DWD - EP Multiwah footswitch

[tedstruk]

finally found the right forum...

OK I cut the board out of the pedal and discovered some real bad looking connections on it, that I will have to remove.
I wrote a schematic for it as it is before I do anything, and I downloaded a couple of free schematics on volume and phase circuits.

Sometimes its better to start from scratch, so I dug around in my shop and found 3 more pots -3pin 200k.

I pulled the 5 way, and made a diagram of the pinouts 1 to 5. there are 10 pins,
Position 1 and 6 have no effect.
Might be a bad switch.
I can't find any volume pots anywhere. Only balance pots, I don't like using balance pots as volume pots, I never can get the response I want, and I always lose some tone or something.

You don't see much highvoltage, loud and clear stage equipment anymore. It's lonely out here.

 

[tedstruk]

updated schematic

I made a few mistakes on the last schematic I posted...
this is an updated version... I will keep looking until I have it right.

 

[tedstruk]

Properly connected board?

This schem shows where I think I would put the wah pot and the battery, but I don't know where I would put the jack inputs and outputs. It also has a battery isolator for an external 9v wall wart. The 5 way works, but the plastic has pulled away from the potmetal housing, so I am considering buying a new one next time I am in a part house...
If you are a good dedicated electronics engineer or something, maybe you could give me a hint as to where to connect the in and out...ground to negative, and everywhere.

 

[tedstruk]

forgot schem!

the board has 6 large holes
A B C
D E F
A is isolated
B is connected to one of the CEcap's after the cap, into the base of the transistor
C is isolated to pins A and H
D is connected to .01 cap and pin F
E is Isolated to Pin G
F is connected to the other CEcap, after the cap, into either the collector or emitter?
I think collector?
Any help nessesary is truly nessesary!!

 

[tedstruk]

On this diagram I added the possible wah connections and the mains.

Main A is always isolated, which as I remember(from school), must be isolated, for the circuit not to ground out.. I don't know what goes in the mains though. IDEA!!!

Is it a harness?

 

[(*steve*)]

The +9v looks wrong. It's not going to connect to a capacitor like that.

 

[tedstruk]

9v...power supply

Ok. I always thought that the power source was isolated with caps to keep it from burning up the other smaller components. what are the 100v and 16v caps doing on a 9v board?

 

[(*steve*)]

As long as they're over 9V it's OK. The 100v capacitor is likely to be a small value that may only come in a 100V rating

 

[tedstruk]

found a bad resistor....

This resistor does not look bad, but I cannot get a continuity signal through it.



checked some other components, then tried it again, and its not blown?

call the ghosts of the pcb controlling agency......

 

[davenn]

Ok. I always thought that the power source was isolated with caps to keep it from burning up the other smaller components. what are the 100v and 16v caps doing on a 9v board?

DC doesnt flow through capacitors ... they are open circuits

Dave

 

[tedstruk]

how many Ma of wall wart would be good for this board?

 

[tedstruk]

assumptions, what a conundrum!

Assuming... I am right in that the caps are the 5 way tonal changes...

then the rest of the circuit must be inputs, outputs and switching.

If the 2 1294s are power caps, instead of wah resistors, then I think it is safe to assume these are the pins that are all supposed to be populated(there should be something in each of these holes.) So they are probably where I put the stickystuff...
how does this look?

A=common
B=9v
C=ground
D=input
E=common
F=output

pins

a=common
b=open
c=open
d=wahpot in
e=output
f=input
g=common
h=ground
j=wahpot out
k=5way
l=5way
m=5way
n=5way

 

[(*steve*)]

how many Ma of wall wart would be good for this board?

What is the maximum current it draws? multiply that by 1.2 and use that as a minimum current rating for the wall wart (more is OK)

 

[tedstruk]

current rating...

What is the maximum current it draws? multiply that by 1.2 and use that as a minimum current rating for the wall wart (more is OK)

ahem, how do I compute the current...

That would be the amount of induction?? like a 500 induction coil would draw 500ma?
if thats true, then 1.2amps would be just right.
I have a 450ma wart, is it possible to increase it to 1.2?

 

[(*steve*)]

ahem, how do I compute the current...

The easiest way is to measure it.

This circuit seems to be battery powered. Connect your multimeter in series with the battery and measure the current.

If it's powered by a small 9V battery then it probably draws no more than 20mA. Since you're not going to find a wall wart rated at less than maybe a couple of hundred mA, almost anything will do.

However, since the circuit is not designed to operate from mains, it may be insufficiently filtered and hum from the external power supply might be heard at the output. To fix this you may need to add more filtering.

 

[tedstruk]

milli wow!

Hey my figures were close to the 20 you said, the board resistors came out 21.2ma!

OK I have a 9v 450ma I can use, but I might need to add some filters. alright!

here is my latest schem on the test modes...

I don't like the first test, because it uses the block for a power source, I think I remember something about not using the block for power in my antient teachings.

I am stuck with the second then. I think I should test with a smaller power, like a 1.5v just to be sure I don't cook anything.

 

[tedstruk]

What size fuse would I put between D and F in the block?

 

[(*steve*)]

I would test it with a small 9V battery first.

I see no need for a fuse, and the leads your suggesting for that are what you have labelled as input and output, certainly not a place to put a fuse.

If you really want one, place it in series with the battery connection. Something rated for 100mA would be fine (if you can find one) otherwise the lowest current above that you can get hold of at a reasonable price. I'd probably go for a fast blow (but as I said, it's likely superfluous unless you're connecting stuff randomly)

 

[tedstruk]

I don't know where to connect the terminals.


I have a board with no schematic that says "input goes here", "battery here" ect.

Me? I would connect the battery in the wrong place and bunr something up!
I wanted a schematic, but I couldn't find one... I can draw one, I knwo what everything does, but I am just not a tech...
sorry!!!

 

[(*steve*)]

Post some good sharp photos of goth sides of the board and we'll see what we can do for you.