Thanks liudr for your help.
I bought it on eBay from a supplier based in Hong Kong.
Yes, I found the schematics - I have attached it.
But I can't find it in there how I could find out about the issue I am talking about - don't you need the PCB layout to see that? - sorry I am a newbie.
schematics-v1.0-dfr0009.pdf (48.4 KB)