ETX-105 FEEDBACK Last updated: 31 October 2005

This page is for user comments and information specific to the new Meade ETX-105EC and ETX-105AT. Comments on accessories and feedback items appropriate to other ETX models are posted on other pages. If you have any comments, suggestions, questions or answers to questions posed here, e-mail them to me and I'll post them. Please use an appropriate Subject Line on your message. Thanks.

Subject:	Re: Now I'm cross - #1244 focuser (old model) on ETX-105 UHTC
Sent:	Thursday, October 27, 2005 16:51:18
From:	Stephen Bird (stephen.bird@btconnect.com)
Most strange. Afraid the only other things I can think of is that
perhaps the spigot that the fastening bolt passes through on the
focusser body is not seated to the full depth of the recess on the 105
OTA. Or possibly that same spigot is too large to rotate inside the
recess of the OTA. Or that you have the wrong gears in the focusser, for
some inexplicable reason.

One final thing that does come to mind, is that in the #1244
instructions, I recall they go to great pains to point out the correct
way round / position that the brass gear that must be, when attached to
the 105 focus spindle. When I attached mine, I reasoned that you should
have the focus spindle mid-way in its end to end travel limits, then fix
the brass spindle gear in such a way that the primary gear lies central
to the length of the spindle gear. the meshing should be comfortable but
not tight, and the smallest dab of white grease should be applied, as
any run out on the focussing spindle will cause either grinding or
slipping, usually at the limts of focus travel.

My 105 is a UHTC, 2 years old, and the focusser is the same age. Merely
grinding the focusser body away as you see in my pictures is sufficient
to allow easy adjustment.

Afraid I'm all out of ideas aside taking the scope to BC&F and asking
them to show you how to fit it, I have found them to be quite helpful if
you turn up in person at Tunbridge Wells.

Regards

Stephen Bird

And:

From:	Mike Snowden (mike.snowden@btinternet.com)
OK, I may have it now - though I'm not convinced how long it will remain
in the right position for...

The answer appears to be 2 things.

1) To put a small shim (about 1mm thick) under the focus axel end of the
intermediate plate
2) To bolt loosely.  As soon as any pressure is applied, the exterior
half of the enclosing case seems to distort, and the gears pull away -
this is not a solid part, and in pulling, the long brass gear loses
lock.  There is still play there, against the torque of the motor, but
it seems basically OK....

It's still looking reasonably clear outside - let's see if I can get
some of Mars on the DSI.  I MUST get around to parfocalising it in the
daylight....

Thanks for the virtual shoulders,
    Mike

And:

Of course, the nice clear sky of earlier has now gone...

One question.  When the focuser is not in, a utility menu (containing
particularly the battery level indicator) is available by holding the
mode button.  Is there any way to get to this with the focuser plugged
in?

Mike

And:

When you hold the Mode button down for 2 seconds, the focusser control
is displayed on the Autostar handset. Using the scroll buttons you can
alternate to other items in this menu. By default the focusser is
displayed first as it is the most likely activity required. When the
focus control message is displayed, you use the up/down arrows to focus
in and out, and the number buttons 1 - 9 to adjust focus speed. The
manual claims 9 speeds are available, I don't believe there are more
than four, as it says something like "Ultra Fine", "Fine", "Slow" or
"Fast" on the display, but that is another story. There is of course an
easy mod to give you extra fine control. Take a look at the attachment,
but remember that you can easily damage your focusser beyond repair if
you are not handy with a soldering iron.

Regards

Stephen Bird

And:

I'd completely missed the scroll feature, though what I had read claimed
four speeds - will try next clear sky.  No more mods will take place
until I've seen how well the it works, particularly with the DSI control
panel.

The focuser has always struck me as an odd device in many ways.  Does
ANYONE use the control box now, given that all new ETX for about the
last 5 years have Autostar, and it's an ETX specific unit.  They could
have massively reduced the cost by dropping this redundant piece, and
maybe they'd sell lots more.

    Mike

And this:

Subject:	1244 Focuser and ETX-105
Sent:	Thursday, October 27, 2005 18:48:17
From:	Mark Oristano (mark@oristano.net)
FYI, if anybody else is having the problem with the #1244 focuser not
fitting on their ETX-105, Stephen Bird's suggestion to file down part of
the housing so it fits better worked like a dream.

Mark Oristano

Subject:	Now I'm cross - #1244 focuser (old model) on ETX-105 UHTC
Sent:	Tuesday, October 25, 2005 19:10:37
From:	Mike Snowden (mike.snowden@btinternet.com)
Borrowed a friend's grinder, shaved off more plastic than I needed to,
and now when it's on, the OTA side does not touch at all.
Unfortunately, the gears aren't meshed either....

Any suggestions?

Mike

And:

From:	Stephen Bird (stephen.bird@btconnect.com)
Oops!

I avoided using a grinder because they looked to be too fierce. I used
coarse sandpaper and small files.

The plastic of the focusser body is obviously not that thick, it doesn't
need to be.

Best option for a repair would be to build it up with a little body
filler from the car repair shop (Halfords or B&Q in the UK) and then
grind slowly by hand until the profile matches. I can recommend Chemical
Metal from Isopon, I use it on my boat and it holds together in a Force
6, submerged in seawater! you will need to use wet and dry paper rather
than sandpaper to sand it down though.

Regards

Stephen Bird

And more:

I had another look at my scope and the pictures again, and to be honest,
as long as the grinding job gives you sufficient adjustment, it does not
make any difference that the part you ground away does mate exactly with
the OTA. The essential requirement is that the focusser body can pivot
around the single mounting screw enough to smoothly mesh the gears
together. Having a gap between the focusser body and the OTA is not an
issue as long as the mounting screw is tight enough (take special care,
do not strip the thread!) to hold it steady. The original problem is
because you had to tighten this single screw a lot to get the focusser
body to distort against the OTA and get the gears to mesh correctly.

From my photos you can see that the focusser body is rotated slightly
anticlockwise as you would expect, since the OTA on a 105 is larger than
a 90. The grinding of the projection in the upper right quadrant of the
focusser when viewed from behind in the photo, which bears on the OTA is
required to allow this rotation. I did play with the rotational
adjustment until the gears operated smoothly and without vibration,
which I gauged purely from listening and feeling the body of the
focusser in operation.

So far I have had 18 months of trouble free service.

Hope this helps.

Regards

Stephen Bird

And:

I didn't mean that I had trashed it - only that more material had come
off than strictly necessary.  There are no points of contact that I can
see between the body of the #1244 and the side of the OTA, but I don't
seem to be able to make the gears mesh.  Between the "jig" effect of the
elliptical piece and the geometry of the locating piece, I don't seem to
have enough play....

And:

Well that is a mystery, my #1244 is definitely an older model and
grinding the body away a little allowed the focusser to merely rotate on
its mounting sufficiently to perfectly mesh the gears. Whilst having the
focusser body fit neatly against the OTA would provide additional
stability and probably help resist the thing being knocked accidentally
out of alignment, provided the mounting screw is sufficiently tight
(taking care not to strip the thread in the process), such surface to
surface contact is not essential. Quite a few people have used the
grinder mod, and I have seen no one who has experienced the problems you
have.

It is probably a daft question, but is your 105 a PE model? And, are you
sure that you have a #1244 rather than a #1247? And, are you sure that
you have an old model #1244, rather than maybe a new model #1244 which
could be for the ETX90??

One last check, open the case of the #1244, ( very carefully as it will
fall apart on you), and check the plastic gears for stripped teeth, plus
any internal damage. As I recall from mine, the final drive gear is
brass, but the internal gears are plastic, plus the axles they run on
sit in holes in the plastic case. They would be easily damaged if the
#1244 was run on the 105 without being meshed correctly.

Regards

Stephen Bird

And:

The gears look fine.

I couldn't find the retailer number anywhere - just the #1244

It's just a 105-UHTC - though I have just have the flip mirror changed,
I wouldn't have expected the back to be different.

Mike

Subject:	Re: ETX-105 focusser
Sent:	Saturday, October 22, 2005 03:21:17
From:	Stephen Bird (stephen.bird@btconnect.com)
The problem with the ETX105 and the #1244 focusser is well known. If you
search Mike Weasner's archives you will find many references to the
problem and various fixes.

Basically the problem is that the #1244 was originally designed for the
ETX90 when the ETX105 did not exist, the #1247 was designed for the
ETX125 again when the ETX125 did not exist.

Along comes the ETX105, and instead of designing a focusser specifically
for the ETX105, Meade found that with a bit of brute force, the #1244
could be made to fit.

What I found is that if the mounting loosen or the gears wear, or any
number of other factors come in to play, that the result is slipping and
/ or stripped gears when the #1244 is used on the ETX105.

The solution is simple. the reason the #1244 doesn't fit is obvious when
you think about it. The ETX105 has a slightly larger diameter OTA than
the ETX90, so the body of the #1244 where the two surface meet needs to
be of a larger diameter, or you have to force the two together until the
body distorts enough for the gears to meet. What I and others have done
is to grind the #1244 focusser body away until the fit is better. Once
done, the gears mesh perfectly and do not tend to go out of adjustment.

Of course, once you grind the #1244 focusser body away, your warranty
for the item will be questionable so it will be a leap of faith. I have
heard that Meade now makes two versions of the #1244, but I have never
seen both on the shelf or advertised, I think that some dealers have
their own stock code numbers and confusion crept in at that level, could
be wrong of course.

Check out this article for pictures and discussion. you will find the
info you need there.
 
http://www.weasner.com/etx/techtips/focuser1244.html
 
Regards
 
Stephen Bird

From:	Mike Snowden (mike.snowden@btinternet.com)
I'm well aware of it - now.  Before that, I had checked that the #1244
did fit, but not carefully enough,

Subject:	Meade Electric Focuser #1247 on ETX-105PE
Sent:	Wednesday, October 19, 2005 14:46:12
From:	Mark Oristano (mark@oristano.net)
I've had the same kind of gear problem I've seen a lot of people write
about... the gears just don't seem to mesh properly, and there's lots of
clicking and very little focusing.

Is the 1247 right for the 105?  Is there another electric focuser on the
market?

Thanks,

Mark Oristano

And:

Sorry, I meant 1244.

This is the second one, and it just doesn't mesh properly.

Subject:	ETX-105 focuser
Sent:	Monday, October 3, 2005 16:43:15
From:	Mike Snowden (mike.snowden@btinternet.com)
Not a happy bunny.  A friend of mine, who was in the USA last week,
brought me back a #1244 focuser, bought from Adorama last week.  I try
and fit it, and no joy, the gears didn't mesh, despite it apparently
fitting perfectly.... Then I find the tip saying "model #0460201 only" -
I have #07077.

I'm going to try the Meade dealer in the UK, and see what they say, but
I'm not too hopeful - the "Angle Grinder" mod may be about to take
place.

Mike

I missed http://www.weasner.com/etx/techtips/focuser1244.html before
telling her the model number, and the Meade site is quite clear what you
have to ask for... So I'm hoping they will clear this up, but as a "grey
import", the UK main dealer doesn't actually need to.  At least there is
a way out...

I'm sure Telescope House will sell the right part, the issue is whether
they will do the swap to sort out Meade's error in failing to point this
out to purchasers on their web site.  TH's service is great, and I would
recommend them as dealer of choice to anyone in the UK.

Subject:	re: ETX 105 UHTC circuit board replacement
Sent:	Tuesday, September 27, 2005 21:57:52
From:	Richard Seymour (rseymour@wolfenet.com)
Although the circuit card is showing visible damage... you have not
isolated/located -why- it blew.  So a replacement card could also
die.
In my own scope, the card blew because a sharp edge on the RA clamp
nut cut through the wires' insulation... simply replacing the card
would -not- have prevented a subsequent recurrance (the cut was
 invisible, but could be felt by fingertip).

You could also try working through Meade Europe ( www.meade.de ).

good luck
--dick

From:	Stephen Bird (stephen.bird@btconnect.com)
Telescope House in the UK have been known to supply circuit boards
without the need to send the scope in for repair. When mine broke in
early August, they offered that, but as I was only a couple of hours
drive away, I took it in and they repaired it whilst I waited. I was
also given a refurbished RA circuit board and gearbox in case the
problem reoccurred, which was a broken gearbox rather than electronics
issue.

On the ETX 105 and 125, the RA circuit board and gearbox are best
replaced as a complete assembly, it makes the process simpler for the
DIY'er, and if you try to replace either the gearbox or circuit board as
a separate item, poor adjustment can cause the gearbox to break again.
Not sure about ETX90's, not seen inside one yet.

Best to ring Telephone House and talk to the service department, I found
they were very helpful. You can get all their numbers and e-mail
addresses from their website:

http://www.telescopehouse.co.uk
 
Regards
 
Stephen Bird

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