David, We are having similar issues with the newly acquired Straight 8 at the RICM. It is part of the first 50 built so there are some differences from later systems. FlipChips were physically damaged and some missing, the fragile plastic pivots on about 20 front panel switches were broken, and it hasn't been powered on for 50 years. We fixed the switch pivots, the power supply, replaced the missing FlipChips and started debugging. We actually got it to the point where it would run programs, but it has now deteriorated to the point where we can't load a RIM paper tape. I am happy that no one is hounding us to get it back in production. We are getting lots of help from PDP-8 experts like you, so we will eventually get it demonstrable. Like you, we have found many failed diodes that don't seem to affect operation. Robust design? On Tue, Oct 29, 2024 at 8:03 AM <vcf-midatlantic-request@lists.vcfed.org> wrote:

Date: Mon, 28 Oct 2024 21:58:17 -0400 From: David Gesswein <djg@pdp8online.com> Subject: [vcf-midatlantic] VCF straight 8 work at workshop

Worked on the VCF straight 8 that was acting up again. It would load the first instruction to execute when you hit the start key but didn't load the next instruction after updating the program counter. Kept reexecuting the first instruction.

TLDR: Found some signals that weren't quite right but fixing them didn't help. Found actual bad diode that was causing the failure but then diagnostics found another fault. Whike working on that memory stopped working when machine on for a while. Ran out of time to determine why so still not usable.

-- Michael Thompson