Sony TC-366 won't stay in play mode

[Keith956]

I've been looking at the Sony TC-366 I picked up the other day and the immediate problem is that the rewind/stop/play/fast forward control doesn't seem to work properly. It won't stay in play or fast forward. I've taken the mechanism out (the bit under the tape heads) and cleaned it but can't see anything immediately amiss, but not really sure how it's supposed to work and what to look for. Has anyone had a similar problem, or any idea what might be wrong?

[ms660]

Might be worth checking the shut off mech. and the tension arm mech. they should set up as per the adjustments in the manual, if not a careful investigation as to why they won't should reveal what's what.

Lawrence.

[Keith956]

Thanks Lawrence, at the moment I have the mechanism out (so not connected to the shutoff etc) and the control will not stay in any position apart from stop, is that normal?

[ms660]

Originally Posted by Keith956

Thanks Lawrence, at the moment I have the mechanism out (so not connected to the shutoff etc) and the control will not stay in any position apart from stop, is that normal?

Can't remember off hand it's 45 years since I last worked on these, I know that they auto shut off if the tension arm drops.

Lawrence.

[teetoon]

Hello. I had this on a TC 377 which has the same mech.
There is a cam spring that becomes mis placed.
I am trying to upload a picture but the file has disappeared.
I will keep trying.

David.

[teetoon]

Here it is after some faffing about. The black spring should be to the right above the notch of the cam. I had to bend it a little to stop it springing back out. It is a known problem.

David.

[Keith956]

Thanks David, Yes that spring did have the end loose. I managed to put the right hand side into the notch in the cam, it seems that either the spring has been stretched a bit or is weak as its barely making the cam return. I'll try again tomorrow.

[teetoon]

I think the cams become sticky aswell and need to be free moving.
I did find some info online in 2019 and was pleased when it all worked again.
I remember it being a fiddle to get the top plate of the mech back on but after a couple times it gets easier.

David.

[SteveCG]

Just to clarify:

Does the tape-recorder show the problem with a tape on it and fully laced up?

[DMcMahon]

I cannot remember the full details but I had lots of fun and games with three TC-399's back in 2019 where all 3 had problems with the very similar (if not the same) mechanism.

Found it really difficut to remove and re-install and when out of the unit inconsistent with their mechanical operation.

One of the problems was definately that same spring, a tension issue.

At least one still does not work reliably in terms of tape transport operation selection, need to revisit them all to quantify this better.

David

[Keith956]

I've found a few comments about the problem not being able to engage play by googling - it seems to be a common problem with the 366/377. It seems to relate to the shutoff mechanism adjustment, or the cam sticking, or a spring loose.

In the first pic the screws highlighted (which have the green paint on) are used to adjust the shutoff according to the manual. The cam to the left, above the spring, is held by a rather weak spring barely visible in the notch at the bottom - this is the one teetoon is referring to. As far as I can see adjusting the plate by loosening the green screws and moving the plate affects whether the cam can pass the lug next to it.

In the other picture there is a screw (circled in green) that needs adjusting also according to the manual.

What seems to be stopping it engaging play though is the cam on the toothed plate - circled in red. When the shaft is turned clockwise, the roller seems to be prevented from entering the next slot (play position) by this cam. If turned hard enough though, it will jump over into the furthest slot (fast forward). On return the cam guides the roller over the play slot so the machine moved straight from FF to stop without ever engaging play.

Whatever I do though, I can't seem to get it to hold in play mode. I must be missing something obvious.

[Keith956]

Well I'm getting somewhere. I stripped down the whole mechanism, gave it a good clean, put it back in the main chassis. There is a hole in the chassis so you can access the screw mentioned earlier - and screwing it in a few turns seems to help. It will now hold fast forward and rewind, but still jumps out of play (into fast forward).

The linkage arm - to do with the shutoff mechanism - doesn't seem to want to fit so something is still not right. It's more of a puzzle than a Rubik's cube.

[ms660]

Re: The last photo, It's possible the "L" end of the rod fit's through the hole that the offset end has been fitted through, I mentioned about this in an old thread about a TC-377 which has a very similar mechanism.

You should be able to remove the adjusting plate and fit that onto the offset end of the rod, don't forget to adjust/check for the 4-5mm clearance when done after re-fitting.

https://www.vintage-radio.net/forum/...d.php?t=159712

Lawrence.

[Keith956]

Ah excellent Lawrence, that sounds like it! I'll give it a try later, thanks.

[ms660]

Originally Posted by ms660

You should be able to remove the adjusting plate and fit that onto the offset end of the rod

Ran out of edit time to correct the above, it should read:

"You should be able to remove the adjusting plate and fit that onto the "L" shaped end of the rod"

Lawrence.

[Keith956]

I managed to fix it, I had assumed the rod went the other way, without any slack in it. It now seems to be working!

There are a couple more issues though. Firstly the brake for the supply spool seems to touch the drive belt when in rewind (see first picture). It might be nothing but that doesn't seem quite right?

Secondly the tape speed switch only seems to move between two positions, 7 1/2 and 3 3/4. I can't quite understand what's stopping it from moving to the most clockwise (1 7/8) position. What does the stepped plastic bit attached to the switch spindle do?

Thank you for all the help so far, this forum is amazing.

[Keith956]

Oops pictures did not upload

[DMcMahon]

Well done on sorting the tape transport control mechanism.

On my 3 x 399's, one of them had a seized solid tape speed selector control and another very stiff to turn to all 3 speeds, had to strip/remove the rotary control and clean up/lubricate the shaft (splined end of which the control knob fits onto to). The seized solid shaft was not easy to extract.

Once again on the 399 (must be similar to the 366) 2 of the actuating flats on the plastic speed selector cam, push (towards the front of the unit) the sprung loaded plunger to which an idler wheel is connected, which when play etc is selected, is engaged with the relevant section of the stepped capstan flywheel to provide 2 of the speeds, I think the third speed was done electrically by a little PCB at the rear of the speed control assembly.

The sprung loaded idler plunger when actuated by the speed cam also operated some other linkage on the front side of the unit.

David

[DMcMahon]

Originally Posted by Keith956

There is a hole in the chassis so you can access the screw mentioned earlier - and screwing it in a few turns seems to help. It will now hold fast forward and rewind, but still jumps out of play (into fast forward).

Do not think I knew about this chassis hole, must check if my 399's have it, could come in very handy later when I eventually revisit them.

David

[Keith956]

David, I didn't notice it at first. There's a hole near the selector knob through which you can see the adjuster screw; to gain access to it there's a slot in the side of the mechanism. Sony must have thought this would need adjusting with the mechanism in place.

In the service manual it says to loosen a screw to locate the idler arm pin between the two slots in the plastic cam. The only screw I can think that might do it is the one that secures the plastic cam to the speed selector shaft, which is completely inaccessible. The photo in the service manual (Fig 11-13) is not clear alas.