Power to stereo drops when ignition on.

[GORDYDJ]

After 3 days ownership of a 2009 Leon. I've gone and left myself without any music.
Yesterday thought I would plug in the android head unit I took out of my previous car. So set about removing the factory unit. Plugged in the android, turned on the ignition, and......nothing. After a bit of head scratching I reconnected the factory unit, turned on the ignition, and.....nothing (was working just prior to removal). After a bit more head scratching. I decided to give up for the. day.
Went out to the car today armed with my multi meter. I have constant & acc power from the quad lock. And the fuses at the back of the radios are fine. I'm at a loss as to what it could be. The likelihood of both units failing at the same time is surely unlikely. And it can't be a bent pin.
Hopefully one of you has experienced the same. And can tell me it's something simple

 

[R3k1355]

Some of the RNS units won't output any audio once switched on. Might be a DAB issue.

Have you tried playing something off a memory card?

 

[GORDYDJ]

Some of the RNS units won't output any audio once switched on. Might be a DAB issue.

Have you tried playing something off a memory card?

Thanks for your reply.
It's not the one with the card reader. And as I mentioned neither this nor the Android unit are powering up. Despite power coming to the quad lock.

 

[GORDYDJ]

Had the multimeter on the quadlock again. On pin 5 (can+) with the ignition off I got 12V. With the ignition on the voltage dropped to 2V. On pin 6 (can-) voltage was 2V with the ignition off and on. There was no voltage at all on pins 3 & 4.
This, to me, seems to be the problem. I would have thought there should be 12V with the ignition on.

 

[GORDYDJ]

Anyone?