Pioneer sx-20K Possible Micro controller issue

[hazmoment]

Hi, so Ive repaired one of these Pioneer stereo receivers before but this fault has got me stumped. I had the usual output transistors shorted which I've replaced along with some other passives which were efffected also. Ive come to power it up but Im not getting my standby led.
There is a handy fault finding block diagram in the service manual, but leads me to asuming IC101 is at fault. IC101 is a: UPD78F0536GK micro controller.
the standby transformer is running and 3.3v is being generated and regulated and is present at IC101, I should also have the pin relating to the standby led high, but is not. and I get no display, no sign of life when I hit the power button and it does not respond to a service mode "reset"
either. I have gone ahead and replaced the MicroController not once, but twice from two sellers on Ali Express. And i have the same result. What should I be doing to move forward with my fault finding, and am I missing something obvious, i.e does this micro controller need programming before it will work?
Hope someone can advise, I have only been able to determine 3.3v is present and the 3.3v on the power button pin goes low when switched on. Cheers

Link below to Service Manual which is actually pretty good and a full schematic is towards the end of the manaul: https://www.manualslib.com/manual/1911908/Pioneer-Sx-20-K.html?page=13#manual

[David_AVD]

The chips you bought as replacement microcontrollers would have been blank surely? That would explain why is does SFA now.

Maybe the original micro was ok and you were (are) missing some critical signal such as the "power good" line?

[hazmoment]

Cheers David. You have basically confirmed my suspicions on the micro. I know nothing about them... So i guess they are programmed very specifically for the task in hand, and to have a blank one programmed by a third party would be uneconomical? So I guess its a good time to stop fault finding then..

[David_AVD]

Unless you can get the original firmware (unlikely) the new micro is of no use.

Is the original one destroyed?

[Chris56000]

Hi!

The datasheet (if you could call it a "sheet!") runs to 983 pages, but it most definitely indicates this device contains flash memory and therefore would require programming before it could be used in any application, so a new device from Ali, etc., would be useless in your receiver!

I would refit the original one back and look for a fault elsewhere – it may not necessarily have been destroyed!

Chris Williams