This page describes work accomplished on the new TMRC layout during
the month of November 2005, as taken from the descriptions posted to
the club mailing list.
- November 05
The system has a persistently intermittent failure mode, which has popped up every month or so over the last year, in which some of the cards on the block card network will disappear from the system for a while, then reappear. The current theory is that there is some sort of problem with the +8 volt power supply, or with one of the circuits drawing from it. Voltage from this supply is regulated at the block cards to provide +5 volts to run the microcontroller among other things. In an attempt to debug the problem, John Purbrick installed an ammeter on the +8 volt system power supply. Under normal conditions, the system draws 7 amps from this power supply, which is rated to 10 amps; the next time the system freaks out, we will be able to see if the voltage or current draw from the +8 volt supply is abnormal. To eliminate one possible cause of the problem, Alvar replaced the regulator circuit for the three block cards in the helix with three separate regulators.
- November 09
Tom finished fixing some minor fit and finish problems with the building David Lambeth built in September. In addition, a fluorescent lamp and inverter from a flatbed scanner were installed in the building and connected to a suitable power supply.
Since the building has no interior, paper was taped over the windows to act as a diffuser. There is plenty of room for an interior in this section of the building, and it should be easy to install should anyone ever actually get around to building one.
In addition, Adam and John McNamara began the messy process of plastering the mountain in the river scene (East Berkmannville). John Purbrick continued work on Middle Heights scenery. Rounding out the John trifecta, John Shriver hung more trolley wire, specifically the wire over the non-functional track that leads off the layout near the turntable. Ed Drozd worked to fix some issues with rolling stock, including properly attaching the wheels to the observation car of the Aaron Burr.
- November 19
The Fall 2005 open house without a hitch! Actaully, there were numerous hitches with the system. System problems started before we even opened, with block cards dropping out at inopportune times (is there ever a good time for block cards to drop out?). The problem was traced to the cable leading from the IMP to the next item on the block card network. New connectors were installed on the cable before the open house, but the problem returned during the event, so the cable was replaced during the dinner break. The server locked up as well. Making this all more exciting is that block cards don't shut off track power when they lose communications with the server, so there were some spectacular collisions (by HO scale standards anyway). At some point the switch card network also failed. Fortunately the switches were all set for the proper routes when this happened.
Attendance at the afternoon session was probably 200-300 total, with 50-60 people visiting at any one time. As usual, there were fewer visitors in the evening, with 10-20 people visitors there at any time.
- November 23
The compressor on the Coke machine failed last Wednesday. As a result, the soda in the machine has been well above room temperature (due to the heat from the internal fans, the fluorescent lamps in the door, and so on.) Despite a prominent sign on the machine to that effect, and despite the fact that warm soda is really icky, the effect on sales was small, only dropping 19% over the previous week. This could be seen as evidence for the addictive nature of the stuff we sell.
A replacement compressor has been ordered and will be installed as soon as it arrives.
- November 30
The Coke machine has been fixed. The replacement compressor arrived Tuesday. John P., John M, James, Alvar and Tom spent a pleasant evening removing the old compressor, cleaning the inside of the machine, and installing the new unit (the replacement is actually refurbished, not new). The inside of the machine is now squeaky clean, since we removed years of accumulated grime. John Purbrick and James looks like they are enjoying the task entirely too much. John McNamara's face expresses a more appropriate level of disgust at the condition of the inside of the machine when we started.
Curiously, the box the new compressor was shipped in was prominently labeled "Antique Refrigeration Unit". We don't think the machine is quite old enough to be considered an antique, and hope it provides many more years of profitable service to the club.
Tech Model Railroad Club of
MIT Room N52-118
265 Massachusetts Avenue
Cambridge, MA 02139
+1 617 253-3269
x3-3269 (on campus)
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