Best way to find faults in the 9V rail?

[VintageGear]

Someone I know hooked up a 110V amp with a 220V amp, and somehow it caused some sort of high voltage loop (no clue how this happened..). Bottom line, his Boss TR-2 is toast.
I took up the repair job, and found out that there are two different versions of the Boss TR-2, and his was a version different from the schematic floating around. Bummer, but no big deal I thought. I replaced the first transistor in line which was blown (2SC2458). The LED came back to life, but this new transistor gets very, very hot in no time with a little burned smell already (10 second testing). So there must be more wrong with it. I don't have time to measure, I'm more than certain the transistor will smoke out prior to getting measurements. I desoldered the other trannies on the board, and placed them one by one in my component-tester I got from Ebay the other day. All tested OK. The IC's involved I cannot test in this tester.
What would be your way of approaching this problem? Go all-out and replace everything? Or maybe a less barbaric option? More than curious what you guys think!

[Kevin Mitchell]

I'd advise you to keep the parts in. If the circuit is behaving differently perhaps you've made some unintentional changes (a short).

I have no experience with that circuit but if there's a power supply section you really should fix that up if things have fried out.

More experienced people will chime in for sure. Best of luck.

[Kevin Mitchell]

Ehh double post. Forgive me.

[karbomusic]

The first thing I would do is read the resistance across +/- Then if shorted or close to it, start tracing along the power paths as to how that could be (power smoothing cap shorted, protection diode shorting and so on) which is actually likely much easier than say debugging "It only whines on cloudy days" or some other less obvious symptom. I wouldn't worry about powering it up until you can make some determinations with an ohmmeter.

[slacker]

If the transistor is getting hot it probably means something connected to it is causing it to draw too much current,this could be a number of things for example a component connected to it that has shorted out or maybe damage to the board causing a short. If you can't find a schematic you're going to have to start tracing the circuit around the transistor to figure out what it is supposed to be doing and what could cause the problem.