4 Apr
1998
4 Apr
'98
9:01 a.m.
Hi Seth:
Take it easy!!!!
It's no where as bad as it sounds.
Seth J. Morabito wrote:
snip
The power supply seems to be worst off of everything.
The boards,
although needing to be cleaned of some spots of mildew, seem mostly OK.
Possibly a few tiny rust spots -- I'd say 100% of the chips are replacable
by easily-found parts, either period pieces or newer pieces. But probably
99% of the chips won't need replacing. They seem to be doing very well.
I have two Cromemco ZPU boards, so even if one has some bad parts,
I should be able to take spares from the other.
Disassemble down to the 'board level'. WASH the boards with Isopropel
alcohol, using a soft brush to disloge dirt/dust, dry, clean the edge
connectors wwith a _mildly abrasive_ eraser, at that point the boards
should be fine. (Including the chips.)
But that power supply... eek. The transformer is
covered in a thick layer
of rust, and the whole thing just looks dirty and mildewed.
Again, wash with alcohol, dry. Then a light spritz of "WD-40" (or
similar), and a wire brush on any _THICK and FLAKEY_ parts od the IRON
part of the transformer. Final 'dry'. aand you should bee to the
're-assembly'/test part of the program.
I think
the best course of action now would be to desolder every component of
the power supply and build a new one -- sadly, losing a bit of IMSAI
authenticity in the process. Oh well... Say, does anyone know where
I can get a pair of 95000uF 15VDC electrolytic capacitors? =) Oh, and
a pair of 10000uF 25VDC -- mustn't forget those.
UNLESS the capacitors are _badly_ corroded, they should have cleaned up
in the general alcohol wash/dry cycle. The probably _DO_ need to be
gently brought back to life. Using a 'Variac' (or similar variable
transformer), fire up the unit with 1/2 or less of the normal input AC
voltage. Gradual increase the input AC untill the normal value is
reached. (An increase of 5v every couple minutes is probably about
right.)
IF this doesn't recover things, _then_ it's "rebuild" time.
Chuck
--
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He, who will not reason, is a bigot; William Drumond,
he, who cannot, is a fool; Scottish writer
and he, who dares not, is a slave. (1585-1649)
While he that does, is a free man! Joseph P. 1955-
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Chuck Davis / Sutherlin Industries FAX # (804) 799-0940
1973 Reeves Mill Road E-Mail -- cad(a)gamewood.net
Sutherlin, Virginia 24594 Voice # (804) 799-5803