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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 8:59 am
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A quick Google search reveals that R1 is 51 ohms and R2 is 560 ohms.

http://www.hobby-hour.com/electronics/smdcalc.php


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 9:43 am
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lnowlin wrote:
A quick Google search reveals that R1 is 51 ohms and R2 is 560 ohms.

http://www.hobby-hour.com/electronics/smdcalc.php


Ok. According to that calculator (thanks for the link, BTW) my pedal has:

R2 = 560 ohms
R1 = 33.2k ohms

33.2k --> 51 ohms is a rather large jump, so I'm wondering if there isn't another digit hidden under the solder? For example, I could believe 51k (if a final '2' is hidden) - but not a value three orders-of-magnitude smaller.

Interestingly, R1 shows very clear signs of rework so it looks like Fender has had some prior EC's around this assembly.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 10:01 am
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Hey shirsch,

Looks like the number is actually 51C, the calculator returns 33.2K when I plug that in. I guess I should have read the entire page before posting, it's under the EIA-96 system.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 10:09 am
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Ok, this is a good data point. We have the same values on the little PCB.

My LED and photosensor are both standing at right-angles to the board, so I'm not going to fiddle with them. I'll try putting a 1mm nylon washer under both sides and see if the extra distance makes a difference. You did say that your updated pedal is shimmed on both sides, correct?


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 10:12 am
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Yep, washers on both sides.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 1:31 pm
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lnowlin wrote:
Yep, washers on both sides.


Thanks for checking... so the only change is the addition of the washers for spacers and for those of us in the USA 1mm = 3/64" :)

But, I'm now wondering if they didn't add the washers simply for the sake of convenience rather than have a new part manufactured and that changing the taper of the arrow is ultimately a better fix in the end?

I haven't opened my EXP-1 up yet, but it appears from the photographs that I've seen that either scraping the white paint off or applying flat black paint in a more gently taper would work and also be a permanent solution.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 2:25 pm
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Tony65 wrote:
But, I'm now wondering if they didn't add the washers simply for the sake of convenience rather than have a new part manufactured and that changing the taper of the arrow is ultimately a better fix in the end?

I haven't opened my EXP-1 up yet, but it appears from the photographs that I've seen that either scraping the white paint off or applying flat black paint in a more gently taper would work and also be a permanent solution.


It took me a few attempts to get the tape placed just right so that it would calibrate correctly. If you don't remove the paint just so it may be worse than when you started. After my original tape fix peeled off I tried repositioning the pcb using shims to point the sensor toward the arrow, this worked very well (just as well as my replacement pedal). As I wrote earlier in the thread, if I had known that was the solution I would have installed the washers myself and saved the shipping charge.

shirsch said that he was going to install the washers on his pedal, hopefully he'll let us know how it works.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 2:29 pm
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Tony65 wrote:
[But, I'm now wondering if they didn't add the washers simply for the sake of convenience rather than have a new part manufactured and that changing the taper of the arrow is ultimately a better fix in the end?


In some respects there's no right or wrong in terms of the electro-mechanical system in the pedal. if the units are consistent in terms of mechanical and electrical tolerances (and that's the issue here, I suspect) it comes down to the software that interpolates the input from the pedal into a log-taper function (volume) or reverse log taper (wah - if memory serves).

Getting pedantic: As long as the input function from the pedal is monotonic and repeatable it almost doesn't matter what it is - it can be translated to the desired end result with varying degrees of difficulty. If this doesn't make sense, my apologies. My background includes embedded software and control system design :-)


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 2:40 pm
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shirsch wrote:
In some respects there's no right or wrong in terms of the electro-mechanical system in the pedal. if the units are consistent in terms of mechanical and electrical tolerances (and that's the issue here, I suspect) it comes down to the software that interpolates the input from the pedal into a log-taper function (volume) or reverse log taper (wah - if memory serves).

Getting pedantic: As long as the input function from the pedal is monotonic and repeatable it almost doesn't matter what it is - it can be translated to the desired end result with varying degrees of difficulty. If this doesn't make sense, my apologies. My background includes embedded software and control system design :-)


OK. :roll:

Did the spacers solve the problem on your pedal?


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 7:00 pm
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The spacers appear to have made a difference. The last part of the pedal travel is actually doing something. But, it's always possible that I was (repeatedly) screwing up the calibration before... I think more feedback from other users is needed before declaring this the solution.


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Post subject: Re: EXP-1 control taper not right
Posted: Wed Jul 18, 2012 7:15 pm
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shirsch wrote:
But, it's always possible that I was (repeatedly) screwing up the calibration before... I think more feedback from other users is needed before declaring this the solution.


I made a separate post on this very subject... the "EXP-1 calibration procedure" leaves a lot to be desired... there is absolutely no feedback that anything is going on during it and the instructions say to simply move the pedal than turn the knob when you're done and apparently at that point it's then calibrated.

Don't have the time tonight to mess with it, but I'm going to try adding the washers/spacers tomorrow and report back how it goes.


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Post subject: Re: EXP-1 control taper not right
Posted: Thu Jul 19, 2012 5:42 am
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to shirsch

Are you experiencing the original problem? That being a deadzone in the pedal travel on either end? I had that with my pedal originally on both ends of the travel. The tape fix corrected it somewhat but certainly not a permanent fix. I beta tested the version of the firmware update that fixes it for Allen and it fixed my pedal. I have full effect over the entire range of travel.

This is like my PC racing games where I set the brake pedal to have just a little deadzone at the top, before it starts to apply brake, that way it makes sure there is NO braking going on when not pressing the pedal and it I happen to rest my foot on it it doesn't apply any braking. With the new firm ware you can do that with the EXP-1 during calibration if you would find that desirable, ie a little deadzone toe down for volume to make sure you are getting the full volume when toe down.


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Post subject: Re: EXP-1 control taper not right
Posted: Thu Jul 19, 2012 7:58 pm
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Okay... I think it's fixed.

First, I saw in another post that someone mentioned they could see the pedal controlling the volume.... moving the pedal and looking at the LCD screen on the Mustang-III the volume control doesn't move, but the volume does indeed change.

Secondly, I did not install the washers/spacers, I followed the calibration procedure Allan (w/ Fender) posted tonight and that seems to have fixed the problem with the pedal travel.

Here's how the EXP-1 calibration procedure should be preformed:
1. With the Mustang-III in the off position
2. Set your pedal to the full heal position
3. Turn on power while holding the UTIL button
4. Move the pedal to the full toe position
5. Rotate the knob to the next preset 01
At this point, calibration will be complete.

This is with Mustang3_1.10 firmware installed.

Doing this results in no dead spot at either end of pedal travel as best I can tell and this is with no washers/spacers installed.


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Post subject: Re: EXP-1 control taper not right
Posted: Fri Jul 20, 2012 3:31 am
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OK, now I'm confused.

Shirsch says that doing the (correct, new) calibration procedure didn't fix the issue. I assume this was with firmware 1.10? But that adding shims did fix it.

Lnowlin had the shims added by Fender and that fixed it. But was that before the 1.10 firmware update was available?

Tony65 says that he didn't need to add shims, but doing the (correct, new) calibration procedure, once it had been clarified by Fender exactly what that procedure is, did fix the issue.

Stinger22 also found that firmware 1.10 (and calibration?) fixed it.

So, are there in fact two different issues here? One that is just a firmware/calibration thing, and one where there is in fact a hardware problem with some pedals, that can't be fixed just by firmware/calibration?

Or are the calibration vs shims just two alternative ways of fixing the same problem?


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Post subject: Re: EXP-1 control taper not right
Posted: Fri Jul 20, 2012 6:58 am
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It is a bit confusing, isn't it? Some people never had any problem with the travel of their pedals and those that do have varying degrees of the problem. My original pedal maxed out just short of half travel and I think one poster said his reached about 70%. I beta tested v1.10 along with some others and while it improved my pedal marginally, it did not solve the problem. I never had any confusion about the new cal procedure.

I believe it all comes down to a tolerance problem or a lack of tolerance in manufacturing specs for the placement of the sensor in relation to the arrow, if it's not perfectly placed it doesn't work properly. When I first opened my pedal I could see that the sensor wasn't placed directly over the arrow. I was able to make my original one work well with the electrical tape but that eventually peeled off so I repositioned the pcb by shimming the edge so the sensor would point more directly at the arrow and that worked perfectly. Fender tech support then said they would replace my pedal. Little did I know that their fix was similar to what I had already done.

Bottom line: If you have the problem and the firmware doesn't solve it Fender will replace it.


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