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Old 02-10-2009, 04:01 AM
philrrtx philrrtx is offline
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Join Date: Jan 2009
Location: Round Rock, TX
Posts: 11
Default A little progress

Got my replacement ST1-1 switches in and replaced the three broken ones in the upper row. I still haven't found anyone with the ST1-3s in stock, and APEM, the current manufacturer, was less than helpful.

So, in a "what have I got to lose" effort, I removed the ST1-3 with the broken-off handle from the lower row, and carefully pried the case apart. The guts looked good, just a broken handle. I then took one of the old ST1-1s that I had replaced, which only had a bent handle, and pried it open. I straightened the spring-loaded actuating pin from the old ST1-1 and used that handle to reassemble the ST1-3. Amazingly, it works. The little U-shaped case, which holds the mounting stud, isn't as tightly crimped on to the insulating block as it originally was, but it is quite functional. If I find a source for them, I'll replace it with a new one, but I can at least continue troubleshooting with my cobbled-together replacement.

The power supply survived its smoke test, and seems to be working OK, although I still need to check the ripple levels. The filter capacitor for the –16V supply looks like it has blown its safety plug, but it wasn't shorted, so I proceeded to apply power. A replacement is on order. Now, can anyone tell me why the front-panel power switch was oriented with down for ON and up for OFF? Seems backward to me.

In other news, the 4K dynamic memory boards I have turned out to be Rev 2, and all I've found for documentation so far has been for Rev 0. Of most interest at this point is how the little slide switches are arranged for address block assignments. Has anyone seen Rev 2 documentation?

Phil
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