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Aha, so you are saying, that if the Bias comes out right, if it sounds good, if it puts out a clean signal with the 1khz test wave, through the various stages and at the right magnitude, that small quiescent 7/10 of a milliwatt might not be something I have to worry about? This would be good news. I could leave it on for hours and check the heat, run it through a dummy load for a couple hours, etc etc... and then call it fixed?
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It wouldn't bother me. I'd think of it as a gee I wonder why thing rather than an OMG what'll I do about THIS thing.Education is what you're left with after you have forgotten what you have learned.Comment
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Just got in a dead BA115a, sure enough it was a dirty headphone jack... Enzo strikes again!!!
Originally posted by Enzo View Post... That's $1.00 for the chalk mark and $49,999.00 for knowing where to put it!Comment
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Sorry for resurrect this old thread, but I'm wondering which way (CW or CCW) to lower the bias of the BA115HP?
I need to turn it down to make sure bias isn't too high for my new transistors.
I accidentally shorted the output pins (J23) so the fuse and MOSFETs blew. I replaced all MOSFETs (IRFP140/9140), drivers Q1 (MJE-350), Q3 (MPS-A06), Q4 (MJE-340) and U5 (NE5532), but accidentally i swapped Q1 and Q4 so the P-channel bank was driven by a NPN, and vice versa. Blew again. I then replaced everything once again, and made sure everything was in place. Before I soldered back new MOSFETs, i powered the amp (with new Q1/3/4 and U5). It stayed on fine.
But putting back the MOSFETs, it blew again.
Surprisingly Q2 survived both times (the J23 output short accident, and now after replacing all MOSFETs two times).
Both sets of MOSFETs was matched. I checked the 10V zeners (D8/D9) with 20V and they stay 10V. D6/D7 also tested fine.
Any thoughts?Comment
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