hueyjones70
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Posts posted by hueyjones70
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I just successfully completed another SV 2.1 on a 600XL. I found it is much easier to follow the instructions provided in the Best Electronics upgrade package. Those instructions have you install components from right to left and that makes it easier to get everything in the right place. After all the parts are installed then I replace ones that the SV 2.1 calls for. The S video is really good but the composite has a lot of color bleeding.
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I was checking the matrix from the pinch connector and from the pins on the bottom of the board and getting different results so I removed some solder from the pins and resoldered the pinch connector. Now everything is working correctly. If it is working correctly tomorrow, I will believe the problem is solved.
The computer and the keyboard are working perfectly today. Problem solved.
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On 1/2/2021 at 7:30 PM, bfollowell said:
I really don't think I want to try painting, but I want yellowed plastic even less. I'll definitely keep it in mind if cleaning and retrobrighting don't give me the results I'm hoping for. Thank you for the suggestion and for showing me exactly which ones you used. It's a pretty rare week that I'm not at Home Depot or Lowe's for something, so picking these up wouldn't be a problem.
On a positive note, I took the mylar out of the keyboard and checked it over really well. It didn't look too bad, so I connected just the mylar and tried pressing some contacts together, but I got no response. I sprayed it down lightly with IA and wiped it down as lightly as I could, just trying to clean it off and remove any oxidation that had built up. I connected just the mylar and tried again and I was able to get some characters on the screen, so it may be OK.
I'm going to try to look up a keyboard restoration video I watched recently and figure out how to completely disassemble the keyboard, plungers and everything, so that I can give it all a thorough cleaning, then I'll reassemble it and give it a complete test.
Wish me luck!
EDIT:
OK, I mentioned wanting to disassemble the keyboard completely for cleaning and looking for an old video. Well, the videos I saw were all related to the mechanical versions, which this obviously isn't. I'm not sure that this keyboard disassembles any further than this and I figured it would be easier to ask rather than take a chance on breaking something.
I already have all of the springs out and in a safe place. Do the white plungers come out? I don't want to pull too hard and break something. This isn't a mechanical keyboard, so there's no real switches or anything in this one. I'm thinking of running it through the dishwasher with the rest of the case and the keys, but I want to disassemble it further if I can, to insure a thorough cleaning. Will this keyboard break down any further? Are any of you aware of any decent videos showing the complete breakdown of a Type-4 mylar style keyboard?
Finally, the two 800XLs that I have each have screws on the inside of the top cover that, when removed, allow me to separate the brown section from the cream section. This 600XL has no screws like this. As a matter of fact, if you zoom in and look at the bottom of this picture, it looks like tabs for the brown section were heated and mashed flat so that they can't come out. Unless I'm completely missing something, it looks like I'm not going to be able to separate these two portions of the top shell. Is this typical of a 600XL?
Thanks!
it is fairly easy to cut the mashed part off and remove the brown part. Afterwards you can get some scrap plastic and use a soldering iron to secure the brown casing.
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On 2/16/2022 at 6:25 PM, StickJock said:
Do any of the things that you have tried change the behavior? For example, the "working" keys move to different keys, or they report a different result?
One of the things that you can do is to remove the KB, and then short the row & column pins on the keyboard connector in order to get different keys. If this works, then the problem is "upstream", likely the keyboard mylar or cable.
Here is the keyboard matrix. Shorting, for example, pins 1 & 10 together should report that the '7' key is pressed. If you can't get any keys reported in this manner, check that you have good conductivity from connector to socket/pins, etc.
Do the numbers represent pins on the pinch connector.
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This is totally irrelevant to the current topic but this 65XE that I have has the best stock video that I have ever seen on an A8. No jail bars and crisp well defined characters.
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I think the problem was with some old solder joints. I touched up the joints on the DIN connector and all of the resistors in the area of the 4050 and when I hooked it up again, all was working.
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I have just finished getting an 800XL back into operation (ALMOST). I had everything working after doing a SV 2.1 mod. Keyboard worked perfectly, had good video with only faint vertical bars. After putting it back together, I have no video, just a black screen. The computer makes the boot noise, I get keyboard clicks, and audio with game carts. I took it apart back down to the bare MB. Still no video, swapped out the major chips and the 4050, still no video. What are my possibilities. I don't have an O scope and my trouble shooting is restricted to a multimeter and replacing parts.
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Mine has 8 4164 RAM chips and 8 empty slots; just like the one in the pictures.
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My 65XE has the same MB as the one in this thread except that it is a PAL. Does that make any difference?
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If I just want to make my 65XE into a 130XE all I need to do is install the sockets in the empty column, fill the sockets with 4164 or equivalent RAM chips and install the CO25953 in the left most slots of U34? I saw a 74LS95 mentioned, where does it go?
On 3/12/2007 at 5:30 PM, Tezz said: -
I guess that in this situation less is more.
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I found a way to mess this mod up. I performed this mod on an 800XL and mistakenly used a 2.2k ohm resistor instead of the 2.2 ohm. The result was a blank screen. Examined the resistors one by one to find the error.
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My latest observation is that when it boots and has that momentary period before it goes crazy, the function keys do not work correctly. If I boot with PacMan, the start key changes the number of players and the select key changes the level of difficulty. Help does nothing. Reset resets.
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Should all of the ram chips have similar voltage on corresponding pin numbers?
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I have found that I must do a significant amount of work before doing any mods. I hadn't done any testing of the computer. The first time I turned it on, it booted to BASIC, I typed a few keys and saw that the KB needed work, then I checked S-video and saw that I had color so I decided to take it apart. I noticed it had a socketed FREDDIE and 6 of the 8 RAM chips were socketed as well as the OS ROM. I socketed the other two RAM chips and went to test it again. It booted to BASIC and after a couple of minutes some of the letters in READY changed and random characters began to appear on the screen. I rebooted and the computer went to self test and again, random characters began appealing on the screen. After that, I couldn't boot to anything and STAR RAIDERS wouldn't boot. I tried SYS CHECK and it appeared to be working but the characters would randomly change. Sometimes syscheck would show some of the ram chips to be defective and sometimes it goes directly to display all ram failure. I am going to have to socket all of the chips so that I can do some troubleshooting. I think I have a PAL 600XL that will provide a test computer.
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I have installed one before in a 1200XL but I didn't have flashjazzcat's BIOS.
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I was considering adding a Rambo or Wiztronics 256K. I don't want to bother with the U1MB because I honestly don't want to spend the time learning how to use it.
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I just opened up one of my eBay purchases and found one of these. Is there any info available concerning memory or video upgrades.
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If anyone has a hopelessly nonworking 1200XL, I have an extra working MB and KB. Maybe we could work something out.
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Does the Peterson upgrade work on a 65XE that has 64K and only one column of RAM chips.
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I found the problem. Apparently the previous owner had intended to upgrade the memory or they didn't know what memory DRAMS were required for the computer. Seven of the DRAMS were 41256. I replaced them and Pole Position boots every time now.
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42 minutes ago, bob1200xl said:
I would guess it is RESET. If so, you can fix it by replacing C7 (just below pin 1 of U23) and changing U16 to a 74AC14.
I can send you the parts.
Bob
OK, I would really appreciate that.
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After repeated trials, I have been able to get PacMan, Star Raiders, and Centipede to work as they should. I get a pop with Pole Position but I have a blank screen, Ace of Aces gives me the same result. On those occasions when BASIC doesn't boot, turning the power off and back on usually results in a good boot. I have a donor board and I will do some troubleshooting with that. I was wondering if upgrading to the 800XL OS would make a difference.
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I have no idea what those last two replies are trying to tell me.
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Posted
I have this one that is not listed: 83S DA 037233 183