DavidMil Posted October 15, 2018 Share Posted October 15, 2018 I was playing 'Eastern Front' on my recently fixed 1200XL and about 20 minutes into the game it froze up for a second and then the screen turned dark green. No sound, no keyboard response, no reboot, nothing. I pulled the cartridge out and tried to reboot again, but just got the same dark green screen. I tried a basic cartridge, and the Super SALT cart too, but no difference. Make a long story short; I swapped all the chips in my good 1200XL with the chips in the bad 1200XL. The good 1200XL booted up fine with all the chips from the bad 1200XL and the bad 1200XL still got the same green screen with all the chips from the good 1200XL. Now I know I've got a board level problem. The voltage regulators (78M05's) are both putting out 5.5 volts and nothing feels hot. I'm also getting 5 volts to all the 40 pin chips at (VCC). My first question is: Can the machine still put out color (that I can change by turning VR1) if there is a problem with the crystal circuitry? Off the top of my head, I'm thinking I got a bad transistor somewhere... Suggestions? David Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 17, 2018 Share Posted October 17, 2018 The thread did not show up as unread for me, and it also showed zero people read it. I hope that this post gets it active and rolling for you David Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 17, 2018 Share Posted October 17, 2018 now that I posted to it the thread reads 106 views and is in the list at the top again so it looks like it's working again. weird error... Quote Link to comment Share on other sites More sharing options...
+bob1200xl Posted October 18, 2018 Share Posted October 18, 2018 I'm going to vote 'no' on this one. The system oscillator has to be working for you to get color. When you power on, hold down the RESET key. Some kind of change, maybe subtle, will show on your monitor when you turn on your computer. This is the video in GTIA and ANTIC powering on. No instructions will execute while you are pressing RESET. If you have swapped out ALL the ICs, you might want to look at the delay line, which is soldered in. The transistors are mostly audio and video, not likely suspects. Bob 2 Quote Link to comment Share on other sites More sharing options...
Kyle22 Posted October 18, 2018 Share Posted October 18, 2018 (edited) Do you have a Logic Probe? It can be a big help to determine if the system clock (oscillator crystal and related circuitry) is working. Edit: As Bob said, look at Delay (C060472). Edited October 18, 2018 by Kyle22 2 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 19, 2018 Author Share Posted October 19, 2018 I'm going to vote 'no' on this one. The system oscillator has to be working for you to get color. When you power on, hold down the RESET key. Some kind of change, maybe subtle, will show on your monitor when you turn on your computer. This is the video in GTIA and ANTIC powering on. No instructions will execute while you are pressing RESET. If you have swapped out ALL the ICs, you might want to look at the delay line, which is soldered in. The transistors are mostly audio and video, not likely suspects. Bob I tried holding down the reset key when powering on the 1200XL. What I got was some wavy lines of slightly darker green on the dark green screen for a few seconds. I'll remove the delay chip next, socket it, and put a new one in it's place. Stay tuned... David Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 19, 2018 Author Share Posted October 19, 2018 Do you have a Logic Probe? It can be a big help to determine if the system clock (oscillator crystal and related circuitry) is working. Edit: As Bob said, look at Delay (C060472). I have a small (and very old) logic probe. It's been at least 20 years since I've used it. I bought it for work on my old 800. I've also got a 'O' scope (almost as old) that I use more often. In another thread I was asking if Sam's had put out a repair manual for the 1200XL so I could see some wave forms. Some one said that you could use the 800XL manual for this but to remember the different chip designation numbers. I'll try that after I swap out the delay chip. Thanks, David 1 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 21, 2018 Author Share Posted October 21, 2018 (edited) Well, some good progress! After swapping out the delay chip, I now have video and sound, just no color. I tried adjusting VR1 but that didn't change anything. The Atari logo is black and white, as is any cartridge I plug in. We're getting there... More suggestions? David Edited October 21, 2018 by DavidMil 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 21, 2018 Share Posted October 21, 2018 color pot could need to be re compressed or replaced... right monitor cord? right plug.... some monitor have a switch for color and b/w or luma chroma modes.. correct chips for monitor? 1 Quote Link to comment Share on other sites More sharing options...
+Stephen Posted October 21, 2018 Share Posted October 21, 2018 I'll assume the machine had colour before it broke. But I do recall the 1200XL does not output colour via the composite line without a mod (think just a single wire needs hooked up). 2 Quote Link to comment Share on other sites More sharing options...
ACML Posted October 21, 2018 Share Posted October 21, 2018 (edited) I'll assume the machine had colour before it broke. But I do recall the 1200XL does not output colour via the composite line without a mod (think just a single wire needs hooked up). Yes, the monitor plug on the stock 1200XL does not have the Chroma signal connected. Why, I have no idea. The composite video on the monitor jack is color as well as the RF output. Edited October 21, 2018 by ACML 2 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 23, 2018 Author Share Posted October 23, 2018 color pot could need to be re compressed or replaced... right monitor cord? right plug.... some monitor have a switch for color and b/w or luma chroma modes.. correct chips for monitor? I guess I 'dinked' with the VR too much. I notice that when I press down a bit the color goes in and out. I've ordered a couple of new ones from Best, along with some eyelets that allow you to remove a socket from the board and solder these eyelets into the PCB and then press the IC's into these eyelets. This makes the IC's the same height above the board as a chip soldered directly into the PCB. I've been thinking about this for awhile as I want to put stereo sound capability in one of my computers. Also, one of my ROM chips can be wiggled a bit because the socket appears to be worn out. I'm going to replace that too. Stay tuned... David 2 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 23, 2018 Author Share Posted October 23, 2018 I'll assume the machine had colour before it broke. But I do recall the 1200XL does not output colour via the composite line without a mod (think just a single wire needs hooked up). I was playing 'Eastern Front' when the 1200XL went belly up. Yes, everything was working fine till then. David Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted October 23, 2018 Share Posted October 23, 2018 ... eyelets that allow you to remove a socket from the board and solder these eyelets into the PCB and then press the IC's into these eyelets. This makes the IC's the same height above the board as a chip soldered directly into the PCB. I'm curious to see a picture of these. Is that just another name for low profile machine (aka turned) sockets? Quote Link to comment Share on other sites More sharing options...
Keatah Posted October 23, 2018 Share Posted October 23, 2018 no Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 23, 2018 Author Share Posted October 23, 2018 I'm curious to see a picture of these. Is that just another name for low profile machine (aka turned) sockets? When they arrive (about three days), I will most definitely post some pictures. David 2 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 23, 2018 Share Posted October 23, 2018 sounds like the low profile precision sockets from back in the day.... they were super pricey and save some height... hole are round depending how low you need to go. in some application those socket and nipping the chip leads might be needed to get it all flush... Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 26, 2018 Author Share Posted October 26, 2018 When I was removing VR1 it fell apart into about four pieces. Replacing VR1 took care of the color problems too so the 1200XL is working fine again! I also replaced the socket for the ROM chip (U12) that was allowing the chip to 'wiggle' back and forth in the socket. Anyway the 1200XL is working fine again. I'll play 'Eastern Front' again to test it out tonight. I always play this game with a floppy drive attached so I can save the game between every turn. I am very pleased with the eyelets from Best Electronics. See the pictures... This is very cool, as I'll be able piggyback any two chips without having to cut up or remove the metal can ( I'll sleep safer now knowing that a direct overhead burst from a nuke won't cause so much EMP damage to my Atari)! Some words of caution... Some of the barrels on these devices aren't closed, so be careful with the solder. And always put the chip in the barrels before you solder the barrels into the PCB as not all the barrels will come through the PCB straight.. David 3 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted October 27, 2018 Share Posted October 27, 2018 Wow, never seen those before! that's the epitome of 'low profile' alright. This might have been an alternative to soldering ANTIC directly to my tf_hh 512k board to get it to fit under an 800XL alps keyboard.... 1 Quote Link to comment Share on other sites More sharing options...
+slx Posted October 27, 2018 Share Posted October 27, 2018 Would you care to post the source for these superlow sockets? Gesendet von iPhone mit Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted October 27, 2018 Share Posted October 27, 2018 Well, I'm glad you're pleased with those low-profile things but honest-to-$DOG I think they look very fragile and I'd be very leery of using them myself for anything that doesn't absolutely require the lowest profile over all over considerations. Low profile machine pin sockets are cheap, and dual-wipe sockets are even less expensive. Both of those options are still way more reliable than the crappy-ass single-wipe sockets Atari and every other company used in the 80's for consumer electronics. But anyway, glad to know you got your 1200XL up and running properly again. That's what matters. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 27, 2018 Share Posted October 27, 2018 once soldered in they are stronger than most any socket 2 Quote Link to comment Share on other sites More sharing options...
DavidMil Posted October 27, 2018 Author Share Posted October 27, 2018 Would you care to post the source for these superlow sockets? Gesendet von iPhone mit Tapatalk Best Electronics. Well, I'm glad you're pleased with those low-profile things but honest-to-$DOG I think they look very fragile and I'd be very leery of using them myself for anything that doesn't absolutely require the lowest profile over all over considerations. Low profile machine pin sockets are cheap, and dual-wipe sockets are even less expensive. Both of those options are still way more reliable than the crappy-ass single-wipe sockets Atari and every other company used in the 80's for consumer electronics. But anyway, glad to know you got your 1200XL up and running properly again. That's what matters. You can cut the plastic to make it any length you wish and you can pop the pins out and press them into the holes in the middle of the tape to be used as smaller 16, 14, or 8 pin sockets. Yes they are flimsy, but once soldered into the PCB they are quit stout. That's why I said to put the chip into the socket before soldering the socket into the PCB because the barrels can become misaligned. I would not recommend these be used for any chip that is going to be continually swapped out on a regular basis. David 2 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted October 27, 2018 Share Posted October 27, 2018 I use a similar process when soldering in socket or pin headers to ensure they're in straight... easy for them to be crooked too. Ie pin headers plugged into a machine socket underheath, or machine socket plugged into the header sockets on top. I imagine these are just as strong once soldered in. 1 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted October 27, 2018 Share Posted October 27, 2018 (edited) yes, but less torsional stress on the lower profile direct board contact ones that david has pointed out. These pass high and low altitude temperature extremes with vibration much better than machine sockets elevated with their plastic spacers... Edited October 27, 2018 by _The Doctor__ 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.