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LXD 750 power 18Vdc or 12 Vdc?

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#1 Eddgie

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Posted 22 February 2009 - 02:42 PM

I have an older LXD 750. It is marked "18vDC" on the power interface jack.

Seems that I saw some newer LXD 750s that were marked with "12vDC to 18vDC".

Does anyone know if Meade actually changed something, or did they just decide that working it on 12vDC was OK?

If not, does anyone know if it can be modified to work on 12v DC?

Thanks!

#2 Fish

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Posted 22 February 2009 - 08:33 PM

Good evening,

The LXD650/750 and LX200 scopes like to see 18vdc. 12vdc will work provided it doesn't drop much while in use. 13.8vdc from most AC power supplies is fine and battery operation is OK as long as there is minimal drop.

The biggest problem with the lower voltage is with the tracking motors. At 12vdc they produce less torque, are more prone to stalling and therefore overheating.

Meade used to make a 12-18vdc converter but discontinued it. Good thing as it really was not up to the task.

So, go ahead and run on 12vdc. Just be sure the voltage doesn't sag under load.

Regards, Marc

#3 Eddgie

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Posted 23 February 2009 - 10:03 AM

Excellent..

I suspected this was the case, that you COULD run it on 12cDC, but SOME circuits don't tolerate it and damage things.

I actually have a multiple volatge DC supply that I bought on the web for about $15 and it works beautifully. Just one more thing to schlep around though, and was hoping to eliminate it. So, it isn't that I don't already have power, just another box to manage.

If there is a good chance it will work, I will just try it out. I have a Radio Shack 3 amp 12 vdc supply that should give a solid 12 volts, and next time I go out with the mount, I will use it and put a meter on it to check the volatage.

I never power it from batteries, so this hopefully will work fine.

So, my biggest concern was smoking something on the power board. It sounds like this is unlikely, so I will try it out.

Thanks! I appreciate your response!

#4 Arctic_Eddie

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Posted 23 February 2009 - 11:53 AM

If you get a PS intended for amateur radio use it will be 13.8VDC and properly regulated. The extra 1.8VDC might make a big difference in performance since you're already low.

#5 Eddgie

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Posted 23 February 2009 - 12:23 PM

I think measured the Radio Shack unit at 13.2. Not well regulated, but all of my other scopes seem to work well with it.

Thanks for the tip though.. If I do have problems, I might try one...

#6 Skywatchr

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Posted 24 February 2009 - 12:06 AM

Do NOT run it at 12v or you risk burning out the motor controllers. I use an IBM Laptop power supply (yellow tip) that is 16v @ 4.5 amp, and the 3.36 amp model will work too. You need voltage and amperage so when the scope slews, it will have enough "oomph" to run it without drawing too much amperage. Running it at lower voltage results in higher amperage draw.

Jeff

#7 Skywatchr

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Posted 24 February 2009 - 12:09 AM

Also, for 12 volt (field) use, I use an Auto adapter made for a Laptop (universal voltage) that can be switched to 16 or 18 volts. They're much cheaper than the Meade 18 volt adapters and work very well. A decent one is regulated.

Jeff






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