G1176 LN Rev.F Problems @ pre-amp section

Hi everyone!

I cant get the unit working.

I noticed problems with the pinning of BF245A, i found two different pinnings (gate and drain) in the datasheets( on the nxp semiconductor datasheet, the drain and gate connection are different from the drawing in the pdf(component placement drawing)...
(i found datasheets of the same devices with different pinnings), curios.. (-> so i mounted this devices 180 ° turned, compared to gyrafs drawing).

I used BC107A instead of BC107B, which should be no problem..


I measured the voltages(listed on the schematics on gyrafs site).
The following points make problems.
Q2 (B pin 0,06 V instead of 1,02 V)
Q2 (0,06 V instead of 0,54 V)
Q3 and Q4 (1,9V instead of 11,98 V)
Q4 (1,3 V instead of 11,5 V)

I nearly measured all voltage noted on the schematics (in the signal line amp section i just measured the voltage at the output trafo (13,7V -> OK)
BD517 and BD518 were replaced by BD135 and BD136

Furthermore i think the 5532 device is working properly (voltage is rising and falling when using the input pot).


Plz help i cant find any error

greetz klaus

Hi !

I have exactly the same voltage problems, and when I trace the signal (1kHz sine) with the scope it's clean before R10, after R10 one side of the signal is already becoming flat, and after Q2 (on it's collector) it's nearly a square signal !
I must precise that I removed the FET (Q1) to get rid of any sidechain influence, as advices by Mark Burnley on that topic : http://www.groupdiy.com/index.php?topic=4481.

Any clues are welcome !

Best regards.

Eric