hi,
Sometimes it happens. ( age ) or possibly cold solder
joint or mis communication on the Digital Controller
and DSP Unit.
• One way to check is to verify each input if it can pass
output ( line Out ) signals.( at the back of the unit )
• If it does then you just have eliminated a large percentage
on electronic circuits troubleshooting.
• There are more details or info starting
on page E 25 of the manual
[PDF]
Download the owners manual - Arcam AVR250 surround sound receiverhave a recheck and triple check on the settings.
But if you need a thorough investigation on the DSP
circuits , it might need a service manual
http://www.service-manual.net/ashop/catalogue.php?cat=300only with a fee.
And be the last resort as to confirmed if it is really the DSP.
• You can use an external amplifier or a signal tracer when
probing signal outputs on the receiver.
• Here is a link for sample troubleshooting :
a ) Start with the input , then to the op-amp IC. b ) check your cable like those above for cothese unit is just a guide, not the same as yours , but the
process o f troubleshooting and principle is the same.
Only if you feel to DIY.