Sony TC-K3 find

Nick_the_'Nole

Super Member
Picked up this little gem at the GW the other day for $13, to replace the mediocre Sony dual deck I had. This thing is in near-perfect shape cosmetically, save a little ding on the cassette door, and it works ok, but I'm having a couple issues with it. First is the 25Vac I discovered running through the chassis, which I found after touching the thing with wet hands. (Ow.) It's there whenever the thing is plugged in, doesn't have an obvious cause like broken insulation or anything, and doesn't affect the operation of the deck. The transformer is isolated from the chassis, and prodding around with my circuit tester doesn't show any problems at the circuit board either... So WTF?

The more annoying problem is the fact that the pinch roller seems to keep getting oil on it, causing it to slip in FF and RW. The metal shaft also seems extremely prone to picking up dirt, and cleaning it and the roller after every time I play a tape still turns the q-tip brown. It doesn't seem to be degraded rubber on the roller, since it's still pliant enough and works fine when it's clean, just that it won't stay clean. Anyone have any suggestions how to prevent this from happening so much?

And BTW, this deck sounds startlingly good when it works properly...
 
This was a mid-line deck in about 1976/77 or so. The top of the line, the K8, had more bells and whistles on it that you could learn about in a week. All of them were built well but from the mid-line down they were pretty much run-of-the-mill gear.

As for the problems you're having, the AC on the chassis means there's leakage through whatever cap that's being used to remove transients on the AC line. I'd suggest that you remove the load from the power supply (can't remember if its on a separate board) and see if the AC stays there.

On the mechanical problems, pictures *might* job the memory of my days on the bench. I don't remember that many Sony decks of that vintage showing up during warranty periods. They had done a pretty good job of engineering the complexity out of the cassette medium. They did sound quite good when they were set up properly, too.

Cheers,

David
 
I'll have to dig out my camera and try to snap some pics. I thought about the cap thing, but I have yet to figure out where it may be hidden away. I can't easily remove the load without what looks to be some serious disassembly and soldering, so until I feel up to that I'm just gonna remember to dry my hands before touching it. The pinch roller is the issue I'm a bit more concerned about, because it's not really a consistent problem... it screws up on some tapes but not others, and there isn't any rhyme or reason to it that I can see. It plays fine, but rewinding and FF slip.
 
As I recall, on this model and several similar there is a plastic retainer that breaks and causes a plate to push up and rub against the right reel table causing wow-and-flutter to become horrible.

The retainer is no longer available, but you can contrive something that will do the job.

Fred Longworth
StereoTech Classic Audio Repair
http://www.repairaudio.com
 
I recorded a mix tape today for the first time in about 5 years, and it sounds really damn good, to the point that I can't really tell a difference between it and the original sources... but it seems it runs a bit fast even with the speed adjusted all the way down. The issue with slipping is starting to work itself out with use, still does it a bit on rewind but FF works fine now, hopefully it'll go away completely once I use it a bit more. But the speed bothers me a bit now, since I want to use this thing to make tapes for the deck in my car. Also, when recording, I have to adjust the right channel considerably higher than the left in order to get an even mix. I know both of these problems are prolly an easy fix and likely due to the age of the caps and such, but I really don't feel like having to redo the entire board in it. Is there any way I could find a service manual for it so I can know what I need to replace and what I don't?
 
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