Crashes when unplugged

dtgn

I'm not sure what I am currently reporting reveals to be a bug, a circuitry problem or a normal behaviour in v0.33, but I often need to hotplug so :

When there is only 1 jack plugged in any audio out (1, 2, 3 or 4), if the jack is hotplugged the LXR often crashes. It might to come from the brief short circuit happening during the unplugging.

Anyone is familiar with this behaviour ?

julian

Normally this should not happen.
That's exactly how I test each mainboard before shipping it out.
I use a single audio cable and hot plug it into every audio out once and never had a crash.
Where is your jack conected to on the other side?

dtgn

It's connected to an XLR audio out coming from a RME Babyface, external USB soundcard.

julian

does it happen on all 4 audio outs?

dtgn

Yes it does.

julian

when it crashes does the sequencer continue to run (playing sound) and just the AVR resets (bootscreen is shown again or weird characters) or does everything stop immediately?

does it also happen with an unconnected cable without being plugged into your interface?

dtgn

I'm quite impressed by your precision employed isolating the origin of the problem !

When it crashes the sequencer stops playing, the steps are erased and the kit is going nut. It doesn't seem to happen when the cable is unconnected on the other end.

dtgn

Any idea how I could debug this ?

julian

this is a hard one!

so it happens when the plug is half way in, probably when it shorts the outs to gnd inside the jack... :-?

maybe there is a short between the plug detect switches and the AVR reset line?
could you check the soldering on P2 on the mainboard connector?
Pin 12,14,18 and 20 are the switch detect lines.

Pin 15 and 17 are AVR and mainboard reset.

I have to think what else could cause this...

nightworxx

Just one out of curiosity: do you plug into an interface or mixer ?

Do you use a plain mono cable or a balanced / fake balanced cable ?

Some interfaces not only do not like this.. i've seen issues in the past with very expensive interfaces, where their balance detection circuit did not shut off properly and even their input DAC died. 

dtgn

@julian I'll check the soldering then.

@nightworxx I'm plugging into an external USB soundcard and indeed there is this fake connexion behind: the sound card input are balanced XLR, so the cable I am using is XLR on one end and RCA with jack adapter on the other end to connect the drum machine.

Do you think that would be the cause of this behaviour ?

dtgn

Actually, it also crashes when using a simple mono jack connected to an "unbalanced jack input" in the interface...

nightworxx

So there is no coincidence at last, this can be ruled out so far.

dtgn

It seems so. But I have no idea how to make sense out of this

nagual

I found a problem with unplugging outs 1 and 2 while playing, and replugging into 3/4, unplugging, and then replugging into 1 and 2.  Plenty of random results such as Load/Save information disappearing, silence in the sound output, a corrupted filename.  I have repeated this action many times looking for consistency in undesirable effects to make an useful report, but I guess it's probably best not to hot plug the jacks during a performance anyway.

dtgn

@nagual : I experience the same kind of erratic behaviours. You're probably right when you say it's best not doing it, but it's very strange that it corresponds to THE EXACT test procedure Julian is actually applying to his units before shipping...

@julian : I finally checked the soldering, which seem fine, visually at least. In order to do a deeper check, I need you to help me how to count the pins. AVR is written on the board but doesn't seem to correpond to pin 15, no matter how I count. Where should I start and follow the pins counting ?

dtgn

@julian : It's not even necessary, there is clearly NO soldering connexion between any pin on P2.