Ditto, no ground on 22 on my MkII or MkIIa

I'm pretty sure it's 22 is aux gnd. I seem to remember it goes...

13 +12
14 acc
15 rear L
16 rear gnd
17 rear R
18 front L
19 front gnd
20 front R
21 aux L
22 aux gnd
23 aux R
24 mic

anyone got a spare harness to hand?

you can test it with a multimeter like this:

I meant, a way to test the motherboard directly for burned out traces. Testing the pins on the sled connector is a good first indicator and would be a good way to lead into "next, open the player and check inside for...". But we still need a way to confirm burned out traces, as well as a way to fix it if it turns out to be the problem.

oops, misunderstood.

the next thing i did was to open up the player, remove the drive tray, pull the analogue connector out and test continuity from the gnd pins in the header to the chassis.

I actually removed the main board from the chassis to do this and I was able to see very thin traces which appeared to be for signal which went from the header through some decoupling capacitors to the pre-amp stage. There was also one relatively thick trace that appeared to go to the rear gnd pin, but without de-soldering the header I was unable to see where it went and if it also connected to the front gnd. Obviously I could only see the top and bottom layers but i would imagine that there wouldn't be too much in other layers as to keep RF interference to a minimum in the output stage.

maybe Hugo could post a small section of the PCB design to see what happens on all the layers around the analogue connector?

Aux isn't grounded, it's a floating ground to cancel common mode noise on the aux inputs. I'm afraid I'm not in the UK at the moment, so posting an image of that part of the PCB isn't easy - Patrick could though, if he's reading?

Hugo

(This seems like a good place to stick a little note restating something that I've seen mentioned before. As Hugo says the aux input should be grounded if the device connected to it isn't grounded to the car body somewhere else, like a portable CD player. If the device is battery powered that make sense, but what's a good way to proced if the aux input device is getting power from the cigarette lighter? I suppose it depends on the internal construction of the player.)

--Nathan

Does anyone know if there are two separate ground traces for the front and rear from the connector on the PCB? it is possible for one to burn out and the other to remain intact?

Oli.