BR-900CD - Trouble with on board mic

[T.C. Elliott]

So I select the onboard mic which is, I believe [ONBRD+EXT] (which makes no sense to me that you can't just have the on board mic as an option) and when I record i have a steady hum at all frequencies at about the -6 range (or slightly less.)  I've recorded two practices and it's annoying to say the least.

I just played with it, and if I plug in a mic chord (and mic) to the MIC 2 slot and then touch it with my hand (ie, ground it) the hum disappears, but if I don't touch the chord it still hums. I take it this is a grounding issue? I'm gonna try other chords and a different mic just to eliminate the possibility of it being a chord or that not having a chord plugged in at all was the problem, but do ya'll think it's a grounding issue in the box itself? And if so, why hasn't it presented itself with my condenser that sits in the MIC 2 slot most of the time?

Let me know if others have had similar problems and if so what if any solutions there are. Thanks much.

[Vanncad]

Hey T.C.,

I have had this problem since early-on with my BR600. 

I can only describe it as the same sound you would get if you put your finger on the guitar end of a 1/4" guitar chord if the other end was plugged into an amplifier.
An annoying hum that disappears if you put your finger on the internal mic (left side only in my case), or the headphone plug.

My problem comes and goes. I have tried changing outlets, batteries, etc. but nothing helps.
Right now my internal mics are working fine, but they seem to have their own mind. I try to record acoustic songs when they are working, and just mic my guitar amp and use an SM58 for vocals when they aren't.

I called Roland Canada, and it was gonna cost me about $100 just to ship it and have them look at it. That's about 1/3 of what the recorder cost, so I decided to just live with it.
If I shipped it, I would almost bet that it would be working fine when they received it, and then they wouldn't even get to hear the problem.

I have heard of other BR600 users with this problem, but still haven't heard a solution.
Kind of sucks, because I have a lot of acoustic songs I'd like to record, but this is kind of holding me back.

Anyways - I hope you find a solution to your problem. Please post here if you do.