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Broken pedal

Started by aron, May 30, 2005, 08:13:14 PM

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aron

May 30, 2005, 08:13:14 PM
I spent the last couple of days fixing a broken pedal.

Apparently several wires have come loose and I was not assured that they had been put back correctly.

In any case, I made the mistake of NOT TAKING A PICTURE before starting. Please DO take pictures if you have a camera.

Interesting things happened:

More wires came loose.
A transistor broke off.
One of the pots lugs traces were broken.
The jacks were both bad - I had replace them.
The DPDT was completely mis-wired. No chance there. The battery and ground was connected to the DPDT (don't ask)

First I fixed the DPDT and tried it. True bypasss worked, but not the circuit.

Next thing I did was measure voltages and the voltages on the IC and transistor were fine! Hmmmm OK, I decided to believe the meter and move on.

I knew I could find the problem quickly with an audio probe. After a quick run to Radio Shack I have an audio probe going.

I got tone through the circuit except for the output. The trace was broken but a pad was missing too. I couldn't find where the output was supposed to come from. In addition, the pedal looked like it was modified before.

There WAS a suspicious big blob of solder on the board.

I started to reverse the circuit and then realized that the big blob was one end of a cap and I believe it's the output cap. I remove the solder and the cap is completely off of what's left of the pad. I bridge the cap to the output lug and the circuit works.

While putting it together - more wires break off - I fix other potential problems etc....

Luckily it's working now.

----

Take pictures before starting.
Take measurements and believe your meter.
Reverse the circuit as needed.
Replace bad components.

Hope everyone is having a good day!

mrsage

#1
May 30, 2005, 08:37:48 PM
:D

Good words to live by!

Thanks Aron!

troubledtom

#2
May 30, 2005, 08:50:03 PM
god.......,i know your pain :x
          - tt

petemoore

.
#3
May 31, 2005, 08:42:29 AM
Sounds like the pedal was 'falling apart at the seams !!!
 What is it ?
Convention creates following, following creates convention.

Steben

#4
May 31, 2005, 09:22:44 AM
I guess it's not a big muff (no IC)...
Those muffies are fun repairing and modding.
The only thing that sucks are broken switches of the russian type (green rusted tank boxes). Up til now I always had to place a second DPDT next to it in a new drilled hole.
  • SUPPORTER
Rules apply only for those who are not allowed to break them

birt

#5
May 31, 2005, 11:24:29 AM
sounds like the problem i'm having with that locobox pedal, its still broken. i guess i'm not experienced enough yet to get out of such a mess. atleast i did make pics before i started :lol:
http://www.last.fm/user/birt/
visit http://www.effectsdatabase.com for info on (allmost) every effect in the world!

jimbob

#6
May 31, 2005, 11:44:27 AM
been there before- i bet its an EH pedal. Not knocking EH but they do seem to have a re occuring issue with that problem. I bought a lot of EH stuff in the last 2 years and that was certainly one of the main issues. That and the slider switches. Otherwise the EH stuff (boards, components, ect.. were almost always in perfect working order.
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

puretube

#7
May 31, 2005, 11:52:16 AM
...but then again, you had an online-troubleshooter...  :lol:  :wink:

Paul Marossy

#8
May 31, 2005, 01:54:19 PM
What the heck were you working on?! That sure is a lot of broken wires to deal with! Not to mention all of the other problems...

jimbob

#9
May 31, 2005, 02:52:25 PM
Puretube- very true!









(support your local brewers)
"I think somebody should come up with a way to breed a very large shrimp. That way, you could ride him, then after you camped at night, you could eat him. How about it, science?"

aron

#10
May 31, 2005, 03:36:57 PM
It was a "transition" Hotcake. It didn't fit the normal schematic so I believe it had been modded at some point.

Very, very fragile since there was no rubber goop to protect the transistor and the wires were very old as well.

george

#11
May 31, 2005, 09:03:45 PM
Quote from: aronIt didn't fit the normal schematic

YOU HAVE A SCHEMATIC??????  :P  :P  :P  :P  :P  :P  :P  :P  :P

you must be VERY good friends with Paul Crowther ...

I have a TL071, a single diode and a JFET which I am going to start experimenting with really soon

aron

#12
May 31, 2005, 09:16:22 PM
I have always had a schematic from a while back and I even posted it in Ampage.

I did it myself like R.G. explains. I made a top and bottom copy and used the two to trace out the circuit.

I decided to not make available on the schematics forum for various reasons. I wanted to know how it worked and when I traced it, I was amazed at how good an op amp clipper could be.

That being said, there are Shaka pedals that sound better; much better (to me) than the Hotcake.

george

#13
June 01, 2005, 04:08:35 AM
Yes I have heard that the hotcake sounds better through some amps than others ...

still I have read enough about it to want to try connecting up the offset null pins on a TL071 in various ways and see what sort of sounds I get.

I may even buy one just to trace it.

I may even end up making a Shaka III or V too! - I have a suspicion certain boutique pedal builders think an op-amp driving a JFET mu-amp sounds good too . :wink:

petemoore

.
#14
June 01, 2005, 12:21:45 PM
I have a suspicion certain boutique pedal builders think an op-amp driving a JFET mu-amp sounds good too .
  They sound good with discretes driving 'em too !
Convention creates following, following creates convention.

Paul Marossy

#15
June 01, 2005, 07:10:54 PM
Ah, that satisfies my curiousity.  8)
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