Stellavox SP7 Help

[JMDUK69]

Hi, I need some assistance and advice. I have 2 x Stellavox SP7 units that have been stored for several years. I've recently cleaned and serviced the units as I would like to bring them back up to being usable. I finally found and received the pinch roller tyres which had perished, and fitted these today.

However, both units have the same issue the feed real (left had side) is running much faster then the take up reel (right hand side) so the tape just spools out and is unusable. Does anyone know what is causing this and if it is a simple fix or do I need to find someone that is able to service the units to make them operate properly.

Many thanks in advance for any help the group can give.

 

[azama]

Hello,

Try the following:
- Place a full spool on the right side;
- Rewind a little;
- Switch to playback.

Is the problem still there?
Normally, it shouldn't.

This means that at the beginning of playback, when the take-up spool should spin the fastest, it isn't spinning fast enough.

The cause of the problem is likely the following:
On the SP7, the motor pulley is normally covered with rubber. Over the years, the rubber has deteriorated and partially disappeared. The diameter of the motor pulley is then insufficient to spin the take-up spool at a sufficient speed at the beginning of playback.

To overcome this, you need to gain about 2 or 3 mm on the pulley diameter.
This can be done simply with one or two rubber O'rings.

This isn't the optimal solution, as the motor pulley groove should normally be V-shaped to trap the belt during drive and prevent slippage.
But it should still work.

 

[stellavox]

Just came across this thread.

Had a similar problem with a customer's deck - and just duplicated it on a -7 that I'm converting into a Stellamaster. Problem has to do with the takeup reel tensioning system. The speed of the takeup reel is determined by the "slip" between its shaft and the pulley on its other end that is driven by the motor belt. This slip is controlled by the wire feedback from a clutch/brake on the pulley and the middle of it wrapped around the takeup reel's dancer arm. The dancer arm can move in or out. When it moves in (towards the headblock), the brake disengages, reducing the "drag" between motor and shaft and hence reducing takeup reel tension. When it moves out, the clutch engages, increasing the motor drag and tension. When working correctly, the arm should be kind of in the middle of it's travel, indicating that the feedback mechanism is working correctly and attempting to main constant tension to the takeup reel.

Your problem is not enough tension, so that the motor won't spin the takeup reel fast enough and the tape spools off the reel. The tension is adjustable. One end of the thin feedback wire is wrapped around a post that can be turned (using an Allen wrench) to increase or decrease tension. Loosening the wire increases the tension.

You can check if the tensioning mechanism is working at all by spooling and playing a tape but NOT wrapping it around the takeup dancer arm. The tape should spool correctly but with maximum tension. Over time Stellavox did add some additional felt disc pads to the bottom of the takeup pulley - like from maybe 3 originally to 5 or so. This privided additional tension as necessary. If the tape still spools off with the tape not wrapped around the dancer arm - may need more disc pads. Disassemble, remove the pulley and look on its underside to see ho many are there.

Hope this helps
,