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@ -10,7 +10,7 @@ On inspection, there are some initial problems that are quite obvious, namely bu
## AC trouble ## AC trouble
Great! Having sorted out the DCV section so easily, I can now move on to the next error the meter displays on power up; Error 202, Hardware failure - AC board. My clue here is that I don't hear any clicking relays and the fault seems to happen almost instantly. This leads me to suspect that the fault is gitial in nature. Troubleshooting reveals that fuse F701 has blown and the meter now has no 14V supply rail on the AC board. Fixing this by inserting one of the spare fuses allowed me to move on, but the error still persisted. Great! Having sorted out the DCV section so easily, I can now move on to the next error the meter displays on power up; Error 202, Hardware failure - AC board. My clue here is that I don't hear any clicking relays and the fault seems to happen almost instantly. This leads me to suspect that the fault is gitial in nature. Troubleshooting reveals that fuse F701 has blown and the meter now has no 14V supply rail on the AC board. Fixing this by inserting one of the spare fuses allowed me to move on, but the error still persisted.
Next I checked the integrity of the signal chain by applying an input and probing around the amplifier; every area seemed to be measuring, odd... trying all the AC measurement modes also showed me that everything was working. Looking back at the symptoms of a digital fault, I turned to checking the Elantek comparators, but these also seemed to be working, oddly enough. That left me to look at the shift register chain, which is entirely digital in nature, and indeed, bingo! Next I checked the integrity of the signal chain by applying an input and probing around the amplifier; every area seemed to be measuring, odd... trying all the AC measurement modes also showed me that everything was working. Looking back at the symptoms of a digital fault, I turned to checking the Elantek comparators, but these also seemed to be working, oddly enough. That left me to look at the shift register chain, which is entirely digital in nature, and indeed, bingo!
It seems that U008 was the culprit. I have a feeling that the failure mode had something to do with the 5V supply disappearing and the A3 ADC board forcing too high a digital voltage into the shift register output. It seems that U008 was the culprit. I have a feeling that the failure mode had something to do with the 5V supply disappearing and the A3 ADC board forcing too high a digital voltage into the shift register output. Interestingly , the shift register in question still put out correct control signals on it's outputs.
![ac fix](3458-WorkLog/imgE.png) ![ac fix](3458-WorkLog/imgE.png)
## Replacing the capacitors ## Replacing the capacitors