E-Pro with Epvm1345 Module pitch issue

Posted: 5/23/2016 3:20:18 PM

From: Minnesota

Joined: 3/9/2013


I have installed an Epvm1345 module in my E-Pro.  The install was successful and my volume response is now working perfectly, no issues there.  However, I am noticing something with the pitch function that may or may not have anything to do with the installation of the module other than the timing of the issue itself. 

The issue is this... when I first power up the E-Pro after it has been off for a day the pitch is locked to a very high constant frequency and stays there until I put my hand within an inch of the pitch antenna after which is then locks on to my hand position and everything returns to normal.  I am wondering if there is a possible tuning issue with the E-Pro that somehow introducing the module has exacerbated? 

Note, this issue does NOT occur if the E-Pro has been on powered off for a short time, only when it has been off for an extended period.

Any suggestions on what may be going on and a possible remedy? 




Posted: 5/24/2016 7:07:43 PM

From: Colmar, France

Joined: 12/31/2007

That's a pure pitch issue which can happen or not, depending on the circuit temperature, here it happens when it is cold, on others when the circuit gets warm, or depending on humidity. That's nothing to worry about - for the moment - since moving your hand once close to the pitch antenna brings everything back in sync.

That's an unfortunate coincidence - the EPVM1345 which sits on the volume board can technically not impact the pitch circuit.

What has happened (and happens earlier or later on most EPros), is that either the variable pitch oscillator has gone somewhat low or the resonant frequency of the innards of the pitch arm has gone somewhat high with the years. A complete recalibration of the pitch section to compensate component aging of the EPro needs an experienced expert, a frequency counter, an oscilloscope and two working hours, thus you better live with the sometimes uncomfortable startup for the moment. When things get worse over the years, feel free to contact me by email.

Posted: 5/24/2016 10:28:09 PM

From: Minnesota

Joined: 3/9/2013

Thanks Thierry for your reply.  I assumed that the two had nothing to do with each other and your explanation makes perfect sense.  The issue is certainly tolerable but I do look forward to the day that I can place my E-Pro in your expert hands for a tune up!

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