Troubleshooting indicated a fault in the 772048 (mod 772041) proportional control valve.
A 470 mf radial electrolytic capacitor was swapped with Mouser # 647UPW1H471MHD, Mfr. #: UPW1H471MHD Aluminum Electrolytic Capacitor Radial 50volts 470uF AECQ200
A Sipex 805LCP integrated circuit was swapped with Mouser # 700MAX805LCPA Mfr. #: MAX805LCPA+ Microprocessor Supervisory Circuit
A CSI 93C57P integrated circuit was swapped with Mouser # 57993AA56/P Mfr. #: 93AA56/P EEPROM 256x8128x16 1.8V
The elevator now decelerates on descent, and operates normally … however …
The control board no longer stores modifications to function parameters.
It loads factory defaults.
According to documentation, the values are correct for initial installation.
I can live with it for the time being.
But I’d like to fix it the right way.
Who can tell me what happened? I’m guessing one or both IC is not an exact replacement.
Generically speaking, an EEPROM is sometimes used not just to store parameters you are manipulating, but also sometimes it is preloaded with data that isn't normally written by the controlling microprocessor. For example, perhaps there are several sub-models of something on this elevator and they need a slight adjustment from model A to model B to model C -- the software may just store this A/B/C value in the EEPROM when it is first commissioned at the factory and that specific parameter is essentially a read-only value never to be written again. So, in this case, putting in a new EEPROM would require you to read the old one and program the new one with the old data before installing it. Of course, this has a possible downside as well if the old EEPROM has corrupted some things.
If getting a factory replacement is an option that is the best route.