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@@ -10,7 +10,7 @@ On inspection, there are some initial problems that are quite obvious, namely bu
 ## 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.
 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. Interestingly , the shift register in question still put out correct control signals on it's outputs.
+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 signals on it's outputs.
 ![ac fix](3458-WorkLog/imgE.png)
 
 ## Calibration
@@ -47,8 +47,10 @@ Firstly, it is possible to lower the current passing trough the reference device
 
 Secondly and majorly is chemical reactions over time, though stable a chip still exists upon a mixure of chemicals all slowly reacting on oneother. Thus [Arherrius' equation](https://en.wikipedia.org/wiki/Arrhenius_equation) comes into play, where reaction rates increase as temperature rises. Emperically this has been tested to double the drift for every 10degreesC.
 
+And then there is also quite a big contribution from mechanical stress- the LTZ1000 is a silicium die placed in a metal can. Whenever it cools down or heats these two materials will expand and contract at different rates. Causing some stress to be transferred to the die trough the glue holding the two materials together, this creating hysteresis at every powercycle.
+
 Thus it is interesting lower the setpoint of the LTZ1000 voltage reference setpoint. Well known on the 3458A is the voltage reference being operated at an extremely high oven temperature. As such I have added a 200K resistor to the voltage reference board at designator X411, decreasing the temperature to about 75degC, giving me a bit more overhead for high ambient temperatures than [traditionally is done](https://xdevs.com/fix/hp3458a/#opt002).
 ![ltz-mod](3458-WorkLog/LTZ-MOD.png)
 
 ## Mechanical touchups
-Unfortunately this unit came without pushrods making use slightly more difficult. After unsuccesfully trying to buy some parts from the manufacturer. I have designed 3D printable pushrods for the DMM to enable hobbyists to repair such missing parts.
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+Unfortunately this unit came without pushrods making use slightly more difficult. After unsuccesfully trying to buy some parts from the manufacturer I have decided to design some #D printable ones. To enable hobbyists to repair such missing parts. These will be added in this article later as I finish up the 3D models.
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