Sony TC-K700ES transport issue?

It was necessary to bend the pinch roller arm somewhat so that it would engage under the head carriage.

With the deck completely reassembled, the FF and REW now work, but the take-up pinch roller does not engage with the capstan. In the play mode, the supply and take-up reels are working, but not surprisingly there is no audio output (since the tape is not being held against the heads).

Is it the case that in the PLAY mode, the head carriage—the mounting-plate assembly to which the heads are attached—moves upward to engage the tape with the heads? Because, if so, that ain't happening.
 
The arm has to be engaged under the head carriage, but not too much, as it could interfere with the chassis, preventing the head carriage to move upward.

Could you post a picture from under ?

Pity I am not currently home, as I have a spare TC-K700ES transport that I could use as a demonstrator.
 
Actually, it's just as well that you don't have access to your TC-K700ES at the moment—I'm not enthused about taking this thing apart again today. So send along the picture when you have a moment, and I'll probably work on it again tomorrow or on Tuesday if I have time.

FWIW, I bent the arm just enough to reliably catch at the edge of the head carriage plate. Any less and it would not catch but scrape the carriage plate and engage the capstan. I can't see how the position of the arm would prevent the carriage from moving. Should it be possible to move the carriage manually?

Also, looking at the head carriage from the bottom in same plane as the plate itself, the left side of the plate is slight raised from the chassis, while the right side is flush with the chassis. Short of a complete disassembly and bending of the plate, I can't see how to level it on the left side.

In any event, when placing the transport in the PLAY mode, the plate doesn't move. Should it?
 
Here is a picture from under, found on the web:

noFtHKDh.jpg


You can see on the right the take-up pinchroller arm not engaged under the head carriage. The supply pinchroller arm is correctly engaged.

The reason why the take-up arm is not correctly set is that a steel ball, used as a bearing, is missing between the chassis and the head carriage, on the right (see ? the head carriage is not parralel to the chassis).
 
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Also, looking at the head carriage from the bottom in same plane as the plate itself, the left side of the plate is slight raised from the chassis, while the right side is flush with the chassis. Short of a complete disassembly and bending of the plate, I can't see how to level it on the left side.
Look at my previous post, seems we have the same problem

In any event, when placing the transport in the PLAY mode, the plate doesn't move. Should it?
It should, at least a little, even with a steel ball bearing missing.
 
The head carriage on my machine looks the same as yours—high on the left side.

If I bend the take-up pinch roller arm so that it does NOT catch on the plate (so it would be as shown by the one in your pix), then it will remain engaged with the capstan, etc.

I have no idea why the steel ball (#216) would be missing on my machine, since it worked in PLAY when I first got it, and the head carriage has not been removed since then. But shouldn't the head carriage move, if only sluggishly, in any case. As far as I can tell, it doesn't move at all.

I'm still in the dark about when and how the head carriage is supposed to move. Is there some reason why it can't be moved manually when the unit is not powered up?
 
There is a big plunger (PM901), located on the other side of the chassis, that moves the head carriage up. If you push it with a finger, the head carriage should move up.

Maybe the missing ball is somewhere, jamming the head carriage.
 
Can the plunger be accessed from the back side of the transport in the same way it's possible to get access by removing a single plate and replacing the belt?
 
I would say yes.

Here is a picture of a 700ES, you can clearly see the plunger on the right, under the black plastic tube (which is an air damper for the door).

file.php
 
Thanks for the pix.

I'll see if I can get any further with this on Monday or Tuesday.

I'll be in touch.
 
HeadCarriage.jpeg

I'm back at it.

If the spring (#218) is REMOVED and downward pressure is put on the carriage, it moves freely. Likewise, with the downward pressure, manually operating the solenoid plunger will move the carriage.

However, when the spring is REPLACED, with the steel ball #216 in place and lubed lightly, and apparently fully depressing the carriage, it nonetheless will not move.

Seems like, since with downward pressure it moved freely before the spring was replaced, with the spring replaced and creating equal downward pressure, it ought to move freely—but doesn't.
 
Here's another thing I don't understand: When the front of the spring is in place—at least I can't see that it can be in any place other than shown in the pix above—it is "seated" under a a tab that is part of the underlying assembly, not the carriage. If that's true (which it seems to be, looking at the exploded parts illustration), then it's fixed (relative to the carriage) and seemingly should stop the carriage from moving forward.

I can't see any other obstruction to carriage-movement.
 
Have you checked that all 3 steel balls #206 are in place.

The carriage (on which the heads are attached) that should move upward/downward is part #213.

As far as I can see, spring #218 is correctly set.

Part #214 (cable holder) seems unsetted.
 
IMG_0142.jpeg

I'm totally mystified!

I can confirm that there is a steel ball under the left side (pix) of #213, but as you can see, the right side flat against the chassis below. There is also a steel ball under the spring. So, possibly, one of the steel balls is missing.

What I don't understand is this: If I remove the spring altogether and then place downward pressure on the carriage, the carriage moves freely as it should, which it also does if the spring is removed and the solenoid is operated manually. On the other hand, when the end of the spring farthest from the heads is attached to the tab, which is FIXED as part of the chassis below, I don't see how the carriage can move. What am I missing here?

Incidentally, the cable holder #214 is only momentarily out of place.
 
I'm also confused because the other end of the spring (under the heads in the pix above) is "seated" on a tab that appears to be part of the underlying chassis. How can the carriage move forward and the spring remain in place?
 
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