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Re: [Amps] SB-200 circuit breakers

To: "Tom Rauch" <>,"Tom Osborne" <>, <>
Subject: Re: [Amps] SB-200 circuit breakers
From: "jeremy-ca" <>
Date: Mon, 27 Aug 2007 11:54:08 -0400
List-post: <>
There are some errors in your explanation also.

If a tube is taking off as an unneutralized oscillator it wont usually pop 
anything except the breaker. Therefore my suggestion to take the cover off 
and watch things. If its a 4 month old tube then there may be a warranty.

If the breaker is on the edge then it wont take much more additional current 
to pop. Changing resistors was mentioned strictly to cut down on the heat 
right next to the caps.

With over 250 SB-200 conversions behind me Ive only seen one bad breaker. 
This does not say that his isnt bad.

Instead of coming right out in the first sentence with insults aimed at all 
who offered suggestions you would have more credibility by toning down the 


----- Original Message ----- 
From: "Tom Rauch" <>
To: "Tom Rauch" <>; "Tom Osborne" <>; 
Sent: Monday, August 27, 2007 8:30 AM
Subject: Re: [Amps] SB-200 circuit breakers

> 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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