Please help, Quad 44 input selector dilemma

[mcc]

I've been using a Quad 44 preamp for a couple of years, and there's always been a problem with the electronic input selector. There are 5 input sources: radio, aux, disc, tape 1, and tape 2. Problem is, whenever I select any source other than radio, the amp will automatically switch itself back to radio anywhere between a few seconds to a couple of minutes later. I had settled for connecting my CD player to the radio RCA inputs, but now, I have a second source (pre-out from AV reciever), which means I finally need to use one of the other RCA inputs.

I saw a thread posted three years ago on a Quad fansite of someone else who had the same problem. Anyone with Quad know-how have any idea how to fix the problem? I've brought this pre-amp three or four times to a local repair shop for a bunch of other problems. Everything else was repaired, but this one problem is something that nobody seems to be able to fix.

Help!!!!

[Lara Croft]

You will need a schematic diagram to properly ascertain
why an error like this would occur, it is likely that Quad would
use a relay for switching inputs but there might also be
some control logic that interfaces with this. Quad are
more than helpful if you want to email them
just go to http://www.quad-hifi.co.uk and then
to the service department. Hope this helps .... Lara:6:

[hermanv]

A possibility, based on a guess.

Some pre-amps automatically switch to whichever input is active, since the radio is always on (is it?) every pause or track silence in a CD for example might cause it to switch back to the radio source.

An obvious test is to see if it stll does this with the radio powered down.