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Old 21st June 2018, 02:06 PM   #15891
coolnose is offline coolnose  Europe
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Quote:
Originally Posted by Blk Dynamite View Post
I've never built one of these and the thread is really long but looking at the schematic on page 9 shouldn't R1 and R2 be 10ohm resistors as well? The 4.7k resistor w the thermistor and the 47k resistors for the gates of the output mosfets? I just like reading other peoples issues to try and learn how to go about trouble shooting and fixing them.
Definitely no 47K resistors anywhere on schematics....

EDIT: I see you edited your post, what is fitted ?

Last edited by coolnose; 21st June 2018 at 02:07 PM. Reason: EDIT
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Old 21st June 2018, 02:06 PM   #15892
WKCox is online now WKCox  United States
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Quote:
Originally Posted by Blk Dynamite View Post
What schematic are you using?
Version 3 board from DIY Audio store.
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File Type: jpg F5_Schematic_w-P3.jpg (97.0 KB, 209 views)
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Old 21st June 2018, 02:09 PM   #15893
Zen Mod is online now Zen Mod  Serbia
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from post #89 (schm attached)

Ra and R2 are 10R ( each)

mosfet gate resistors are 47R each (R13 and R14)

in fact , observe that numbers without suffix are for Ohms , all other having approporiate suffix K for KiloOhms

NB that there is later iteration , with P3 added in sources of input JFets , for altering THD spectra and lesser demands for matching of active parts

Click the image to open in full size.
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Old 21st June 2018, 02:13 PM   #15894
WKCox is online now WKCox  United States
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Quote:
Originally Posted by Zen Mod View Post
for starters , both drain pots need to be at bloody minimum ..... zero...... nada........ zilch
Just for clarification, zero ohm or 5K ohm to begin bias settings?

The build guide says to turn pots fully CCW to start bias setting which should give you zero volts across R7 and R8. So, I have pots positioned as in the pictures and turned pots fully CCW but I get 2.8V across R7 and R8 instead of zero.
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Old 21st June 2018, 02:18 PM   #15895
Blk Dynamite is offline Blk Dynamite  United States
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Quote:
Originally Posted by Zen Mod View Post
from post #89 (schm attached)

Ra and R2 are 10R ( each)

mosfet gate resistors are 47R each (R13 and R14)

in fact , observe that numbers without suffix are for Ohms , all other having approporiate suffix K for KiloOhms

NB that there is later iteration , with P3 added in sources of input JFets , for altering THD spectra and lesser demands for matching of active parts

Click the image to open in full size.

ok thank you. When the previous poster had commented


" Removed and inspected amp boards and found R1 (4.75K) and R2 (47.5K) flipped."


I was confused and thought that may be were theyre having some issues
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Old 22nd June 2018, 02:29 AM   #15896
WKCox is online now WKCox  United States
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Turned P1 and P2 fully clockwise (not CCW as stated in build guide) and bias adjustment fell into place. Bias set with zero offset. Ready for some music.

Thanks Zen Mod!
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Old 22nd June 2018, 08:51 AM   #15897
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CW or CCW is thing I'm often remembering for second or two ; I'm used to believe in my instruments , not my memory

so , for proper setting operation ,connect as many DMM you have , prepare coffee or tea , relax and enjoy in process.

Assembly of Japanese bicycle require great peace of mind



learning new trick/thing or two is for me more exciting than (having) entire new amplifier .......
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Last edited by Zen Mod; 22nd June 2018 at 08:54 AM.
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