Film-Tech Forum ARCHIVE: Speco LP270 problem

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Posted by Ian Bailey (Member # 1752) on 09-24-2006, 05:21 AM:

This problem is very intermittent and only happens on one deck.
The payout arm will come back to rest in the stop position and the motor still drives causing film to wrap around the brain.
I have replaced the Payout PCBd under the deck and have checked the magnet's position and that it is not loose.
To stop the motor driving I think you just tap the payout arm against the stop post,I'd have to check on that.
Cheers Ian

Posted by Tim Reed (Member # 137) on 09-24-2006, 06:08 AM:

Is the platter disc's axle bent, causing the arm to not return fully to the rest position?

If that isn't the case, it really sounds like the magnet isn't quite positioned correctly relative to the payout arm.

Posted by Steve Guttag (Member # 268) on 09-24-2006, 06:33 AM:

Here is my question...on the SPECO LP-270, the payout has three speed positions...one is off, one is relative to the take up speed and one is "full-on."

How close to the bumper for full-on does the platter go to full-on? I tend to set mine to 1/4" (about 6mm) or so. I want to say the manual calls for something closer to 3/8" but that feels too far to me.

Juts give resetting the magnet a try...that is have it swing further over until it always shuts the platter off. Then verify that you still get the full-on position.

Note, there are two position settings on that magnet...there is the roational one with the magnet arm relative to its shaft and there is how far the magnet extends towards the PCB. You might also try setting it so it is a little further away from the PCB (loosen the holding nut for the magnet to reposition it).

Posted by Ian Bailey (Member # 1752) on 09-24-2006, 08:35 AM:

Thanks Tim/Steve
I think you are right with the magnet position and I didn't realise that there was 2 adjustments.
Now I'm not sure if I've been setting the magnet correctly.
What I normally do is set the pay out arm roughly 1/2" or so from the Full On Post and have the magnet central to the P.CBd.
What would be the correct setting for how close the magnet is to the PCBd? I don't see why the magnet should be adjustable in this direction.
Cheers Ian

Posted by Dave Macaulay (Member # 813) on 09-24-2006, 10:16 AM:

The magnet distance affects how much arm travel each sensor is active for, you want a "dead zone" at the off end of the arm travel.
I don't think you can set the thing with power off. There's AC on the heat sinks on the card though, be careful. With the takeup slack, you won't have any payout power in the middle arm position so you can set the magnet angle to leave about 3/8" of travel to the "tight" stop when the motor runs at full speed. Then pull the takeup dancer about 1/2 way and check that the payout motor is unpowered for the first inch or so of travel (from slack), then runs at low speed (power from the takeup powerstat) until about 3/8 inch from the "tight" stop where it gets full power.
The distance setting is usually OK but if you can't get enough power-off arm travel you may need to move the magnet further away.
You don't want too much full power arm travel... when the platter overspeeds and the slack loop passes itself, things tend to get messy in a hurry.