[cctalk] Re: Identifying This Component from VT100 Monitor Board

-----Original Message----- From: Brent Hilpert via cctalk <cctalk(a)classiccmp.org> Sent: 05 January 2026 19:54 To: General Discussion: On-Topic and Off-Topic Posts

Cc: Brent Hilpert <bhilpert(a)shaw.ca> Subject: [cctalk] Re: Identifying This Component from VT100 Monitor Board - Were those measurements made in-circuit or out?

- The photo-board has the same component IDs as the Mar82-board schematic. However the photo-board layout differs from the Mar82-board layout. So, for as much as can be discerned from the photo, it appears or suggests they did make two board layouts for the same circuit. What could make some sense for the photo-board is if they were using one

the B411s as a fast non-saturating clamp diode - actually wired and

to function as CR406. In which case you would expect: CR406.C == GND (A) CR406.B == GND (A) CR406.E == Q414.C (K) This would explain why (one of) the collectors is connected to GND. This would want a high BE reverse breakdown V though. Might there be a BC connection underneath the transistor on the component side?