power supply voltage for EQ5 dual axis motors

[eifionglyn]

Hi all,

Many moths ago I burnt out the dual-axis hand controller on my EQ5 mount - the regular RA and Dec motor type, and have just managed to get hold of a new hand controller.

Not wanting to burn out the new one, I checked the voltage my power supply was pushing out with a meter. With it set to 6v I was measuring 9.5 across the output terminals, so I clicked it down a few settings till I got 5v across the terminals. Plugged in the hand controller, and it didn't work, just the LED flashing red. So I pushed the PSU up one setting, still not 6 according to the switch on the PSU, but 7.5 according to my meter. Still the same thing, LED flashing red, no motors turning, though oddly the RA would turn if I unplugged the Dec motor, then if I plugged the Dec motor back in the RA would continue to turn, until I used one of the slewing buttons, then the motors would stop and the LED flash red.

I didn't want to try the PSU set to 6v, as I was measuring 9.5 on it and was frightened of burning out the new handest, and then I remembered that my lead acid battery charger has a 6v setting, tried it with the meter and it was bang on 6v, so I plugged that into the controller, and same result again, LED flashing red, no motors moving.

To hell with it I thought, and set my original PSU to 6v on its switch, 9.5v measured, and plugged in the hand controller, and it worked fine. RA motor tracking and the RA + Dec motors spinning as they should in response to the slew controls.

I'm sure my measurements are accurate, unless I have two meters that are both faulty in the same direction by the same amount.

So I have a few questions hopefully some more knowledgable person can answer.

Is the PSU showing me 9.5v on the meter because I am measuring it when there's no load on it, does it drop down to the 6 it is set at as soon as it's connected to a load?

Why didn't it work when connected to a 6v supply from my battery charger - is something marketed as a charger different from a power supply?

Am I harming the hand controller by continuing to use the PSU set to 6v even though I'm measuring 9.5v across the output terminals?

Thanks in advance,

Eifion

[Cornelius Varley]

Does your psu have a regulated output ?

Peter

[eifionglyn]

I'm not sure, I shouldn't think so. Its only a little cheap multi voltage thing

[Cornelius Varley]

Mostly that it is not regulated and is the cause of your problem.

Peter

[eifionglyn]

Aha, thanks for the tip, after reading up a bit about them it seems that what I'm seeing with the voltage being higher than set when not under load is consistent with it being an unregulated supply, so it's probably delivering six-ish volts when set to 6v and under a load from the motors.

It will probably alright, it served me well with the previous controller, until I plugged it in with the unit set to 9v, had been using it for something else and forgot to check the setting. But I don't want to risk blowing another one with six-ish volts so have ordered one of these which is regulated

Low Power Multi-Voltage Desktop Power Supply : Multi Voltage Power Supplies : Maplin Electronics

Thanks for the help Peter.

Eifion

[Tinker1947]

If your PSU is unregulated as you draw power from it the voltage will drop, so that why your motors don't work when the settings are low, get a proper PSU and it will be sorted...

[eifionglyn]

Thanks for the advice all. Regulated voltage PSU arrived from Maplin and all is working as it should. Also the voltage selection switch on it is recessed and very difficult to move by accident, so hopefully I won't blow this handset!

[182570]

slightly confused here,just bought the eq5 synscan upgrade and this says it's 12 volts for the power supply ,this is also stamped on the plastic cover on the controller,has the power supply changed recently? I have ordered the psu 13.8v 7amp regulated supply from Maplins,and don't want to blow the new upgrade.

[182570]

ignore above post,have double checked and it is 12 volt,(should pay more attention)

[Cornelius Varley]

ignore above post,have double checked and it is 12 volt,(should pay more attention)

It wouldn't have hurt it. The voltage range for the Synscan is 11 - 15v.

Peter