I have a second Kenwood KA-7300 that's been sitting for a couple of years with a "no power up" status and decided to have look at it yesterday. When turned on with a DBT it checks ok. Rail voltages are good at 50v +/- at PS (pin 3 and 4) through to Pwr. amps. Relay circuit voltages check ok as well. The relay and its transistor trigger are both good. Voltage on PS at pin 19 & 20 is 70mv. Voltage at Pin's 6 and 2 of TA-80W also read 50v. Pin 5 of TA-80W is 0v. Not sure if the Trio power packs are shot or if its something else.
If you still need help with this amp, you could try the Kenwood forum at AudioKarma.org
https://audiokarma.org/forums/index.php?forums/kenwood-trio-kensonic-accuphase.168/
@taineasy
https://audiokarma.org/forums/index.php?forums/kenwood-trio-kensonic-accuphase.168/
@taineasy