EL34 CCS help - diyAudio
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Old 24th March 2006, 10:07 AM   #1
navin is offline navin  India
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Default EL34 CCS help

THe pic attached is the CCS.

A friend assembled the CCS boards and discovered a problem.
The circuit has a "direct connection" between the 6SL7 and the 6SN7 stage. This means the CCS will have about 261 volts at its collector. The current is about 14.5 mA . So dissipation is about 3.8 watts in the MPSA340 used there. This is too much for the MJE340.

Note that if the stage was " ac coupled " with a dc blocking capacitor in between then the cathode would be at just about 7 volts.

FYI...

this is the amp
http://www.diyaudio.com/forums/attac...amp=1136905599

The power supply http://www.diyaudio.com/forums/attac...amp=1100080737
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Old 24th March 2006, 10:50 AM   #2
EC8010 is offline EC8010  United Kingdom
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MJE340 is rated at 20W dissipation (with heatsink). Just add a heatsink with 8C/W thermal resistance or better.
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Old 25th March 2006, 02:59 AM   #3
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thanks.
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