Problem calibrating my SkyWatcher Explorer 130P SynScan AZ GOTO scope

[red1902]

Hi

<Reposting this under Equipment Help>

I have been having difficulty calibrating my recently purchased SkyWatcher Explorer 130P SynScan AZ GOTO scope.

While I understand this is not uncommon, I feel I have followed all the instructions and read numerous help forums and believe I have avoided the usual pitfalls (Long/Lat, American dates etc).

Today I discovered the SHOW POSITION function, so bypassing all calibration settings and simply using that function I observed the following.

Simply using the UTILTY FUNC > SHOW POSITION, whenever I rotate the scope through approx 360 degrees, the function displays 524 degrees of rotation.

ie it thinks it has rotated further than it actually has. 360/524 suggests it is moving only 68% of the requested rotation. Rotation is smooth but the error is consistent all the way round, ie at 90 degrees it thinks it has rotated 131 degrees.

This explains why when using two star calibration, it never even gets close to the second star. I have to slew it round quite a distance to align it with the second star. Unnervingly, it always reports alignment successful!

It is pretty consistent - every time I try this it records 524 degrees of rotation when the mount has only moved 360 degrees.

I've tried the restore factory settings - no change.

Am I doing something stupid? do I have a faulty mount? or is there some calibration setting I have overlooked?

Thanks for your help

[ronin]

No direct knowledge of the unit you have but on other gotos there is a calibrate motors/drive action. Meade scopes require you to tell the handset the scope that it is plugged into. You could tell the handset that it is plugged into an LX10 but really have it plugged into a ETX80.

Is there an option to select the mount that you have?

Just wondering if the default for the system is Mount A while you have it plugged in to Mount C. They will have a default setting which could need changing.

The different mounts have different gear ratios so I would suspect this as the simple answer.

[red1902]

Thanks for responding

It is a straight out of the box widely available package, so you'd expect it to just work, but yes, I had thought it might be a motor calibration thing. It almost sounds like a 2:3 gear ratio misconfiguration.

The mount is described as a "SynScan™ AZ GoTo Computerised Alt-Azimuth HD Go-To Mount" and the handset is a "SynScan™ AZ hand control". I've trawled the Handset for a configuration option to specify different mounts in case it came misprogrammed, but to no avail - perhaps it just alludes me. Also tried the reset to factory settings option.

I have contacted the supplier.

[Mikea]

Hmmm.. That is strange. I have the same mount but have never seen this behaviour. What version firmware does the handset report?

[red1902]

Synscan AZ Ver.03.08

[roebuck]

I had a similar problem with eq5 synscan turned out I had set date in english format and not american: mm/dd/yr.

[Mikea]

Ver 3.08 is the latest version and is supposedly suitable for Dob and Alt-Az mounts. I'm still running 3.07. I wonder if anyone else has an AZ GOTO running 3.08?

[RascalUK]

I have exactly the same set up and not had a problem. The second star align is generally in the vicinity unless my batteries are running down in which case anything can happen.

You do not need to set any mount type. Don't even think you can.

If you are totally positive your date and long / lat is correct and in the right order it must be faulty?

Be wary though. I had my long / lat in back to front and wasted two hours of frustration first time out.

[Capricorn]

Be wary though. I had my long / lat in back to front and wasted two hours of frustration first time out.

Just 2 hours.

Someone once had it wrong for about 4 weeks and was swearing blind everything was right. Another person drove to their place, put it in right and drove home.

[Capricorn]

Just looked through the Sherwoods site. You can get Synscan for:

EQ6, HEQ5, EQ5, EQ3-2, AZ Goto (Yours?) and the Merlin Table Top mount.

All the handsets look identical and as the ratios inside the mounts will all be different (all the EQ ones are different) either you can set the mount or the handset is flashed dedicated to one specific mount.

The latter seems unlikely, however I suppose that the mount could tell the handset what mount it is via simple jumpers on the PCB. (Possible option for ease of use)

Leaves the idea that you set/specify the mount or you have managed to get the wrong handset. Wrong handset probably means someone has opened two scopes up in a shop and put them back in the wrong boxes, so someone else is having the opposite problem.

If flashed with the wrong firmware it would need reflashing or replacing. Would have expected the handset to state what mount it is for somewhere

Think a phone call to OVL is required or return to shop (?) where it came from. New handset is easy, reflash is fairly easy, changing jumpers is easy if you know what to set to.

[red1902]

Thanks everyone

Shop (Rother Valley Optics) have suggested I return the handset and cable for testing. If that comes up clean they will take a look at the mount.

[Mikea]

Far be it from me to contradict OVL, but wouldn't it be better to ask them to check out the mount and controller at the same time?

[malc-c]

I've just looked at mine, and the SynScan unit is clearly marked "EQ5", so it should be obvious if the wrong synscan unit had been supplied, unless as Capricorn has suggested some internals had been changed. Does anyone know if the handsets are different between models ?

[Capricorn]

Interesting reading. The firmware in the handset looks like it is either EQ or AZ.

There is Motor Control firmware (updatable) and I guess that this firmware identifies to the handset the type of unit that is in use. It could just identify to itself the unit and simply reinterpret the handset commands. As in Slew at 9x and just calculate what 9x is for the system.

There does not appear to be anything that the user sets to identify the general system.

Information is under the handset menu: something like Utilities, setup, versions - it is in the manual that came with the scope. If plugged into the AZ system it will report the MC firmware.

The Synscan manual (just Synscan not AZ Goto) does not really mention AZ mounts, all diagrams and words are for EQ mounts.

[red1902]

So, just to close this thread out...

The problem was a missing jumper on the mount motherboard - JP2 to be precise.

Once the jumper has been inserted, the mount behaves just fine.

Thanks to my supplier - Rother Valley Optics - for identifying the cause and to everyone who offered suggestions here.