Bought a new pedal, and... it stopped working.

[Nyklus]

I dont know exactly what happened here.
this pedal was working fine just a few days ago,
I bought it used of craigslist.
It's from a small boutique maker up in ontario canada

I took the
The Pulse pedal by magnetic audiotone
http://www.magneticaudiotone.com/Magnetic_Audiotone/Effect_Pedals.html

to an electronics guy and he said, it looks like the adapter input is a switched polarity,
i guess maybe a switched polarity doesnt matter for the LED, because that still comes on.
but the problem is that the effect circuit no longer functions.
whats confusing is that i used the same adaptor that the pedal came with, which is 12v, and the pedal says 9v.
that may be a problem, I might have over powered the circuit.

i posted some pictures of the circuit on this page
http://referencethisstuff.tumblr.com/

[artifus]

looks like it is this: http://folkurban.com/Site/PWM-715.html

*also* check those jack connections are not shorting - looks pretty tight in there. good luck.

[effection]

It's definitely Escobedo's PWM



What do you mean by the effect no longer functions, and did it ever work for you?

[Nyklus]

yeah it worked just fine when i got it.

and it does look exactly like a wobbletron.

magnetic audiotone, had a lifetime warranty but they seem to have up and left, their websites still up but their email doesnt work and they dont update their facebook.

[Nyklus]

what i mean by the effect no longer functions is that in bypass mose it still works. so its not the input, and the LED comes on, but the IC chips its running into arent producing a signal.

I tried audioprobing, the ground of the output and i poked around the circuit with the lead, none of the arms of the chips are doing much. silence.

[alparent]

12v should be OK for 386 and 40106. Check the datasheets of  your particular IC's.

Pictures are always a good way to get us to help you 

[Hallmar]

Oh man, that pedal looks simple enough.

That's so freaking cool!

8-bit guitar pedal? oh man oh man

[Nyklus]

SO i figured out what happened.

I used a reverse polarity adapter on her and that why she stopped working,

Im wondering if any of you might have any idea, from looking at the circuit, what would take the brunt of reversed polarity mishap.

could be the capacitors or the chips. i have everything i need to replace them, just looking for some pointers.

[CodeMonk]

First picture below the hand drawn one.
The black component with the silver stripe
According to the schematic, its a 1N4001 diode.
Try replacing that.

[Nyklus]

Thanks!, I tried jumping the leads of the diode with alligator clips, still no dice.
Do you think i would need to actually remove the diode to to test or is jumping the leads enough.

I figured it was ok because other PWM schematics dont even include diodes there.

[CodeMonk]

Pin 6 is where the power gets to the 386, so its possible that may have gotten hosed.
I may be wrong here though (My brain takes awhile to get going after I wake up:) ), but I think that may be a possibility.

And yeah, its better to test suspect components out of the circuit.. You would only need to remove one lead from the board for that diode.

If you aren't getting any signal with a trace out of pin 5 of the 386, then I would say it is toasted.

[slacker]

Going by this picture http://24.media.tumblr.com/7affb2621d1bc2ae8e89b16cebc3d431/tumblr_mkn3qv5gjH1sn9smpo1_1280.jpg they copied Tim's polarity protection, the polarity protection diode is in series with the supply so it will protect the circuit from reverse polarity or AC without blowing, even if it was blown it would have still protected the circuit and jumpering it should make the circuit work.

What voltage do you get if you power the circuit and measure between the striped end of the diode and ground?

[Nyklus]

thanks for the ideas, ill check the diode voltage this afternoon,

[Nyklus]

I just check it and i get 4.91 volts

[toneman]

Take it back, take it back, take that thing right outa here.
Right away, far away, take that thing right outa here.

Songwriters: STOVER, JEREMY S./BROWN, KEITH

http://www.lyricsfreak.com/c/cream/take+it+back_20034172.html

[Nyklus]

can't cant can't cant. I'd rather just fix it.

[Jdansti]

What is the voltage of the PS when it's NOT plugged in to the pedal?


What is the voltage of the PS when it IS plugged in to the pedal?

[Nyklus]

ill have to check it out tomorrow.
but I figured the battery I am using wouldn't power the board unless I had a cable in the input so
for that 4.9 v. I had it plugged in.

[jpwilksch]

I read jdansti as meaning measure the power supply output voltage when a) the power supply is plugged into the pedal, and B) when the power supply is not plugged into the pedal.

By the sound of it your power supply is a 9V battery, so measure the voltage across it, in and out of the pedal.

[Thecomedian]

what I remember my dad teaching me was that you measure voltage by choosing a node and then choosing ground. If want to measure the voltage difference, you measure from one node to the next, which won't be the same value as the voltage for either node alone.


nodes = wires inbetween components.