Heathkit H8's & H9's (was Help to identify a Selectric based terminal)

On Tue, 2007-04-17 at 13:13 -0400, Barry Watzman wrote: On Navy ships, a large chunk of zinc is connected to the steel hull at some point. Then, when oxidation, and other electro-chemical degradation takes place, this "sacrificial anode" is where essentially all the corrosion takes place. Every now and then, the remnants of the zinc are removed, and a new block is attached. (It's VERY easy and cheap to replace a block of zinc - repairing a thinning, corroding hull is quite another matter.) Somehow, I think the header pins on the H-9 were acting as sacrificial anodes in that machine. You're probably in a MUCH better position to answer this than I am. An H-9 was the first terminal I OWNED to use with my IMSAI 8080. Previously, I had borrowed a Teletype ASR-33, with the punch and all... whatever the exact model is. Anyway, after about two or three days, I would literally have to take the damned thing apart, and clean off all the headers (with long pins) by which all the various boards were interconnected. It took about an hour to do reliably, and would provide a solid, guaranteed 24 hours of uninterrupted use. But, usually by about 48 hours, a few "flaky bits" would start showing up on the screen. I never noticed data transmission being compromised, but, as time went by, I would have to keep more and more of what SHOULD have been on the screen in the organic neural network I carry around with me at all times for just such mechanical failures. After a while, the effort of trying to read the screen, and fill in the flaky bits, would convince me to take it apart again, and start over. I was *WAY* poor at the time, and could not afford to eat the difference and replace it. I ALMOST soldered in the various boards several times, but never did, for fear that something ELSE, like the sockets, was or were involved. When I moved back to the mainland, I was more than happy to sell it cheaply. I had almost forgotten all the heartache... Thanks for the reminder. <Grin> I agree, but that option wasn't available in 1977.... Peace, Warren E. Wolfe wizard at voyager.net