Airshack Posted August 2, 2019 Share Posted August 2, 2019 I have a 99/4A which squeals like a pig when I turn it on. Loud constant tone — no video output. Any known solutions? Do we have any known service manuals scanned for the 4A? Quote Link to comment Share on other sites More sharing options...
jrhodes Posted August 3, 2019 Share Posted August 3, 2019 I am not a expert by any means, but i would say check the ram. 1 Quote Link to comment Share on other sites More sharing options...
Airshack Posted August 3, 2019 Author Share Posted August 3, 2019 Thanks! I guess that’s a good start for all of these old machines. One technique I’ve seen is piggy-backing the RAM to check for open-failures. If that doesn’t work I’ll be pulling RAM and adding sockets one by one. Quote Link to comment Share on other sites More sharing options...
Airshack Posted August 3, 2019 Author Share Posted August 3, 2019 (edited) My understanding is that bad RAM usually results in garbled screen with colors upon startup. I’m getting no video at all — black. Edited August 3, 2019 by Airshack Quote Link to comment Share on other sites More sharing options...
ti99iuc Posted August 3, 2019 Share Posted August 3, 2019 maybe you should check at this website, Xad Nightfall repaired lot of TI99 and has lot of experience: https://www.nightfallcrew.com/?s=ti-99+repair 1 Quote Link to comment Share on other sites More sharing options...
+chue Posted August 3, 2019 Share Posted August 3, 2019 (edited) Some tips for the "black screen with noise" issue at the following blog post: The blogpost references John Guion's guide to troubleshooting. I had posted a comment in the blogpost linking to the full text of the guide at whtech. The comment was never approved, so is invisible. I post the link here for your reference. http://ftp.whtech.com/articles/limanews/CONSOLE.TXT Edited August 4, 2019 by chue fix whtech link 2 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted August 4, 2019 Share Posted August 4, 2019 I put the 99/4 TI troubleshooting manual up on WHT sometime back (in the 99/4 folder, IIRC). I have two different versions of the 99/4A TI troubleshooting manual, but I still need to scan those in. 2 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted August 4, 2019 Share Posted August 4, 2019 6 minutes ago, Ksarul said: (in the 99/4 folder, IIRC) I searched for "99/4" in... http://ftp.whtech.com/sitelist.txt would you believe ...not one instance! 1 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted August 4, 2019 Share Posted August 4, 2019 Here's the folder for you. 2 1 Quote Link to comment Share on other sites More sharing options...
AwkwardPotato Posted August 4, 2019 Share Posted August 4, 2019 Black screen & cacophony usually isn't the VRAM; check the ROMs and 6810 SRAMs. 3 Quote Link to comment Share on other sites More sharing options...
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