MEADE #1247 FOCUSER MOD FOR ETX-125PE Last updated: 31 August 2008

Subject:	Meade 1247 Focuser on ETX-125PE mods
Sent:	Wednesday, August 27, 2008 13:35:55
From:	Tom McKechnie (tjmck@mts.net)
Thought I would drop you a line on my experience while modifying the
Meade 1247 Focuser to fit the ETX-125PE.

First off, I have an original version PE with the flimsy LNT and flat
plastic red dot finder.  I do not know if the new LNT / hooded red dot
finder version has the same interference issue of the focuser cord lock
hitting the LNT 'bracket'.

I purchased a used 1247 through the Buy and Sell forum on Cloudy Nights
(Thanks again Kolenka!).  I had been looking for the electronic focuser
for a long time and had read most of the feedback correspondence and
tech tips regarding the focuser on your site.  The one I found the most
helpful was -
http://www.weasner.com/etx/archive/feedbackMar05/etx-pe.html, Subject:
1247 electric focuser, From: Frank George.  It showed a picture of a
Meade modified 1247 fit to a ETX-125PE.  The detail needed was the
relocation of the cord from the front cover (great photo of the existing
old hole) to the rear cover.  I decided to replicate the modification.

Upon taking the three screws holding the cover off and opening the
focuser, I took pictures to ensure proper re-assembly.  After looking at
the covers, gears, motor and printed circuit board (PCB), I took
additional photos of the PCB detailing the cord wiring.  I then used a
pair of needle nose pliers to gently squeeze the cord lock and pull it
from the cover hole.  I removed the cord lock from the cord and
contemplated removing the cord wires from the PCB.  I then looked at the
cover hole where the cord lock had been removed and compared it to the
RJ-11 connector on the cord.  It looked like the RJ-11 would pass
through the hole.  I threaded the coil cord through the hole and sure
enough the RJ-11 passed through by depressing the connector latch on the
RJ-11.

I took the rear cover to the drill press, setup the drill and vise and
drilled two offset holes (located as shown in the pictures from Frank)
to replicate the oblong cord lock hole on the front cover.  I then
passed the RJ-11 through this hole and that's when I found I would have
to remove the PCB and the motor to allow for re-assembly.  I took care
to route the wires as they were in the unit upon opening with the
exception of the cord which was now routed through the back cover of the
focuser.  This re-assembly was somewhat difficult particularly the
routing of the motor wires, alignment of the center gear shaft and
seating of the focus shaft drive gear.  I put it all together, mounted
it on the scope and heard a clicking  no focusing was happening.

Looking through the original cord hole on the front cover, I could see
that the motor gear was slipping on the center gear.  This happened only
under load.  If I took the focuser off the scope the gears operated
smoothly.  I took it apart to re-evaluate.  I found that I had placed
the motor back into the housing with the flat sides of the motor closest
to the center gear.  The flat sides allowed the motor to deflect and the
gears to slip under load.  I remounted the motor with the rounded side
closest to the center gear.  This solved the problem and the unit is on
and functioning smoothly.

Without the motor issue the modification would have taken 30 minutes.  I
still need to fill or cover the front hole.  Hope this helps others
trying to do the same thing.
 
Thanks again for the great site.
 
Tom McKechnie

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