25 Feb
2013
25 Feb
'13
1:12 p.m.
On Mon, Feb 25, 2013 at 3:59 PM, Cindy Croxton Electronics Plus
<sales at elecplus.com> wrote:
I have been testing my C64s today, and 1 works
perfectly, joysticks and
game, etc.
Hooked up via DIN cable to 3 RCA to Commodore color monitor, everything is
fine.
Perfect.
My questions are these:
1 of the C64 powers on, but absolutely nothing appears on the screen.
That is the most common failure mode, called "the black screen". Most
common cause is a faulty "PLA" (Programmable Logic Array). It can be
replaced with the PLA from another machine or can be burned from a
blank 82S100. Second most common cause is bad DRAM - 4164s. It's
usually the PLA.
1 of the C64 has a totally different pin configuration
for the monitor and
disk drive, only 5 pins for the monitor. The FCC ID, model number, etc. is
exactly the same as the others, but these connections are different. Any
ideas?
The oldest Rev boards have a 5-pin DIN for video - the 5 pins that
line up with an 8-pin DIN carry the same signals, IIRC. They used to
make a 5-pin video cable that worked with both models. I've even used
an ancient (1960s) 5-pin DIN *audio* cable with RCA breakouts, but the
colors didn't match up (IIRC, that cable was 2 black, 2 red, but I
found the signals I needed in there).
You will probably need to find/make a 5-pin DIN video cable for that
one or sell it untested.
Not sure about why you'd see a difference with the disk interface.
That should be a 6-pin-DIN on all C-64s (and VIC-20s, where it
appeared first).
-ethan