26 May
2003
26 May
'03
2:54 a.m.
In message <m19K2Ap-000IzYC@p850ug1>
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
:-)
I'm more interested in collecting old home computers. I have been known to
break that rule once or twice, though.
Even then you'd not be totally lost without a
schematic if you knew the
type of valve that was supposed to go there (quite likely to be a double
triode, actually). The heater connections should be darn obvious, and you
can easily distinguish grid from anode from cathode with a little
practice. The only problem would be keeping the right anode/grid/cathode
together.
I'm not that good with vacuum tube circuitry, but if the computer is
based
on digital logic or microprocessor technology and the parts are available,
I'd at least have a go at fixing it. Now I've developed a trick for getting
the parts that are to be replaced out of the PCB without FUBARing it...
Anway, can somebody please tell me how running a
machine (as opposed to
having it on statick display) is going to cause valve holders to break in
half?
Valve overheats, base was (hypothetically) made of crappy materials, base
cracks, then the heat of the valve cracks it in half or whatever.
Highly unlikely, but not outside the realms of possibility. Then again, it
could have occured during shipping...
The oldest
machine I've worked on... Hmm... That's a tough one... I guess
that would be the Jupiter Cantab "Ace" computer I'm restoring^W rebuiling.
Oh, a relatively new machine (must be, it's got one of those new-fangled
microprocessors [1] in it) :-) [1] As opposed to an old-fashioned microprocessor,
meaning a sequencer
running microcode. Both DEC and HP used the word in this sense in the 1970s.
Didn't I mention that I was planning to buy some LS logic chips and build my
own CPU?
Then again, I might just cheat and buy an FPGA...
Later.
--
Phil.
philpem(a)dsl.pipex.com
http://www.philpem.dsl.pipex.com/