Apparently output pin 2 of IC303 is at a logic low (0V) so the base of Q707 is also at 0V and it is turned off. This means there is collector current through Q702 and thus no base current through Q701. Q701 is therefore also off so its collector voltage is zero (you don't show the rest of the circuit so I have to assume that Q701's collector load goes to common). IC701 is a 10V linear regulator which provides 10V (9.9V measured) from the 29V supply.
Q701 goes to a box fan...the protection circuit is switching the sub woofer speaker off(via a relay)as soon as the power is switched on.
I have checked all the voltages and speaker,wiring,fuse,solder,connectors etc. and this was the only bit that was different from what I expected.
Are the printed numbers with the arrowheads supposed to be the expected voltages on those nodes (under some specific set of conditions)? If so, the I don't understand why 15.0 is shown on the output pin (pin 3) of the IC701. It's suspicious that it is 10V below the assumed 25V on pin 1.