Anyway, I decided to have a play about with my DR-550 earlier today. I connected a pair of headphones and got quite a lot of static hiss, even with the volume control at zero. This only gets marginally louder as I turn the volume up to full. The left channel is noticeably louder than the right channel and there is a sort of distorted click in time with the beat coming out of the right channel. This click is audible even with the volume at zero and no other sound coming through. It clicks in time with the flashing red tempo light (with a slight double click on the first beat of the bar).
Wondering whether the headphone output had a fault, I then connected it, using the L and R 1/4" jack outputs, to my mixer. Got the same results. Overall level is pretty low and I had to max the volume controls on the mixer (both the channel and master) to get a reasonable sound level.
Finally connected it in mono to the mixer, using the L(Mono) 1/4" jack output. This time I got the distorted click in both left and right ears.
All of the above happens whether the drum machine is powered by batteries or PSU (I tried two different, known working, official Boss PSUs).
Decided to try my Boss DR-670 after this only to find that it too has a problem
Whenever it makes a sound (either through hitting one of the drum pads or playing a pattern), the drum machine reboots. If I play a pattern that is silent for two beats, it will restart on the third beat when the first actual sound is played. Otherwise it seems okay. i.e. I can navigate through the settings, change from song play to pattern play, switch drum kits etc. Again, have tried with battery power and a PSU but it's the same with either.I Googled the issue and have found a couple of other people who have experienced the same problem on other forums but no joy identifying a fix.
Bit of a long shot but has anyone encountered either of these issues / got any suggestions as to what might be wrong with either machine?