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Bug #269

K2 : ERROR 304.6 - Ohms sources; 70nA and 770nA

Added by tin about 10 years ago. Updated over 7 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Target version:
Start date:
07/18/2012
Due date:
% Done:

0%

Estimated time:

Description

Cannot measure 0.7V ±0.07V at A/D IN.

Switches in R354 for the 70nA ohms source by closing the analog switches at pins 1 and
12 of U332. Q324 (HI OHM pulled low) is on while Q312 and Q320 are off. This selects
R354 as the only source resistor. No other resistor is in parallel with it. The load is again
R394 and is connected to common through Q328. 7V will appear across R354. Op Amp
U322 is set up for x1 gain. Measure 0.70V at A/D IN.

Suspect:
R354 and Q324.

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