On Sun, Oct 11, 2020 at 8:13 PM jim stephens via cctalk <
cctalk at 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