rfancella Posted February 10, 2023 Share Posted February 10, 2023 Hello all! I have been working on my newly acquired 800. Half the keys do not work. With help reading a couple posts here, I tested the mechanical switch on the board for a key that is not working and it's fine. I tested most of the traces on the back of the keyboard and they all seem good as well. I tested the ribbon cable, same there. I read a post about swapping the 4051s and see if the working/non working keys move. They in fact do. I tested both chips in my TL866 and one testes good while the other does not. So, I found some online replacement chips and am wondering if they are compatible? The original is an RCA CD4051BEXV and the replacement one is a TI CD4051BE. Will this TI chip work as a replacement? Thank you, Ron Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted February 10, 2023 Share Posted February 10, 2023 The TI chip should work fine. Mouser has them for $0.90 each. I'd get 2 and swap them both.....especially with what you pay for shipping. 1 Quote Link to comment Share on other sites More sharing options...
TZJB Posted February 10, 2023 Share Posted February 10, 2023 8 minutes ago, rfancella said: Hello all! I have been working on my newly acquired 800. Half the keys do not work. With help reading a couple posts here, I tested the mechanical switch on the board for a key that is not working and it's fine. I tested most of the traces on the back of the keyboard and they all seem good as well. I tested the ribbon cable, same there. I read a post about swapping the 4051s and see if the working/non working keys move. They in fact do. I tested both chips in my TL866 and one testes good while the other does not. So, I found some online replacement chips and am wondering if they are compatible? The original is an RCA CD4051BEXV and the replacement one is a TI CD4051BE. Will this TI chip work as a replacement? Thank you, Ron They seem to have the same specifications so should work fine. Quote Link to comment Share on other sites More sharing options...
rfancella Posted February 10, 2023 Author Share Posted February 10, 2023 8 minutes ago, reifsnyderb said: The TI chip should work fine. Mouser has them for $0.90 each. I'd get 2 and swap them both.....especially with what you pay for shipping. 2 minutes ago, TZJB said: They seem to have the same specifications so should work fine. Thank you both so much for your speedy responses! This forum always amazes me! I found a lot of 5 nos on "thaBay" for $6.00. Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 10, 2023 Share Posted February 10, 2023 Pretty much any generic CMOS CD4051B chip should work, since the application is non-critical from a timing stand point. Found some even cheaper at 10 pieces for $4.59 shipped. AliExpress BUY Link EDIT: Be sure to select the CD4051BE box, because when you first land on the page the CD4052BE is the default selection, which wouldn't work. Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted February 10, 2023 Share Posted February 10, 2023 (edited) But expect a long wait for them from AliExpress..Sent from China by the slowest way possible..Great for price if you are not in a hurry.. As you can see from the page, it's around a month for delivery.. Edited February 10, 2023 by Mclaneinc Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 11, 2023 Share Posted February 11, 2023 11 hours ago, Mclaneinc said: As you can see from the page, it's around a month for delivery.. That's pretty much a worse case scenario. Usually I get stuff within 2 weeks. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted February 11, 2023 Share Posted February 11, 2023 (edited) Edited February 11, 2023 by _The Doctor__ 1 Quote Link to comment Share on other sites More sharing options...
zylon Posted February 11, 2023 Share Posted February 11, 2023 15 hours ago, reifsnyderb said: The TI chip should work fine. Mouser has them for $0.90 each. I'd get 2 and swap them both.....especially with what you pay for shipping. I used a pair of those on my 600xl last week, no problems. 1 Quote Link to comment Share on other sites More sharing options...
Mclaneinc Posted February 11, 2023 Share Posted February 11, 2023 4 hours ago, mytek said: That's pretty much a worse case scenario. Usually I get stuff within 2 weeks. Good to hear, I've only had one case where stuff was mega early, normally it's bang on the expected date from the sale. I don't mind, I'm ready for that date, if it comes early, all good. 2 Quote Link to comment Share on other sites More sharing options...
+Larry Posted February 13, 2023 Share Posted February 13, 2023 Are the 4051 chips used in any other Atari computer? Quote Link to comment Share on other sites More sharing options...
reifsnyderb Posted February 13, 2023 Share Posted February 13, 2023 7 minutes ago, Larry said: Are the 4051 chips used in any other Atari computer? Yes. All A8's use them between the POKEY and the keyboard to scan the keyboard matrix. 2 1 Quote Link to comment Share on other sites More sharing options...
+mytek Posted February 13, 2023 Share Posted February 13, 2023 Yes as @reifsnyderb pointed out all A8's use them for this purpose, with the reason being to simplify the number of connections that would otherwise be required of Pokey to scan the keyboard from 16 (8x8 matrix) down to 8 (6-bit counter and two key response pins). Quote Link to comment Share on other sites More sharing options...
zylon Posted February 13, 2023 Share Posted February 13, 2023 15 minutes ago, Larry said: Are the 4051 chips used in any other Atari computer? They're also used by the 5200 systems. 4051, and 4050 are great items to keep on hand. Quote Link to comment Share on other sites More sharing options...
TGB1718 Posted February 13, 2023 Share Posted February 13, 2023 How about this one 🤣 https://www.ebay.co.uk/itm/403985382090? 1 4 Quote Link to comment Share on other sites More sharing options...
bfollowell Posted February 13, 2023 Share Posted February 13, 2023 2 hours ago, TGB1718 said: How about this one 🤣 https://www.ebay.co.uk/itm/403985382090? Idiot... 1 Quote Link to comment Share on other sites More sharing options...
mimo Posted February 13, 2023 Share Posted February 13, 2023 It's Rare, like white dog poo 2 Quote Link to comment Share on other sites More sharing options...
rfancella Posted February 13, 2023 Author Share Posted February 13, 2023 4 hours ago, TGB1718 said: How about this one 🤣 https://www.ebay.co.uk/itm/403985382090? Doohhhh.... Quote Link to comment Share on other sites More sharing options...
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