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24 volt supply question.


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I'm an electrical numbskull so I need help; I am awaiting a Tak EM200 mount which will work (but agonizingly slowly) on 12 volt. It prefers 24 volt.

And I have a laptop power supply which can be set, among other voltages, to 24 volt. However, at over five grand I do not want to fry the Tak on arrival! Are all computer transformers wired tip positive? Is there some way I can test polarity? Am I missing anything else here?

Olly

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However, at over five grand I do not want to fry the Tak on arrival! Are all computer transformers wired tip positive? Is there some way I can test polarity? Am I missing anything else here?

Ummm... are you sure the Tak is rated at 24V? The reason I ask is that, if it is a 24V unit, I'm surprised that it works at all when fed with 12V.

Polarity can be checked with a voltmeter ... cheap digital multimeters are readily available, easy to use & useful for various other tasks (e.g. checking fuses to see if they've blown). And no, tip positive is very common but by no means universal! But if you haven't fried the mount already, your 12V supply must have the correct polarity ... with protection circuitry, reversed polarity means no operation; without it, no operation plus a nasty burning smell as some chips on the circuit board depart this world.

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Olly, if you have access to a digital voltmeter, and you apply the electrodes to the ring plug on the end of the cable from the transformer, put the positive lead to the tip, and the negative lead to the body of the plug. If the tip is positive, then the reading on the meter will show the voltage output. If the tip is negative, the reading will be preceeded by a negative symbol thus -24v, or whatever the output is.

I hope I explained that sensibly.:(

Ron.

Make sure DC Volts is selected. Some have a switch for that purpose.

Edited by barkis
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Hi Olly,

I use a step up transformer to 24V poss centre.

Can't you find out the polarity from the laptop instructions ?

Why don't all mounts have a protection circuit built in ? There was a board ( not Tak ) that got fried at Kielder. That John Rose I told you about just happened to have a board in his van. Lucky or what ?

Just remember, if in doubt...... don't.

Dave.

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Why don't all mounts have a protection circuit built in ? There was a board ( not Tak ) that got fried at Kielder.

I think it is highly likely that Tak would build in polarity protection. The companies that don't are the mass market ones, where the profit margin is tiny and the few cents the polarity protection circuit would cost come off the margin.

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You would think so wouldn't you. However, I've read dire warnings on the Tak forum about making sure you don't mix it up. This may apply to the older mounts I don't know. Tak used to make a mount years ago with centre negative.

Dave

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Ask away! FIrstly the whole business about buying anything Takahashi is complicated because everything is an extra. FSQ106 is x million dollars. Lenses, rear group, add y million... I'm joking, but only just. I just overlooked it.

I have no idea what their power supply costs but when an ST4 cable is reduced (ahem) to ninety euros I don't know if I want to know...

Olly

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Hi Olly, (sorry if I am telling you how to suck eggs)

The Tak website gives some info in the EM 200 specifications section but it mentions a couple of different panels ie USD-3 and the Tema 2. Which one is yours? It refers to 12V and 24V and in both cases the central pin is positive. It appears that the 12V and 24V difference will determine how fast the scope will slew.

The spec sheet does not state how much current (amps) the mount pulls under load and only says that Operating Voltage is 12V / 24V DC.

The power supply that you decide to use has to be of the same polarity and this may be marked on the PSU as it is on the panel of the mount.

Also the power supply has to have enough amps to do the job, the mount will only take what it requires. It is when the power supply cannot meet the demand wires get hot or fuses (if you are lucky) will blow.

Personally I would take into account the value of the mount and be very sure that the PSU is correctly rated before I flick any switch.

Regard from Dave Galvin.

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Edited by David Galvin
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