nelsress begins his WOPL 400 project

nelsress said:
Thanks Joe. Regarding the fuse length yes, I was wondering about that and I think my query regarding it was lost in a bunch of other, more important questions in one of my recent posts, I'll take care of that. When I check the bulk caps, do I put the negative lead from my meter to the chassis ground or to the copper buss ground, somewhere else or is any ground okay? I have yet to see my DMM read minus volts but then most of my experience using it is in commercial and residential electrical work.
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DMM negative to copper bus bar, DMM positive lead to the tips of each of the respective rail fuse holders.
 
Gepetto said:
DMM negative to copper bus bar, DMM positive lead to the tips of each of the respective rail fuse holders.
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Using the bus bar as the negative contact I get 0.163 VDC and 0.166 VDC on the tips of each rail fuse holder. I am getting +88 VDC and -88 VDC on the bulk caps, on the bright side. :)
 
nelsress said:
Using the bus bar as the negative contact I get 0.163 VDC and 0.166 VDC on the tips of each rail fuse holder. I am getting +88 VDC and -88 VDC on the bulk caps, on the bright side. :)
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So you are getting nothing through the fuses then...are the fuses connected to the bulk caps?
 
Gepetto said:
So you are getting nothing through the fuses then...are the fuses connected to the bulk caps?
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Not directly, the only wires going to the rail fuses are ones from the backplane boards so I'm guessing that's the problem? Sounds like an easy fix (at the risk of sounding like a craigslist ad!!) so what did I miss this time?? Thanks Joe.
 
nelsress said:
Not directly, the only wires going to the rail fuses are ones from the backplane boards so I'm guessing that's the problem? Sounds like an easy fix (at the risk of sounding like a craigslist ad!!) so what did I miss this time?? Thanks Joe.
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Well that will do it every time Nelson. You need a connection from the bulk caps to the tip of each fuseholder to get any juice. That is what the #10 internal tooth lugs were for that came in the wire kit.
 
DOH!

Gepetto said:
Well that will do it every time Nelson. You need a connection from the bulk caps to the tip of each fuseholder to get any juice. That is what the #10 internal tooth lugs were for that came in the wire kit.
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Thank you Joe, I'd rather it be my stupidity than a REAL problem. :) I don't remember seeing the lugs but I'm betting they're there somewhere in all my stuff! I'm going to go out and check my parts shortly and make those connections and I'll no doubt have some juice where it's supposed to be!
 
Sparks!

laatsch55 said:
Yep...
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Okay, the power has been off of the amp for over 5 hours, I went to test it just to make sure it didn't have a charge and the one lead slipped off the cap screw and accidentally touched the other lead of my tester while they were touching the positive and negative terminals of the power supply caps and the ensuing "pop" and sparks startled me considerably. I thought these things dissipated their charge in half an hour or so! Is it because they weren't connected to the backplane boards? Hopefully I didn't hurt the capacitor, I did melt a bit of a groove in my one test lead though and blackened the cap screw a bit. :) That cap is now down to 28 VDC but the one I didn't do that to is still at 71 VDC. What size resistor do I need to dissipate the charge on these monster caps? I'm almost positive I don't have anything large enough on hand, but I might.
 
nelsress said:
Okay, the power has been off of the amp for over 5 hours, I went to test it just to make sure it didn't have a charge and the one lead slipped off the cap screw and accidentally touched the other lead of my tester while they were touching the positive and negative terminals of the power supply caps and the ensuing "pop" and sparks startled me considerably. I thought these things dissipated their charge in half an hour or so! Is it because they weren't connected to the backplane boards? Hopefully I didn't hurt the capacitor, I did melt a bit of a groove in my one test lead though and blackened the cap screw a bit. :) That cap is now down to 28 VDC but the one I didn't do that to is still at 71 VDC. What size resistor do I need to dissipate the charge on these monster caps? I'm almost positive I don't have anything large enough on hand, but I might.
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1K 2W will do it
 
nelsress said:
I'll see if I've got anything that size or larger, thanks Joe. Do I just touch one end to positive on the cap and the other one to the bus bar?
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Yes, the 1K resistor will warm slightly as it dissipates the stored energy.
 
nelsress said:
Okay, the power has been off of the amp for over 5 hours, I went to test it just to make sure it didn't have a charge and the one lead slipped off the cap screw and accidentally touched the other lead of my tester while they were touching the positive and negative terminals of the power supply caps and the ensuing "pop" and sparks startled me considerably. I thought these things dissipated their charge in half an hour or so! Is it because they weren't connected to the backplane boards? Hopefully I didn't hurt the capacitor, I did melt a bit of a groove in my one test lead though and blackened the cap screw a bit. :) That cap is now down to 28 VDC but the one I didn't do that to is still at 71 VDC. What size resistor do I need to dissipate the charge on these monster caps? I'm almost positive I don't have anything large enough on hand, but I might.
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If you don't melt the tip off a #2 Phillips....YORE NOT TRYIN!!
 
nelsress said:
Great, thanks Joe. Could I have damaged anything with this blunder or is the worst that could have happened that I could have gotten zapped?
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No , you got lucky and l;earned your lesson without hurting anything. Now, had you shorted the caps to anything on the backplanes.....you'd be pulling them...
 
LOL

laatsch55 said:
If you don't melt the tip off a #2 Phillips....YORE NOT TRYIN!!
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I've done that on the job but not with my hands in an amp....yet! I'll try harder, on something I care less about, over!

Hey Lee, I was reading through some of your build threads earlier and you mentioned working for the mine. I had a couple friends who worked for the mines and lived in Gillette. I'm sure the odds are you don't know them but figured I'd ask-do you know either Brad Ross or Harold Bailey?
 
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