My experience with a friends DM-50 led to the discovery of a faulty
volume control. This might be the same issue with your's - dunno.

Basically, the DM-50 design (and maybe DM-31?) uses a digital rotary
encoder to convert the position of the knob to a digital signal that can
be read by the microprocessor on several binary weighted lines. There is
contamination inside the control, so some of the output lines don't
solidly connect. This causes an rapid ceaseof the amplifier output when
the volume is intermittantly wound up very high, the sudden rise in
current triggers the protection circuits.

Have a twiddle with the volume control while watching the display. It
should increase the dB volume setting shown (and the volume played)
without any non-sequenatial jumps. If it does jump about, then the above
explanation is likely, and you will need it looked at.

thanks, Adrian

my pidgin understanding of the stereo makes me think that you're right
about the way that the volume control is implemented, and i wouldnt be
entirely surprised if this is the cause as we've been redecorating of
late and as a consequence there's a fair amount of dust about even
though we've been careful to keep the thing out of the rooms we're
working in, which could well have gotten into the it and therefore
caused the contamination you mentioned. Also, ive actually been using
the volume control rather than the remote quite a bit, in order to
avoid getting paint on anything (and using my foot to do so at that,
which if you've seen me attempting any any of balance you would know
isnt the most delicate of methods).

so sounds from what both you and trevor are saying like i am going to
have to take it somewhere - im unwilling to let it die as i think it's
a great piece of kit and would rather not replace it. but at least i
now know that i couldn't have DIYed it and saved myself a few quid.

cheers again,

chris