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Old 19th October 2005, 12:12 PM   #1
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Default PASSLAB x2 preamp question

Passlasbs has release the X2 premap serivce manual in his site,but I have found a problem about the power supply,from the SCH,the The positve supply use N channel MOSFET Q1 which the type is IRFP240 and the negative use P channel MOSFET IRFP9610,the two MOSFETS with different package,but we check the PCB layout in service manual,it seams like the same package.anyone know this issue,please give you advise .

thanks
adams_leo
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Old 19th October 2005, 01:21 PM   #2
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Adams_Leo,

You could use a IRF640 in TO220 to fit the drawing ; 200volts 11Amps

Any similar type to a N channel with >=200volts and >4 Amps will fit ...

PS: Nelson gives us a way ahead preamp design, even for today "audiophile use".
So try to be imaginative ; its diy after all !

Alain.
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Old 19th October 2005, 01:34 PM   #3
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Default Alain,thanks you very much,I will try it.

adams_leo
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Old 19th October 2005, 07:32 PM   #4
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I checked, and it is an error on the schematic. Use an IRF610
if you like, although a 240 would work fine. Another case of
modifying earlier schematics on the computer - its predecessor
was an IRFP240.

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Old 20th October 2005, 02:38 AM   #5
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Mr.Nelson Pass,thank you very much.I should build the preamp.
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Old 20th November 2005, 12:26 PM   #6
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Quote:
Originally posted by Nelson Pass
I checked, and it is an error on the schematic. Use an IRF610
if you like, although a 240 would work fine. Another case of
modifying earlier schematics on the computer - its predecessor
was an IRFP240.

Thanks Nelson Pass,but I met a other problem about the RELAY1 and RELAY2 in power supply schematic.could you tell me the RELY driver voltage?

thanks
Leo
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Old 21st November 2005, 08:36 AM   #7
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If I remember well, two 24V relays are in series in X2...which means, little bit less, than 48V
You can calculate from +85V supply voltage, with resistor-divider, -MOSFET voltage, etc...
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Old 21st November 2005, 06:17 PM   #8
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There is also a resistor in series with the relays. I recall they
are 24V types, but are operated at a lower voltage.
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