System/36 still sleepin' Suggestions?

From: Richard W. Schauer <rws_at_enteract.com>
Date: Sun Nov 5 21:15:38 2000

On Sun, 5 Nov 2000 THETechnoid_at_home.com wrote:
> The machine has two 8" hard disks mounted on thier sides with ends
> latitudinal. They are stacked one top of each other in a sturdy rack with
> some shock absorbing characteristics.

8"? Measure again, I think they're 14". BTW pay attention to the little
diagram showing which way to point your thumb when you flip the latch
holding the drives in (they swing out if you hadn't noticed), or else
it'll bite.

> Sure have, it is the big red toggle on the left side of the machine. The
> hum does not change

Flipping the Unit Emergency switch won't start the machine nor make a
difference in the buzz. It only enables the power.

> No, sometimes I think I hear a 'tick' in there but I may be imagining
> things. It certainly has nothing to with pressing the power key on the
> face panel. I'm supposing that the panel is dependent on other things
> than the power supply given the ensybeentsy chicklet power-on button....

You're probably hearing the control transformer expanding and crackling
(!) It's normal; they're all ferroresonant, meaning they operate
saturated-core and get hot. The power that goes through these
transformers gets rectified and filtered, but does not go through any
regulator stages- the transformer regulates. It uses the AC frequency and
the core saturation level as constants to maintain a regulated AC voltage
on the secondary. There is a very high voltage (550 VAC) secondary
winding with a (physically) large capacitor across it; don't disturb it,
it's necessary for the regulation.

The control logic is what's going to turn on the main power when you press
the power button. Should it come to it, there is a way to second-guess
that logic and force the power on.

> Maybe the big-red switch is tarfu. I can check it with my VOM. Should I
> hear anything or see anything after hitting that switch? Docs seem to say
> I should have a quiet machine but a live panel on which the chicklet power
> key resides.

That's right. If the switch is off, you will get a Power Check light when
you press the power button. If it's on, the power will come on (it's
supposed to, anyway).

> If this switch fails, is it possible it is at fault for the 'no lights at
> all' condition? It is one of those 'coke machine' keys and I'd rather not
> have to tap it with a drill to cycle it a few times....

No. It will (I think) default to the Normal position. I haven't looked
into my System/36 in a while, but I can if you get stuck.

Richard Schauer
rws_at_enteract.com
Received on Sun Nov 05 2000 - 21:15:38 GMT