Is there a wire color code standard?

gusfinley

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I've wondered this for a while.

Is there a standard code for wire color when it comes to amps? Or perhaps a few? There ought to be at least some MIL specs about this.

I have set my own color code which is:

  • Red - Highest Voltage ( First DC out of rectifier, Output Transformer center tap, etc.)
  • Orange - Second Highest Voltage (Screen Connection to Power Tubes, etc.)
  • Yellow - Third Highest Voltage ( DC Connection to Preamp Plates )
  • White - High Level AC Voltage ( From preamp plates after decoupling capacitor )
  • Blue - No DC, input to grid
  • Brown - Low DC voltage ( Between tube cathodes and Bias resistors )
  • Black - Ground

I sometimes use green for other connections that don't fit in above

Of course there is the black/red or green twisted solid wire used for heaters.
 

Tom Kamphuys

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Or this:
Wiring-Colors.gif
 

Platefire

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I kinda went by code on some things but this is what I do:

1-White=Grid low voltage AC that the signal travels through amp, decoupled by coupling caps to block high voltage DC
2-Red=All DC voltage generated from power supply from rectifier to first gian stage v1
3-Green or sometimes Black=Ground. I prefer Green for grounds but if I'm running short sometimes use black.
4-Orange=Cathode related
5-Green Cloth insulated wire=Heater wiring twisted. No chance getting it confused with green ground wire because my heater wires are alway cloth and always twisted together.
6-Black/White/Green AC Power cord=As by NEC black is hot, white neutral and green Ground to chassis.
 

JuneauMike

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These are the kind of posts that make me wish TDPRI gave users their own way to store in a folder or pin certain posts for later use. Thanks for the thread.

But it seems like its more important that you at least have a color code and adhere to it rather than use a prescriptive one. I always try to do that and I think mostly I do.
 
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Old Tele man

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Although not a WIRING code, I use this coding in equations for emphasis:

BLU = high voltage, B+
BLU = lower voltage, screens, etc.
RED = current
VIO = power, ie: BLU×RED
ORG = transconductance (gm); perveance (G)
BRN = resistance (R), reactance (X), impedance (Z)
GRN = grid voltages: DC bias & AC signal.
GRY = amplification factor, mu
 
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jhundt

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I used to build my amps using that EIA color code, and still do as much as practical. When I lived in Oakland CA I would grab discarded tv sets that were illegally dumped - old ones, and they were full of masses of pre-tinned, stranded cloth-covered color-coded wire. I had bags full of the stuff. I wish I had kept it all when I moved...

The colors make it a lot easier for me to quickly identify the different circuits.

Here's my version, it is the same as the one above but I used purple (or violet) for the bias supply circuit.


Chassis Wiring Color Codes

BLACK Grounds, grounded elements, and returns
BROWN Heaters and filaments (off ground)
RED B+ power
PURPLE Bias supply
ORANGE Screen Grids
YELLOW Cathodes
GREEN Control Grids
BLUE Plates
GRAY AC power lines
WHITE Miscellaneous
 

clintj

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Fender sure didn't.

Fifties:
Plates, grids, cathodes, tone controls, B+, tremolo networks - yellow. :)

Hammond didn't either, the chassis I stripped out had multiple color wiring but I think it was more to avoid crossing wires.

I used as much of that article as I could during one build. Made a pretty amp, but was a bit of extra work rotating through the colors as I wired it.
Did any of the major amp companies use this color code?
 

SSL9000J

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I use two different colors for the heater wires, usually black & red. It makes it easy to keep the heater wiring consistent. Sometimes I'll color code the wires according to their respective component, for example preamps=blue, phase inverter=red, tone stack=white, etc. But usually I'm not picky and just grab whatever is at hand and flag it with a wire label to keep track of what's what as I build.
I've noticed power transformers generally but not necessarily use red for B+, green for 12.6/6.3V, yellow for 5V, black for center tap, all of which sometimes have a stripe of a different color as well. Always test first, though! Not sure about output transformers. To be honest, until you get to the connection from the power tranny primary to the wall, the color doesn't really matter.
 




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