Pre-electrocution questions

[sladef34]

OK - I'm at the point where I'm ready to plug this baby in and test some voltages.
I'll say right up front that I'm nervous about this, not having a lot of experience working with electricity.

I have a couple of questions that I hope some folks can help me with:

1) When I discharge a capacitor (I built a tool using a 10K/5W resistor), is it ok to attach the negative lead to the plate/chassis, or do I need to
connect the neg. lead to the - end of the capacitor?

2) I am a little confused with the instructions on page 38.  They say to first attach the neg. lead of my ohmmeter to ground/terminal 12.  Then it says to turn the chassis over and re-connect the neg. lead to the ground buss.  I assume that I'll be testing these voltages with my chassis upside down so that I can easily connect the leads to the various terminals.  Why would I first connect a neg. lead to terminal 12, and then immediately move it somewhere else?  I'm also not sure what the "ground buss" is - I actually thought the terminal strip with terminal 12 was the ground buss.

Sorry if these are boneheaded questions.  It probably gives some indication into how nervous/careful I want to be monkeying with this thing when it's live.

Thank you for any clarification anyone can provide.

Slade

 

[Grainger49]

The Crack will discharge the power supply caps in a few minutes.  If in doubt take your meter and measure the voltage across one of the caps in the power supply circuit.  An easy one to get to is the one across terminals T12 and T13.  If it is below 20V you are safe.

As for clipping to terminal T12 and then the ground buss I can't answer that.  I'm as confused as you are.  I would just put the Crack belly up, clip the black lead to the ground buss (bare wire that is silver colored) that is at the IEC power entry module and going to the screw through the top plate then take the measurements with the red lead.

Terminals T11 and T16 are grounded by being bolted to the top plate.  Along that strip T12 is ground for one power supply cap, T14 is ground for another power supply cap and T15 and T13 are high voltage DC. 

 

[sladef34]

Thank you so much Grainger.

I clipped onto the AC ground buss as you indicated and checked my voltages - everything was looking really good, until...

I believe I shorted across A8 and A9 with my ohmmeter probe and fried that LED.  :-(

I'll post a new topic with some questions on this.

Thanks again!

Slade

 

[InfernoSTi]

I've built several amps from Bottlehead (Quickie, Crack, Stereomour), a kit from another vender, and a from scratch pre-amp....I always fry/break/mess up something.  Doc is so great about helping out when these little things happen....shoot him a PM and visit.  And whatever you do, don't get worried or lose heart...you will sort through things...I've seen it over and over and over thanks to the fine folks on this forum!

John