EFW2 Startup Problem

[joelshort]

For a long time now I've been noticing a random startup issue.  What will happen is I will connect the power and the wheel will spin.  I then connect the capture software and connect the filter wheel.  However when I first issue a filter change the wheel does not move and the capture software just sits there waiting for a response and eventually hangs.  I can resolve this by simply unplugging the filter wheel and plugging it back in and then all is well.

Just recently I had the filter wheel off the scope and was doing some testing with a new camera.  I noticed that when I supply power to the EFW2 it will spin but NOT get to position 1.  It will stop between position 4 and 5.  So I power cycle and this time the wheel gets to the correct position 1.  This is repeatable: the first time powering up the wheel stops prematurely.  The second power up it stops correctly.  Every time.

Any thoughts as to why this could be happening?

[joelshort]

Just to update this thread...I believe the problem is fixed.  The problem was that the OAG screw that was closest to the filter wheel center was actually rubbing something internal to the FW.  I shaved that bolt down just a bit and the problem has disappeared.  Perhaps that particular screw was out of spec.

[vince]

Hi Joel,

If the screw was slightly too long it would cause the problem you describe, the screws supplied with the OAG should be M3 x 8 mm, do you know how long yours were?

Best regards
Vince

[joelshort]

I'm sorry Vince, I mis-spoke.  The screw in question was not one of the original ones supplied with the OAG.  I replaced one of those screws with what I thought was an equivalent one.  I thought the new screw was the same length as the original but apparently it was just a hair longer.  There's been no problem since shaving down the screw just a tiny bit.