M20 input level disappears

[Mavril]

HI,

 

I thought I read about this issue before in this forum but I can't seem to find the topic below.

 

I have an M20 (+ L2m, L3m and L3s) and specific inputs are currently dropping out.

 

In my practice room pysical mic inputs 7&8 (which take electronic drums stereo) will drop out after about 5-10min. There is not drop in output from the drum module but there is no input level coming in.

Examining further I can see the channel strip inputs for 1,2,7,8 all greyed out like there in no connector in them... when there physically is.

 

If I plug into another pair of channels, they work fine. If I cycle power on teh unit the channels come back... for a while.

 

WTF is going on with this thing? did this sort of thing happen before or was it my imagination? Why that block of channels?

 

After the dramas with my L2ms (which I have only just had returned from the fan replacement - and haven't tested properly yet) I am afraid to take this out in public until my faith in the reliability is restored.

 

Mavril

[SiWatts69]

From what I recall of similar issues, there is a small plastic bit inside the XLR sleeve ring on the M20d input that sometimes gets jammed.

litesnsirens mentioned it some time back and, if I recall correctly, the solution was to jiggle the tab to free it up. If that resolves the issue short term, it might then be worth getting the unit sent away for testing.

 

I believe it has something to do with some XLR plugs being slightly thicker than standard and it jamming the pin but I haven't had it so am commenting purely from memory.

[Mavril]

Thanks for the reply SiWatts69.

I've had a good look at the connections and I'm not sure it's the issue. If there was a physical connection issue then why would it be an issue only after a number of months and not straight away? Also, I would assume that if I have the problem, turn it off an then turn it back on, it should still be there. If it is a contact corrosion thing, same deal (or working the connection should produce crackle and restored sound), definitely not a coordinated block at once?

 

I noticed also that a few channels that I have muted (mics) were showing as muted in the icon but were not muted in perform menu and the screen was unresponsive to unmuting them. When I went to patch the inputs to another channel the system was extremely slow to respond (in the region of 20 sec). This is software glitchy by my reckoning and cycling power for a fourth time appears to have stabilised it for now.

 

I will be monitoring this and am feeling gun shy about using it until I can pin point the problem. I guess the only thing that is relatively recent in this machine is a CF card, Samsung 64GB SDXC type 10 unit. Its high speed and shouldn't be affecting the unit like this even if it is a bad egg. It has been working fine for more than a couple of weeks with this memory card.

 

Any other occurences spring to mind?

[ArneLine6]

Does it behave like this without the SD card? We have seen some slow SD cards causing trouble..

[Mavril]

Apologies for the delay in getting back Arne, Im out of town.

 

I'll give it another soak test when I'm back home. The SD card is not a slow card, I purchased it specifically for the purpose (not to say that it can't be faulty). Is there a posibility that the SD card could cause this sort of problem?

 

I would have thought that th SD would only interact with the system when armed to record, I was only routing my stereo input through to the L3ms, no recording.

 

I have been using the gear to de stress when I get back from a work roster away, the last thing I'm looking forward to is fault finding the thing that is supposed to put me in a good mood :)

[wersonnst]

This Happend because  the Switch signal which detects an insertet XLR OR 1/4" is based on Ground Potential.

The Pluged in detection swiches are ativated by losing Ground.

The Ground Potential for each channel is connected via seperate spring elemet's to the casing. (Picture)

The casing GROUND is only connected by screws.

The most m20D's where this happend are an few years old where the surface begin to oxidate and the Ground Potential gone away.

The Harware had Ground Point's for Cable connection's but thy were not used , maybe in the building process they saved money (cabel).

If there is Garranty Use it!

[dboomer]

There is a quick and easy test to see if you have lost the ground connection.  With nothing plugged into any input jack just look on the screen.  If the ground has been lost an input would appear on the screen.  Are you getting a screen full of inputs when nothing is connected?

 

The ground you show is accurate, but it is only one of two redundant grounds.  The other ground is made when the jack is pulled into the chassis withe the bolt.  Two sharp pins, part of the jack, pierce the chassis.  This is the method used by most manufacturers for products in this range.  

 

So what would the outcome be if the ground was lost?  Well for regular full balanced microphone and line sources probably nothing.  A ground connection is not needed.  If you had a phantom powered mic it would probably not power up.  Only unbalanced inputs would be lower in level and possibly a bit buzzy sounding as well.

 

[wersonnst]

No I don't get a screen full of inputs when nothing is connected? (Yes in an test without case)

And Ground is seperat for each chanal so it would be more one.

For the Signal the Ground is not nesseary, but for the input detection of XLR OR 1/4". If it lost Ground it will detect 1/4" Jack first. And that could be the Problem.

To check this lose the screws of an Kombi Jack and test it.

 

For me I solved the Problem by Grounding all canal 's and the top back and bottom case  by wire.

 

 

 

  

 

I had the Problem on Chanal1.

First all was good but after an wile the signal Droped to 25%. Maybe 12db Pad for 1/4" i'm not shure if the Pad is hardware.

The signal droped is the same as when i connect the Mic in the 1/4". 

After many Tests i could aktivate the Drop by pusching the XLR jack hard in.

After disconect and Pushed it gently in all is normal but rattling a little bit it dropt again.

I open'd the kombi jack but no problems to see. (picture)

An other Problem is on Stage, that the cabel's of hanging to the Ground and pulling on the Kombo Jack's in the right way to loosing Ground.

 

Nice Mixing everyone.

M20D Rocks.

[actdmusic]

No I don't get a screen full of inputs when nothing is connected? (Yes in an test without case)

And Ground is seperat for each chanal so it would be more one.

For the Signal the Ground is not nesseary, but for the input detection of XLR OR 1/4". If it lost Ground it will detect 1/4" Jack first. And that could be the Problem.

To check this lose the screws of an Kombi Jack and test it.

 

For me I solved the Problem by Grounding all canal 's and the top back and bottom case  by wire.

 

 

 

  

 

I had the Problem on Chanal1.

First all was good but after an wile the signal Droped to 25%. Maybe 12db Pad for 1/4" i'm not shure if the Pad is hardware.

The signal droped is the same as when i connect the Mic in the 1/4". 

After many Tests i could aktivate the Drop by pusching the XLR jack hard in.

After disconect and Pushed it gently in all is normal but rattling a little bit it dropt again.

I open'd the kombi jack but no problems to see. (picture)

An other Problem is on Stage, that the cabel's of hanging to the Ground and pulling on the Kombo Jack's in the right way to loosing Ground.

 

Nice Mixing everyone.

M20D Rocks.

 

Nice! 

 

I had a different problem with my original mixer and Line6 was amazing and replaced it! Very good costumer service! Up there with the best. 

 

But my new mixer started to have problems with the main left and monitor A outputs.

The warranty (for the old mixer...) as expired. I don't think the exchange for a new one under warranty would extended it...

 

So, this fix will only fix the input problems? I don't have input problems...  But maybe the outputs also have grounding issues. 

There was a fellow user on this forum that reported the output problem solved by resetting the ribbon connectors. My guess is that by disassemble and reassemble the case he made the grounding better by cleaning and resetting the ground contacts to the case. 

 

Makes any sense?  I didn't open the M20d yet...

[Dougdrums]

Hi, I know this topic is a few years old now, but, anyways.

 

I got my mixer when it first came out, it cost me 2250 euro.  over the years i noticed little odd things happening with level changes.  I was so busy working with my band that i had no time to stop using the mixer and it only happened like once a month.  I have a had few months off gigging and decided to try and get the issues fixed.  I sent it back to musicstore.com to get fixed.  they told me that parts alone would cost 800 euro and to fix it all would cost more than a new mixer.  I am very disappointed with this.  plus that fact that there have been no firmware updates for year.  I am wondering if line 6 would like to offer something so that i can be a happy customer again?  When this mixer works it is fantastic, i love it, its just a shame that it is not reliable.

 

Thanks.

[silverhead]

You will need to contact Line 6 directly (see Contact Us link at bottom of this page). This is a user forum not frequented by the Line 6 personnel who may be able to help you. 

[Dougdrums]

46 minutes ago, silverhead said:

You will need to contact Line 6 directly (see Contact Us link at bottom of this page). This is a user forum not frequented by the Line 6 personnel who may be able to help you. 

 

ok, thanks for the information.