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[ajmogis]

I'm working on an A800 where there is something causing some excess friction in the travel of the prestabilizer roller.  At first I thought it was the dashpot, but when I disassembled it to see if it was dirty (which it wasn't), I noticed there was no change in the motion of the roller assembly.

Has anyone experienced this before?  Could the solenoid assembly/armature be doing something to cause this?

EDIT: It's gotten so bad that the pinch roller won't engage without me giving it a nudge. Then when I hit stop the rollers don't disengage back to the stop positions.

[Dave Hecht]

After you checked the dash pot, did you try adjusting it for lower resistance? If the pot is not adjusted correctly, it can cause the symptoms you describe. If the puck still hangs up with the dash pot set as low as possible you may have a bad solenoid. I have had to replace a few of those over the years, but more often than not, it was just a dash pot adjustment.

Dave Hecht

[ajmogis]

Yes it was with the dashpot set for lowest resistance.  Even with the dashpot completely disassembled there was still resistance, so it looks like I will have to find a new solenoid.

Anyone have any suggestions?  Oh, how I long for the days when Studer still had a legitimate parts department.

[Mike Cleaver]

It's been years but check the mechanical alignment of the solenoid and it's plunger.
If they are not correctly aligned, the plunger can stick, iirc.

[Dave Hecht]

Try Mike's suggestion first. I don't recall ever having a mechanical alignment problem with the solenoid, but it's worth checking. Another issue I've had is with the surface of the plunger getting scored from years of use. Last time I ran into that, I just disassembled the solenoid, cleaned the dust out, and reconditioned the plunger. To recondition the plunger, I picked up some graphite powder at the local hardware store, poured some in a tex wipe and applied to the plunger. Worked great, actually better that I expected.

Dave Hecht

[ajmogis]

Thanks for the suggestions.  Much appreciated.  

[ajmogis]

Solenoids turned out to be fine.  I traced the problem to the joint between the stabilizer arm and the linkage connecting it to the pinch roller arm.  It seems like maybe there's something inside where the pin is that's binding up the whole thing.  I put a small drop of WD40 and then a small drop of oil in there and it loosened up enough to work properly, but it seems like there's still something inside the joint.  There's no way to get that pin out is there?

[slothus]

I think I had a similar problem once, although it wasn't a total bind, more an anoying squeak when the mechanism released. I think I moved the position of the offending linkage down the pin and changed the position of the jesus-clip to the lower position (if there is such a thing). Seemed like there was a burr or some such wear causing it.

We might be talking about different linkages in that area though, I'm not in front of a machine to check. That did drive me nuts for a couple of weeks though from memory.

Brent Punshon

[ajmogis]

Working the joint loose with a small drop of machine oil seems to have done the trick.  Everything is working smoothly with the pinch roller assembly.  Now I can get back to the more troubling issue on this machine.  I'm going to start a different thread for that one because I'm stumped.

Thanks for the help.