Help, just fired up f6, store boards, calvin fets, one side ok, other wont bias past .1v, how do find what i cooked? hopefully not too boned, never saw or smelled anything.
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exact schematic , what exact outputs ?
OK , it is long thread (original one), but we covered every possible ookup there already
OK , it is long thread (original one), but we covered every possible ookup there already
r2 .1v, idont know to test fets, so far between the 2 boards nothing jumping out at me. will un mount and check solder joints
Pat,
I'm guessing the side that is not biasing up correctly has 4.5V across the zeners?
What are you using for R7 and R8 and what value zener are you using? What
are you rail voltages?
I'm guessing you may need to change to higher value zeners and decrease R7 and R8.
Cheers,
Dennis
I'm guessing the side that is not biasing up correctly has 4.5V across the zeners?
What are you using for R7 and R8 and what value zener are you using? What
are you rail voltages?
I'm guessing you may need to change to higher value zeners and decrease R7 and R8.
Cheers,
Dennis
decrease R7 and R8 to 3K3
whenyou get proper 5V1 across zenners , if you can't still bias it properly , add green or red LED in series with zenners , opposite cathode orientation versus zenners
or replace zenners with 6V8
whenyou get proper 5V1 across zenners , if you can't still bias it properly , add green or red LED in series with zenners , opposite cathode orientation versus zenners
or replace zenners with 6V8
Original circuit had Jfet outputs that only need a couple volts to bias.
Some Mosfets need as much as 6 volts from zener.
Some Mosfets need as much as 6 volts from zener.
left channel biasing correctly with 6v at zeners, same ingredients in right channel but its unhappy. i must have something wrong
Thank you all for the help, I know all of you have forgotten more than I know! I ordered the parts, 6v8 zeners and 3k3 resistors. This means 2 things I hate, waiting, and desoldering / rework........grrrrrrrrrrrr! I'll be back, have a good day, and be careful out there.
She's alive! I made the suggested changes, fired up, set bias at .5v, offset at 0, let it cook, checked, looked good, and now she's making music! I only had a old cheapo tablet handy to run it off of for now, still sounds good though. Thank you Nelson Pass for the design, and thank you to the store, if not for boards and fets etc and 6L6's build guide and help from others I wouldn't have built it. Now, I need to build a pre amp! For tonight though, back to the music.
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