Are you changing the position of the belt to go to 33 1/3? Really it would be impossible for the table to only spin at one RPM as the pully has two different diameters, the smaller one for 33 1/3 and the larger one for 45 rpm. When moving the belt on the motor pulley, change it's position on the platter to keep things even. |
Many thanks. I know it sounds impossible, but I initially thought it might have been due to different tension in the belt between the two speeds. Now, however I believe its the actual motor. Reason being, if I remove the belt, the motor will spin BUT on second attempt it does not. If I then move the motor slightly up or down i can get it to spin once or twice but then not again until I move it slightly up or down again. By doing this, with the belt connected, i can eventually get the platter to spin at 45. BUT no matter what I do it will not spin at 33.
Do you know where I could obtain a new motor, or is there some maintenance I could perform on the motor. Thanks again. |
The most insane solution!!!! I replaced the belt with a piece of string and the table now works perfectly!!!!!!!! I guess the problem was the belt!!!! |
As you may know, that motor is never "off". The push you give to the platter seems to engage some sort of clutch to then drive the platter properly. My guess is that there is some critical loss of torque for some reason, such that the motor cannot get going up to mechanical advantage needed for 33 rpm, but it is probably barely OK to get going using the 45 rpm part of the pulley. To test that, you might try starting it at 45 and then flick the drive belt down to the 33 pulley, see if it can then stabilize at that speed. |
There's no clutch in the Spacedeck's motor. It's a simple AC synchronous motor, intentionally too weak to start the mass of the platter from a stop. The Spacedeck's designer, the late Tom Fletcher, argued that the motor's real job is just to keep the platter rotating. He believed that motors powerful enough to put the platter in motion were therefore oversized for their real job and vibrated too much. I vaguely recall experiencing the original poster's problem once. As I recall the issue is really that the motor (which is on a separate chassis or pod) has moved slightly closer to the platter, reducing the belt tension and causing it to slip on the pulley. Replacing the silicon belt with a string fixed the symptom because the string has greater "traction" than the OEM belt. My suggestion is to clean the belt with some cold water and dish soap, put it back in place, and move the motor away from the platter a small distance. |
Thanks, Rob. You are most likely correct. Fletcher's idea of how to use the motor was closely allied to that of Lloyd Walker, except Lloyd uses a much heavier platter than did any of Tom's designs (well, never saw an AnnaLog or a Dias in the flesh). I never experienced this particular issue with my Hyperspace. Occasionally I noted that the motor had crept too close to the platter, but it still worked fine to bring it up to speed. So, why does this Spacedeck work fine at 45 rpm but not at 33 rpm? I would think that belt slippage would be a factor at either speed. |
45 RPM is harder for the motor to pull than 33 1/3, like trying to get your car moving in 2nd gear instead of first. If it will work at 45, the problem is not the motor. |
I suspect that the reason the belt doesn't slip at 45RPM is because the 45RPM pulley has a larger diameter than the 33RPM pulley. Since the grooves for both speeds on the Spacedeck's platter are the same diameter, the belt must stretch to accomodate the bigger pulley. That stretch probably means that the belt is pulling "harder" on the 45RPM pulley than on the smaller one. The distance between the motor and platter seems to be critical. I have a PDF copy of the NA dealer manual and it calls for 6mm between the two pieces. |
One other thing to check: due to its weight, the motor sometimes will slip down in its pod over time. When that happens, the grooves on the pulley no longer line up with the grooves on the platter. |
Good point, John. I'd forgotten about that NA motor quirk. Here's what the dealer manual says about the motor height: "The motor height is adjustable and it is important to line up the grooves on the pulley with the grooves on the platter. Make sure the table is leveled first. If you need to raise or lower the motor, do so by pushing on the motor itself. It is snug in its housing, but it will move."
You shouldn't need to loosen the screws holding the motor to the housing to do this. |
That was an occasion when my Spacedeck motor spins at varying speeds and at times it does not stop at all. That was real insanity then.
I replaced the motor and from then on, I never leave the motor on. If you touch the motor, you will notice that it does gets warm in its standby state. |
I just got a Nottingham Ace Space which is basically the Space Deck with a pre-set tonearm and cartridge. How far away should the motor be from the back right leg of the table? Should it touch? Does moving it further away change the speed? Sometime it sound just a little bit slow. Anyone else notice this? |
No it shouldn't touch, I think Nottingham recommends 6 cm from the edge of the pulley to that of the platter? In any case, in mine, it never really made a difference where it was placed. The best just have to be stretched enough, and not too much.
For the record, the AceSpace is not a Spacedeck preset with tonearm and cartridge, it's a Spacedeck with improved bearing if I'm not mistaken. The fact that you got it preset has nothing to do with it. |
It's 6mm not cm. Yeah, somewhat different bearing, improved or not I don't know, didn't compare. |
