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Old 21st April 2010, 11:49 AM   #3611
Salas is offline Salas  Greece
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Leds alight, good progress. Now, you got the BC550 killed I hope and not the two JFETS under it. But it can be the other way or both. Change the 550 first.
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Old 21st April 2010, 02:34 PM   #3612
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I changed Q3 BC550, now the measurements are:

Leds-GND
Right 7.66 need to reduce to 7.3V?
Left 7.32 OK

V across R17
Right 328mV need to increase till 350mV?
Left 350mV

R10/Q2-GND
Right 8.4V need to increase till 10V?
Left 9.4V need to increase till 10V?


R1/Q3-GND
Right 7.4V need to increase till 11.5V?
Left 11V need to increase till 11,5V?


R7-GND
Right 8.6V need to increase till 10.3V
Left 10.3V

Drain Q5-GND
Right 21V adjusted with trimmer R6
Left 21V
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Old 21st April 2010, 02:46 PM   #3613
Salas is offline Salas  Greece
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Do you have 45V B+ on both channels?
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Old 21st April 2010, 02:57 PM   #3614
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Measurements done loaded with RIAA:

Right B+ 42.1V
Left B+ 45.2V

Have I to increase or decrease till 45V B+ with RIAA loaded?

Last edited by merlin el mago; 21st April 2010 at 02:59 PM.
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Old 21st April 2010, 03:04 PM   #3615
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When the system is loaded as it really plays, see that you got 45V B+ on both channels and then compare/trim DC points between channels.
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Old 21st April 2010, 03:09 PM   #3616
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OK adjust two channels for 45V B+
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Old 21st April 2010, 03:24 PM   #3617
Salas is offline Salas  Greece
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OK. Trim the right referenced to the left.
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Old 21st April 2010, 03:26 PM   #3618
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45V B+ both channels:

Leds-GND
Right 7.3V
Left 7.32

V across R17
Right 331mV
Left 351mV

R10/Q2-GND
Right 11.53V
Left 9.94V

R1/Q3-GND
Right 11V
Left 10.63V

R7-GND
Right 11.57V
Left 9.99V

Drain Q5-GND
Right 17.5V
Left 21.1V
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Old 21st April 2010, 03:36 PM   #3619
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Trim your right R6 trimmer to get 9.94V on R10/Q2.
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Old 21st April 2010, 03:53 PM   #3620
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Done both 9.94V

Last edited by merlin el mago; 21st April 2010 at 04:04 PM.
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