ETX TECHNICAL TIPS Last updated: 23 December 2000

ETX-125EC Right Ascension lock fix

Sent:	Friday, December 22, 2000 17:36:43
From:	plloukota@juno.com
I've noted that a fair lot of users are complaining about the excessive
torque requires to 'lock' the RA clutch on a ETX125EC.  After I reached
a point that it hurt my thumb to get it tight, I decided to have a look
inside as this wasn't right.  What I found was very interesting and
somewhat disappointing too.

1. Meade cut corners on this one.  After I removed the lower clutch plate
I found what I consider, very poor workmanship.  Mead had used a center
punch to put two dimples on the plate surface.  This is the plate that
tightens up against the main drive gear.   I also noted that the total
clutch surface is a bit lacking but that's the design and I have to live
with it.  What really bothered me was the Mickey Mouse way they
attempted to increase the clutch friction with these punches.  the
picture shows the ware pattern as being the dimple edges and a small
amount 180deg from the dents.  This would help to add some friction
UNTIL the punch ridges wore down a bit then the clutch would take a
gorilla to tighten.

My fix was to remove the plate and drive gear, resurface the plate (a
good file or lathe works here).  Once the plate is flat, all of the
leached grease and metal dust was removed.  I then fabricated a
intermediate friction plate from .032 fiber clutch material I had around
the shop.    this plate fits between the outer plate and gear and is
soft enough to allow more contact surface area under compression.  Be
very careful how you reassemble the AMP punch-block connector.

The clutch now does not slip when being driver by the motor under normal
conditions but will slip when driver into the stops.

I think that the punch marks in the plate was someones attempt to get
the product out the door.  But that's just an electromechanical
engineers opinion.

Anyway this worked for me.

Doug Loukota

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