ETX TECHNICAL TIPS Last updated: 10 August 2001

#541 AC Adapter fix

Sent:	Thursday, July 5, 2001 17:12:17
From:	d.birmingham@worldnet.att.net (David Birmingham)
I had purchased the #541 AC Adaptor from The Science Company almost two
months ago. When the first one arrived, it was defective right out of
the box. I didn't even take it apart since the 30 day return policy was
still in effect. I merely e-mailed The science Company and they in turn
told me how to go about returning it for replacement. By the time I got
the replacement I had my new ETX-125EC boxed and shipped to Dr. Sherrod
for a Supertune, which was the BEST thing I did. When the scope returned
I enjoyed using it, with the #541 AC Adaptor for about 10-12 hours on a
couple different nights. Then the clouds came and stayed, which they do
in Michigan, so I didn't have a chance to get the equipment out, That's
when I build the Sherrod Modified Pier.

Any, to cut to the chase, when I did next get out the scope and
equipment I plugged everything in, and NO power. The 30 day time had
elapsed by now, so this time I took the #541 AC Adaptor apart. Soldered
to the IC board inside was a glass 5 amp fuse that had blown. I have a
computer surge Adapter that always plugs into the wall socket before the
extension cord, so I do not know why the fuse blew. I can only say the
thing was built with cost effectiveness in mind.

I decided I could come up with something better than direct solder to
the IC board, and Radio Shack "The Shack" was the answer. One $1.59
Automotive inline Fuse Holder and a four pack of 5-amp Slow-Blow Fuses
and I was back in business. This makes the unit field repairable as long
as you add one small Phillips screwdriver to your accessories.  Oh, you
will have to CAREFULLY drill out the two holes in the IC board to accept
the wires on the in-line fuse holder, I use a 1/32" drill bit also a
small soldering pencil and de-soldering tool along with wire strippers.

Attached is a photo of the finished modification. There is plenty of
room inside the case for the holder. After I completed this fix I
thought, and checked, for enough room to mount an external fuse holder
so it would not be necessary to open the case in the field. There is if
the holder is mounted on the back of the cover centered in the middle at
the bottom below the label.

Dave

Subject:	Re: #541 AC Adapter fix Telescope Tech Tips
Sent:	Wednesday, August 8, 2001 21:44:21
From:	d.birmingham@worldnet.att.net (David Birmingham)
As I stated in my article on the Meade #541 power supply fix last July
5th there should be a way to mount an external fuse holder. There is,
and I finally got around to doing that little project. After a trip to a
commercial/residential electrical supply store I came home with a "Panel
Mount" fuse holder (sorry, it had no number on the package). It is the
kind that has a bayonet cap holding the fuse in the holder which is
mounted from the inside. The particular holder I came up with is without
wires, so two short lengths will be needed to attach it the circuit
board in the power supply. The proper size hold was drilled in the back
cover in the lower right corner. The hole was moved in 1 1/8" from the
edge (to miss the screw stool) and roughly .5" up from the joint of the
two halves of the cover. With the slow blow short fuses I purchased at
the "Shack" I needed a spring to take up the slack for the fuse length.
In my treasure chest (junk box) I found a spring from one of those
be-fold closet door guide systems that fin perfectly in the holder. The
only modification I needed to do was to crimp one end of the spring to
stop the fuse from sliding through. After the drilling, soldering and
installation I came up with the finished fix as shown in the photo.

I hope that this information might be of some use to other star gazers
who run into the same problem that I did. In my estimation your site
should receive more awards than it has, and since you help other owners
of Meade products to enhance their lack of QT perhaps a little backing
from them as well. And you do have one cohort in the form of Dr. P. Clay
Sherrod that is one of the most knowledgeable people of telescopes I
have ever known!

Return to the top of this page.

Go back to the Tech Tips page.

Go back to the ETX Home Page.