Important
Rajiva has issued a firmware update v3.59 Revision D
which should be installed. Follow the link on this page
Upgrades, add-ons and fixes
As with any mount/tripod that is meant to 'fit' just about any scope and for any climate, the HEQ5 isn't perfect. I've
also come up with a few simple 'fixes' for things that Synta forgot about, or should have built in.
Knowing a bit about electronics and programming; and being able to handle a soldering iron means
that I've been able to drag my HEQ5 from it's niche at the bottom of the mid-range consumer mount category to
be able to run with the luminaries of the range such as the Losmandy GM-8.
Here is my list.
- A dovetail bar for the C8
Not really part of the mount but something I had to do. The dealer I purchased the HEQ5 from had some in stock
and I picked up the 'long' one. The HEQ5 does come with a bar, but it would have meant a lot of fabrication
to put it on the C8. The long bar just fit with a bit of judicious use of a drill press (to open up some
screw holes etc.). One hole had to be drilled/tapped in the rear cell of the C8. We did this with the
scope intact which meant removing the corrector to clean out some aluminum debris. Not a big problem but
it meant a re-collimation in the field. About a 2 minute job with the spring modification I had already
done to the C8.
- Shortening the upper altitude adjustment screw
The first thing I noticed was that with the C8, one counterweight at the bottom of the shaft was just barely able
to balance it. Putting both counterweights on meant that they needed to be up near the top of the shaft and at
42 degrees latitude, they banged into the upper adjustment screw. Five minutes with a hack saw and Dremel tool fixed that.
- New lubricant and worm adjustment (Three pages)
Yes, on the HEQ5 Synta uses that black goop (I'm sure it's made from kindergarten paste) they call
lubricant. I've replaced it with lithium grease on both axes. This makes balancing a telescope both
very easy and very precise. While it's apart adjust the worm engagement. RA procedure is here, the
procedure for the declination axis is here and the diagrams for the correct tool and
how to adjust worm shaft end-float is here. Sorry, no pictures.
- Lower tripod brace (see link to my home-made brace)
This is a 'home-brewed' item that I came up with and that was realized with the expertise of Dave Rubenhagen.
The legs on the tripod are only 1.5" OD and need all the help that they can get. As shipped the legs are braced against the side of
the tripod head by the spreader. The lower brace lengthens the 'triangle' and stiffens the mount considerably.
- Mahogany tripod legs (see link to my tripod legs)
The thin-wall steel legs on the HEQ5 are lacking a little, especially if you are carrying heavy loads or doing imaging. Here
you can read about how I replaced them with good-looking, solid mahogany legs adjustable for leveling.
- One-knob RA axis worm adjustment ( See link to my page )
No more setscrews! This complex-looking mod allows single screw, spring-loaded adjustment of the worm on the RA axis, or,
setting 'perfect' engagment at any point on the gear.
- New counterweight shaft ( See link to my page)
The 'stock' shaft is 18mm in diameter and is both a bit flimsy and can move. Doug Dieter provided me a new shaft and Dave Rubenhagen did the necessary conversion work. The new shaft is 22.5mm in diameter and threads into the end of the declination housing. It is both stronger and stiffer.
- Motor control unit and hand controller updates (see link to my page)
On the 'must have' list and available for 140 Euros from the Rajiva in Germany. The
electronics update provides the following features not available on the stock drive:
Motor control unit
- Adds 32 step micro-stepping to the stock Synta motors
As shipped the HEQ5 uses 3.75 degree/step rate with no micro-stepping.
- Fine guiding at 1.3x, 1.67x or 2x
As shipped the HEQ5 will guide at 2x only
- Custom user-defined tracking rates
- ST-4 compatible auto-guiding
- LX200 auto-guiding
- Periodic Error Correction with 256 measuring points (includes PEC table 'touch up')
- Backlash compensation in both axes
Configurable compensation direction and number of microsteps to use for compensation
- IntellyTrack (dynamic tracking - optional)
This gives the mount the ability to track at any speed in BOTH axes. This ability allows the tracking
of comets, asteroids; or just to adjust the mount to an imprecise polar alignment. It trains itself
dynamically as you track the object. Can be used with PEC but unlike PEC there is no set 'training'
that has to be performed.
- Sidereal, lunar and solar rates
- LX200 GOTO through RS-232 serial port (Optional)
Just about any software that will handle 'LX200 Generic' commands can be used to control the
mount. The Goto is limited to 40x which is quite slow, but still useful.
- DSLR (Canon) shutter control (with some home-brewed electronics)
- Focus motor support with high/low speed (two motors... as above)
- Cooling fan control (as above)
- Support for 100:1 Conrad gears (see below)
- Updatable firmware
Hand controller
- Focusing control
- LED colour change. The green 'on' LED is VERY bright. The MCU update uses green only for PEC.
- Menu driven control for many features of the new MCU
Custom breakout box with anti-dew heat control (see link to my page)
The Rajiva MCU update provides for RS232 communication, ST-4 auto-guiding, focus motor control etc. But, to realize all of this you'll
need to build some kind of 'breakout box'. Here are some instructions along with a thought on a custom circuit etc. It all works at once
now.
Conrad motor transmissions for both axes (see link to my page)
These are on the 'must have' list and are available for 35 Euros from Rajiva. The
MCU Update above is required due to the different reduction value. These transmissions are from Shayang Ye in Taiwan and marketed by Conrad in Germany. They are precision gearboxes with metal gears
instead of plastic, and they come properly lubricated in a stiff enclosure. The stock Synta gears are just 'tacked' into the
metal tub on top of the stepper motors. I've completed the upgrade now and it makes a lot of difference.
Fixing more of Synta's bad engineering (see link to my page)
Some people who have done the MCU update have reported that they're getting electrical 'noise' from the TQ2 relay on the
original board. Synta, in their ultimate wisdom, decided to drive the 5v relay with 10v; 2.5v over the datasheet maximum.
This can drastically shorten the life of the relay, and contributes to the 'noise'. A simple modification fixes the problem.
Along with the above, the hand-controller needs looking at. Barring building a whole new one (a future project) here are the problems I found and fixes for them.
Smoothing out the azimuth adjustment motion ( see link to my page)
The machining on a Synta mount not being perfect, I wanted to ease the tension on the azimuth adjustment knobs while smoothing out the motion. A simple bearing surface did the trick.
New azimuth adjusment knobs ( see link to my page)
The plastic azimuth adjust knobs that shipped are very cheap. Here are some cheap to make replacements.
Illuminating the polar alignment scope (see link to my page)
There is no illumination for the polar-scope's reticule on the standard HEQ5. Rajiva has put the ability to
add one onto his MCU Update board. Here's a short page on how I did it.
Other things I've done to make life simpler
- Hand controller 'mount'
There's nowhere 'secure' to put the hand controller. You can hang it from the cable in the 'notch' in edge of the
spreader/eyepiece holder or just lay it on top; but it can and does get knocked off easily. Go to Home Depot (or your
favourite DIY superstore) and buy some 'Industrial Velcro'. These come in 2x4" sheets or 2" circles and have really good adhesive. I
use it to hold my power bus/heater controller to the flat on the mount and it's secure. Cut a section off of both
types and put some on the flat on the RA axis casting opposite the RA lock lever. Also, cut some smaller pieces
and put them on the tripod near the top of the leg. Now put the opposite
Velcro on the back of the hand controller. You now have a place to 'store' the hand controller (on the RA casting) and
a quick place to hang the hand conroller (on a leg) for quick access. Simple.
- Index marks
The RA, dec and latitude index arrows are all but impossible to use in the field as they're matte black (the same as the 'background') and extremely
difficult to read. This is the simplest 'fix' in the list. Paint them white with a very fine brush and good quality
acrylic paint (or whatever wears well). Also, the 'index' for the date/time ring is very small, very fine and very
hard to see. Run some paint into it and quickly wipe off any excess. It's still small and fine, but it's now a lot
simpler to see.
- Polar scope cap tether
I got tired of putting my polar scope cap down in the dark and 'losing' it so I put a tether on it. Simply drill a hole in the cap and a hole in the top cover and use a suitable rubber band or pulley belt as a tether. Use a 'figure of eight' knot at each end to hold the tether in place. If you want to seal the holes use hot glue and then trim it.
- Screws
Replace ALL the screws and setscrews that hold the mount together. They're all the cheapest quality and DON'T fit any normal screwdrive. My tools are Snap-On so I know that they're good; the screws just don't fit. I replaced the black screws that hold down the motor cover with stainless cap-screws. The fancy plated screws that hold the axis locking levers look good, but they're crap too. Don't buy more cheap screws; go to a fastener vendor with examples and buy double what you need. Keep the extras in a pill bottle with your toolkit (you DO have a kit with all the tools needed to work on the mount with you observing... don't you?).
- Linux Software (see link to my page)
The only software for Linux that I could find was command-line and only implimented a few of the commands available
to the drive's firmware. So I started writing an application in perl-GTK2 that would provide all the the needed
functions for configuration and control of the mount.
- Windows Software (external site)
The best package out there to configure/control your newly upgraded HEQ5 is from Doug Dieter and can be found at
his website. This is what you'll need to enable the goto and
IntellyTrack features of the electronics as unfortunately, the Linux software is unable to enter the keys.
Future projects
There are a couple of things I'd like to do with the mount which will involve it being 'hors de combat' for a while. The first
is to lap the RA worm/wheel together to reduce periodic error. The second is to look for some thrust bearings that will fit the
worm shafts and replace the roller bearings that are in there now. I don't know how much that will help things, but the theory
is that the (perhaps) 5lb of thrust on the bearings will wear them out quicker. It's not a priority right now. The last is to
replace the plastic top cover with aluminum or brass. That would be very 'sexy'.
On to part 5 - The Price
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