Some time ago I was trying to repair a powered mixer which used a TA7317P output protection device.
It turned out that when I got more devices from another distributor they worked exactly as expected. The relay turned on after a delay of a few seconds and all voltage readings made sense.
So in future I will test any TA7317P devices to confirm that they really do seem to be TA7317P before fitting them.
Whether the devices were fake or accidentally put in the wrong package I do not know.
I sent them back to the original distributor today.
I would like to thank everyone who assisted me in that thread, particularly Franc Zabkar.
I also fixed the Yamaha XM6150. In addition to both darlington output transistors being short circuit, one of the emitter resistors was open circuit despite its appearance.
Old Guy