Sony TC RX70ES Cassette Deck Repair (Belt Swap, Lube)

Sony ES Cassette Deck


No great pics of the deck during this post, maybe I will update.

So I swung by a Goodwill to donate some things, and did a quick check. I never find vintage computers, and most of the video games are picked over. I never find that copy of Space Quest III. But on this trip I did find a Sony TC RC70ES. I debated with myself over it for a little while. It didn’t have the wood ends, so it doesn’t really seem like a ES home component. But it is an ES deck. Less than a year ago I picked up the Nak 680 and have been enjoying it, so why not a little competition? And I tried to fix my childhood Sony dual tape deck and failed — so that still stung a bit. Should I? Yeeeaaa why not.

Brought it home right as I went on vacation. Diving in Jupiter with Eric, Chris and Mary! Chilling in Key West. South Beach Miami! Silverball Museum in Del Ray! Hanging with family. And pre-ordering some belts for this thing from eBay.

So when I got home from vacation the parts were there and ready to swap.

First, the old belt was nasty AF. It was goo, and the goo got on everything. Rubbing alcohol cleaned it off well, but I have no idea if that will hurt the new belts.

Removing the first layer to get to the flywheels was no problem. But the next layer of disassembly resulted in parts popping out all over. So service manual was found, so that is good. People care enough about this model for it to be out there.

Got it back together, annnnnd BAM. Sounded bad. I had to play with the speed adjustment on the motor, but I don’t have a real reference tape. I recorded 400hz from youtube on the Nak (which is not speed calibrated) and threw it in the Sony. It seemed to be moving all over the place.

But the Nakamichi didn’t just work. It seemed to come to life after playing a tape or two and loosening up. So I ran a tape on the ES.

After one side it started squealing. LOUDLY. I ran. I ran so far away. Hit power button. Did some quick google research, and as I remembered the pointer is to the drive motor that moves the capstans. So I put a drop or two of oil on it via a syringe type device used for purging air from printer lines. It cleared up pretty quickly. But not sure if mineral oil is ideal.

The speed still seems to be unreliable, and I don’t know that I really like the sound quality. The CrO2 tape that I recorded Capital Cities – A Tidal Wave of Mystery on the Nak when played back on the Sony just isn’t the same. First the deck detects the CrO2 and you loose high end I think. And there is more hiss. So far I don’t have much of a love relationship with the deck, but I still like the Nak 680 a lot.

Also, after working on the Sony ES deck I now know that I could have probably fixed that childhood Sony deck with motor lubrication. The mechanisms are still crazy complex, kudos to the Sony engineers that came up with auto reverse system and rotating head and all of that.

Time will tell on this deck. Next will be to get a real calibration tape. But I fear I might have to rebuild the motor as well, and I’m not sure of my motivation on it.

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