Dynacord powermate 1600 block diagram.

[hs5424]

Hi All,
I obtained a schematic diagram for the above mixer but I am wondering if a block diagram exists as I am trying to fix a problem in the protection circuit which I find a little confusing using a circuit diagram only. In the good old days the workshop manuals always had a block diagram with a circuit discription. Very useful for fault finding.
The protection light is perminently on. The right sode has a -80DC on the feed to the speaker, hence the protection led on. I have removed all the O/P transistors which checked out OK. I tested all other transistors in circuit which seem ok also. I did find D512 short but having replaced it and checked all its associated transistors I still have the problem.
Any help is appreciated.

[hs5424]

I might be making progress finally.
While comparing the voltages between the good side (left) and faulty side (right) I was working in the area around Q500, Q501 I discovered that when I measured the voltage on the base of Q500 using a digital meter the fault cleared and the o/p relay engaged. Its an MJE350 so when I get back to it later I will replace this transistor and also Q501. They both reasured ok in circuit but replacing them will be the real test.
See the attached marked schematic.