chrisfischer - 09 June 2014 06:58 PM

FYI - Just measured the the Main outputs with a meter and the right side is measuring 2 volts, left side zero, (though both sides actually are leaking signal.) Sounds just like your other thread with the popping issue.  I assume the transistors are the same type 2SC2878 used in the XF as ES?  Are these also the same on the AIEB2 boards too?

All of the analog outputs have muting transistors, so I suggest that you check both the main and assignable outputs for DC. Older gear used the 2SC2878 leaded devices (headphone circuits still often do), newer ones use the surface-mount version, 2SC3326, for the line outputs. Only the original type should be used. The surface-mount transistors are soldered to the underside of the boards. Having the service manual is useful, as it will detail both the disassembly procedure and help you identify the parts.

I’ll let you determine whether your soldering skills are up to the task - it can be a challenge if you haven’t done it before. Otherwise, buying the JA board or having someone else do the repair might be prudent.

Best of luck in getting this resolved.

By the way, from what I can determine the failure of the muting transistors does not seem to be spontaneous, and I don’t think there are a great number of Motifs with an unrecognized problem. It seems to be more prominent with gear that’s connected/disconnected on a more regular basis, rather than that which is left set up and infrequently disturbed. It might be caused by surges while making connections, possibly from static electric discharges or charged/leaky input capacitors in other gear being connected to. Also, to be clear, it’s not something that happens exclusively with Yamaha gear - the particular transistors are used in other gear, and similarly develop leakage in that equipment.

Great info.  I checked and sure enough both AS-L and AS-R are reading 1.6 volts.  I need to figure out if my setup is causing this to happen more frequently.  The power should be stable because it is run through a Triplite UPS back up but I wonder if something with the signal chain could be zapping them.  The fact I have had issues in the past with the AIEB2 boards and now this is suspect. Maybe all the cabling should be plugged in before the board is powered up and unplugged after the power is off.

I will order the JA board, replace it and then determine if I want to tackle soldering the new components or having someone else do it.  Either way, having a back up board is a good idea.

Thanks again!

chrisfischer - 09 June 2014 08:48 PM

Great info.  I checked and sure enough both AS-L and AS-R are reading 1.6 volts.  I need to figure out if my setup is causing this to happen more frequently.  The power should be stable because it is run through a Triplite UPS back up but I wonder if something with the signal chain could be zapping them.  The fact I have had issues in the past with the AIEB2 boards and now this is suspect. Maybe all the cabling should be plugged in before the board is powered up and unplugged after the power is off.

I will order the JA board, replace it and then determine if I want to tackle soldering the new components or having someone else do it.  Either way, having a back up board is a good idea.

I’d doubt this is related to power stability, even if you hadn’t mentioned using a UPS. It’s certainly a good idea to make interconnections before powering up, and to disconnect things after they’re powered off. Although it might not reveal anything, it wouldn’t hurt to check for DC on any inputs you’re connecting to. Phantom power accidentally applied can damage output stages, and the muting transistors are right at the output. A good DI should be able to provide protective isolation.

See http://www.sounddevices.com/notes/general/phantom-power-and-unbalanced-outputs/
http://www.soundonsound.com/sos/jan13/articles/qanda-0113-3.htm

 

chrisfischer -

Thanks again!

You’re welcome!

I am now using a Radial DI8 so this will hopefully help in the future.  Thanks again for all of your fantastic assistance!

UPDATE: I ordered a new JA Circuit Board for approrx $160(Part# WU494900)and had it sent overnight.  It arrived today and it took me about 20 minutes to swap into my XF8.  PROBLEM SOLVED! Everything is working great now.  My original hunch was correct after reading other threads that the muting transistors were leaking.  I plan to replace the transistors on the board I took out so that I will have a back up in case this happens again.  Super easy fix, thank you Motifator Forum and thank you 5pinDIN!

Is this a common defect that Yamaha will correct or is it on a case by case basis?  Or is it a bad lot of transistors?

chrisfischer - 11 June 2014 01:32 PM

UPDATE: I ordered a new JA Circuit Board for approrx $160(Part# WU494900)and had it sent overnight.  It arrived today and it took me about 20 minutes to swap into my XF8.  PROBLEM SOLVED! Everything is working great now.  My original hunch was correct after reading other threads that the muting transistors were leaking.  I plan to replace the transistors on the board I took out so that I will have a back up in case this happens again.  Super easy fix, thank you Motifator Forum and thank you 5pinDIN!

Yes, your original hunch indeed was correct. I’m glad that you’ve resolved the problem.

It’s good that you got the DI. A passive DI will isolate the Motif’s outputs from excessive DC voltage due to possible sources such as phantom power. However, the transformers in such DIs typically step down from line to mic levels, which effectively makes them step-up in the opposite direction. That means live connecting should still be avoided - I’d suggest that neither the Motif nor what it’s going to should be powered at the time, if at all possible. In addition, when setting up I’d make the connection at the Motif outputs last, and disconnect them first when breaking down after the session. That should help avoid the possibility of a significant voltage pulse being applied to the Motif’s outputs.

robinvt - 11 June 2014 01:50 PM

Is this a common defect that Yamaha will correct or is it on a case by case basis?  Or is it a bad lot of transistors?

I wouldn’t call this a “common” defect, and it’s also not a problem exclusive to Yamaha gear - please see my earlier post(s) where I addressed this and its possible causes. Nor is it apparently due to a bad lot of transistors, since the failures have occurred over several years.

The transistors being used are a type that have special characteristics. They are specified by the manufacturer (Toshiba) for muting and switching use. Used within their ratings, they seem reliable. Whenever equipment has to interface to the outside world (that is, other gear), there are always some vulnerabilities.

Thanks for you quick response!

I am facing a similar problem ... What if I continue using the board .. As while playing the board bleeding audio does not cause much problem to me ... Do I run the risk of damaging it further. If I use a DI box will it resolve the problem I m facing now.

sougatpaul@gmail.com - 27 September 2016 04:59 PM

I am facing a similar problem ... What if I continue using the board .. As while playing the board bleeding audio does not cause much problem to me ... Do I run the risk of damaging it further. If I use a DI box will it resolve the problem I m facing now.

Welcome to the forum.

If your XF has leaky muting transistors, a DI box will do nothing to resolve any bleeding audio or distortion.  A DI box, used properly, might prevent the problem from becoming worse. If there isn’t currently a significantly audible issue, then you could ignore it until it becomes worse.

Under any circumstance, it’s best to make sure your Motif does not get connected to an input that has phantom power turned on.

5pinDIN - 27 September 2016 05:24 PM

sougatpaul@gmail.com - 27 September 2016 04:59 PM

I am facing a similar problem ... What if I continue using the board .. As while playing the board bleeding audio does not cause much problem to me ... Do I run the risk of damaging it further. If I use a DI box will it resolve the problem I m facing now.

Welcome to the forum.

If your XF has leaky muting transistors, a DI box will do nothing to resolve any bleeding audio or distortion.  A DI box, used properly, might prevent the problem from becoming worse. If there isn’t currently a significantly audible issue, then you could ignore it until it becomes worse.

Under any circumstance, it’s best to make sure your Motif does not get connected to an input that has phantom power turned on.

Thanks 5pinDIN for your prompt response really appreciate it.. please suggest which DI to use in order to prevent phantom power from the mixer. Can this leaky transistors be replaced / repaired or the entire PCB needs to be repaired and need an approx repair estimate. Earlier posts in this regard are of 4 to 5 years back, hence the query.

This problem happened to me also.

XS8...using assignable out for a click to the drummer. Worked fine for awhile...then the click started bleeding into the mains.

Traded the XS8 in for an XF8......boom....problem solved.

sougatpaul@gmail.com - 28 September 2016 12:53 AM

[...] please suggest which DI to use in order to prevent phantom power from the mixer. Can this leaky transistors be replaced / repaired or the entire PCB needs to be repaired and need an approx repair estimate. Earlier posts in this regard are of 4 to 5 years back, hence the query.

I’d suggest using passive isolation - perhaps others will suggest particular models. The transistors can be replaced by a competent technician, but if you’re capable of replacing the JA board yourself, that could be less expensive. You might want to contact Yamaha to determine current pricing.

sougatpaul@gmail.com - 28 September 2016 12:53 AM

...please suggest which DI to use in order to prevent phantom power from the mixer....

I would highly recommend This Stereo DI Box...good professional quality.