My first trace: Capacitor color and number codes

[Kindly Killer]

First of all, here's where I'm at: I have done a lot of builds from schematics, sourced parts and such. I just started studying electronics - books, videos,etc. - because I have some ideas for things I want but I don't know exactly how to execute my ideas. One of the skills I thought I should develop is tracing. I am starting with what seemed like it should be baby-simple: a vintage Marshall Blues Breaker pedal. It is a simple circuit, few parts, huge board with traces as thick as a finger, plus I have two of them, so if by some chance I break it just looking at it, I've got a backup.

BUT I traced the schem and started to write in values and I'm stumped on a couple capacitor value decoding issues.

C4: it says A5E with 224 under it, but then you rotate it and it says M9B with 829 under it. So I assume it's 220nF because that's a sensible value, plus it matches other people's traces, but WTF!? What are the other letters and numbers?

BTW I have a couple iPhone apps that translate codes - my problems are not a matter of adding zeros or remember which color means what.

C1 and C2: First I am having trouble discerning colors. I did an overlay in Photoshop to make the trace, so I can just sample the colors and see where they are on the color wheel, but I am really having trouble figuring orientation and distinguishing colors. My best guess at these was 17nF.

So I guess my overall question is, what is the right way to get values from components if you are unsure? I could lift one leg of each component, but that greatly raises my chances of breaking it. BTW these have become extremely overvalued since John Mayer "discovered" this pedal that nobodies like me have been using for 20 years LOL, so it would make sense to keep hackage to a minimum.

[Earthscum]

These are crazy... never seen caps like that before.


From: http://en.wikibooks.org/wiki/Electronics/Component_Identification

"Axial ceramic capacitors
These often have a yellow body, and use the same color band system as resistors, except that the value indicated is in pF."

http://www.robotroom.com/Big-Trak-2.html Pic of one like yours.

From what I can tell, it's (top to bottom) RED - BLACK - ORANGE - BLACK or PURPLE - GRAY

I keep an LED flashlight handy just for this purpose. The ones that have a bluish light seem to work best for highlighting the colors (basically UV enhancement... the same thing that makes your "whites whiter, and your brights brighter"... things to avoid when washing your hunting camos, lol). That flashlight has saved me several hours of measuring questionable resistors, not to mention shining from the backside of a board to check traces for cracks or bridging. Also, made finding all the resistors dumped on a tan carpet a whole lot easier!

[Kindly Killer]

Thanks for info.

I just picked this up again. Looking under a magnifier, I settled on Brown Black Orange, which means 10nF, which matches others' traces.

BTW I built a GGG kit a while back, thinking I could sell my oldies and make some money. It doesn't sound the same - waaaaaay too bright; I've never heard or played a vintage Bluesbreaker that sounded like my GGG kit. It mentions on the GGG schematic that some units had alternate values - both of mine have those alternate values and they sound like every other vintage one I've heard. I.e. if you want the right sound from the GGG kit use the alternate values that they suggest on the schematic http://www.generalguitargadgets.com/pdf/ggg_mbb_sc2.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a . The only other difference on my pedals is the resistor between input and ground is 2.2M on mine. I changed the values on my GGG board and now it sounds right.

[MikeH]

Thanks for info.

I just picked this up again. Looking under a magnifier, I settled on Brown Black Orange, which means 10nF, which matches others' traces.

Makes sense:  Brn-Blk-Or on a resistor is 10K (10,000) and 10nF is 10,000pF.  I actually like that system better.  I swear every time I match a cap code to a value I have to count out the number of zeros in my head.

[ayayay!]

I swear every time I match a cap code to a value I have to count out the number of zeros in my head.

You're not alone, sir...