Grand_National Posted November 18, 2020 Share Posted November 18, 2020 Sorry, posted this in the wrong topic area and I don't know how to move it. Hi. New to the forums. So, back in the day, my father and I both used Atari 8-bits as our first home computers. It actually was my computer in college. Fast forward....I thought it would be "cool" to show my son what it was like back in the "old days" of computers. I wanted to hook one up to a modern TV, so I planned to use composite out on my Dad's 800XL after my mom had given it to me several years agao. After finding a 5 pin and some RCAs, I thought I was ready to go. I plugged in the power supply ready to start working on the composite out connectors, turned it on, but NOTHING happened. No red power LED, absolutely nothing happened when I flipped the switch. I've checked the pins on the 7 pin DIN and the power supply is still putting out 5-5.10 volts. I should mention I have a CO61982 power supply (rectangle, white top, black/brown bottom), not an ingot PS. I opened up the case (dated inside Jan 27, 1984) and tested a few places with my multi-meter and the board has 5 volts. I wasn't expecting this issue with it doing absolutely nothing. The question now is, what to do next? Are there common issues with these old machines which I should look in to? After opening it up, I looked for bloated capacitors, or anything generally discolored or melted, etc., but nothing stood out. The only thing I noticed was the keyboard ribbon where it connects into the edge connector on one side seems a bit, well, "fried", such as corroded. The keyboard ribbon cable traces themselves also look discolored at both ends; where it goes into the edge connector on the motherboard and also where it goes into the keyboard, sort of like "blackened" like they took too much voltage. I can't ask my father if when it stopped using it, it had actually died or he had just moved to a PC since he is no longer around. I'm looking for some ideas on how to test this box to hopefully bring it back to life. Ideas? Tips? All feedback is welcome. Thanks in Quote Link to comment Share on other sites More sharing options...
mimo Posted November 19, 2020 Share Posted November 19, 2020 does the TV do anything when you power on? Any flicker of life or does the TV not see a signal. Do you have a different TV to try it on? by modern standards the Atari does not output a signal that some modern TVs recognise. If possible you could try an RF connection for testing If you made the cable yourself check that you have made the correct connections. As for the LED not lighting, I know that this is not uncommon for the XE mylar keyboard even if the unit works correctly in every other way, as your mylar sounds to be very corroded this may be the issue but I don't have much experience with XL mylar keyboards. Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted November 19, 2020 Share Posted November 19, 2020 Can you post some detailed photo's of the internals where you think "stuff" may have happend, may help us guide you. Quote Link to comment Share on other sites More sharing options...
xrbrevin Posted November 19, 2020 Share Posted November 19, 2020 it is possible that it has powered on - the power LED gets its supply via the keyboard connector can you double check your display cable? or try an RF connection? Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 19, 2020 Author Share Posted November 19, 2020 Thanks! I was thinking in the same direction. I really don't know if its putting out any video signal via RF or the monitor port (I never made the cable yet), and that would be good to know, but I ran out of time to hook something up. Maybe the LED isn't lighting up due to bad mylar and the unit is actually on? I'll take a pic of the mylar connection where it goes into the connector on the board this evening and post. Thanks again!? Quote Link to comment Share on other sites More sharing options...
mimo Posted November 19, 2020 Share Posted November 19, 2020 (edited) 23 minutes ago, Grand_National said: Maybe the LED isn't lighting up due to bad mylar and the unit is actually on? Correct. Worth noting that new replacement mylars are available fairly cheaply if required, I bought one from a forum member here ( Duddie) Edited November 19, 2020 by mimo Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted November 19, 2020 Share Posted November 19, 2020 I see you’ve measured the power output of the PSU - it’s time to open the machine and measure Vss and Vcc on each chip and ensure everything has good ground and power connections. Remove and reseat any socketed chips to break any oxidation layers on the contacts. If those steps don’t get the machine to boot, find and download a copy of SAM’S COMPUTERFACTS for the 800XL (it’s on Atarimania) and follow the troubleshooting steps. Good luck. Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 20, 2020 Author Share Posted November 20, 2020 Thanks guys. Well...I went from 'expected' to 'unexpected' to 'sort-of expected'. I originally expected the 800XL to work as soon as I plugged it in. When I did, it unexpectedly didn't light up the power LED and I thought it was dead. Tonight, I connected my home-made video cable (I could only find the 2 part metal shielding case and the plastic cover to my 5 pin, but not the actual 5 pic middle section which is obviously the key component to the connection that I've had laying around for 20 years, so I used an old 5 pin off of an old PC keyboard - yes I still have one that old laying around) - and it probably has absolutely no shielding BUT..... the TV got wavy diagonal lines when I turned on the power. There is LIFE! But what's the quality of life? After I realized the pin outs on the webpage for the 5 pin were the for the female connector on the back of the XL and not the male connector and swapped the connections for composite, and I had VIDEO! The 'old girl' greeted me with 'Ready'. WOW! I tested all of the keys and everything seems to work. The machine is fine (except the power LED is dead). Something I'd like to fix but I can certainly live with. So, I have a mostly working machine (sans LED) and I'll take that 'sort-of expected' result any day. Since I'm fairly certain I have a mylar keyboard, where can I buy I replacement? Best kinda scares me at this point (unfortunately). 1 Quote Link to comment Share on other sites More sharing options...
mimo Posted November 20, 2020 Share Posted November 20, 2020 @Duddie sells really good quality replacement mylars. I have one in my 800xl. Glad it's working. An AVG cart or sdrive-max , or one of the other modern storage devices would be a great addition. Enjoy Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 20, 2020 Author Share Posted November 20, 2020 Well...maybe I rejoiced a bit too soon?!? I have no sound. As I recall, shouldn't I have an electronic key-click by default? And if at the prompt, if I enter SOUND 0,10,10,10, shouldn't I get a tone? I've tried every pin on the 5 pin (and tested the cable) and both Red & White RCA connectors into the TV. All I can get is a "buzz" when I make the connection. Any ideas on this one? Quote Link to comment Share on other sites More sharing options...
mimo Posted November 20, 2020 Share Posted November 20, 2020 You should get a key click when typing. A buzz could be from an incorrect/ bad connection or a bad ground. Any chance of testing via RF signal? Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 20, 2020 Author Share Posted November 20, 2020 Thanks I was able to rig up an RF connection. I get (very poor) video and (complete) audio through that (key clicks and ex: sound 0,10,10,10). I tried the audio through the monitor jack again, but again I got nothing but a buzz. I checked the continuity of the 5 pin audio pin connector to the cable end and its definitely good. I was thinking that maybe the AV (RCA) cable portion of the connection may be an issue (the cable is still not permanently connected), so I swapped that out with another single RCA straight through connected to the audio jack on the TV (I tried both left and right separately). I also tried a direct connection to the 5-pin (not using the cable or DIN connector). This time I don't get a buzz, but rather I get nothing at all. So, how would I diagnose a monitor-port-only audio issue? POKEY is good or I wouldn't get correct sounds through RF, right? I've read how someone else had an 800XL no-audio-monitor-port issue, but I don't think there was a resolution. Thoughts? Ideas? Next Steps? All comments are welcome. Thanks Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 20, 2020 Author Share Posted November 20, 2020 Could it be the LM358N opamp or would RF audio also not work? I found another thread where audio was low and the opamp fixed it, but the audio low was also the case over RF as well, I believe. Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted November 20, 2020 Share Posted November 20, 2020 40 minutes ago, Grand_National said: Could it be the LM358N opamp or would RF audio also not work? The output from the LM358 feeds the RF modulator, the connection from the output of the OP Amp also goes via the resistors in the diagram below, should be quite easy to check the continuity with a meter Quote Link to comment Share on other sites More sharing options...
manterola Posted November 20, 2020 Share Posted November 20, 2020 Maybe you don't need a new mylar. Diagnose that is going on with the LED. It could be the keyboard connector, the edge of the mylar connector (you can cut with scissors 1cm, half inch or less of that edge to fix that), or the led itself. Use your multimeter to follow the 5VDC from the motherboard to the led and figure that out first. You can do something similar with your multimeter in AC mode to follow the audio signal while the Atari is producing a sound vs with it is not. It should be pretty obvious the difference in AC voltage between the two cases, so you can follow that signal (using the schematics available in image format or from Sams book) and see where the problem is. Good luck. Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 20, 2020 Author Share Posted November 20, 2020 Dragonstomper, you asked for some pics previously. I think I can post some tonight as the edge socket connector where the mylar is attached is very oxidized. Nothing else seems damaged. I will also do my best to trace and measure the resistors. Thx. Manterola, I will also try the AC mulit-meter testing on the output. Thx. Regarding repairing the mylar Manterola suggested, if the edge is not damaged upon removal, I think I may try your (Dragonstomper) procedure which you posted in 2009. "The oxidized Mylar can be resurrected most of the time by cleaning it with a product called "Goo Gone" (Usually available at your local Dollar store). I have used it to bring several of them back. I just get an old T-Shirt and soak a small part of it with the goo gone. rub it on the oxidized Mylar and leave it for about 5 minutes. then I use a green dish scrubber, put some goo gone on it and scrub the Mylar with it (not too hard just a moderate amount of pressure). this usually takes the oxidation off and Voila! It works. =)" Quote Link to comment Share on other sites More sharing options...
manterola Posted November 20, 2020 Share Posted November 20, 2020 Yep, the scissors trick is a 5 seconds work once you are ready to perform it, so it worst a try. Just be super careful about not cutting too much as it happened to me years ago: it worked wonderfully!, all the keys started to work, but I could not close the case since the keyboard mylar was to short... I ended up getting a new mylar. Another thing that happened to me: I ordered a new mylar and nothing changed. At the end was the keyboard connector located at the motherboard which had problems making good contact with the mylar. I replaced that connector and everything worked. The original mylar was perfectly functional. Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted November 20, 2020 Share Posted November 20, 2020 (edited) 1 hour ago, manterola said: You can do something similar with your multimeter in AC mode to follow the audio signal while the Atari is producing a sound If you do this, set the sound to a low frequency max volume, pure tone, that way you should get a resonable signal to follow. I've seen the SOUND setting somewhere, I'll see if I can find it Edit: SOUND 1,255,10,15 should do it Edited November 20, 2020 by TGB1718 Quote Link to comment Share on other sites More sharing options...
Grand_National Posted November 21, 2020 Author Share Posted November 21, 2020 Update: I connected straight lead pins (rather than a cable) directly in the monitor port and connected them to my stereo amp and........... I had sound! So, the question now was, is my TV not accepting the sound signal?!?! (huh?) or something else was going on. Unlikely its the TV since I've used that audio input before and the 800XL should be being anything weird with the sound signal. I had tested each DIN pin separately on the cable to map out the wiring of the cable and I thought I was set. Q: "When is a 5 pin DIN not a fully functional 5 pin DIN"? A: When it comes from a PC keyboard. I saw another post with the same issue I ended up having, but I thought it was an isolated case. The DIN does have 5 pins and 5 wires, but not all pins go to the wires. One of the wires goes to the metal connector case and you guessed it, the pin I needed to make contact for sound with was the pin without the wire. The connector is molded plastic, so I can't really open he connector up to rewire it. I must have touched the casing by accident when I was testing it. But all is not lost. I found the center section to the 5 pin I had from 20+ years ago. I wired that and I now have video and sound out of the monitor port! So, my only really issue left (that I know of, is the power LED being dead). I ran out of time tonight to pop open the case again, but one edge of the kbd connector was pretty oxidized. I believe it was the higher numbered pins. If I'm reading the schematic correctly, the power seems to go in pin 19 & 24 (through a resistor). Does anyone know if pin 24 is for the LED? or maybe the LED is powered some other way? Thanks again, for all of your help. Quote Link to comment Share on other sites More sharing options...
manterola Posted November 21, 2020 Share Posted November 21, 2020 Yep. Power for the led comes from 24. Then return from pin 18 Quote Link to comment Share on other sites More sharing options...
BillC Posted November 21, 2020 Share Posted November 21, 2020 17 hours ago, Grand_National said: but one edge of the kbd connector was pretty oxidized. When I was working on an Atari a little while back I just dipped a Q-tip in isopropyl alcohol and rubbed it on the keyboard mylar connector to clean off the oxidation. Quote Link to comment Share on other sites More sharing options...
svhovater Posted August 5, 2023 Share Posted August 5, 2023 On 11/20/2020 at 1:25 PM, manterola said: Yep, the scissors trick is a 5 seconds work once you are ready to perform it, so it worst a try. Just be super careful about not cutting too much as it happened to me years ago: it worked wonderfully!, all the keys started to work, but I could not close the case since the keyboard mylar was to short... I ended up getting a new mylar. Another thing that happened to me: I ordered a new mylar and nothing changed. At the end was the keyboard connector located at the motherboard which had problems making good contact with the mylar. I replaced that connector and everything worked. The original mylar was perfectly functional. where did you find the replacement connector for the motherboard? Quote Link to comment Share on other sites More sharing options...
manterola Posted August 5, 2023 Share Posted August 5, 2023 @tf_hh and Best Electronics, last time I checked. 1 Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted August 5, 2023 Share Posted August 5, 2023 1 hour ago, svhovater said: where did you find the replacement connector for the motherboard? I have loads from old 600XL mini board connectors but I believe you are not in the UK. Quote Link to comment Share on other sites More sharing options...
svhovater Posted August 5, 2023 Share Posted August 5, 2023 2 hours ago, manterola said: @tf_hh and Best Electronics, last time I checked. Good tip - thanks. Part number CO61793 Quote Link to comment Share on other sites More sharing options...
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