22 Jul
2012
22 Jul
'12
11:37 a.m.
It looks like I'm back in business collecting vintage computers. I
went to the town dump today and found what looks like an H89 but the
model number tag on the back says NN89-29. I haven't tried opening it up
to see what's inside yet but it has a floppy drive so I assume it isn't
just a H19 terminal. Also, on the front it says "Heathkit Computer".
If it is an H89/Z90, then it will be quite tightly packed inside and not
easy to work on. From memroy, the floppy drive comes out easily, and
it's best to that that out early on to have better acess to the other bits.
Even though I've had vintage computers before
I've never followed good
procedures when trying to bring them up. Usually, I just plug in the
power cord and hope for the best. I'd like to do a little better this
time. Can anyone suggest an approach to bringing this beast to life that
minimizes the chances that I'll fry it the first time I power it on?
The PSU is linear, and mostly jsut behind the floppy drive. But something
is tellign me that there are voltage regulators on at least one of the
logic boards (the H19 terminal board?) so it's not totally trivial to
test the PSU on dummy load. Iseem to rememer when I brought my Z90 to
life, I started by temporarily tuning it into an Z19 terminal and gettign
that to work first.
I certainyl did test the bare PSU on its own, that may include the
regualtors for the comptuer section. I also seem to rememebr that many,
if not all, of the ICs on the terminal board were socketed, so I pulled
those, at least the hard-to-find or expensive ones, and powered up at
litte as I could co check votlages.
-tony