DIY circuit diagnostics/fixes

Anyone know anything about DIY circuitry diagnostics and/or repair?? I have an old Toshiba 3200sx that was working just fine (pictured) but it appears I may have shorted a board when trying to install an old ISA networking card. Does anyone know how I can go about troubleshooting this to find exactly what is wrong? Currently the machine will refuse to turn on. I will flip the on switch on the power supply, I hear a faint click (not the switch) and the front LED indicators flash on then off quickly. On occasion, the thing will actually turn on and boot, but that has only happened twice. I'm no stranger to soldering or using a multi-meter but my skills are nothing to write home about. Any help or resources would be much appreciated!

>>4720 Well, if stuff actually shorted out maybe check if there are any chips with magic smoke holes, or stuff like caps with the tops blown open or other visibly damaged stuff. Also, if you can't find anything obviously broken, maybe start by checking the input voltage when plugged in, and also after you press the power button.

>>4720 >I hear a faint click (not the switch) and the front LED indicators flash on then off quickly. On occasion, the thing will actually turn on and boot Iirc the T3200 has an integrated power supply, so maybe its a power relay switch (if there is one, I'm not sure) that's damaged? This would explain the click and that sometime it works normally.

>>4746 >>4720 this kind of thing

Was there any popping noise or acrid smell when you think you first caused the short with the ISA card? Have you opened the case at all yet, done any visual inspection? You may be able to inspect the power supply, see if the pins are labeled, and possibly power it off an ATX supply for a modern tower for troubleshooting purposes. That would at least narrow down where the fault lives. I'd bet it runs off the usual +5v and +12v and ground rails like they use today, maybe just 12v. If it uses any weird voltages, you might have to obtain a variable bench DC supply, or maybe just rummage through the old wall-wart bin at your local thrift store until you find the proper voltage at an adequate maximum amperage. Hopefully you just borked the power supply, maybe only blew a fuse. Also, always consider with old hardware like this that perhaps it failed because of something age-related that has nothing to do at all with that ISA card, and you're just attributing one to the other due to cognitive fallacies. I can't count the number of times I've done that. Sometimes the foundation of your beliefs is an assumption and should be questioned. Anyway, respectfully and carefully open the old girl up and take some pics of the boards inside and send 'em this way, that's really how I could be most helpful. Good pics in focus so screen-printing is legible if possible. Note any burn marks, leaking caps or batteries, staining, bulging capacitors, weird smells, dust or debris bridging contacts, dead bugs, etc.

Also, have you grabbed a flashlight and looked around inside that ISA port? Checked for any bent pins? The fact that the power supply makes a click and the indicator flips on and off causes me to suspect that it's running a PSU self-check, finding a fault, and shutting down to preserve itself. That's my instinct, anyway. You can check an ISA pinout to see where the powered pins are. https://old.pinouts.ru/Slots/ISA_pinout.shtml