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Re: [Amps] SB-200 circuit breakers

To: "Tom Rauch" <>,"Tom Osborne" <>, <>
Subject: Re: [Amps] SB-200 circuit breakers
From: "Tom Rauch" <>
Reply-to: Tom Rauch <>
Date: Mon, 27 Aug 2007 08:30:15 -0400
List-post: <>
I've never seen so much off the cuff bad advice on something 
as simple as a circuit breaker problem.
Let's put a little common sense into this!

The bleeders are 30K 7 watt. There are six of them. HV is 
around 2500V max. The type of resistors used never age down 
in value, they only go up.

That means bleeder current must be less than 15 miliampers, 
and that is less than 40 watts total. 40 watts at 120V is 
1/3 of an ampere.

Anyone who thinks 1/3 ampere can affect an 8 amp breaker 
needs to think again.

If we took the bleeders to infinite resistance by cutting 
them out, the line current would hardly change.

The same is true for capacitors. If the capacitors were 
drawing enough current to trip the breakers they would be 
spewing crap all over inside the PA.

If it was a tube, he would be hearing a bang or pop or 
changing R12 or the grid resistors.

If he is running the amp on 120 and opening a breaker, and 
if that SINGLE breaker turns the amp off, he has a bad 
connection in the primary wiring. Either one of the jumpers 
on the 120/240 terminal strip is open or missing, the OTHER 
circuit breaker that isn't tripping is open, a primary is 
open, or there is a cold solder joint on the terminal strip 
or the breaker that isn't tripping.

If he is running it on 240, it is almost certainly a bad 
breaker (which is VERY common).

240V is the ONLY wiring configuration where the breakers are 
in series. On 120, they drive parallel 120 windings. You 
can't possibly open just one primary on 120 and have the PA 
shut down.

73 Tom

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