Products > Test Equipment
Keithley 2400 SourceMeter review and teardown
openloop:
--- Quote ---U660 AD7849 is hot and not changing the current setting.
--- End quote ---
U660 is voltage (not current) control.
Although fried DAC would explain observables nicely.
kawal:
Yes U660 is removed and the situation is not changed apart from NVdac showing +12V everything else looks the same :palm:
TP213 was -0.75V
Getting expensive
Either way why is there -240V on the output when teh output is not enbaled.
openloop:
--- Quote ---U660 is removed
--- End quote ---
Don't rush into things. :)
TP213 (THE control) can be driven down either by voltage drive: TP205 near U211 (not TP206!) OR by current drive: TP207 (near U213)
Please check those voltages. (to figure out is it current control that screws things up or is it voltage control)
kawal:
TP205 = 0.566V
TP207 = -7.4V
Openloop
Do you have a schematic of this unit ?
openloop:
--- Quote ---Do you have a schematic of this unit ?
--- End quote ---
Nope, just bad experience. ;D
--- Quote ---TP207 = -7.4V
--- End quote ---
So the current control is bad...
Let's check the summing point where feedback is added to (current) DAC's output:
R238 pin 1: DAC
R238 pin 2: DAC + feedback
R238 pin 3: feedback
What are the voltages on those pins?
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