15 Jun
2006
15 Jun
'06
11:08 p.m.
On Thursday 15 June 2006 09:43 pm, Ethan Dicks wrote:
On 6/16/06, David Vohs <netsurfer_x1 at
fastmailbox.net> wrote:
I have that setup, and it really doesn't do all that much, and surely
doesn't work on most all of the machines that I have encountered that gave
the "blank screen" symptom. We got it because we were a c= "factory
service
center" at the time. I still have it someplace, but have no idea where it
is and am not too worried about finding it. :-)
I have an SX-64 that has (apparently) a serious
problem. On powerup it
shows nothing on the screen (checked the settings and and also hooked up
an external monitor) along with an occasional crackling sound from the
speaker. Keypresses are not registered by the machine.
Anyone got any ideas as to what the problem could be?
If the power supply is working (check for +5V at the corner of a TTL
chip if you can't find it anywhere else, and see if you can see the
glow of the CRT filament), the next thing to check is the PLA. It's
identical with the one in the C-64, so you can borrow one there. If
it's not either of those, you'll have to start chip-level debugging
(unless you happen to have a C-64 diagnostic cartridge and cable
harness, a tool sometimes used by C= dealers for debugging _mostly_
dead machines). If any of the DRAMs feel _really_ hot (too hot to keep
your finger on),
that's a symptom of fried RAM, an occasional cause of inertness.
Occasional?
The ROMs are different from a C=64, but the only
changes to the kernel
are to remove the tape routines (no cassette connector), and change
the default color scheme and startup message.
I have repaired SX-64s that needed a kernel rom by putting one for a c64 in
there and it worked just fine, with the main apparent difference being the
screen colors as you mention. I never took notice of the tape functions,
though.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin