Air conditioning, Elliott 803 fault finding and classic cars
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Scorchio - the weekend was a very hot affair and we saw some very nice classic cars and bikes on Sunday.
Air conditioning springs a leak
During last week it was found that the air conditioning had decided to dump all it's water over the floor in the server area so it had to be switched off. Peter V, Kevin M and John G took a look on Saturday. They found that the bracket holding the internal unit was not level and the drain pipe going out of the wall was going up-hill, not down so the unit could not expel the water. The bracket was adjusted so it was level and the drain pipe was taken out of the wall and put into a bucket. This has resolved the water leak problem and a final solution when they to drill a separate whole for the drain pipe should be completed next week.
IRIS is behaving itself
The IRIS air traffic control system has been working without any problems over the past month so it looks like the earthing mods done to the cabinets has solved the problems. It is also coping with the very hot weather as well which is good to see.
Elliott 803 store fault investigations
Peter O spent much of Saturday working on the top 4K store fault which is proving difficult to find. The problem occurs when loading programs into the top 4K store but not when running test programs so it is pattern dependant. To prove this he wrote a modified test program that loads into the bottom 4K store and then copies itself to the top. It then does a comparison between the two copies and stops when it sees a difference. This resulted in a comparison failure which could be reproduced, which is a big step forward from last week. Further investigation found it to be the 17th bit that was failing and he then found that the sense amplifier associated with reading the 17th bit from core store had previously been replaced (new solder on the joints). Peter tried replacing it with two others but both still resulted in a failure, so investigations moved from the read area to the write area - the thought being that the bit was actually being written wrong rather than being read wrong. On investigation Peter found the inhibit line was always on regardless of writing a 1 or 0 (which is not correct). However, on checking the same thing a bit later it appeared to be working fine, so more work is needed to understand what is happening and where the fault may be. Good progress Peter.
Alpha server move
Due to the excessive heat that the Alpha server generates and the fact that we can't have the air conditioning on all the time meant the cabinet was getting too hot and sounding an alarm. It was decided that the Alpha should be moved elsewhere and we finally decided on the workshop. The server was shutdown and disconnected from the power supply (which actually meant all the servers were shut off for a short period). An space in the workshop was found and the server was finally moved into its new home near the end of day. Networking and power were also configured ready for it to be switched on again. Kevin M should be able to get it going again during next week or next Saturday.
Bletchley hosted a classic car event on Sunday so the parking and grass areas near H block (where the museum is) was full of cars and bikes. This managed to attract a lot of visitors and with it being very hot, it was a very nice day out. The museum was also very busy and thanks to some of the volunteers we were able to open from 12 noon.