how to do a "Brake Torque Adjustment" by moving the tiny spring on the bottom of each brake adjusting arm to a different notch setting. You can see the notches in photo 3 below. I tried doing this adjustment on each brake, but it did not solve my tape stopping and spooling problem. You can try this Adjustment first, but it didn't work for me. I put the springs back to their original notch settings.

 

[Wildcat]

That was the same Sony reel deck I had for several years. Looks the same! I didn't take the time to adjust or refurbish the brake, but I recall it did dump a perfectly good reel of Maxell UD35-90 all over the place when I used it once after having it sit for a few years. (I hit stop while it was fast-winding.) Worse than that, I had it up on a higher shelf at a later time, and somehow one of the spring-loaded reel retainers had come unscrewed--had a reel fall on my head!

That was the last straw though, and I ended up selling it to a local who knew how to work on these. I was the second owner; the first owner had bought it new, and took it with him to Vietnam during the war, recording messages to send back home to family, along with playing music he'd taken with him. So mine had a lot of "miles" on it!

One thing that never worked well (due to age) was the speed selector. It not only changed the speed, it also changed the equalization on the sound during playback at low speeds (especially 1-7/8 ips), so there were times I had to work the switch up and down a few dozen times to get it to play back reliably. That might be something worth hitting with DeOxit (or similar) if you find that the higher frequencies cut in and out at the slower speeds, or something just sounds "off."

 

[vitorzoom]

The Sony TC 730 when well adjusted and calibrated makes good recordings. I'm glad you did it.