So far, so good. Nothing but rodent detritus and crud came off. Most importantly, the ammonia smell is gone after cleaning. The PDP-9s were purchased by Evans and Sutherland in Salt Lake City. They were used to design one of their graphics machines. An E&S employee took them home and used them until the mid-90s for his post E&S business. They were in a rodent invested shed when we got them. We have been cleaning one up. The process so far has been to vacuum the board, then put in the ultrasonic cleaner in a solution of water, simple green and trisodium phosphate. The boards are then rinsed and air dried. We have NOT tested that this does not damage these particular boards, but we have used this process extensively in other restoration projects without ill effects. Bob Roswell broswell@syssrc.com 410-771-5544 ext 4336 -----Original Message----- From: David Gesswein via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> Sent: Thursday, September 3, 2026 9:49 AM To: vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> Cc: David Gesswein <djg@pdp8online.com> Subject: [vcf-midatlantic] Re: Before and after pictures of a sample PDP-9 card (cleaning) Much worse than the VCF straight 8 was. Its going to be a "fun" project. Did any of the transistors fall off? I exchanged emails with someone restoring a straight 8 where the can transistors were falling off the boards due to leads rusting throught. I think he replaced all of them. Did get it working. On Wed, Sep 02, 2026 at 03:38:39AM +0000, Bob Roswell via vcf-midatlantic wrote:
The Computer Museum @ System Source just received two! PDP-9s. Plan is to get one working.
So far, we are removing the filth! Have a look! https://museum.syssrc.com/pdp-9-restoration/
Bob Roswell broswell@syssrc.com 410-771-5544 ext 4336