#1
Hello!
This post is meant to help others identify and correct a mistake that I detected on the stock wiring of the Chapman ML1. I do not know if this error is present in any other ML1's as I only have access to my own.

I'm the owner of a Chapman ML-1, from the first run of continuous production model, like the one on the picture bellow.


Since day one I noticed the volume pot was not working properly, from 100% to 5% the volume was on full, and would only drop in the last 5% in a very noisy way. I figured it was just a bad pot, and so I would just change it, eventually. Please mind I do not live in the UK, so the shipping cost of sending the guitar back to Andertons would be 8x or more the cost of a pot.

Fast forward almost two years, and last Saturday I decided enough was enough. I bought a pot, opened up the guitar and started drawing on paper the schematic of the factory circuitry. To my surprise, the guitar was miss-wired. I double and triple checked, ans the wiring was wrong, and the "dead pot" effect matched the faulty wiring perfectly. Here is the factory schematic, including the mistake (the oscilloscope represents the jack, to where the amplifier would be connected). Notice the green node. The output from the 3 way switch is directly connected to the volume pot floating end, the tone pot, and the jack. Essentially the volume pot does nothing, except when it is completely "off" and ground the jack, cutting off the signal.

Instead, the schematic should look like this. Notice how the previous green node is now divided into two separate nodes (green and blue). After re-soldering a couple of wires to match the fixed schematic, everything works as supposed. The volume pot now progressively cut down the volume over all of its rotation, without any "scratchy" sounds.

I love this guitar to pieces, and Chapman offer great instruments ar a good value, however, I feel this problem should have been detected at the Quality Control they were so keen to display to the public (there is even a dedicated video).
Last edited by amiguels at Apr 10, 2016,
#2
Wow, that's a pretty obvious mistake. Seems like someone would notice an empty pot lug.

Anyway, no company's QC could possibly (feasibly) be 100% effective. Sometimes things get through the cracks. It's when these things keep happening that people should start to question things.

This is great to know, especially for people who may stumble here via Google.
#3
That's really strange.

Oh well. At least the fix won't cost anything.
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#4
I have a Chapman ML1 from the NAMM 2014, Chapman's first NAMM... Ryan, RNA Music, got the NAMM demo models from Rob Chappers himself and i bought one, there is no COA thou.. funny thing is i never plug it in so i don't know if it has the same issues you mentioned. I may need to check it out. thanks for the heads up.
I have Washburn guitars 'Maverick Series' and bass 'Bantam Series' and a few pedals and amps, but man I wish to have more patience and drive practicing my playing, if it's equal to the modding itch, then I'm golden.
Last edited by psp742 at Apr 17, 2016,