Digitech JamMan Delay EMI problem and solution

, , , , , 64

JamMan DelayI wrote about my love of looping back in 2010, when the new JamMan Solo and JamMan Stereo were announced.

Now, I’ve finally replaced my old Oberheim Echoplex Digital Pro with a shiny new JamMan Delay.

This unique pedal combines a looper with a nice delay modeler.   It doesn’t do everything my old Echoplex did, but it’s a nice leap forward in technology- with stereo recording, tons of memory (and SD card expansion), stereo recording, USB connectivity and software librarian, not to mention some really nice delays.

But before we get to happiness, let’s first talk about a major manufacturing issue, nearly a total deal-breaker.   If I hadn’t figured out a solution, I would have had to return the JamMan Delay and seek looper nirvana elsewhere. 

When I first powered up the JamMan Delay and plugged it in to my Vox AC15, I was greeted with a faint but persistent “beep beep beep” sound, in time with the flashing tempo LED.

I tried different guitars, different cables, different power outlets, different amp, different physical location, etc.   The only thing that made any difference was to unplug the input cable.  The beeping was loud enough that if used on stage, it would be blasting this annoyance through the PA!

Could they really have released such a great product with such a fundamental design flaw? It seems unlikely.  I called Digitech tech support and they assured me that there’s no design flaw- their bench units sound fine- my unit must be defective.   So I returned the unit for exchange, but the replacement did the same thing.  What are the chances- two bad ones in a row?!  So I returned it again, and the third unit had the same problem.  These three units spanned serial numbers of about a thousand units!  If not a design flaw, then could it be a very extended factory/QC mistake?

JamMan ribbon cable over jacks and circuit boardUnwilling to throw in the towel, I opened up the unit, and found that the internal ribbon cables connecting the front panel to the main circuit board were laying right on top of the input jack and over the processor.   These ribbon cables carry control signals and power to the LEDs – and the proximity of these cables to the jack/processor clearly causes problematic electro-magnetic interference.

 

 

JamMan ribbon cable folded and out of the wayThe solution is simply to fold and push the cable the other direction.  When the lid is closed, the cable will be resting well away from the main circuit board and jacks.  This completely solves the noise issue.

I let Digitech know about the solution and they assured me they would contact the factory to make sure they were aware of the issue.

 

I’ll be using the JamMan Delay in some upcoming videos, so stay tuned!