Mtlatc Posted January 2, 2023 Share Posted January 2, 2023 Plug in my board to tested wall plug. On 5V pin I’m getting about 0.9v on 12v pin I’m getting about 26v and on -5v pin I’m getting 0. What would be your troubleshooting start point? FWIW all caps look good. Thanks. Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted January 2, 2023 Share Posted January 2, 2023 Well ...There are at least two different types of voltage regulator boards for the 4A. We are talking about the TI-99/4A? It appears that the switching supply uses a full-wave rectifier. While the linear supply does not. So after checking the transformer, the next stop is the rectification section. Linear: Switching: No unusually bad smells? 3 Quote Link to comment Share on other sites More sharing options...
Mtlatc Posted January 2, 2023 Author Share Posted January 2, 2023 Is the Linear from the 4/A. No smells. 1 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted January 3, 2023 Share Posted January 3, 2023 Upon initial visual inspection(from this angle). The thing that sticks out the most to my eyes, is that the switch housing, looks to be coming loose/uncrimped. Quote Link to comment Share on other sites More sharing options...
Mtlatc Posted January 4, 2023 Author Share Posted January 4, 2023 That switch is solid. The 12V and -5V are reading correctly now so I only have the issue of a 0.9V reading on the 5V. Anyone ever tried troubleshooting this one? Quote Link to comment Share on other sites More sharing options...
+acadiel Posted January 4, 2023 Share Posted January 4, 2023 Yep, verify that the switch is working... and then possibly check other voltage points. Check out the Sam's Technical manual here: 1 Quote Link to comment Share on other sites More sharing options...
Mtlatc Posted January 4, 2023 Author Share Posted January 4, 2023 18 minutes ago, acadiel said: Yep, verify that the switch is working... and then possibly check other voltage points. Check out the Sam's Technical manual here: Can't thank you enough. I have been searching all over for this type on information on the power board!!!! 1 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted January 4, 2023 Share Posted January 4, 2023 2 hours ago, Mtlatc said: ...so I only have the issue of a 0.9V reading on the 5V. My first thought would be TIP31(TO220), and the passive components in series between it and the +5V output pin.(L4,R9,R10) ...perhaps an underside shot of the board, would reveal something. Quote Link to comment Share on other sites More sharing options...
Mtlatc Posted January 5, 2023 Author Share Posted January 5, 2023 3 hours ago, HOME AUTOMATION said: My first thought would be TIP31(TO220), and the passive components in series between it and the +5V output pin.(L4,R9,R10) ...perhaps an underside shot of the board, would reveal something. Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted January 5, 2023 Share Posted January 5, 2023 Well... I've never had issue with TI's, board soldering--Until now! Perhaps it's just the pic. but, even the 14-pin DIP's legs, don't look like they were heated enough to get much flow. These areas should have been treated with a somewhat higher priority. 1 Quote Link to comment Share on other sites More sharing options...
Stuart Posted January 5, 2023 Share Posted January 5, 2023 Do I recall a problem that the voltages weren't marked correctly on the PCB, or didn't match the schematic, or something? So the OP might not be measuring the voltages that they think they are measuring ...? Quote Link to comment Share on other sites More sharing options...
Mtlatc Posted January 12, 2023 Author Share Posted January 12, 2023 On 1/4/2023 at 4:04 PM, HOME AUTOMATION said: My first thought would be TIP31(TO220), and the passive components in series between it and the +5V output pin.(L4,R9,R10) ...perhaps an underside shot of the board, would reveal something. Going to give you the big assist on this. Long story short I replaced the TIP31 and the UA723CN (which I managed to smoke during troubleshooting) and it only cost me about $1.80 (USD). The board is now functioning as designed and at the proper voltages. Now just need to plug it in to something and see where I am. Thanks! 5 1 Quote Link to comment Share on other sites More sharing options...
HOME AUTOMATION Posted January 12, 2023 Share Posted January 12, 2023 Yes, sir! When there is a wrong to right... Mighty Mouse will win the FIGHT... 1 Quote Link to comment Share on other sites More sharing options...
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