RSwipeCA Posted November 22, 2014 Author Share Posted November 22, 2014 Not the most elegant. But it should do the job. 1 Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 23, 2014 Share Posted November 23, 2014 (edited) I am in the same exact boat as you are with a 130XE, dead with a red/brownish solid screen and a lot of very hot RAM chips (actually burns your finger if you keep it there long enough). I've been trying to fix that mobo for the last couple of weeks, on and off. I have all the major ICs and the main bank of RAM socketed and tried with working chips, no cigar! so far.... Next I will try to trace a fault to the OS, don't know how exactly as I don't have an oscilloscope, just a logic probe at my disposal. When I've seen your thread I was immediately interested as we live through the same experiences. I hope one of us can finally get their machine back to life and help the other to possibly figure out how to fix his. Good luck..... Edited November 23, 2014 by atari8warez 1 Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 23, 2014 Author Share Posted November 23, 2014 I am in the same exact boat as you are with a 130XE, dead with a red/brownish solid screen and a lot of very hot RAM chips (actually burns your finger if you keep it there long enough). I've been trying to fix that mobo for the last couple of weeks, on and off. I have all the major ICs and the main bank of RAM socketed and tried with working chips, no cigar! so far.... Next I will try to trace a fault to the OS, don't know how exactly as I don't have an oscilloscope, just a logic probe at my disposal. When I've seen your thread I was immediately interested as we live through the same experiences. I hope one of us can finally get their machine back to life and help the other to possibly figure out how to fix his. Good luck..... It's nice to know there is at least two of us in the same boat lol. The help I have got so far from the guys here has been invaluable. I will keep plugging away 'till I either hit a brick wall or get it running again. I will do my best to document the proceedings so it can act as at least a path for others to follow - at least as a pointer to a possible fix. My RAM was as hot as you describe, since replacing they at least appear to be running at normal temps. As you can see I still have a few IC's to socket yet, will be completing that over the next few days. Hopefully we will get to a point where we make some headway. But I am sure there are many things that could be wrong, and not necessarily the same thing with both systems. Definitely keep in contact, lets see who succeeds or gives up first lol. 1 Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 24, 2014 Share Posted November 24, 2014 But I am sure there are many things that could be wrong, and not necessarily the same thing with both systems. Definitely keep in contact, lets see who succeeds or gives up first lol. Yeah, may not be the exact same problem but we at least have the same symptoms.. lol...As you said, if one of us succeeds it may help the other in some way. Quote Link to comment Share on other sites More sharing options...
Bryan Posted November 24, 2014 Share Posted November 24, 2014 Troubleshooting analog is usually easier than digital. With analog the symptoms point to the problem, but with digital you need the vast majority of components to be working before anything happens at all. When people post about their dead machines, they tend to think that the symptom of a blank screen is more useful than it really is. All it means is that no code execution is happening. You could pull out almost every chip except Antic, GTIA and the CD4050 and still get a blank colored screen. So, if it's not one of the common causes then it'll turn out to be some random failure that probably won't apply to anyone else's situation. 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted November 24, 2014 Share Posted November 24, 2014 most failures turn out to be common failures though... chaos theories often end in a pattern.... 2 Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 24, 2014 Share Posted November 24, 2014 That's what we are hoping for... lol 1 Quote Link to comment Share on other sites More sharing options...
Joey Z Posted November 25, 2014 Share Posted November 25, 2014 Not the most elegant. But it should do the job. While I guess this works fine, I've had decent success just using a piece of solid wire as a pin. That way you don't have to chop a pin off of another chip. 22 or 24AWG seems to be a good size, fits in most sockets. 24 might be a tad loose in a machined pin socket though. 1 Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 28, 2014 Author Share Posted November 28, 2014 (edited) Hi Guys, Ok, so I received the GTIA, ANTIC and CPU chips that I ordered. I haven't had a lot of time to play yet, but after swapping the CPU no change still just red screen. After swapping ANTIC no change still just red screen. But, after swapping GTIA the screen is now a even blue. But, no 'Ready' prompt. Here's a picture. I think that this particular symptom can indicate missing BASIC ROM?? I have to go out now, but I plan to socket that chip also, and I will risk swapping over this suspect BASIC ROM with that in my other working 800XL. Sound like a plan? Edited November 28, 2014 by RSwipeCA Quote Link to comment Share on other sites More sharing options...
Bryan Posted November 28, 2014 Share Posted November 28, 2014 The color pot must be readjusted for each GTIA, so there's no way of knowing at this point what color the new GTIA is producing... not that it matters. 1 Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted November 28, 2014 Share Posted November 28, 2014 No. A missing BASIC ROM won't keep you from booting. A (really) bad ROM might, but it would have to be in the circuit. Is there any noise (pops, SIO activity) when you power on? Bob 1 Quote Link to comment Share on other sites More sharing options...
russg Posted November 29, 2014 Share Posted November 29, 2014 No. A missing BASIC ROM won't keep you from booting. A (really) bad ROM might, but it would have to be in the circuit. Is there any noise (pops, SIO activity) when you power on? Bob you can take the BASIC ROM out. It should boot to self test. 1 Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 29, 2014 Author Share Posted November 29, 2014 (edited) No. A missing BASIC ROM won't keep you from booting. A (really) bad ROM might, but it would have to be in the circuit. Is there any noise (pops, SIO activity) when you power on? Bob Hi Bob. There is no noise, pops of any kind when I power it on. you can take the BASIC ROM out. It should boot to self test. I took the BASIC ROM out and still the same red screen. I adjusted the color pot to go from the blue back to the red screen. I have socketed all the chips marked with blue tape. I retested the XL after each socket installation as I went - no change from red screen. In the image the BASIC ROM is removed but that was also socketed and fitted for testing. I swapped all the chips marked with the blue tape one by one into my socketed spare 800xl. Every one of those chips when placed into the good XL had no ill effect on the good XL. It booted to the 'Ready' prompt every time. When I swapped the chips from the good XL into the bad one they had no effect on it. It still produced a red screen. EXCEPT the two chips in the centre of the mobo ( marked with the red 'x' ) when either or both were swapped from the good XL into the bad one, upon power up the screen just went black. When I swapped those two chips from the bad XL into the good one it still booted to the 'Ready' prompt - Hope that makes sense. So, even with my very limited knowledge of this topic it appears that the socketed chips are functional?? And that something else is going on. If it's supposed to boot to self test without the BASIC ROM then clearly, as it's not, that's an indication of further issues I am guessing. I have a logic probe and good multimeter. I can download the schematics? Is it time to start checking voltages etc? I am running the power supply that boots my good XL. Dumb question - does the keyboard have to be connected for an XL to boot? I just thought that all I have done so far, regarding test reboots, has been done without it attached. As Peter Gabriel once wrote, "Don't give up, you still have friends"........ or was it Kate Bush... . Edited November 29, 2014 by RSwipeCA Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 29, 2014 Share Posted November 29, 2014 Peter Gabriel did Sledgehammer... not that it's quite to that point. 2 Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 29, 2014 Author Share Posted November 29, 2014 (edited) Peter Gabriel did Sledgehammer... not that it's quite to that point. Ha. Now you got me thinkin'. The line comes from 'Don't give up' from Peter Gabriel's 'So' album. Just found it on my shelf - had to blow the dust off! But yeah, it's not the point of this discussion. lol. But I understand that a sledgehammer may be looming on this motherboards horizon. Nah, only joking. Edited November 29, 2014 by RSwipeCA Quote Link to comment Share on other sites More sharing options...
BillC Posted November 29, 2014 Share Posted November 29, 2014 Is that something translucent over the part# of the Mexican 6502C CPU(CO14608 - U8)? There is something by pin 32 that might be that or possibly cracking/discoloration. Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 29, 2014 Author Share Posted November 29, 2014 Is that something translucent over the part# of the Mexican 6502C CPU(CO14608 - U8)? There is something by pin 32 that might be that or possibly cracking/discoloration. Ah. What that is is a little dab of red ink from a permanent marker. I dotted all the chips from the suspect XL just in case I got them mixed up with the new ones, or the chips from the good XL. Well spotted though! Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted November 29, 2014 Share Posted November 29, 2014 Do you have a clock on pin 37 of the CPU (U8)? It should toggle 50% on your logic probe. Bob Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 29, 2014 Share Posted November 29, 2014 does the keyboard have to be connected for an XL to boot? I just thought that all I have done so far, regarding test reboots, has been done without it attached. No it doesn't, the computer should boot without the keyboard. Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 30, 2014 Author Share Posted November 30, 2014 (edited) Do you have a clock on pin 37 of the CPU (U8)? It should toggle 50% on your logic probe. Bob Ok. First time I have used a logic probe. I attached it to a motherboard ground and to the middle line at the power switch which showed a value of 5.4v. When I probe pin 37 it lights Low and has a pulsing beeper and flashing yellow LED. A Narrow High Pulse? Ah, should I be testing using TTL or CMOS? Under TTL both high/low LED'S illuminate with the same flashing orange and pulsing beeper. I assume that both high/low indicates 50% toggle? I have the SAMS schematic. I have checked all the pins on U8 All are correct EXCEPT for pin #6 should be P but is H No Pulse, pin#7 should be P but is L No Pulse and Pin# 36 should be P is H no pulse. Sorry I am pretty new to this sort of thing, eager to learn the basics at least. I know that I could rapidly be venturing out of my depth. Edited November 30, 2014 by RSwipeCA Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 30, 2014 Share Posted November 30, 2014 (edited) As far as i know you need to use the TTL setting Edited November 30, 2014 by atari8warez Quote Link to comment Share on other sites More sharing options...
Bryan Posted November 30, 2014 Share Posted November 30, 2014 Pretty sure you've got a CPU clock if you're getting a sync'ed screen. If you're looking for something to replace next, I've seen the 74LS158's (RAM section) go bad. This is really a job for an oscilloscope at this point. Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 30, 2014 Author Share Posted November 30, 2014 As far as i know you need to use the TTL setting Yes, I am using that now thanks. Pretty sure you've got a CPU clock if you're getting a sync'ed screen. If you're looking for something to replace next, I've seen the 74LS158's (RAM section) go bad. This is really a job for an oscilloscope at this point. I have just checked all the ram chips. According to SAMS and according to my good XL all the RAM chips U9 to U16 are HI on pin3 when they should be P. Chips U9 and U10 Pin6 should be P but are 0 dead. All the chips on my good XL are as per SAMS Schematic. Chip U2 looks problematic from a probing standpoint Pin4 should be P its 0 Dead. And Pins 10-15 should be P but are all HI no pulse. lol @ "If you're looking for something to replace next". All fun and games. Quote Link to comment Share on other sites More sharing options...
atari8warez Posted November 30, 2014 Share Posted November 30, 2014 (edited) Ok, here's an update for my situation, to recap: - I had a dead 130XE with shows no life of sign and a red solid screen, - Removed all RAM chips (mt4264) from the main bank and installed sockets and new RAM known to be good - NO CHANGE, still dead with red screen, - Removed most major ICs (CPU, Antic, PIA, Pokey and ROM) installed sockets and new ICs known to be good - NO CHANGE, still dead with red screen, - Noticed that some of the extended bank RAM chips (the 3 chips at the top of the extended RAM column) were getting extremely hot, but at first I thought they shouldn't matter and the computer should have normally booted with all new RAM chips in the main bank. Well turns out this may not always be the case. Just out of curiosity i removed the first 3 RAM chips that are getting very hot and the computer started to boot into BASIC... yay!!, but there still seems to be some problem, sometimes when I tap on the remaining RAM chips I would see random junk/noise appearing on the screen, so I will now remove the rest of the extended bank RAMs and see where I am going from there. Now, I don't know how this may help you with your problem on the 800XL but I just wanted to tell my current situation. Edited November 30, 2014 by atari8warez 1 Quote Link to comment Share on other sites More sharing options...
RSwipeCA Posted November 30, 2014 Author Share Posted November 30, 2014 Ok, here's an update for my situation, to recap: - I had a dead 130XE with shows no life of sign and a red solid screen, - Removed all RAM chips (mt4264) from the main bank and installed sockets and new RAM known to be good - NO CHANGE, still dead with red screen, - Removed most major ICs (CPU, Antic, PIA, Pokey and ROM) installed sockets and new ICs known to be good - NO CHANGE, still dead with red screen, - Noticed that some of the extended bank RAM chips (the 3 chips at the top of the extended RAM column) were getting extremely hot, but at first I thought they shouldn't matter and the computer should have normally booted with all new RAM chips in the main bank. Well turns out this may not always be the case. Just out of curiosity i removed the first 3 RAM chips that are getting very hot and the computer started to boot into BASIC... yay!!, but there still seems to be some problem, sometimes when I tap on the remaining RAM chips I would see random junk/noise appearing on the screen, so I will now remove the rest of the extended bank RAMs and see where I am going from there. Now, I don't know how this may help you with your problem on the 800XL but I just wanted to tell my current situation. I now have sockets for all the chips. I am going to start the process of socketing the remaining chips on my board. Should make things a little easier on this 800XL. 1 Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.