A long shot......marshall pedl 91016...

Started by whomeno, September 29, 2018, 02:01:35 PM

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whomeno

I'm looking to build a 91016 foot switch for a dsl40cr. Hard to find and the price is out of this world at 200.00 for a foot switch.
dose any one here have one. that they could do a schmatic on? Going to get the amp in a few mouths will not be able to afford the foot switch.
Thanks
Gear as of now
Gibson 2017 Les Paul Tribute T
Epiphone Les paul Special (upgraded)
Marshall DSL 20 Head
Peavy Valve king 20 W
2 X 12 Cabinet with celestion vintage 30 & celestion G12T-75
And a lot of pedals

codycale

I am also interested in this same thing.  If anyone has one that they could post a schematic or pictures of, it would be greatly appreciated.

pinkjimiphoton

is there some special vegematic function this fs provides?

usually anything marshall is just short to ground for each segment. if its using a din/midi style plug, its still fairly easy to figure out usually once ya have the amp in front of you.

not familiar with the amp in question, so, need more info... what's the plug look like? jack? how many functions does it support? etc etc

that will get us a lot further than just a model number
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"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

pete74

Bump. 
Does anyone know what's being done in this FS?    From what I've seen it's using a standard mono 1/4" cord/jack to handle 6 switches.   

The 2 button switch that comes with the amp is TRS which makes sense.   But the 6 button one plugs in the same jack on the back of the amp.   

pinkjimiphoton

thats weird, 6 functions on one trs?  i'm betting it has to do with voltage levels... different voltages may tell the amp what to do.. in that case, its usually diodes on some of the switches, so each switch presents two different voltage levels, or maybe even three... sounds crazy and weird but it should work.
i'm not familiar with the switch, but have ya tried contacting marshall directly?
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

pete74

Quote from: pinkjimiphoton on February 09, 2020, 01:04:51 PM
thats weird, 6 functions on one trs?  i'm betting it has to do with voltage levels... different voltages may tell the amp what to do.. in that case, its usually diodes on some of the switches, so each switch presents two different voltage levels, or maybe even three... sounds crazy and weird but it should work.
i'm not familiar with the switch, but have ya tried contacting marshall directly?
I personally haven't, but have read many comments that they won't disclose any of these details.   One thing I just thought of though, the amp provides some power to the fs as the stock one has LEDs and no other power source.....

LAAF

Has anyone made their own 6-Way pedal using the MIDI interface? Seems quite possible and customizable at a low cost. Now that I'm retired I may want to design one, but it would be nice to leverage work that has already been done.

LAAF

Well I couldn't wait, so I built my own MIDI version. Seems to work quite well now with some code changes.

https://youtu.be/yKC5l1sZTKw?si=mrrGjBgXTF8QsTCF


R.G.

There are a lot of ways to get many functions with only a TRS footswitch, but they are not simple. There is most probably a controller/processor involved at either the amp end, possibly at the footswitch end as well. Sensing a tap on a string of resistors is probably the cheapest way to manufacture the pedal, so it's likely to be what is really in there, but an alternate, and nearly as cheap way is to put a microcontroller in the pedal and have it just send ASCII or Morse code or some such, probably proprietary and encrypted messages back to the amp. If it's string-of-resistors, finding one and hacking it open solves the problem. One good choice is to make friends with a respected (and probably backlogged) amplifier repair tech.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

LAAF

#9
Since they need to run the LEDs reliably, my guess is that they are modulating data on a DC level known as Power Line Communication (PLC). The DC level is used for powering the electronics (microcontroller and LEDs) and the data is then AC coupled to the power line.

marcelomd

#10
Hi,
This is the schematic for the DSL40: https://music-electronics-forum.com/filedata/fetch?id=849830&d=1528852809

Let's see...
- Tip, ring and sleeve are connected to pins of a microcontroller. They have pullups to 5V;
- One of the pins can be used as an analog input, but I don't believe it is used as such;
- No dedicated 5V to power the footswitch, which more or less rules out a microcontroller there;
- Sleeve can be dis/connected to ground via EFFECTS SW;

So
- We can operate the footswitch like a keyboard matrix;
- We can have different buttons short different combinations of the uC pins;
- Maaaybe the ADC pin is used as such and each button presents a different voltage;

EDIT: Found an incomplete schematic of the DSL100 that has +12V, Ground and a "FSW" net connected to the footswitch jack. It doesn't show where it's connected, but points to power and one serial data line.