I have replace all of the components in the standby circuit because the unit came on, works on the pre amp very well, but does not work post pre amp. Although the TDA's showed no sign of damage nor fault via meter reading compared to new ones, I changed all of them. I replaced all of them after discharging the caps first, and on power up, there was a massive explosion of all 4 TDA's. I did fail to replace the insulators behind the TDA's and silicone, but from what I see, as well as the heat sink not being in contact with the chassis in any way, and the fact that pin 2 is also the back and ground to all TDA's and pin 14 is the -power rail. Would I have grounded these out to short? Anyway, the blasted thing would not come out of the standby/mute even though the preamp was perfect. Is there another way I can substitute the TDA modules for something different? Hopeful.