atari8warez Posted January 23, 2015 Share Posted January 23, 2015 I have this 600XL with what seems to be an extra keyboard connector board that goes between the keyboard connector on the motherboard and the 600XL keyboard ribbon cable. Did anyone see that before and know what it is used for?. This particular 600XL does not have any upgrades other than the 64K Ram mod. Here's a photo of the extra connector board: Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted January 23, 2015 Share Posted January 23, 2015 Yeah, it's common. They used those to regulate the power the keyboards, or something to that effect. Sometimes I just take them out, but just leave it in if you want, no biggie. Quote Link to comment Share on other sites More sharing options...
atari8warez Posted January 23, 2015 Author Share Posted January 23, 2015 I am doing a few upgrades to this 600XL and this extra piece is getting into the way of fitting the keyboard cover properly, so i was wondering if removing it will do any harm. Quote Link to comment Share on other sites More sharing options...
Rybags Posted January 23, 2015 Share Posted January 23, 2015 Fairly sure mine's got that, NFI if taking it off will endanger anything. The multiplexor ICs are still mega-cheap off-the-shelf parts and Pokey is extrememely common and under 10 bucks so if any of those blow it's nothing major. Quote Link to comment Share on other sites More sharing options...
sup8pdct Posted January 23, 2015 Share Posted January 23, 2015 Its a current limiting resistor pack.800xl has it built in to motherboard if i recall. not sure if it is for the multiplexers or for the mylar keyboard circuit. James Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted January 23, 2015 Share Posted January 23, 2015 Surely it's also needed to line up the ribbon properly, since the connector on the adapter is offset. Quote Link to comment Share on other sites More sharing options...
Marius Posted January 23, 2015 Share Posted January 23, 2015 In my main 600XL I removed it. I have been using that 600XL for about 4 years with very much keyboard work (coding in assembler) and never had a single issue. One thing to add though… I removed the PCB keyboard with a Mylar version. It had originally the most awful keyboard possible, and I had a defect 800XL floating around, with a very nice keyboard. So I took that keyboard (with the mylar foil connector) and connected that directly to the main board of the 600XL. But indeed… I have heard it has a functionality. IIRC … when you make certain key combinations (you press simultaneously certain keys) there could go something wrong, but like I wrote above: heavily used 600xl here, mylar foil keyboard, not that part from your picture, not a single issue ever. Quote Link to comment Share on other sites More sharing options...
flashjazzcat Posted January 23, 2015 Share Posted January 23, 2015 I wish I still had that 600XL Cherry keyboard which passed through my hands a while back: it was the only variety I really liked. Quote Link to comment Share on other sites More sharing options...
+Larry Posted January 23, 2015 Share Posted January 23, 2015 It has another advantage if you remove the keyboard cable very much for work inside the A8. It should be much more durable for repetitive insertion/removal. I have an 800XL with a messed up keyboard cable, so I carefully stripped the insulation and plugged it into the 600XL connector. Now I can remove/insert it without fear of damaging the cable further. It does make a snug fit in an 800xl, but still closes up OK. Incidently, my 800XL keyboard works perfectly with whatever added resistance there is. -Larry 1 Quote Link to comment Share on other sites More sharing options...
atari8warez Posted January 23, 2015 Author Share Posted January 23, 2015 (edited) It is about 465Ohm per resistor, this one isn't a mylar foil keyboard, and yes it makes safer for multiple removal/insertions, I guess I just have to find a way to make it fit properly with the U1MB upgrade in the vicinity. When I look into my own 600XL i see no difference in the motherboard as far as the keyboard circuitry is concerned, so the resistor pack must have something to do with the keyboard itself. Thank you guys for the tips. Edited January 23, 2015 by atari8warez Quote Link to comment Share on other sites More sharing options...
Bryan Posted January 23, 2015 Share Posted January 23, 2015 I always assumed it was some last minute RF fix. Quote Link to comment Share on other sites More sharing options...
+orpheuswaking Posted January 23, 2015 Share Posted January 23, 2015 Comparing the probably 15 600xl units that have come through my hands in the past I only have one single unit that had that connector, interestingly it was also the only one to have that specific keyboard type in it. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted January 23, 2015 Share Posted January 23, 2015 Just take it out. They bend the ribbon too much, etc. you won't miss it. Quote Link to comment Share on other sites More sharing options...
atari8warez Posted January 24, 2015 Author Share Posted January 24, 2015 I would have tried it but It's not my computer Paul, and I don't want to risk anything on somebody else's atari. I am just moving the U1MB upgrade to the other corner of the case so that it wont interfere with the keyboard cable. Quote Link to comment Share on other sites More sharing options...
Paul Westphal Posted January 24, 2015 Share Posted January 24, 2015 Oh, sorry. Rip it out anyway. Lol! Quote Link to comment Share on other sites More sharing options...
Jinks Posted January 24, 2015 Share Posted January 24, 2015 Oh, sorry. Rip it out anyway. Lol!Noooooooooo!!!!! lol! 1 Quote Link to comment Share on other sites More sharing options...
GoodByteXL Posted January 24, 2015 Share Posted January 24, 2015 Did anyone see that before and know what it is used for? From all the 600XL machines I had the chance to peek into only two (NTSC-types, Chelco made) were missing this Adapter. It's purpose is to debounce the keyboard. Quote Link to comment Share on other sites More sharing options...
Joey Z Posted January 24, 2015 Share Posted January 24, 2015 From all the 600XL machines I had the chance to peek into only two (NTSC-types, Chelco made) were missing this Adapter. It's purpose is to debounce the keyboard. that doesn't really make sense since the OS has it's own software debounce. There'd have to be capacitors to debounce the KB. More likely, it's this: mylar KB's have a built in resistance because of the nature of their construction, while keyboards with mechanical switches have a lot less resistance. So this board may have been present to add the proper amount of resistance to the keyboard to allow the POKEY to scan properly without issues. Regardless, I'm sure atari added it for a reason, so I'd leave it in if it's not a big deal to build around it. Quote Link to comment Share on other sites More sharing options...
atari8warez Posted January 24, 2015 Author Share Posted January 24, 2015 Yeah, it should be there for a reason, so I am keeping it and I already moved the U1MB to it's new location. Quote Link to comment Share on other sites More sharing options...
+kheller2 Posted February 23, 2019 Share Posted February 23, 2019 Bump. Was there ever a real reason this board was used? It almost makes sense for it to be on specific keyboard types for resistance... but I have yet to find it on any of my 600XLs with various keyboard types. I'm just wondering. I've never really explored or worked on 600XLs that much and just started to recently. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 23, 2019 Share Posted February 23, 2019 I've answered this when dealing with 130XE mylar issue please seek out and read the posting explaining the design and why the resistors are on there. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 23, 2019 Share Posted February 23, 2019 The type of keyboard used is known as a "Low-resistance contact" keyboard, theresistance being about 1000 ohms or so. As you use the keyboard, theresistance of the contacts tend to go up as it wears and oxidizes. For the regular keyboard and the RESET key this increase in resistance causes no problems as of yet but time passes (decades) keys will begin to cease registering. But theconsole keys (OPTION, SELECT, and START) are read by a different IC, andthe change in resistance will eventually keep the console keys fromworking. (The HELP key is actually read as just another letter key).The fix to the problem is to decrease just enough resistance by either adding resistors in parallel for the keys so that it is high enough not to make the computer read the keyas pressed, but low enough that when the console key is pressed, thecomputer will recognize it. I've probably messed up some values or added a zero or whatever over the years as I forget more and more of this stuff. so look up and experiment or correct the values the design is the same... you can fix a mylar keyboard that has gone oxidative by fiddling with either paralleling the resistors or replacing them with lower values/ changing the resistor out. The connector with the resistors should remain in, it has more than one purpose, both electronic, and mechanical. 2 Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 23, 2019 Share Posted February 23, 2019 (edited) Also check out stuff written by Alan Haskell in the book "Mods,Fixes, and Upgrades" available from Best Electronics, 2021 The lameda,Suite 290, San Jose, Ca.5126. leave the board in the computer, it's a happy thing. Edited February 23, 2019 by _The Doctor__ 2 Quote Link to comment Share on other sites More sharing options...
+kheller2 Posted February 23, 2019 Share Posted February 23, 2019 leave the board in the computer, it's a happy thing. My question was asked because I have several w/o said board, possibly all the 600XLs I have do not have the board. And some pretty early ones in the lifecycle. Quote Link to comment Share on other sites More sharing options...
Brentarian Posted February 23, 2019 Share Posted February 23, 2019 My question was asked because I have several w/o said board, possibly all the 600XLs I have do not have the board. And some pretty early ones in the lifecycle. I have 5 600XLs (early to late) and none have the board either. Quote Link to comment Share on other sites More sharing options...
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