Homebrew API 500 Rack - Ground Question

[Wallybob]

I'm building a DIY version of the API 500 rack and I'm confused about how the various ground pins (1:chassis ground, 5:audio ground, 13ower supply ground) should be connected in the rack. Anyone have any knowlege or recommendations they would like to share? Thanks in advance.

 

[CJ]

rack or lunchbox?

if you are racking some units, then the chassis will probably be grounded to the rack, which is all you need,

the audio and pwr supply grounds will not need to be connected to the rack,
but they will be electrically connected via the chassis into the rack,

are yo running an external pwr supply?

 

[Wallybob]

It's a stand alone lunchbox with an external supply.

 

[CJ]

cool,

i used the old school octal tube socket and plug routine,

this gives you enuff room for 8 wires,

for tube projects this is handy because you need 6.3/12.6 ac, 12/24 volts for relays, 48 volt phantom for mic pres, and the high voltage B+ for the tubes, plus the ground wire.

for the lunchbox, maybe you only need plus and minus, i don't know, so a simpler connector would be in order, or simply hard wire it by soldering the ground wire from chassis to chassis and then soldering the power wire from supply to circuit board,

you can use one wire for ground, it runs from the pwr supply to the chassis and serves to ground the chassis to the pwr supply for less hum and also is the path for the electrons running from the pwr supply to the lunch box,

inside the lunchbox>

connect the audio grounds to the chassis at one point, close to the circuit board,

connect a chassis ground wire from the lunchbox chassis to the tube socket or whatever connector you use,

signal grounds on the I/O jacks can be grounded to the chassis where they are mounted,