Re: Desoldering pump to avoid

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OK, I'll keep that in mind. Given the sort of nonsense I often get
up to with scalpels, blunt blades are quite a possibility.

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Re: Desoldering pump to avoid
Once upon a time on usenet Trevor Wilson wrote:
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Fuck off with your insults. I read further down the thread and see you've  
got commercial interests and good reason to insult me for your own profit.

As for reading this post further - no thanks.
--  
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy  
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Re: Desoldering pump to avoid
Once upon a time on usenet Phil Allison wrote:
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Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers sound  
far better than anything else *I can afford*. They were originally made in  
Auckland by an ex-employee of Perreaux in the 1980s. I have a couple 1970s  
Perreaux band PA amps too and use the low channel of one for a subwoofer  
amp. (I used to tour with a band doing stage lightning and soundmixing in  
the 1970s.)

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Yeah, seems a stretch of the imagination.

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Indeed. To insult me as a lead-in to his reply to me shows that he's not  
good with people - unless he's just brave when he's behind a keyboard....
--  
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy  
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Re: Desoldering pump to avoid
On 10/04/2017 9:15 PM, ~misfit~ wrote:
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I think he firmly believes in his own spin.











Re: Desoldering pump to avoid
Once upon a time on usenet Clocky wrote:
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Ok, thanks.

That's the worst kind of religious nutcase. (Think Jonestown...)

Cheers,
--  
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy  
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Re: Desoldering pump to avoid
~misfit~ wrote:

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** You just reminded me of the Perreaux BJT amplifier I saw and serviced in the early 80s -  it was " P2200 " IIRC.  

The design was reminiscent of a PL700, but with two large power transformers.
The transformers had their 120V primaries and 65V secondaries wired in series. The mid point of the secondaries went to ground and the ends to a bridge rectifier and pair of large filter electros.  

Now, there is a *BIG* problem with this idea: in order for the DC voltages on the electros to match, the load current drawn from plus and minus supplies must match exactly -  cos nothing forces the two transformers to share the 240 supply evenly.

As it was the DC rails were offset by 11 volts at idle, due to a 10kohm / 10W resistor on the positive side that fed a speaker relay.

On music programme, the rail offset varied about the 11 volt value.  

The correct way is to have the secondaries wired in parallel, thereby forcing equal sharing of the AC supply voltage - but that could not be done in this case.

Peter Perreaux made no similar error with his MOSFET models, he got nearly everything near perfect, particularly with the heatsinking and fan cooling set up.

There was one oversight though, that caused a lot of grief for owners about 5 or 10 years later. Anyone here know what it was ?


....  Phil  

  


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