That happened here a few weeks ago. Fluke 8000A DMM. After a transient, it would only display even digits. Turned out the 7447 display driver developed an internal short on its 1's input. The MOS A/D chip was fine. Whew!
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Chuck Harris via Groups.Io <email@example.com>
Sent: Sunday, January 05, 2020 10:36 PM
Subject: Re: [TekScopes] Trying to bring back a AA501
I am having trouble imagining how a 15V CMOS device could spontaneously
generate 5V on one of its outputs.... I can see ~0V, or ~15V, or even 7.5V,
but 5V is an odd value for a device that has no resistors in it.
Are you sure that it isn't being bullied around by whatever it is driving?
old style CMOS has very little drive capability.