I have actually seen this before on my G1 a few times, many years ago. ? It went away, so, I thought it a firmware glitch. ??
But it¡¯s possible it¡¯s not reading encoder pulses properly so keeps moving but I cannot answer "why in centring"? ?? Can you change the centring rate to see if this changes?
All I can offer at this time is to ask is it happening in Ra or DEC or both axes? ? It¡¯s possible an EEPROM issue or encoder PLD readers on main board that reads motor encoder pulses! ? These had a programmed life ~15/20 years plus (according to datasheets) but, the their program input retention was not limitless in time due due to ¡well, I¡¯m not sure decay in gate programming?.?
But these can be changed or re-programmed. I've never tried to program one in situ I have removed them programmed a new one put it in. ? That was to fix drive encoder reading issues and on G1s and these are known failure point for many reasons.?
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Whether this is your issue ¡I cannot say but, I suspect a sidereal rate check could determine the issue. ? On a G11 the Ra motor axes rotated at 9.5737s per Revolution. ? What you can do is take out Ra motor set it up on a desk, put a pointer on the motor pinion and time it for 10 revolutions as it passes a marker¡that¡¯ll be enough to check it.?
I say Ra because it¡¯s used the most compared to DEC axes PLD.?
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But I¡¯m only guessing here I mean it could be stiction of the axes (like friction)..... I just don¡¯t know!. ?Oh if you have Varistors Rv1/2/3/4 on the main board measure them both ways with an ohm meter (power off) they can cause encoder pulse degradation. ?Removing them fixes this. ?? See image on my google drive
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Lastly what ver EEPROM do you have?
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cheers..ill await your reply.?? I'm sure Paul has seen or heard of this!
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Brendan
