25 Feb
2013
25 Feb
'13
3:59 p.m.
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.
My questions are these:
1 of the C64 powers on, but absolutely nothing appears on the screen.
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?
_____
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2899 / Virus Database: 2641/6130 - Release Date: 02/25/13
25 Feb
25 Feb
4:12 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
4:28 p.m.
Well, not totally a black screen, just nothing on it.
When u turn the C64 on or off, the screen flickers for an instant, then
blank screen.
This particular also emits a very faint screech or whine.
I prob have a 5-pin to RCA somewhere, will scrounge some more.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Ethan Dicks
Sent: Monday, February 25, 2013 3:13 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Commodore 64 question
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
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2899 / Virus Database: 2641/6130 - Release Date: 02/25/13
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2013.0.2899 / Virus Database: 2641/6130 - Release Date: 02/25/13
5:15 p.m.
On Feb 25, 2013, at 4:12 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
On Mon, Feb 25, 2013 at 3:59 PM, Cindy Croxton
Electronics Plus
<sales at elecplus.com> wrote:
I have a similar problem; I've noticed that the IRQ line is
constantly asserted, which it's not if I just pull the VIC
(of course, that could be because the boot routine is
crashing; the VIC otherwise looks like it's probably working
fine, since it emits a proper NTSC black screen with color
burst).
Is there a relatively simple test that can be done with an
analog scope (no storage) that can determine whether the
PLA is bad? Some of the outputs, at least, seem to toggle.
I'd like to narrow it down before I put down the money for
a replacement part.
- Dave
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.
4165
days inactive
4165
days old
3 comments
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