Pepper Posted November 12, 2017 Share Posted November 12, 2017 I know reliability comes to mind. But what are the pros and cons of when replacing the TMS9900 that you bung in a DIP socket to make life easier the next time ? Inquiring minds want to know Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted November 12, 2017 Share Posted November 12, 2017 I tend to socket any chips I remove as a general rule, as it limits potential damage to board traces over the long term. I just use gold plated machine-pin sockets when I can find them. They are a bit harder to find for the 64-pin 9900 chip, but I just looked in my parts box and turned up about 20 of them, so they are out there. 1 Quote Link to comment Share on other sites More sharing options...
+Lee Stewart Posted November 12, 2017 Share Posted November 12, 2017 Though the TMS9900 does not have as sturdy a pin construction as modern CPUs that routinely use them, perhaps (if there is room) a ZIF socket would be the best choice. ...lee Quote Link to comment Share on other sites More sharing options...
matthew180 Posted November 12, 2017 Share Posted November 12, 2017 I would not use a ZIP socket. I don't think they are designed for long-term mounting of chips, and they are expensive. Also, I can't remember ever having to replace the 9900 CPU itself, so a ZIF socket for such a rare event would be overkill, IMO. If a 64-pin socket cannot be found, you can always use SIP pin headers. Quote Link to comment Share on other sites More sharing options...
Pepper Posted November 13, 2017 Author Share Posted November 13, 2017 I would not use a ZIP socket. I don't think they are designed for long-term mounting of chips, and they are expensive. Also, I can't remember ever having to replace the 9900 CPU itself, so a ZIF socket for such a rare event would be overkill, IMO. If a 64-pin socket cannot be found, you can always use SIP pin headers. SIP pin headers will work nicely, they are very handy ! Finding a 64 pin DIP that is 2.54mm pitch seems to be hard on eBay, but Mouser has them. I need to go through troubleshooting this spare board that I have again, before I start unsoldering everything. The -RESET line is set high all the time... which makes me suspect the TMS9900. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted November 13, 2017 Share Posted November 13, 2017 Here is one good one, and I buy stuff from this vendor all the time. Here's another one that ends up a little cheaper because it only gives you two (instead of six). 2 Quote Link to comment Share on other sites More sharing options...
Stuart Posted November 13, 2017 Share Posted November 13, 2017 (edited) I need to go through troubleshooting this spare board that I have again, before I start unsoldering everything. The -RESET line is set high all the time... which makes me suspect the TMS9900. Have you tried replacing the TIM9904 clock chip which generates /RESET? (May be a 74LS362 on very early boards.) It is sometimes already socketed which makes life easy. Edited November 13, 2017 by Stuart Quote Link to comment Share on other sites More sharing options...
Pepper Posted November 14, 2017 Author Share Posted November 14, 2017 Have you tried replacing the TIM9904 clock chip which generates /RESET? (May be a 74LS362 on very early boards.) It is sometimes already socketed which makes life easy. No I've not tried replacing it yet. It's not socketed on this board.. (My working TI99/4A is lol). I'm going to do more poking around before unsoldering the beast... Quote Link to comment Share on other sites More sharing options...
+helocast Posted November 14, 2017 Share Posted November 14, 2017 Here is one good one, and I buy stuff from this vendor all the time. Here's another one that ends up a little cheaper because it only gives you two (instead of six). Used both as I keep them in my watch list! Sometimes we're on the same wavelength. 1 Quote Link to comment Share on other sites More sharing options...
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