Sunday, 26 June 2016

Electro-Harmonix Soul Food

I don't think I need to talk too much about this one, there's a lot of info online already (not enough pictures though. Photograph your stuff). This is EHX's budget version of the Klon Centaur, apparently with very few changes from the original.


This one arrived dead, nothing happens when power is applied. Probing around with a 9V supply connected doesn't find voltage anywhere. I started at the DC jack, and found that there was no continuity between the tip and the PCB. After desoldering, the DC jack still had an open circuit internally. This was probably mechanically damaged.
The 3PDT footswitch board has the True Bypass/Buffered Bypass switch of the original Klon and KTR.

D2 & D3 do not look like the "magic" Klon diodes. Internet consensus says they are Schottkys.
With a new jack installed it still had no power to the ICs. Diode D4 is connected across 9V to ground as reverse polarity protection, but as there is no series resistor D4 had become shorted, presumably by an incorrect power supply. I pulled it and replaced with 1n4007 as I have a lot of those. Works as expected now.

I would imagine there were two incidents that caused it to end up like this. Someone used a power supply of the wrong polarity and burned out D4, and someone broke the jack by forcing in the wrong connector or stepping on the power cable while it was plugged in.

For anyone else working on these modern EHX pedals, I have found that plastic spudger tools that are sold for opening electronics (particularly phones) work quite well for pushing on the DC jacks to remove the PCB from the enclosure, and don't leave any scratches.

8 comments:

  1. Was wondering if you had any further problems after replacing the d4 diode...mine just crapped out

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    1. No problems, but not a huge amount of use either. What did you replace it with? Did you use an AC supply accidently at any point since swapping it?

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    2. Havnt fixed it yet...prob gonna order a 1n4742 cause its apparently what the old one was...i used a onespot on it for a few months no problem so im not sure

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    3. Havnt fixed it yet...prob gonna order a 1n4742 cause its apparently what the old one was...i used a onespot on it for a few months no problem so im not sure

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    4. Not sure. Double check that the replacement died too, maybe? They usually fail as shorts (like mine) and the pedal should work with the diode clipped out if you have the right power supply.

      I have heard that the charge pump is the next most likely point of failure on Klons.

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  2. Just bought a "dead" Soul Food that's on the way. Told that it powers up and then LED fades after one second. Any initial thoughts on where to start?

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    1. This comment has been removed by a blog administrator.

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  3. Hey thanks for this! Just got one for free and fixed it, per your advice. Cheers!

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