Got too greedy... dead machine?

From: Oliver Skelton <>
Date: Mon, 12 Apr 1999 18:31:35 +0900

Hi international rescuers...

I got greedy after fitting the Nova & decided to clock the DSP to 50MHz
(one of my long list of pending aims).

Now the machine does not boot at all.
Black screen, no disk activity.
Unfortunately, as a lazy amateur, I messed with too many things under
the bonnet to be sure of the area to check, so any pointers would be
welcome. I resisted the temptation to rewire the nemesis with coax, but
I did touch the following:

1) 50MHz oscillator wired to the 2 free solder pads near the DSP. I
didn't cut the track between DMA & DSP clocks under the main board (or
even look at bottom of main board at all) as the track was already cut
on top - I just had to remove the 40MHz wire from Nemesis (folded back &
insulated). I took the 5V pin from the 5V I found on the motherboard
connector for the keyboard. As I recall, there were 8 pins in a row and
the keyboard is only plugged into the front 4 of these. I found 5V on
the 5th from the front.
If I installed the new oscillator correctly - the corner with the dot is
the corner with the pin which is not connected to anything.
I also put a small rectangular 3 fin heatsink diagonally on the (square)
dsp - retained with heat conducting compound & 2 spots of superglue.

2) I looked under the psu to identify the SCC chip- I am thinking of
changing to the ESCC later as per HSMODEM suggestion (I think it was the
square chip with 4x11 legs marked AM85C30-10JC. It doesn't look easy to

3) I looked under Falcon 4mb memory card to see what's there. (TOS ROM,
of course)

4) 040 CPU heat sink was loose - obviously disturbed by Nova fitting.
Removed double sided tape & put back with heat conducting compound.
(I am hoping the compound is better than the tape anyway. At least I now
know for sure I have a 33MHZ cpu).

5) I snipped off the 5 wires from Nemesis which were bundled up (leading
nowhere). I was worried they might be acting as a radio transmitter.
(i.e. blue from J10, pink from J11, green from J5, red and orange - from
between the white 40mHz clock to DSP and the brown wire).

6) One of the 3 wires to the LED on the front of the CLAB case came off
the chip it was soldered to. This chip is at the right front of the
machine as you look at it in normal use. It came from the second pin
from the left of the row of pins closest to the rear. I soldered it back
and taped the lead down to try and prevent it happening again.

7) Removed & looked under ab040 card - looking at the Nemesis buffer to
see what I might do with it in future.

Then I got an ear bashing for playing with my Falcon instead of doing my
expenses... so I hurriedly put the Falc together.
Too hurriedly. I accidentally plugged the AB040 card in too far forward
so that each row of pins was shifted to the wrong side of the
(Half the pins hanging in the air)
When I tried to boot I got vertical blue stripes on the screen
(something I saw one time when fitting Nova card... but which was
probably just a bad contact at that time).

Once I rectified the above screw-up I had the totally dead Falcon

Any suggestions/recommendations - hopefully which keep soldering to a
minimum as the more I solder - the higher the chance that I will do some
serious damage.

Received on ma. april 12 1999 - 18:00:38 CEST

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