I’m curious if anyone else has had this issue with their Motif XS…

My XS8 has been sitting unused for a couple of yrs now because of a problem it has been having.  After it has been on for a period of time (say, 10-20 mins or so) the audio output cuts off...EVERY time.  This occurs with only audio and power cables plugged in...no pedals, USB, firewire or other cables.  It produces a small pop to whatever amp that it’s plugged into (similar to the sound it would make if someone just powered the XS8 off with an amp on) and then it ceases to send audio out.  If the XS8 is physically powered off after this happens, there is no pop to the amp like there normally would be if it were powered off while the amp is on.

After this point, there is no output to the MAIN L&R;or the Phones. 
The DIGITAL OUT continues to work fine. 
There is a very (very!) faint signal going to the ASSIGNABLE L&R;when I direct audio to it.  And it’s only slightly detectable when the volume control is all the way up. 
Rebooting the XS doesn’t help.  If I let it sit for awhile (an hour or so) it will repeat this behavior after 10-20 mins.

All other functions continue to work when the audio cuts out…
all lights and menus continue to function, song and patterns still scroll, midi out still works, etc.  I can even successfully record/export a song out to a WAV file during this state.  Everything seems to be functioning properly with the exception of the audio out issue.

It seems to me that it may be a preamp and/or heat issue (tho the keyboard is always used in controlled/moderate temperatures).  Is this most likely a preamp overheating, or are there any other suggestions as to what might cause this?  What are the possible parts needed?

Any help is greatly appreciated…
stan

Welcome to the forum.

From a cold start (before the problem occurs)…
If you assign a Drum Voice key or Performance Part to the Assignable Out jacks (see page 18 of the XS Owner’s Manual), is the level at those outputs normal?

Yes, 5pinDIN...the assignables work before the audio cuts out, but not after.

stantheman - 01 May 2015 01:03 AM

Yes, 5pinDIN...the assignables work before the audio cuts out, but not after.

OK, I just wanted to verify that all the audio outputs were working initially, but none afterward.

First, I’ll explain a bit about the XS audio circuit. The digital signal source for the main L/MONO and R outputs goes through a DAC (becoming analog), some amplification, the MASTER VOLUME slider, and some additional amplification. The PHONES output is taken from the Main outputs, and goes through an additional amplification stage.

The ASSIGNABLE L and R outputs are similarly derived, but from a different DAC than the other outputs, and the signals don’t go through MASTER VOLUME.

All of the analog audio outputs have a muting transistor as the last active device right before their respective jacks. They’re controlled by a common voltage applied to the base of each transistor through isolating resistors. Based on your description of the problem, it appears that when it occurs, all the muting transistors are being turned “on” simultaneously (which pulls down the signal). That would seem to suggest the muting control voltage is being incorrectly applied.

However, the muting transistors themselves have a history of failing, and I’ve posted several times about the problem. Bad ones cause various problems, depending on the degree of failure and number of transistors which are bad. While I’m not aware of them causing problems with the control voltage, it would probably be worthwhile to check for bad ones first.

Here are some previous threads, which include information on testing for the problem:
http://www.motifator.com/index.php/forum/viewthread/461702/
http://www.motifator.com/index.php/forum/viewthread/472531/
http://www.motifator.com/index.php/forum/viewthread/474301/
http://www.motifator.com/index.php/forum/viewthread/475145

If there’s significant DC found at any of the analog audio outputs, I’d suggest dealing with that before looking elsewhere.

Please let us know what you find.