hyperma 3 Posted April 9, 2020 Report Share Posted April 9, 2020 On 4/3/2020 at 7:09 AM, simmconn said: I'm not sure if I understand your reply. In the Megatron the first stage uses 12AU7, and the second stage uses 12AX7. What do you mean by "provide 24db gain to drive pair 12au7s"? Sorry,the first stage 12au7s to drive 12ax7. Quote Link to post Share on other sites
jamesmking 141 Posted Wednesday at 01:32 PM Report Share Posted Wednesday at 01:32 PM (edited) My apologies if this has been asked before.... As normal my first steps in a build is to get the circuit diagram and reverse engineer the gerbers to check them against each other.... looking at the circuit diagram pdf the decoupling caps have been omitted... fair enough, however 1. the circuit diagram shows a single 150K resistor from the led D3 to ground but the reverse engineer of the gerbers has two 150K resistors in series to ground.... 2. the gerbers seem to have two 330K resistors, one each from the 300V line to anodes 1 and 2 of the 21ax7. These resistors are not on the circuit diagram... here is my reverse engineer with components in pink missing from the pdf: NOTE this circuit diagram has not been checked Edited Wednesday at 01:40 PM by jamesmking Quote Link to post Share on other sites
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