Sony TC-560 | Slow Fast-Forward & Rewind
 

Hi, I have a nice Sony TC-560 reel-to-reel tape deck which I found a few years ago in the back of a truck, en route to a dump.

I have since fixed a few issues it had (dirty heads, sticky switches, belts, VU meters...) but one particular issue that I just can't seem to fix is the torque in fast-forward and rewind modes. It's really slow to accelerate and the top speed is nothing like I'd imagine it should be. A lot of the time it stops before reaching the end of a spool.
I have used two different motors with two servo amp boards, one of which was recapped and no combination of these parts changed anything. Though now I realise that fast-forward and rewind by-passes the servo amp board anyway, I think.
I have the service manual, but I am not particularly knowledgeable when it comes to schematics and I don't have a scope or any of that fun test equipment. I really don't know where to start looking, though I did start replacing capacitors on the power amplifier board (again, no change).

I really hope someone here can shed some light on this problem and help me out. Thanks in advance.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

The TC-560 I see in an online photo looks to have the one AC motor and idler drive system for fast wind, used in many Sonys of that range and era.

The rubber tyres on the idlers can go hard and slip.

Possibly the motor's capacitor needs replacing.

Be careful of playing "back coated " (matt black backing) tapes as many have sticking and shedding problems, although this may be more of an issue in record and play.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

The motor in mine is a DC motor (D-503F) and there aren't any idlers.
I have seen Sony models with what you are describing though.
If it makes things easier I can attach pictures.
Do you know if it's allowed to post screenshots of service manuals?

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

You can post snippets of service info to illustrate a subject under discussion, but not complete manuals.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

You can post the whole schematic no problem.

Lawrence.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

OK, cool. Thanks for letting me know. I'll be sure to share sections of the manual that are relevant.
The only board I can think of having relevance to this issue is the power amplifier board, as in fast-forward/rewind it by-passes the servo amplifier board.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

Perhaps a strip and clean of the motor? The ability of this model to run from 12Vdc was a selling point.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

I don't think that'll work, as I've had this exact issue with two motors, one of which I did strip and clean and it didn't change anything. I think it could be something to do with the power amplifier board. There's got to be something there that affects how much torque is put out, right?

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

On some machines SSS (Sticky Shed Syndrome) can also badly affect fast wind in both directions. Some non back coated tapes can also suffer with shedding of the oxide front side of the tape.

Check the whole of the tape path for any sticky tape deposits.

David

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

I have cleaned it and even with no tape reels on the deck it is quite slow.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

Is the voltage across the motor as it should be in REW/FF?

Lawrence.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

I would absolutely love to find out how to check that. I have a digital multimeter, but that's all.
If the voltages aren't as they should be, what should I then look at? I'm just going to re-iterate that I can't read schematics.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

It's easy with the schematic, it's on page 16 of the service manual, go towards the bottom right of the schematic and opposite where the Notes are there's a small circle with a M inside it, that's the motor.

In REW/FF the servo's motor drive transistor below it is bypassed by a switch (S14) and a 12 Ohm resistor in series with that switch (shown to the right of the servo's motor drive transistor)

Physically the actual measuring points for the voltage across the motor can be found by looking at the servo board layout on page 29 of the service manual, on the right hand side of the first drawing you can see the motor represented again by an M, you can see it's connected to the servo board by a Red and a White wire, measuring between those two points with a multimeter set to measure DC on a suitable voltage range will indicate what the voltage is that's being supplied to the motor when in REW or FF.

Lawrence.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

Awesome. I truly appreciate your thorough, detailed explanation. I will take a look and report back when I can. :)

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

OK, so...
I've tested the motor with the multimeter from the red and white wires in forward, reverse, fast-forward and rewind. The voltages were as follows:

Forward - 6.6v
Reverse - 6.6v
Fast-Forward - 10.7v
Rewind - 10.6v

Meanwhile, what looks like an old, red resistor with no colour bands on it, labelled "4PA 12Ω SEF", gets pretty toasty. Actually, quite hot. I couldn't rest my finger on it for more than two seconds.

I'll attach an image of this component and another image of where it is if you were to just look at the back.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

With those voltages it sounds as though something is dragging too much either lack of lubrication or possibly to much friction/back tension from the supply or take up spools.

Lawrence.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

I will have to consider lack of lubrication, as this problem exists even without any tape or spools on the deck.
The component I pictured, could that be the 12Ω resistor you mentioned earlier? I'm worried about how hot it gets. Would you be able to recommend me a replacement?

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

Yes, it looks like the 12 Ohm resistor that's in series with the REW/FF switch and the motor, that type rarely increase in value, having said that you can measure it's resistance with a multimeter set to measure resistance on a suitable resistance range, with the power disconnected and the main function selector set to Stop it should measure 12 Ohms or thereabout, if it does then it's ok, you can also work out how much current is flowing through the motor when in REW or FF by doing a simple Ohms Law calculation....measure the voltage across that resistor (the voltage between its two ends on the tag strip) and divide that voltage figure (in Volts) by that resistors measured resistance (in Ohms) and that will give the current in Amps.

Lawrence.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

With the power off and disconnected the resistor measures at 12.4Ω.
In fast-forward and rewind the voltage, when measured across it's points on the tag strip, sits at around 4.5v.
If I understand your description, I then have to divide the voltage (4.5) by the Ohms (12.4), which gives me a value of 0.362.

Re: Sony TC-560 | Slow Fast-Forward & Rewind
 

Yes, that's correct, 0.362 Amps or 362 mA (362 milliamps)

From that we can now say that the 12 Ohm resistor is ok and that the power it's dissipating approx. 1.63 Watts (the current multiplied by the voltage) is ok for it's rated wattage (3 Watts in the parts list in the manual)

Lawrence.