Reggie wrote some excellent articles back in 2012 about the Vision Microsystems EPI800 and VMS1000. The article "Vision Microsystems VM1000 & EPI800: Brains, Batteries, & Busses" explains the real time clock chip (see link below).
This past August I purchased a new chip from Mouser for $15.11 plus shipping.
To change the chip you will need to remove the wiring and ribbon cable from the DPU, remove the cover from the DPU, find the chip on the top circuit board and replace it. On my plane I take the DPU out and do the chip change on the bench.
Here are links to the articles written by Reggie. See the third article for the real time battery chip.
Vision Microsystems VM1000 & EPI800 Displays -- How the Backlights Work & Fail.
RV Drivers, This is the first in a series of planned posts regarding the Vision Microsystems VM1000 and EPI-800 engine management systems. I'll plan to hit various topics with tidbits I've learned over the years regarding these great systems--I'm certainly open to requests if you have a...
vansairforce.net
Vision Microsystems VM1000 & EPI-800: How to Avoid the "MPT Blues"
Vision Microsystems VM1000 & EPI-800: How to avoid the "MPT Blues" This is the 2nd in a series on the Vision Microsystems EPI-800 & VM1000 Engine Management Systems. As a reminder, I’m not a certified avionics technician but an experimental aircraft owner & enthusiast like you. My intention is...
vansairforce.net
Vision Microsystems VM1000 & EPI800: Brains, Batteries, & Busses
This is the 3rd in a series of posts about the Vision Microsystems (VMS) VM1000 & EPI-800 systems. As a reminder, I?m not a FAA certified avionics tech, just an avid experimental aircraft enthusiast & EAA member passing along what I?ve learned to the community that?s given so much to me. This...
vansairforce.net
Vision Microsystems VM1000 & EPI800: What version do I have?
This is the 4th in a series of posts about the Vision Microsystems (VMS) VM1000 and EPI-800 engine management systems. As a reminder, I’m not a FAA certified avionics technician, just an avid experimental aircraft enthusiast and EAA member passing along what I’ve learned to the community that’s...
vansairforce.net
Vision Microsystems EPI-800 & VM1000 Displays: LCD Precautions & Black Ooze Failures
Vision Microsystems EPI-800 & VM1000 Displays: LCD Precautions & Black Ooze Failures This is the 5th in a series of posts about the Vision Microsystems (VMS) VM1000 and EPI-800 engine management systems. As a reminder, I’m not a FAA certified avionics technician, and I don’t consider myself a...
vansairforce.net
Also, back in 2014, John P, discovered that on his VMS1000, he needed to replace the digital processing chips and that solved his problems. Here is a link to that thread:
Does anyone know of suitable replacements for the signal processing chips on the analog board of a 2001 series VM1000? At least one of my chips is bad. The installed chips are Intersil DG407DJ chips. I cannot find any of these, or the newer DG407DJZ's, in stock anywhere in the country. I...
vansairforce.net
I swapped PM's with John P this fall and his unit is still operating properly. Also, I check with Mouser and the digital processing chips referenced by John P are still available.
Unfortunately, on my older EPI800 the digital processing chips are Texas Instrument and discontinued. I could not find an alternative supply.
Hope this helps.
