LD Systems LAX6BMDA Schematic

[Joe bags]

Hi there!

I'm looking for schematics for an Ld Systems LAX6BMDA. It's a powered mixer. The problem I had with it was all the led's on the level meter lit up when the unit was powered on and no sound on output. I found a faulty diode connected to one of the voltage regulators so I replaced it with a similar one (not the exact one mind you!) Powered the unit up and the same fault appeared. All led's lighting up. Then I put a signal through it to see if I got anything out of the headphone output to narrow down the fault. The unit then started to work all of a sudden albeit just on the left side.

So I thought it must be a dry joint or loose connection somewhere.

Powered off, powered on again, original fault appeared again.

Inspected the pre amp circuit board. Found two stressed resistors, so decided to replace them.
Now on turning on the unit no power comes to the preamp board of the mixer.

So think I need schematics to continue with the repair.
I got on to LD Systems and got a swift reply but I got sent the user manual not the service manual

So just checking here if anyone might have schematics?
Any comments or suggestions on the repair welcome.

Thanks

Joey

[Enzo]

Sure looks like a missing power rail.

That mystery diode, any chance it was a zener and you replaced it with a plain old diode? There should be a couple of darn similar circuits, one for each polarity, see if you can compare the two supplies and get anywhere.

[Joe bags]

I replaced a 1N5819 diode with a 1N4004. The resistors I replaced were actually links which were 5 ohms. I read the colour code brown, black, brown and figured they were 100ohms. So when I replaced the resistors again with the proper value the unit came up and started working.

Result!