Polarity of DC adapters...can they cause problems?

I'm trying to figure out what the polarity is on the ETX 125 DC port.
I have a portable 12v battery pack I want to use to power it but the end on the lead you plug intom the scope has reversable polarity...

Anyone got any ideas? I dont want to fry my poor baby.

Polarity is very important!!! You could easily fry the electronics by getting it wrong. Some devices use a diode to ensure that getting it wrong wont harm things but then some dont. A shame since diodes cost fractions of a cent. Usually most things are centre positive meaning the middle of the jack plug should be positive.

You would see a symbol like thris --C+-- (with the C wrapped around the +.

You really need a multimeter to test for sure. You can get a cheap one for around a fiver in maplins.

Often the point where the jack plugs into the adaptor is marked. See if you can find such a mark.

Like Dave said, it is absolutely critical that you get this right.
I saw someone get it wrong with an LX90 a few years ago and it I had to dismantle the scope and perform alot of surgery to get it fixed.
The etx does not have a built in protection fuse.

The power is positive-tip, i.e the center is positive and the outer side is negative, if in doubt get a cheapo volt meter in maplin in Limerick.

Thanks Dave,
Yes the center pin on the scope is definatly positive.
It's jawdroppingly easy to make a huge blunder.
I'm supprised Meade do not make this clearer in the instructions.

Sorry lads, one last question! :oops:

Ok, So the power tip on the ETX is +

My instructiuons say,
''For appliance with positive polarity, the adapter must be connected with the + symbol in front of the word TIP "
(see photo bellow)
www.flickr.com/photos/56066598@N00/226076427/

Is this right?

Yea, I'd say so, at least in transformers I've used.