TASCAM 52 - motors are turning in the OPPOSITE direction to each other

High_Freq

High_Freq

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Happy new year.

Has anyone experienced a problem where the reel motors turn in opposite directions to each other on a TASCAM 50-series deck?

I've owned a TASCAM 52-DB for about 15 years, and have enjoyed some good use from it, it has always run pretty well. For those that aren't familiar, it's a two-track 1/4" 15 & 7 1/2 IPS machine whith unbal and balanced ins-outs. It's on the same chassis as the TASCAM 58 1/2' 8-track and shares some parts. Built like a tank. I haven't had a chance to use it much over the last couple of years, but recently went to start it up. Somehow I managed to fry the "spark killer" caps that are attached to the power switch, smoke was pouring out the top. I replaced the switch itself and the caps, so the machine is powered again. (As an aside, the machine is stamped EUR, I'm in AUS, and the spark killer caps were rated 125v - the manual shows these should have been 250v, which is what I replaced them with). While I had the machine opened up I decided to pull the reel motors just in case they were part of the problem, and to clean out any carbon build up on the commutator.

After reassembly, I threaded a tape, hit PLAY. Tape went everywhere. Tried again, in rewind... tape went everywhere. I tested it with empty reels, just by holding the tension arms to get the reels moving. Interesting results:

RW: Supply side - CCW (wrong)
Take-up side - CW (OK)

FFWD: Supply - NIL (brake off, freewheels) - OK? Not sure about this result.
Take-up - CW (wrong)

PLAY: Supply - CCW (OK)
Take-up - CW (wrong)

The reel motors are turning very strongly. The capstan motor is fine.

From these results, you can see that in RW and PLAY, the motors are turning in the opposite direction to each other, and that both motors are affected at different times. In FFWD, the supply side motor has the brake off and no power, it just seems to freewheel, which might be as intended, I don't know, but nonetheless the take-up side turns in the wrong direction. I wondered if I'd reassembled a motor with the main casing back-to-front, which might have reversed the magnetic polarity, so I pulled the supply side motor again and reversed the case, but this didn't change the results at all. I also checked the wiring, but this also seems correct; the manual shows that one motor is wired onto the JOINT PCB "white-shield-red" and the other "red-shield-white". I also took photos before I desoldered the motor wires, and I'm confident they were resoldered correctly. I haven't had the guts to reverse the wiring on one to see if it makes a difference.

So, I'm at a loss on this one. The only other piece of conjecture I can offer is this: when the "spark killer" caps in the power switch burnt, I was looming up the tape, and turned the supply side reel by hand, and remember thinking it was quite stiff. Could this have caused a power spike, which damaged something inside the motor (say a capacitor?) Or is there some comparator circuit which detects motor direction which could have been fried? I can't find any clues in the manual.

Any opinions or advice? Thanks.
 
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High_Freq said:
RW: Supply side - CCW (wrong)
Take-up side - CW (OK)

FFWD: Supply - NIL (brake off, freewheels) - OK? Not sure about this result.
Take-up - CW (wrong)

PLAY: Supply - CCW (OK)
Take-up - CW (wrong)
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I don't know this machine but wanted to point out that all the motors are turning the wrong way - even the ones that you have labelled OK. With no tape loaded, the supply side should always turn clockwise - even in play and fast forward, while the take-up should always spin CCW - even in rewind.
 
I wasn't aware of that. Do you know why this is the default? They do seem to be wired up opposite to each other, which could explain it. So what is it about tape being loaded that makes them spin in the right direction? Is it tape tension, the tach roller? I was holding the tension arms to fool the machine into thinking there was tension, and to defeat the end-sensor circuit.


In a way, all motors turning the wrong way seems like better news than some turning the right way sometimes, and the wrong way other times... it could just be one problem affecting all globally.
 
They should always be as James says, but what should happen is the torque changes. When playing, the supply spool should try to rotate clockwise, but with very low torque so the tape has no problem being pulled hrough by the capstan and pinch wheel. The take up spool also has anticlockwise (CCW) power to gently spool th released tape. Hit rewind and the supply spool torque rises to full, with take up remaining low - this spools tothe left reel and the back pressure keeps the turns neat and consistent. Hit FF and the right spool rams up to full torque, with just back pressure from the supply one. They never have a need to rotate the other way. So your supply spool will always be driven clockwise and the right take up spool always tris to rotate anti-clockwise (CCW) You should be able to feel the change in torque. Over the years it's been felt pads touching each other or actual direct control of the motor power. Often spooling issues are binding or open brakes. On my Tascam 34, there is a button to turn off the take up spool to allow the tape to spool onto the floor - a dump facility, as in dump to a bin.
 
James, just had a quick look at your website & facebook. So is there another mod revival?

Two lovers kissing amongst the scream of midnight
Two lovers missing the tranquility of solitude
Getting a cab and travelling on buses
Reading the graffiti about slashed seat affairs
 
Hi Rob. What you have described makes sense. I didn't think it was relevant in my original description, but when I hold the tension arms in and enter any of PLAY, FFWD, RW, the reels spin at top speed. I think I'd better try it again with loaded reels, and report back. Maybe I have a torque problem - torque is always at maximum? I did read in the manual about "Flash" power, which is an initial higher voltage signal to get the reel moving. What if it is always stuck in flash voltage?
 
Yes - I'd load it with a tape you don't mind stretching. The tension arms job is to go fully one way when the torque is high but under play speed. sort of float in the middle. A good rule of thumb test is to put it into play and with the ordinary cine 3 prong spool spline only (not a NAB adaptor- just the small centre 'pin') squeeze it between your thumb and third finger - usually your weakest one. you should be able to stop it spinning, just. This is the kind of low torque setting for both spools in play. If you cannot stop it turning like this, then that's rewind/FF torque.
 
Hi Rob. What you have described makes sense. I didn't think it was relevant in my original description, but when I hold the tension arms in and enter any of PLAY, FFWD, RW, the reels spin at top speed. I think I'd better try it again with loaded reels, and report back. Maybe I have a torque problem - torque is always at maximum? I did read in the manual about "Flash" power, which is an initial higher voltage signal to get the reel moving. What if it is always stuck in flash voltage?
Click to expand...


Just to make sure we are aligned to the same terminology as it relates to the 52’s tape path, tension arms and their positional impact on reel motor rotation, when the tension arms move toward the vertical centerline of the face of the deck, the voltage signal to the servo system increases and along with that the power to the motors. So when you say you held the tension arms “in” I read that as you allowed them to be all the way to their midline stops toward the vertical centerline of the face of the deck…which should trigger the tape-end sensor and put the machine at STOP. If the tension arms are held all the way “out”, or moved away from the centerline of the face of the deck, the voltage decreases and the power to the motors decreases. With no tape loaded and the tension arms at their maximum distal positions from the centerline (away from the centerline), and the machine put in any mode other than STOP or PAUSE, the reel tables should not be spinning, but then as you start to move the supply tension arm toward the center, the supply reel motor should start spinning clockwise. And as you start to move the takeup tension arm toward the centerline, the takeup reel motor should start spinning counter-clockwise.
 
High_Freq said:
James, just had a quick look at your website & facebook. So is there another mod revival?
Click to expand...
In my world Mod never went away - there have always been a couple of labels specialising in the genre but this year has seen releases from some of the stalwarts of the 1979 revival.

I'm not sure how sophisticated the 52 is, but the tension arms often have sensors on them which control the power to the motor. If the arm is down the motor goes onto high power whereas if the arm is pulled up the motor should reduce its torque.
 
jamesperrett said:
I'm not sure how sophisticated the 52 is, but the tension arms often have sensors on them which control the power to the motor. If the arm is down the motor goes onto high power whereas if the arm is pulled up the motor should reduce its torque.
Click to expand...
Yeah that’s basically what I was saying ^^^^^^, only on a Tascam 50 series deck, like many others, the tension arms swing along a horizontal plane vs vertical.
 
Sweetbeats, I think we have the same understanding of the tape path. Let me put it this way: if I hold the two tension arms in a "due south" or "180"position, both motors turn. Varying where the tensions arms are, further in towards the centreline, or further out from the centreline, changes motor behaviour.

I just ran a few more tests. Firstly I tried what Rob said, using 7"reels. I just can't get it into play mode to even get a feel for the torque, because the take-up reel turns CW, dumps what tape I wound on by hand, and triggers the end sensor. At the same time, the supply reel dumps tape on the floor. I think about 60 feet of "Viva Espana" in glorious 3 3/4 IPS 4 track stereo was on the floor...

I tried manipulating the tension arms with empty reels. As you described Sweetbeats, in PLAY mode, holding them in the outermost position (furthest away from the centreline) sees them not turning at all; gradually moving the tension arms inwards allows them to move at a slow speed, which increases the more inwards you move the arms. Once the arms reach the 180 deg position, the reels seem to be roaring at top speed (ie, full FFWD or RWD speed). Any further movement towards the centre doesn't add any speed, and moving fully inwards triggers the end sensor, and applies the brake. The direction of rotation during this test was Supply side = CCW, Take-up = CW.

So I may well have a torque problem. But do I still have a separate direction of turn problem, or will correct torque sort that out?

I might pull the take-up motor and check with a compass whether swapping the case direction changes the polarity, although as I mentioned above, this didn't make any difference when I did it to the supply side motor.

Wiring the take-up motor in reverse is harmless but pointless? I might try it just to see what happens.
 
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Hi James. "Sound Effects"by The Jam gets a regular spin in this house. However if I was getting a free trip back to 1979, I would stay right here in Melbourne and get down to St Kilda to see The Boys Next Door, who would shortly be changing their name to The Birthday Party. There's still a remnant of that sound and attitude here, but perhaps not with the same intensity.
 
Update: Fixed.

I reversed the read and white leads on each motor, and there it was. No tension problems, nothing. Perfect playback. It really is a beautiful tape machine.

Thanks for your help gentlemen.
 
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