How intelligent is Pioneer's vsx amp/rec "power off" protecting mode?

[FinPioneer]

Hi,
I would like to have an answer to the foregoing title in order to find out if it's worth repairing my Pioneer VSX-859RDS.
History: A friend of mine used this Amp/Rec and connected two speakers (8 ohm) to the connectors on the rear panel. Apparently one of the speakers was short cutted and consequently the auto protection was triggered and the Amp was powered off.
After he forced several times the Amp to power on again, the display disappeared.
The speakers were removed and I got it back with the remark: It doesn't work, something might have happened.
I opened the housing and switched several times the Amp on but the protection switched it off immediately. Once it didn't switch off for 3 sec max and one of the 39kohm resistors on the Rear Amp assy was starting to smoke.

It seemed the rear amp assy (AWX7570) has been damaged by the short cutted speaker.

I removed the whole V-amp assy (AWX7578), including the rear amp assy and the front amp assy (AWX7569).

I found out that the rear amp assy was damaged: blown up end transistors IRF9540A(S) and IRF540A(S) and the double resistor 50 milliOhms (ACN7097).

Now back to the question: I switched on the amplifier, with the whole V-amp assy(+ front and rear amp assy's) removed .

The display worked fine for some time and I switched the Amp off manually.

Repeating this step however resulted in switching the Amp on for 3 seconds and then the autoprotect mode powered the Amp off again.

Is Pioneer's protecting mode that intelligent that it detects not only errors but also missing boards? The answer will be quite important to me because getting the spare parts here in Finland is quite troublesome and also rather expensive.

Is there anybody in the field who might answer this question?

By the way,I have measured all the regulated voltages + 5.6V, +5.6V (proc),+5V, -15V, +15V,+12V and they all are present. Also the power supply is working normally, all the voltages are present. It's only the processor on the main board that detects "something" and starts powering off the Amplifier.

I have got all the schematics, including those for the model VSX-35TX

I would be very grateful for any comments or additional info

 

[j_garcia]

I would guess the system only needs to be smart enough to know the board is missing yes; it likely sees it no different than a short.

Buy a new one and send your "friend" the bill.

 

[slipperybidness]

Buy a new one and send your "friend" the bill.

That is the real solution to this problem

 

[Xotes]

Good evening. I'm having quite the same issue here, the rear amp assy (7570) got damaged in some way, and my amp is no longer working. I was wondering if you did buy the board, and if you did, if the amp has worked since ?