MP-2 - Signal LEDs not working

[Rawk777]

Hi!

Since I have my MP2 (bought used in 2016), I've never seen a green or red light on the "Signal LEDs". The "Comp Thresh" light does seem to work.

Is this a common known issue? Is there something I should do?

[rnolan]

So the units working fine though ???
You should see a brief (green) flash on all the leds when you turn the power on (seems to go from bottom to top then comp led), and the reverse when you power off. This should indicate they work (part of power up test I suspect)
There's a section in the MP2 manual (toward the back IIRC) which describes the signal levels where the led will light (green or red). If the signal doesn't get high enough to trigger a led, they won't light. I tend to get occasional green flashes on lower gain patches and solid green sometimes on high gain patches. On clean patches with compressor they get a bit more excited, lots of green flashes.
So it will depend on your patch settings.

[Rawk777]

They do not light up on power on/off.

[rnolan]

Mmm, they should, does the unit still work ok otherwise ?? MJMP, this is more your territory  :wave:

[MarshallJMP]

Well it could that the chip controlling these is busted or it has been removed.When the chip goes down it usually brings on all leds (red ones) and it pulls down the voltage so people remove the chip or detach the connectors.So check it if the chip is still on the small pcb were the leds are attached too.

Downside is that this chip (CE425) was a custom chip made for ADA and is not available anymore.

[Rawk777]

The chip is still there.

The 3 connectors from the small board to the main pcb are still there too (k501, k500, k800). K501 and K800 where secured with hot glue.

[MarshallJMP]

Okay,seems that the chip is busted anyway.You could see if there's 15V between pin 2 and 10 of the CE425.

[Rawk777]

I read 17.5.

[MarshallJMP]

Mmmm should be 15V.Anyway it doesn't matter,seems the chip is busted or you just need feeding enough signal into it.Because they lit it up green at a certain level.But i don't think that is the problem.

[Rawk777]

The "comp thresh" and "output clip" do not use the same chip?

[MarshallJMP]

No the chip only controls the level leds.

[vansinn]

We talked about this years ago..  re-designing that chip. It's the only non-availavle item, and a pretty dang pity for otherwise functional MP-2's.
Shouldn't be that difficult; IIRC, basically just a bunch of voltage comparators that could be assembled on a board fitting the socket, no?

[MarshallJMP]

There's more to it else ADA wouldn't have made a special chip. ;)