Need help repairing an Atari 600XL
Christian Hedemann
I bought an Atari 600XL some weeks ago on a fleamarket and it seems like
the computer's out of order... can someone help me finding the defect part?
The symptoms are that when I power it up, the red LED on the keyboard
turns on and for about a second the screen has a brown-like color - then
it's black again.
It doesn't matter if I use the HF- oder monitor-output, it's always the
same... the red LED turns on, stays on, short brown screen and then black.
I already pulled out all ICs and put them back in their sockets.
Bye,
Christian
Docrotcod
Thomas
"Christian Hedemann" <hed...@gmx.de> wrote in message
news:42fa6f18$1...@news.isis.de...
Kryten
> The symptoms are that when I power it up, the red LED on the keyboard
> turns on and for about a second the screen has a brown-like colour - then
> it's black again.
Could be any number of things.
Electrolytic caps dry out over time, and EPROMs fade (though Atari used
masked ROMs which do not fade).
You'll have to do some probing, see what signals seem active and which do
not.
Docrotcod
"Kryten" <kryten_droid...@ntlworld.com> wrote in message
news:GywKe.4575$1F5...@newsfe4-win.ntli.net...
Russ Gilbert
"Christian Hedemann" <hed...@MUNGEgmx.de> wrote in message > Hi,
big ones and put in a known good one. Figure out which are the
RAM chips, a bad one might be hotter than the others. Try holding
down the OPTION silver key at power on, this will disable BASIC
and maybe you'll see a blue screen. Then there's purchasing a
logic probe, which won't do you much good unless you have a working
600XL to compare with. I think your power is OK, as the red LED
comes on, should be 5 volts at the power adapter. I guess this is
a PAL 600XL, so things may be a little different from a NTSC one.
Finally, maybe get a 800XL, it is a more useful computer, the 16K
600XL can just about only run cartridges. Good luck.
Russg
get a correct BLUE screen
Kryten
news:MIwKe.23$P34.2@okepread07...
> But based on the screen he is getting it seems to be the processor.
It could be anything. Dead ANTIC, dead GTIA, dead modulator, dead caps in
the video signal path, dead ROM, dead support logic, broken PCB tracks,
etc...
Saying there is nothing on screen is as vague as saying there's a guy lying
down not conscious. Could be a heart attack, epilepsy, drink, sleep,
sunstroke, etc.
Really need a bit more info to go on.
Otherwise we're just working in the dark.
Christian Hedemann
> down not conscious. Could be a heart attack, epilepsy, drink, sleep,
> sunstroke, etc.
>
> Really need a bit more info to go on.
>
> Otherwise we're just working in the dark.
...I am no electrican, but a trained system-electrician (=if it doesn't
work, change the board. If that won't work, change the whole system).
^_^; So the most useful tool in this case I possess and learned to use
would be a multimeter...
My hope was that:
- it would be a well-known problem (since the screen shows a brown-like
color for a second and the power-LED is on - at least it's not
completely dead)
- or that someone could tell me what to check and which values are
expected there
- or that someone could tell me "Hey, buy an Atari 'dunnowhat' since
most of the chips are compatible", because then I wouldn't have to wait
for decades until a cheap Atari 600XL would turn up on eBay.de.
Maybe someone even knows a good source for replacement parts besides
buying a whole system at eBay?
Bye,
Christian
Christian Hedemann
> big ones and put in a known good one. Figure out which are the RAM
> chips, a bad one might be hotter than the others.
> Try holding down the OPTION silver key at power on, this will disable
> BASIC and maybe you'll see a blue screen.
Blue screen doesn't turn up: brown color and then black.
> Then there's purchasing a logic probe, which won't do you much good
> unless you have a working 600XL to compare with.
Hm, I never used a logic probe or an oszilloscope and I haven't got a
working 600XL to compare with, too. ^_^;
Next week I've got the chance to get an 800XL, but I guess that one
wouldn't help me, right?
> I guess this is a PAL 600XL, so things may be a little different from
> a NTSC one.
Yup, a PAL one.
> Finally, maybe get a 800XL, it is a more useful computer, the 16K
> 600XL can just about only run cartridges.
:-)
I wanted to get a 130XE first, but when I saw this "bargain"(?) for 12
Euro including an Atari 1010, four original games and six books about
programming at the fleamarket, I couldn't resist.
And I've got enough time to spend some hours trying to revive an old
computer from the dead...
Bye,
Christian
Bill Garber
A good source for parts for all Atari systems is Best Electronics.
http://www.best-electronics-ca.com/Default.htm
Bill Garber
Russ Gilbert
"Christian Hedemann" <hed...@MUNGEgmx.de> wrote in message > > Probably not
too helpful, but if you could get some A8 ICs, pull the
> > big ones and put in a known good one. Figure out which are the RAM
> > chips, a bad one might be hotter than the others.
> A8 = Atari 800XL?
Sorry, A8= 8-bit Atari, XLs, XEs, 400, 800, XEGS, all are 8-bits because
they use 8-bit code, 16-bit address.
> > Try holding down the OPTION silver key at power on, this will disable
> > BASIC and maybe you'll see a blue screen.
> Blue screen doesn't turn up: brown color and then black.
OK, probably not valid anyway (the BASIC chip may still be bad.)
> > Then there's purchasing a logic probe, which won't do you much good
> > unless you have a working 600XL to compare with.
> Hm, I never used a logic probe or an oszilloscope and I haven't got a
> working 600XL to compare with, too. ^_^;
> Next week I've got the chance to get an 800XL, but I guess that one
> wouldn't help me, right?
NO!, a working 800XL would be very helpful. It is unlikely tho
that the chips would be socketed, which apparently your 600XL is.
You really don't want to be desoldering un-socketed chips, but socketed
ones, if carefully done, preferably with a IC puller, but could use a
screwdriver.
Even if the chips aren't socketed, you might get an idea using a logic
probe,
probably about 10 or 15 Euros. There are schematics that have the
High, Low, Pulse for all the pins of the Large ICs (40 pins, and maybe
the small ones too). The chips in the 800XL are the same for both, just
in different places, you can tell what is what by the numbers on the chips.
eg. CO14806 for the CPU, probably CO12296 or CO21697 for Antic,
CO14805 for GTIA, CO12294 for Pokey, maybe CO60302 for
BASIC, CO61598 for OS, etc. I think I'm right here. Your PAL
Antic and GTIA are definitely going to be different, PAL Antic=CO21698
PAL GTIA=CO14889. (Looking up a bunch of IC codes....)
Of course, make sure the 800XL works. Sorry, I got lost.
> > I guess this is a PAL 600XL, so things may be a little different from
> > a NTSC one.
> Yup, a PAL one.
>
> > Finally, maybe get a 800XL, it is a more useful computer, the 16K
> > 600XL can just about only run cartridges.
> :-)
> I wanted to get a 130XE first, but when I saw this "bargain"(?) for 12
> Euro including an Atari 1010, four original games and six books about
> programming at the fleamarket, I couldn't resist.
> And I've got enough time to spend some hours trying to revive an old
> computer from the dead...
>
> Bye,
> Christian
Right, I hate to lose an Atari also, it is worth it to try to salvage one.
You could use your multimeter to check the main power lines (Vcc).
Probably just one of those large chips is bad, and I agree with
Kryten, the CPU would probably be the first to try to swap in.
Good Luck.
Russg
Lee
multi-meter to verify that you have exactly 5 volts coming from the
power supply. Then check the voltage with the computer turned on, it
should still be exactly 5 volts. Best way to do that is with the cover
and RF shield off. Power supplies going bad are the most common thing
wrong.
Because of the above you then need to check for over-voltaged ram chip
damage by testing which one(s) are uncomfortably too hot to touch with
the computer turned on. 4416 is the base number for the 600XL ram
chips and you only have two (16K machine after all), mine say
TMS4416-15NL for example. You might try the same test on all the chips
if no ram chips are found to be very hot and your voltage is perfect.
B&C may have a 'pack' of 40 pin chips to use for substitution testing
or am I thinking of the long defunct Techno-vision? At any rate,
subbing out the big chips is your only real hope short of an EE degree
AND a scope if you get this far and haven't found a problem.
The good news is that the 600XL makes a good source of 40 pin parts for
the 64K 800XL and 130K 130XE? Look for B&C in the Vendors list in the
message titled 'Welcome to comp.sys.8bit' - That message is the group's
FAQ and will have current contact information for Atari vendors.
Russ Gilbert
the Vcc. One of these places would be where you would attach the
clip on a logic probe.
I think you could see the power sources in the schematics for the 600XL
(PAL, I'm pretty sure) at:
http://www.dereatari.republika.pl/schematy.htm
Kryten
news:rx5Le.334$k92...@newssvr19.news.prodigy.com...
> I think you could see the power sources in the schematics for the 600XL
> (PAL, I'm pretty sure) at:
> http://www.dereatari.republika.pl/schematy.htm
Note that all the diagrams are zipped PCX, and my PC doesn't handle that
image format. I can convert them into PNG (which uses less space than the
zipped PCX!) for anyone else who cannot read PCX.
I converted a few circuits for the kit I have:
http://homepage.ntlworld.com/kryten_droid/Atari/800XL/Atari_circuits.htm
Christian Hedemann
> multi-meter to verify that you have exactly 5 volts coming from the
> power supply. Then check the voltage with the computer turned on, it
> should still be exactly 5 volts.
With an Atari connected to it, it goes down to 5.65V.
When checking the power supply, I saw that pin 6 had a loose contact
(sometimes 0V and sometimes 4.xV) and changed the plug. It didn't help.
> Because of the above you then need to check for over-voltaged ram chip
> damage by testing which one(s) are uncomfortably too hot to touch with
> the computer turned on.
I checked the temperatures of all chips when the 600XL was turned on for
about 20 minutes. They ranged from "cold as room temperature" up to 41°C
(U2) but most are somewhere between 30°C and 35°C.
Bye,
Christian
Christian Hedemann
> the Vcc. One of these places would be where you would attach the
> clip on a logic probe.
Okay, err... what's a logic probe? I saw those things in a catalogue,
but I have got no clue what to measure with them and... hmm, what they
"do" or how to use them. :-)
...even the shopkeeper of the electronics shop in town (where I bought
my plug for the power supply) couldn't tell me what a logic probe is. ^_^;
Then... I read the schematics and checked the main power places (the
number on the line outside of the rectangle is the number of the leg,
right?).
I only got voltages of about 5V to about 7V between vcc and vss, except
for one IC: U15 (74LS375N) with less than 1V... somewhere around 0.3V.
Bye,
Christian
And thanks for the hint that the 800XL has soldered ICs. :-)
Russ Gilbert
"Christian Hedemann" <hed...@MUNGEgmx.de> wrote in message > > One other
thing. I said check the main power places, I think called
> > the Vcc. One of these places would be where you would attach the
> > clip on a logic probe.
> I'm pretty sure that I am outing myself as a newbie to this now... ;-)
> Okay, err... what's a logic probe? I saw those things in a catalogue,
> but I have got no clue what to measure with them and... hmm, what they
> "do" or how to use them. :-)
> ...even the shopkeeper of the electronics shop in town (where I bought
> my plug for the power supply) couldn't tell me what a logic probe is. ^_^;
Ahh, a logic probe is a pen like device that you connect to a 5V source
with the wire that comes from it and it is a pen-like device that usually
has a LED and a metal pointer that you touch a point on a pin or trace
on the computer mother board. It will give an audible sound, one
of three sounds, a low sound, a high sound or a pulsing sound for
the low-high-pulse state of the point you're testing. In conjunction with
a schematic that has the 'logic' H L P of points on it, you might be
able to find a point that isn't right and figure out a problem. The
Schematics that are at the site I mentioned don't have these 'notes'
as to the logic of pins and points on the schematic. I have a 130XE
schematic that does have these points. Actually, I'm not sure I ever
accomplished anything with my logic probe. Except maybe by going
back and forth between a working and non-working mother board.
ie. I guess the logic probe wouldn't help much.
Replacing the chips
is the most likely way to fix it. And I don't know if the 800XL in
question has sockets or not, your seller probably doesn't know because
you'd have to open it up and take the RF shield off to see the chips.
I think theres a fairly good chance the PAL 800XL has sockets, only
because your 600XL has them. Maybe Andreas or one of the other
Euro-A8ers could say.
> Then... I read the schematics and checked the main power places (the
> number on the line outside of the rectangle is the number of the leg,
> right?).
I'm not sure what rectangle you're talking about, a big rectangle is
the chip, with pin numbers. I think most power ponts are a small circle
with +5 at them. Small rectangles are resistors with the numbers for
the Ohms. The +5v power points will have +5A or +5E, the letter
representing the source of the power, which you can see in one of
the schematics that has the power supply jack and on-off switch.
> I only got voltages of about 5V to about 7V between vcc and vss, except
> for one IC: U15 (74LS375N) with less than 1V... somewhere around 0.3V.
>
> Bye,
> Christian
>
> And thanks for the hint that the 800XL has soldered ICs. :-)
It may or may not have sockets. But if you can verify that it works,
you'd have a working computer. The pins on the Large Scale Integrated
circuits, the 40 pin ICs should have just about the same logics on
the 600XL and 800XL.
Getting ahead of the game, the next thing you'll need is a SIO2PC
or APE cable to access the 1000s of programs available. Use
your PC with a serial cable as a disk drive.
Russ Gilbert
The numbers for the pins on the schematic goes like this.
u
1 40
2 39
3 38
4 37
etc.
Looking down on the chip, with the 'u' meaning the notch, I think
the notch is always to the left as you look down on the mother board.
My example is a 40 pin chip, but smaller chips have the same idea.
Start at 1 go away from the notch, then up the other side of the chip.
Kryten
> Without an Atari connected the power supply has an output of 5.95V.
> With an Atari connected to it, it goes down to 5.65V.
Hmm, I think mine was 5.5V (10% high, erring on the safe side).
> I only got voltages of about 5V to about 7V between vcc and vss,
Are you sure your meter is okay?
If your PSU is driving 5V into the machine, you should not be seeing 7V
anywhere (assuming there is no step-up converter inside!).
Most computer logic chips expect VCC to be 5V +/- 5% or 10%.
So 7V sounds seriously unhealthy and I would not leave it switched on for
any length of time.
Swapping chips around would only destroy more chips...
> one IC: U15 (74LS375N) with less than 1V... somewhere around 0.3V.
That's definitely wrong.
Are you sure you got the right pins?
Christian Hedemann
>
> Are you sure you got the right pins?
Bye,
Christian
P.S.: I'll check the voltages again, but tomorrow... today's my birthday
party. :-)
Christian Hedemann
> Most computer logic chips expect VCC to be 5V +/- 5% or 10%.
little bit around 5.00V (less than 5%).
Bye,
Christian
Rick D.
You have the right power supply.
You are using a TV, so pressing ctrl + 2 does not buzz?
Holding START and turning on the XL does not produce a buzz?
Then its the cpu, pia, ram, or OS rom most likely.
Rick D.