Find out polarity of device for using ac-dc adapter

[aspfun]

I have a audio recorder (Edirol R-09HR High-Resolution WAVE/MP3 Recorder) need to use ac-dc adapter.
There is no any marker to tell me polarity of input in this device.
(I check the adapter from amazon.com for this device which I do not have, there is no marker as well)
I have a Radio-Shack ac-dc adapter which I can adjust polarity.
The porblem is how to find out this audio recorder input polarity, that is, is pin "+" or "-"?

 

[vk6kro]

It runs off battery power, so remove the battery and measure to find out which side of the battery holder connects to the outer side of the input plug. This will tell you the polarity.

It can use two NiMH AA cells, so the supplied AC adaptor would have delivered about 4 volts, but it may have included circuitry to limit the charging current.

You can tell this by measuring as above (from the battery holder to the input plug) but check where both battery connectors go on the input plug.
If they both connect directly, you would need to control the charging rate externally.

Roland supply an AC adaptor so you may be able to get a replacement if yours is not working or you have lost it.

This is a high end product and you may damage it if you are not sure about this. So, you would need to get the proper adaptor.

 

[vk6kro]

I found the user manual for this.

http://www.rolandus.com/products/productdetails.php?ProductId=960

It says that the unit cannot recharge NiMH batteries, so you have to charge them yourself.

It also says several times that you should use their adaptor. While this may be to their advantage, you probably should follow this advice.