BA23 Power Supply (H7684-A / H7864-B) Replacement

This 100% new power supply, fondly named H7864-C, is a 1:1 replacement for the Astec AA12131 (DEC p/n H7864-A, H7864-B) power supplies.

It is physically compatible and will fit in any BA23 housing, and will work with any PDP11, MicroVAX (KA630/650/655) or RTVax.
Electrically it meets or surpasses all of the original power supply requirements. Continue reading “BA23 Power Supply (H7684-A / H7864-B) Replacement”

KA630/650/655 TOY Battery Replacement Board


This little project solved the annoying re-setting of the time and date and console language preference every time I powered up my MicroVAX II’s (and III’s).

The old 180mAH NiCad battery pack (DEC p/n 12-19245-01) is hard to come by, slow to charge, and memory effect, ugly leaks and old age made it useless on all my MicroVAX computers.

Please note: this revision A design does not offer protection against battery over-discharge. See the newer Revision B post. Continue reading “KA630/650/655 TOY Battery Replacement Board”