Wrong Voltage

A few days ago, a friend of mine borrowed my Biyang 5-way adapter.

Well, I have absolutely no problem using the adapter. It is supplying enough power to all 5 '9V' pedals attached to it. However, that wasn't the case for this friend of mine.

Here is the story: He said the adapter is faulty.
Reason: It failed to give enough power to two of his pedal and it spoiled his Korg Pandora PX5D. Only his DS-1 and chromatic tuner was powered up.

Apparently, he failed to notice that the power supply for his Pandora PX5D is a 4.5V d.c. and my adapter supplies 9v to each. So... his folly spoiled his $300 PX5D and not the adapter.

I asked to see the two pedals which was 'so-called' underpowered. A quick look at the power jack and it was written '18V d.c.'. Well, he can't expect my 9V adapter to supply twice the voltage, isn't?

So.. please check the power input of the pedal and the output of the adapter before joining them together..