A320 CVR test (on FFS)

[helmet]

Can someone clarify what exactly an A320 CVR does during the test? In T/L: 'CVR test incorrect'. Not many more details given....
Looked at FCOM and not much clearer. How long does the test run for-only while button held on x-time? What tone(s) emitted?
If it makes any difference, the simulator is late 80's Rediffusion built.

[IFixPlanes]

Hi helmet

Our AMM says:
...
The test circuit is activated when the CVR TEST pushbutton switch on the overhead panel is pushed. The circuit consists of an oscillator producing a 600 Hz signal and a switching circuit which switches the oscillator output to each of the channels on the recording head in a sequence from 1 to 4
P.s.: A NOTE remark: it can be also a 800 HZ tone. Depends on the CVR PN.

http://img292.imageshack.us/img292/2702/cvr5cm.th.jpg (http://img292.imageshack.us/my.php?image=cvr5cm.jpg)

So a test runs as long as you push the button and 600(or 800) Hz tone is produced and send to the channels.
HIH

Ingo