I have a relatively small layout, powered by a Postwar 275 watt ZW.
The next time I have a bad board, I am going to start by checking the diodes, then replacing the three electrolytic capacitors with new ones with the correct values.
Last step will probably be replacing the four 3-wire transistors. (if changing the capacitors doesn't fix the problem)
Currently, Radio Shack has the correct capacitors available individually. They do not have all of the transistors available individually, but by purchasing two different inexpensive assortments, I was able to get them all with some spares.
As I posted above, I do plan to buy a few of each component the next time I place an order with Digikey. I think I have also identified the correct spade connectors (male and female) on the Digikey site, and will order some of them too.
After the second failure, (with the wrong capacitors installed), the two transistors closest to the speaker wires were getting quite hot. Now they get mildly warm after leaving power continuously on for several minutes.
Since I changed the four 3-wire transistors and all three electrolytic capacitors, I don't really know what caused or solved the problem with certainty. I do know that the board wasn't all better until I replaced in oversized 100 MFD cap with the correct 22 MFD cap.
