Mustang GT- More reliable 4 button foot switch

Started by Elantric, May 12, 2017, 06:09:48 PM

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I had more opportunity to play both GT 40 and GT 100 , along with

Expression pedal and 2 versions of the 4 button foot switch for a few hours:

I observe that with Mustang GT firmware 1.1.0 ,

MS-4 (( Mustang III)
the MS-4 ( Mustang III) Footswitch is more compatible with the EXP-1 Expression pedal , allowing the EXP-1 Toe switch to toggle between GREEN Mode (Volume) and RED Mode ( Assigned FX Control)

I observe the ULT-4 ( GDEC3) footswitch is less compatible with the EXP-1, the EXP-1 Toe switch toggles between a mode with both the GREEN and RED LED are lit (Volume) and a mode with no LEDS and no function

I also observe that the foot controller interface using non shielded speaker cables between amp and pedals remains just as flaky as the Mustang III , works 85% of the time or will lock up if you navigate too rapidly with your foot. Fender Support specifies to avoid using standard coax instrument cables for Mustang (III/GT) foot pedals because the high capacitance negatively impacts the data clock edges of the communication link to the pedals, (this is why Fender ships the 4 button pedal with 1/4" plug speaker cable)

MGT-4 ( Mustang GT)

The Mustang GT MGT-4 method of the Bank up / down selection on MGT-4 by Pressing 2 switches at once works for Bank Up ( 2 right switches , but I had to avoid Bank Down ( 2 left switches) because 90% of the time the pedal would switch modes or accidentally engage the Looper and enter Record mode, even though the pedal still displayed that I was still in PRESET Mode - just knew I had entered Record mode because 60 seconds of recording instantly starts the playback of recorded tracks.

Cant trust this at a gig I hope the official MGT-4 pedal reacts better when it arrives next week , but if you are able to use these Mustang pedals ( any generation) reliably, count yourself lucky.

Quote from: dazco, post: 24112233, member: 1963This is something i thought of too, and it's one of several switching things that i find so stupid that fender went the way the did with the GT. I have no use for a looper, but even if i did the fact that one mis-step and you could become the laughingstock of any audience you play for is to me a utterly insane design decision. Combine that with the lack of the 2 button switch support and i find fender's decision regarding whats important in switching on the GT puzzling. It's supposed to be an upgrade. In any case, tone for me is #1 by far and i much prefer the GT and switching wise i'm ok with what it's cone to be aside from the idiotic looper minefield. But i modified my footswitch with the MIII by taking switching out to other areas on my board and i intend to redo it now with the mode switch removed from the housing and put elsewhere on the board using a monetary footswitch since the stock one is nothing more than a plunger that triggers a tiny plastic circuit board mounter switch. This way i;ll never accidentally hit the mode switch, and i will always have my switch in effect mode which is all i really need from it.

sounds like a plan

Here is the older generation 4 button design. need to improve the reliability
I plan on modify  / re-engineer the existing Fender footswitch circuit for use with a battery pack 
(Fender  uses a variation on the old 1988 IVP Pitchrider remote pedal design with  data and power" on one wire using one 1/4" mono cable )

But in practice there is data loss / lockups of the foot switch that requires rebooting the Mustang GT amp  = 20 seconds of dead air mid song

I suspect disassembly and adding a small application of Caid De-oxit on the switch contacts might improve reliability


I tested my Mustang GT40 with latest Firmware and the Fender EXP-1 Expression Pedal and MS4 4 Button Footswitch - (with Magnetic Overlay)
for 1st minute of operation - the EXP-1 Toe Switch operation was very erratic - but after a few full treadle sweeps and toggling the Toe switch - it reacted as if the Mustang Amps "self calibrates & learns" the connected Expression pedal and 4 button footswitch - things became more stable the longer I used it - but after 15 minutes I still encountered occasional problems with the Expression pedal  Toe Switch 10% of the time. There are status LEDS Green for Volume Mode and Red for Assignable FX Mode

But the 4 button footswitch is far more stable than its ever been - I like that I can tap the footswitch for the current patch to adjust the tap tempo.

and the EXP-1 works well as a global Volume Pedal  - but the Toe switch to change it to Expression control for assigned FX ( Wah, Reverb amount, etc.) remains inconsistent - but works correctly 90% of the time.

I used the factory supplied 1/4" un-shielded cables (see pic able) for the footswitch and EXP-1


EDIT 3/21/2020
I upgraded my Mustang GT 40 to the latest FW 3.0.31,

Test #1 - I connected my new GTX-7 Footswitch, and tried the new functions - no crashing, no random patch changes - all seems logical and very functional

Test #2 - I connected a Footpedal daisy chain using Official Fender connection method using the stock Fender supplied 2 wire TS Cables

* Mustang GT 40 Footswitch Jack > Fender EXP-1 Expression Pedal > GTX-7 Footswitch

and tried ALL the new functions = no crashing, no random patch changes - all works solid and very reliable now. ( Big Change compared to old 4 button FSW and V2 Firmware)

THANK YOU FENDER and the current Mustang GT/GTX R&D Team, for sorting out the major deal breaker I have always had with the Mustang GT  Amp Series
(Now off to get my GT200 out of storage to apply the new V3 Firmware
and try the new sounds


Rumor is Fender cleaned house and put the same R&D team that developed the new Tonemaster DSP Amps on the Mustang GT/GTX and they cleaned up the code and made it more reliable


Does anybody have an active link to the MS4 schematic (and while at it any of the Mustang schematics)?

In the past I have seen Fender based links along these lines but they are all dead now:

Mustang V: