"charles" wrote in message
...
Have you tried replacing the cell/battery? I had this with the 10kg
kitchen scales and a new CR2032 cell fixed it (always check the fuel
before stripping the engine!).

When I started as a maintenance engineer (over 50 years ago), the golden
rule was "always check the power supply first", It's stood me in very good
stead over the years.

I had a problem with a hard disk TV recorder (a PVR) which would boot up and
present its initial menus and would act as a tuner (converting aerial input
from digital TV into SCART output) but would not show the recordings on the
hard disc or allow new recordings to be made.

I suspected a failed hard disc and, because I had nothing to lose, removed
the disc to see if it would spin up and could be read by connecting it to a
PC. Answer: yes it spun up without any problem and Windows could see two
partitions but could not detect filesystems on them. I later learned that
they were probably UNIX-specific filesystems - I bet if I were to connect
the disc to my Raspberry Pi nowadays the disc could be read; I might try it
one day as a class exercise!

Something made me check the supply voltage and I found that the PSU produced
a no-load voltage of 12V, but this dropped to about 8 V as soon as I plugged
the lead into the PVR. Fortunately I had a spare PSU from a hard disc caddy,
with the same connector (which was wired in the same polarity - I checked!)
and was rated at the same voltage and at least as much current as the old
one.

The device immediately sprang into life and had worked fine ever since. So I
now always suspect the PSU whenever any device misbehaves and check that the
on-load voltage is close to what the PSU is supposed to produce.