cbmeeks Posted June 29, 2016 Author Share Posted June 29, 2016 I actually may do that. I hate having dead, vintage computers. Plus, I want to improve my diagnostic skills. My problem is that I have so many projects...lol Quote Link to comment Share on other sites More sharing options...
RickyDean Posted June 29, 2016 Share Posted June 29, 2016 I actually may do that. I hate having dead, vintage computers. Plus, I want to improve my diagnostic skills. My problem is that I have so many projects...lol Been there , doing that!! Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted June 29, 2016 Share Posted June 29, 2016 It is for things like this that I had one of my mother boards completely socketed BITD. It made testing a bit easier. . . Quote Link to comment Share on other sites More sharing options...
RickyDean Posted June 30, 2016 Share Posted June 30, 2016 Yeh, I have one right now that I will be fixing(one of the white rails got knocked off while stored and the 32k with diodes has to have some wires resoldered) that I had almost completely socketed even the 9900 ceramic processor. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted June 30, 2016 Author Share Posted June 30, 2016 Other than just swapping parts, what are some tips for debugging a dead board? Perhaps some continuity testing? Voltage tests? Quote Link to comment Share on other sites More sharing options...
RickyDean Posted June 30, 2016 Share Posted June 30, 2016 If you google each chip with the word datasheet you can find a lot of information about every IC chip on the board plus if you go to ftp://whtech.com/datasheets%20and%20manuals/Datasheets%20-%20TI/you will find a wealth of info there. Get the schematic of the TI and check voltages to each IC starting with the processor. A lot of problems are in the area of the IC's that are closest to the expansion side port. If you have garbled video then the dram IC's are often to blame. The clock crystals are pretty hardy and I have only seen a couple in my experience that have gone bad, but they can, the same with transistors. A logic probe to check if the IC's are working per the design, or if you have access to a device that can clamp onto an in circuit logic chip or remove the chip(desolder) and check it with a IC tester for functionality( but might as well socket at the same time). Looking for bulged capacitors or checking the resistors to see if they are still in factory ranges(usually not an issue, but with 30+ year old machines). Make sure the power supply is giving the correct voltages and any regulators are still functioning. Some tips, some of the more experienced gentlemen here can give more detail. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted June 30, 2016 Share Posted June 30, 2016 Other than just swapping parts, what are some tips for debugging a dead board? Perhaps some continuity testing? Voltage tests? Interesting question... there are testing harnesses and kits for other computers of the era (Amiga, Commodore, Atari 8-bit and ST,) but I have never seen one for the TI. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted June 30, 2016 Author Share Posted June 30, 2016 Those are good suggestions. I need to get me a de-soldering pump considering all of the vintage hardware I have that could use a little TLC. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted July 1, 2016 Share Posted July 1, 2016 TI made a nice troubleshooting guide for their consoles that was used internally. I put the version for the 99/4 up on WHT in the 99/4 folder. I may also have the one for the 99/4A around here somewhere too. If I turn it up, it will also be scanned and put up onto WHT. Note: the one for the 99/4 will be similar enough to the one for the /4A that it will give you a lot of troubleshooting ideas. . . Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted July 1, 2016 Author Share Posted July 1, 2016 That's awesome. But what is this WHT you speak of? Thanks! Quote Link to comment Share on other sites More sharing options...
RickyDean Posted July 1, 2016 Share Posted July 1, 2016 That's awesome. But what is this WHT you speak of? Thanks! WHT == ftp://whtech.com/datasheets%20and%20manuals/Datasheets%20-%20TI/ Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted July 1, 2016 Share Posted July 1, 2016 (edited) WHT has a plethora of TI goodness from a documentation standpoint. Between it and the book archive over on Hexbus.com, you have just about every reference work for the system ever made (at least the ones in English). To get some of the ones in German, Italian, French, Dutch, Swedish, and Danish you have to go to the Italian User's group site that Ciro maintains. I probably should start scanning some of the Argentine Spanish ones I have too, as many of those are unique. . .although they also had translations of most of the Compute! books there too. Edited July 1, 2016 by Ksarul Quote Link to comment Share on other sites More sharing options...
Ed in SoDak Posted July 2, 2016 Share Posted July 2, 2016 I plopped a small 12v computer fan on the vents behind the cart port. I ran it off a multi-voltage wallwart from Radio Shack. 6 or 7.5 volts output was less noisy and did the job. Had to buy a separate coffee warmer afterwards, the TI quit keeping my cup warm. My guess on the fail is a RAM chip. It takes all 8 to make a byte, so a single bad chip can scramble the works. The 4116 is a pretty common fail, it was used in a lot of older computers. A bad one scrambled the screen on the Timex TS1500 I bought. On that one, we used the add-on RAMpack for some working RAM to load and run a memory test program and figured out which bit was failing and traced the data line to figure out the chip to replace. Piggybacking a known good chip on each 4116 may not uncover a bad one, but might change the behavior enough to show the problem is in the RAM. YMMV, I had a couple bad TI boards I never did fix. One I pulled all eight RAMs and socketed them for swapping other chips to no avail. -Ed Quote Link to comment Share on other sites More sharing options...
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