On Sun, Oct 11, 2020 at 8:13 PM jim stephens via cctalk < cctalk@classiccmp.org> wrote:
> > I agree. Most devices are expected to be heated briefly to soldering > temperatures, not heat soaked at that. > > Temperature in this case is much different than heat. The designers of > the devices must take into account what temperature is require to do the > solder assembly function, and minimize the amount of heat the device is > exposed to. > > On wave soldering machines the heat was quite low, and these would have > been assembled then. Even with current radiant oven techniques, the > parts would fall off if there was an extended heat exposure. They do > that often enough now with heating problems with devices, with open > circuit failures happening. > > If you're lucky and have a quick fire department response, the setup > time on the equipment is at least 4 or 5 minutes. Unless there's > physical danger and the building involved may have people trapped, they > take time to assess the fire, the propagation and there's more time > before they attack. > > I've seen a couple of events and a couple of full exercises, it doesn't > happen quickly. Fire departments are sadly known for letting buildings > burn into the basement if it saves life or property of other nearby > structures. You'd be lucky to get this out of a burned out building in > most cases. Once the fire is knocked down the heat will be present for > quite some time afterwards, as they let it cool and clear flash fires, > and take care of nearby property. > > thanks > jim > Well, we'll see how bad these things really are. The idiot I am, I struck what I consider to be a reasonable deal for the 11/70 and 11/45 and I'll be picking them up in November on a trip to SF I already had planned. What can I say, I'm a glutton for punishment. A friend of mine went out and ot a number of decent high-res pictures of the units. The backplanes/wirewrap don't appear to be physically damaged, and the boards inside look pretty decent, though I'm not holding my breath. (I was particularly surprised that none of the pot-metal card stiffeners were warped or bent due to the heat, even near the front on the 11/45 where it's clear most of the heat was present.) I do have a friend with a spare set of 11/70 boards. What sold me though was that the 11/70 has a PEP70 + Hypercache board set installed (which would be really cool, assuming anything in there can be made to work again). I figure worst case, I get a couple of DEC racks that'll work fine after some sanding and repainting, and maybe I can send the chassis off to Ethan if repair turns out to be impossible. - Josh