EM200 caput

[MartinB]

I've had a miserable time since the obsy was finished in August as I've droned on about before. Software problems initially but recently all sorts of electrical problems. The mains adaptor for the mount packed in. Then the spare one seemed to be causing a vibration, I thought it was the adaptor. 2 night ago I ran it off a power tank. The guiding was very poor in a strange way that I couldn't identify. During the night the connection to the mount was lost because the power tank had run down. The EM200 is very frugal on power normally. Used a 12v power supply tonight but there was a voltage drop during slews (indicated by the Kendrick dew controller) and the slew would stop. Used another power tank. Everything ran reasonably for around 40 mins after which the tank had been completely drained.

I can only think the mount electrics are shorting somewhere.

God knows what happens now. I'm sure there's no warranty. I'll get on to Nick Hudson at Trutek who supplied the mount. John Rose of Astrodevelopments is also very helpful with this sort of think. I only hope it can be sorted in the UK and that it doesn't have to be shipped back to Japan.

One thing I'm sure of, it won't be cheap and I think I'm going to be out of action for some time.

If any electrical gurus on here have any advice or suggestions I'd be very grateful

[beamish]

Sounds like that obsy been jinxed Martin- I really hope it's not too expensive to fix and quick too !

Good Luck with it

[steppenwolf]

Jeez, Martin, you are going through a bad patch. Have you run the mount on its own to see how it performs - just in case there is a problem with power drain from another component?

Are you able to put an ammeter in line with the PSU so that you can monitor the current drain?

[MartinB]

Steve, I haven't got a clue when it comes to electronics. I've recently bought a multimeter since my new year resolution will be to address my ignorance. It's a good point though, I suppose it could be the dew controller but I doubt it. My AC adaptor was just connected to the mount, I think it was a faulty mount rather than the adaptor that was causing the mount to vibrate at mains frequency - not able to supply enough current.

[steppenwolf]

A real basic question - does the mount get at all warm? This would be an indication of high current drain.

[Ant]

That's not good news mate, I really hope it's easily fixable.

just had a thought. You can buy little devices that sit over wires and tells you the current that a device is drawing...

Maybe you could get one of them, it might help you to find the source of the drain - it may not be the mount.

[barkis]

What a rotten time you are having Martin, you don't deserve these headaches. I do hope it is not too serious a problem.

Do you know if the overload is apparent in both slew directions, or in any one in particular. I know you are methodical in your setting up, and good balance is something you impressed upon me, so I know it can't be that..

If you have a multimeter, do a test on your main mount supply cable, just to make sure you have not developed a high resistive connection. Put the meter on to Ohms, select the lowest Ohm rating, and do a continuity check on the cable. First the centre pin on the Mount end, and it's corresponding supply end. Do the same for the negative line. In each case, the Ohms reading should be zero, or very close to zero. Any highish reading needs investigating. Also, there should be a zero or very low reading if you connect the meter across the two cables, the +ve, and -ve.

This is with the cable taken off the mount and supply altogether.

Bit of a shot in the dark, but it's worth a shot.

Ron.

[MartinB]

No Steve, it isn't getting warm, I wondered about that.

Ron, I'll check on the resistance. The scope was balanced with a tiny weighting to the east as per usual. Dec was balanced, the em200 doesn't really need an offset here since I can turn off dec all together when tracking at this focal length.

[Beyond_Vision]

You could use this device from maplins to power the mount from a 24v supply it will regulate the it's output to 12V (3Amps Max) and you can monitor the current drawn.

http://www.maplin.co.uk/module.aspx?moduleno=115314

All you have to do is plug it inline.

Regards

Kevin

[MartinB]

Excellent, thanks Kevin. I'll give that a go

[bazza]

Martin, I don't know much about the EM200, but I'll try to help.

Looking at the specs of the EM200, it says 12/24VDC.

Now, I know there can be some issues when you try to operate the G11 at 12V, it needs 18V to work properly.

Is it possible that this is the issue and it needs more than 12V?

I hope I'm not coming up with stupid ideas here!!

I don't know what sort of mains adapter you have/had....mine was from John at Astrodevelopments and I've never had any problems.

I take it with everything else disconnected, the mount is still struggling?

Barry.

[Capricorn]

Power tanks run off of lead acid batteries, if they get drained they get damaged and do not work as well. Eventually they are just dead. The manufacturers should really use deep cycle batteries but they cost more, so they don't and the power tank fails. And it isn''t a long time or several cycles of draining that will highlight the problem.

That may well be part of the problem with using power tanks. If you have used them several times and drained them then they could be at the end of their time.

One of the suppliers, Celestron or Maplin has a question and answer page, one question was Are the batteries deep cycle? The answer being "No and therefore they should never be allowed to get fully drained as this damages the plates and will render them useless."

My motor bike had an alarm, it drianed the battery, I had to fit new ones at about 6 month intervals.

[MartinB]

Update - seems I need to learn some basic electronics. The problem probably isn't the mount:hello2:

The regulated power supply is connected to a 4 ways cigarette lighter adaptor. Each of these is rated to 1A. When the mount slews in full speed in both RA and dec at the same time it can apparently draw up to 2.5A. If I run it directly off the power supply through a 24v converter no problems. Not quite sure why the power tank has been going flat so quickly but maybe it is just knackered. Anyway, a lot more hopeful now.

Hope to check the current being drawn when tracking in the near future when I can borrow an appropriate bench supply.

[pvaz]

Glad to hear that!

Would be a shame if you had to fix it.

[Ibbo!]

Thats good news

Steve

[Merlin66]

I dumped the powertanks and went over to the 20Ah gel cell batteries some three years ago - use a triple stage electronic charger - haven't lost a battery since or had any power problems.

I also use one of those car computer transformers 120W capacity ( converts 12V to 15V/ 16V/18V etc)

Drive the HEQ5pro/ NEQ6pro at 15V and the Lx200 at 18V.

Keep a separate gel cell for the dew heaters etc etc.

[beamish]

XLNT news Martin !

[barkis]

Good that It is not serious after all Martin. I hope you confirm it with a power supply soon. Your Xmas will be a lot happier once you know all's well.

Ron.

[Helen]

That sounds encouraging Martin! Hope it does turn out to be something easily fixed.

Helen