The day was dominated by a lot of physical labour by Neil and Dave with the T86. Work continues on the flooring, removing the hard-to-get-at bits which includes under the drawer unit and the transmitter cabinet. Didn’t get to the flooring under the Transmitter as the drawer unit was enough of a challenge. Anyway, drawer unit and flooring removed from under it. All the chrome handles have now been removed from the T86 equipment racks and have been replaced with bits of rope. You have to be able to pull on something! A T86 man was also asked to drag up memories from 37 years ago on how to release the runners for the equipment draws in the Tx rack.
CHARGE was a problem when we first switched on the LCP but that was resolved with some edge connector cleaning and the Ferranti representative (Pete M) letting us know that the -5V DC supply to CHARGE should actually be -5.2V DC; adjustment made! Time will tell if this voltage adjustment has any impact on the CHARGE instability which we have put down to mains problems.
Pete M and Pete H carried on with some spare unit testing which takes a lot longer than expected. We now have a few spare boards for the Argus, enough to hold a stock of spares in the LCP.
Pete M also tested (again) the RGB to VGA converter he obtained which now recognised there was an RGB input, as a result of the -5.2 V DC, but trying to drive a VGA monitor resulted in an ‘out of range’ message. Pete has given this a good try but the non-standard timing of the frame, etc. is defeating us.
This was our last team working Saturday before Christmas.
We removed the floor covering in the T86 radar as we knew it was really spongy when you walk on it. The T86 doors had been left open for considerable periods when the T86 was ‘in store in the open’ (another expression for abandoned) and evidence had already been found that water ingress had rotted sections of the floor. The floor covering consisted of the original plywood covered with a green lino and that in turn had been covered with rigid insulating sheets, that being covered with hardboard and a mottled green lino ( Swedish update). It was obviously a good water proof membrane in that whatever water got in wouldn’t get out! Removing the floor covering revealed a sodden, slimy, mass of wet and rotted hardboard and plywood. Fortunately the actual floor of the T86 is aluminium but the wheel arches are steel, a bit corroded but in reasonable condition. The T86 floor is now drying out. Two issues remain; what do we do about the flooring under the Tx rack and draw/AC units?
Also managed to test some A700 boards, an MP140, 8 Channel Serial I/O and two ME172 Floating Point boards. All three were serviceable.
Back in the workshop checking out the spare Archive 2150L tape drive revealed that the rubber drive bush was turning in to a black goo. We haven’t found a source of spare bushes, not surprisingly, so are sourcing a length of rubber/silicone tubing to see if the same trick as used on the original Cipher Quarterback tape drive can be used As expected the rubber bush size for the Cipher is different to the Archives!
Another workshop task has been to check out the two FT81 terminals and four keyboards we now have as spares. The four keyboards are serviceable although one had lost it’s ‘beep’ but a slight tap on the diaphragm of the beeper and it was brought back to life. One keyboard is brand new and ex Bloodhound, Ser. No. BG8002. A second keyboard is also ex Bloodhound but the label with the Ser. No. has been removed at some time. One monitor originally had no horizontal hold until it warmed up but a tweak on the H Hold pot sorted that. The other had a bigger problem in that keyboards would not work, or do strange things when plugged in. This was found to be a defective SKT1, a 15 pin D-Sub. It looked like something nasty had got in to it at some stage, probably from a dead battery on the video card as this had happened to our original FT81. A good quality 15 pin, through hole, D-Sub was sourced and the faulty one replaced. The opportunity to change the hefty 3.7V back-up battery on the video card was also taken as we had recently acquired a few spares. Both monitors and all keyboards now fully serviceable.
The spare display monitor was taken from the workshop as last week the Tech Sup’s monitor had lost its vertical hold and Pete M did his best to adjust the monitor but no way would the monitor stop scrolling . Surprise, surprise, when we fired up the LCP yesterday the Tech Sup’s monitor was perfectly OK and ran all day without a problem!