[R-390] SP 600 Wiring Colors

[Tisha Hayes]

Funny,
The one commonality I have seen with SP-600 wiring.. if you have even the
slightest provocation, tear it out and replace it. Especially anything that
penetrates to the front panel.

On the '600's I have known (I really cannot say love, they are like a
stepchild that you just know is up to no good), the wiring insulation turns
to a million little crunchy pieces as soon as you remove the front panel.
This usually happens where the wiring goes through those rather sharp-edged
circular holes in the lower chassis.

So you do the standard thing; sigh, snip off the wire lacing (and it was so
pretty looking) gently work that one wire loose, unsolder it from whatever
pot or switch it was attached to and thread on a thin piece of spagetti or
heat-shrink tubing. Usually it takes an entire six to ten inch length of
tubing and as you are going more of the insulation chunks are breaking off
of that wire. Looking closely you see that many of the conductive strands
are corroded and broken on that one wire. You bravely muddle along and now
that wire looks all pretty.

Hmm, getting ready to re-bundle everything else and you find that you
cracked insulation on three or four other wires while working on that one
wire... Darn. Now the experience gets repeated on those too. This is
turning into a day-killer.

Ok.... it is now 11:45 in the evening, you have done a half-dozen of those
wires. A few times you find that the cracked insulation extends all the way
into the lower chassis but you are set in your mind; "there is no way I am
cutting apart the lacing in the lower chassis". Yea, keep thinking that,
maybe it will help you sleep at night. Wait until you need to do something
silly like replacing a bad paper cap or BBOD."

All this happens because you wanted to fix a slipping tuning dial. Maybe in
your zest for cleanliness you disassembled the brass plate that retains the
geartrain under the front panel so you could make the tuning bezels look
pretty. (been there, done that) and you used brass cleaner to make all of
that stuff look nice. Maybe you were really foolish and used something even
in the slightest bit greasy so the edge of the tuning dial is slightly
slippery so the brass wheel that is driven by the tuning knob is no longer
gripping the edge tight enough (that is what usually causes a slipping
tuning knob, weak hairpin springs, corrosion on the cadmium plated front
pan and the little gear carrier that is supposed to be spring loaded
against the edge of the display disk, all quite clever for its day.).

BTW, even though it caused me almost a week of grief, fixing other things
that geartrain looks spectacular! I strongly recommend that if you have
metal that needs to be polished, give "Simichrome Polish" a try. It smells
ammonia based but things I have polished ten years ago still look brand new.

-- 
Ms. Tisha Hayes. AA4HA

 *this would be a good one;   ""In this denial of the right to participate
in government, not merely the degradation of woman and the perpetuation of
a great injustice happens, but the maiming and repudiation of one-half of
the moral and intellectual power of the government of the world." --
Fredrick Douglass"*