Why wont my skywatcher auto-tracking mount work? At All...

caleb · #1 19-04-2009, 02:35 PM

Hey, I have had my MAK80 for some time. But after going through several battery packs I decided to cut the cord and solder some clips on their. For use with a 12VDC transformer or a 12V rechargable battery.

Well it worked quite reliable for a while but not any more. Although it might go on for a few seconds, or the keypad will flash repeatatly.

The RJ45, or ethernet/phone style plug is slightly damaged, as the clip that 'clicks' it in broke off and I will have to hold it or put in a position so it will stay. Although holding the plug, I'm sure that all contacts are in contact. So I cannot say this is the problem.

So does anyone have any ideas?

TrevorW · #2 20-04-2009, 04:25 PM

Maybe it's because these scopes propably use a regulated power supply and unless the substituted power supply was regulated then it can cause problems.

I think

Glenhuon (Bill) · #3 20-04-2009, 06:51 PM

If the supplied voltage falls too low this will happen. Had the same problem with mine when I let the 12v battery discharge too much. The mount will draw ~2 amps when slewing, if the power supply is not rated for this or more it will drop the voltage below the critical level (seems to be around 11v). Same with a faulty/low charge battery. Pretty sure there's a warning on Andrews site (?) re the Synta systems not being built to tolerate unregulated supplies.

Bill

caleb · #4 21-04-2009, 01:08 PM

Ok, thanks Bill. That seems to be a valid reason. I guess when you buy the 8!!! AA's for some $$$'s one or two of the batts may go before another

So all up they don't last very long.

caleb · #5 22-04-2009, 05:24 PM

Well, I went out and bought some new batteries today. Chucked 'em in to find it still wont work

I tested the batts with my multimeter to find 13.5V, so is this too much?

As well as the 'middle' of the plug being the positive, I'm sure the middle is usualy the negative

Just hope I can sort it out or my astronomy life is over

Omaroo (Chris Malikoff) · #6 23-04-2009, 07:04 AM

Quote:

Originally Posted by caleb

I'm sure the middle is usualy the negative

NOOOOO!!!!!!!!!!!!!!!!!! Hardly ever! I hope that you didn't wire up your external supply with a negative centre and try it.... which might explain why it doesn't work now on batteries either.

caleb · #7 23-04-2009, 10:36 PM

Well, it was working although the hand control felt as though it was warm.

And another thing with wiring, I'm prety sure white is positive and black is negative, welly welly. Black is pos and white is neg in Skywacther lingo

Actualy, come to think of it I ran the power into the battery pack with +/- (without batts) so I guess it was running through correctly.

I wanna get a t-mount crank'en.

Glenhuon (Bill) · #8 24-04-2009, 10:45 AM

Caleb, Synscan plug is centre pin Pos. In the battery case the Spring is Neg and the opposing pad Pos.
If the handpiece is getting warm, thats not a good sign. Methinks you need the services of an electronics doctor to give it a physical.
If your external supply is unregulated and poorly smoothed it could cause the warming and ultimately do permanent damage. Its the "ripple" in the DC that causes the problems. 13.8 is OK as its nominally 12v rated and will tolerate a couple of volts over. The idea is that when you start to pull extra power from it during slewing for instance the voltage doesn't drop below critical.

Bill

Quote:

Originally Posted by caleb

Well, it was working although the hand control felt as though it was warm.

And another thing with wiring, I'm prety sure white is positive and black is negative, welly welly. Black is pos and white is neg in Skywacther lingo

Actualy, come to think of it I ran the power into the battery pack with +/- (without batts) so I guess it was running through correctly.

I wanna get a t-mount crank'en.

caleb · #9 24-04-2009, 01:35 PM

I'm not sure if an electronincs doc could do much, the problems are usualy invisble... Although I could be wrong, my bro is a sparky so I'll ask him.

I guess I can look around for a new hand controller.

Robert9 (Robert) · #10 24-04-2009, 02:20 PM

They should build these things with a series protective diode to prevent damage by reversed polarity input.
Robert

caleb · #11 24-04-2009, 04:23 PM

Thats what I would have thought, I'm prety sure the diodes heat up when they are stopping current.

Robert9 (Robert) · #12 26-04-2009, 01:49 PM

Quote:

Originally Posted by caleb

Thats what I would have thought, I'm prety sure the diodes heat up when they are stopping current.

No, if they are not passing current then there will be no heat generated. P=IxIxR if I=0 then P=0. No power, no heat. If however there is a current by-pass diode across the power input socket which will carry the current if there is a reverse polarity connection, then there would be heat generated by that diode and any series resistive current-limiting component in the by-pass circuit. But if there is a reverse polarized protective diode which will just stop current flow, then why bother with the current by-pass.

No, if things are getting hotter than normal, then it is my guess that something internal has blown.

Never rely on unconventional colour coding. Red positive and black negative - OK. Anything else, use a meter.
Robert

caleb · #13 26-04-2009, 03:06 PM

Zaps · #14 26-04-2009, 06:42 PM

Quote:

Originally Posted by caleb

And another thing with wiring, I'm prety sure white is positive and black is negative, welly welly. Black is pos and white is neg in Skywacther lingo

Older DC "standard" was Red positive, Black negative. More recently, particularly with regard to photovoltaic systems, the Americans appear to have successfully changed the "standards" again, this time so that black is positive and white is negative.

No point bashing SW because you didn't bother to Google "polarity" +DC +colours...

marki · #15 26-04-2009, 07:02 PM

From pg 3 of the synscan manual.

The Synscan should be powered by 11 - 15V DC power supply (tip positive) capable of producing a continuous current of minimum 2 amps.

futher down ....

The power indicator will flash when the power is low. Continued use at this point may damage the Battery. The power indicator will flash rapidly when the power is extremely low. Continue to use the same battery may damage the SynScan system.

Mark

Robert9 (Robert) · #16 26-04-2009, 08:48 PM

Caleb, what sort of AA batteries did you buy? You should have alkaline rather than the standard cheapie. Only the alkaline will be able to deliver the current you need. Try Energiser or Duracel. Remember, the pimple cap is positive ( + ) and the plain end negative ( - ). The battery holder will be marked, but as a guide, the spring end is negative.
Looking at the manual I read that the hand controller receives its power via the RJ-45 cable. Are you sure the broken plug is making good contact. Your comment that sometimes things worked and sometimes didn't suggest you may have a faulty connection, and possibly that fault has become permanent rather than intermittent. With correctly applied power either from AA cells or an external battery (check out using a meter that the centre pin is positive before you plug it into the controller) try wiggling the broken connector. If you can get a response, tape the connector firmly in place then try the hand-controller buttons for any signs of activity.
If you can get the scope working, a computer shop should be able to help you with a straight through RJ-45 cable. (Someone else might like to comment on this, please feel free.)
Good luck,
Robert

caleb · #17 26-04-2009, 08:55 PM

I'm not sure if it's Synscan. I this its just some other Skywatcher thing.

I'm using Everedy batteries and my DVM is indicating the middle is positive with 13.5V

I also tested the contller pins with my multimeter but the two pins on each side didn't seem to register.

Robert9 (Robert) · #18 26-04-2009, 09:04 PM

Does the voltage change when you turn on the power switch?

caleb · #19 26-04-2009, 09:11 PM

Quote:

Originally Posted by Robert9

Does the voltage change when you turn on the power switch?

Unfortuantly there is no switch, but I can plug it in and test from the battery pack. I can try that tomorow afternoon though, I'm not very happy with not getting a public holiday...

So I'll have to wait...

Robert9 (Robert) · #20 26-04-2009, 09:19 PM

OK Caleb. I'll check in again tomorrow night. If the voltage drops significantly it means that either the batteries are flat or are unable to provide the current. If the Eveready batteries you are using are just the plain red ones, then I don't think they can provide the power. You'll need to get alkaline batteries as I described previously (Energiser or Duracel.)
Sleep well.
Robert