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Old 10-31-2017, 02:47 AM
MittieOd MittieOd is offline
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Join Date: Oct 2017
Location: Germany
Posts: 1
Default Errata for the V2.0 O2 Desktop Amplifier (ODA) layout

• The text labels for R20 and R21 in the power supply CRC filter section
wound up on top of the board rather than the bottom. These are two of the
0.51-ohm 2W surface mount resistors.
• The ¼” output jack has the label “U$1”. Should be J6.
• By the output jack, some text says “if R70 & R71 are not being used, install
jumpers”. That should say R88 and R89. Those two resistors positions
have three holes to accommodate different size resistors. Put the jumpers
from one end hole to the other, right over the middle hole. Bare uninsulated
jumper wire (22 gauge recommended) is fine, and it doesn’t matter if the
bare jumper touches that middle hole in R88 or R89.

• The pin 1 dot on IC2, the LME49990 gain chip closest to the board edge,
wound up on top of the board rather than the bottom. The pin 1 dot on
both IC1 and IC2 should be toward that nearest PC board edge.
• The label for JP11 in front of IC4 extended onto the pad. I’ve switched that
to a fixed font from proportional and dropped it one font size to fit.
• I forgot the “band down” lettering on D11 and D14, the Zener diodes in the
DC output offset null section. The cathode band on both of these end-
mounted diodes should orient down against the PC board.
• Not an error, but a reminder: the JP18 V+ power supply output pad
jumpers up and down (any of the bottom two holes to any of the top two
holes). The JP19 V- power supply output pad jumpers sideways (any of the
left two holes to any of the right two holes).
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diy, headphone amp, mini3, o2, objective2

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