Working on a friends of mine NES-101.
Story is he had a lightning strike in his neighborhood while he was playing the NES. After power came back on, NES only went to gray screen once he changed the power supply (original power supply was directly plugged into wall and has zero output now). He gave it to a NES repair guy who said it was the capacitors without even looking at it. The guy charged him $50 to replace the capacitors and it still is gray screening.
I step in at this point and start buy just doing a front to back eval of it. The caps the guy replaced are of the correct size and properly installed. The power supply section of the NES is functioning properly (tested both downstream and upstream of the 7805 regulator).
When I powered the board directly from my variable power supply (8.5v supplied directly to the input side of the 7805) it is consuming 1.2amps and the CPU chip is getting insanely hot (I shut it off at 109ºC and climbing on the CPU). PPU heated up and stabilized. I am leaning twoards a bad CPU, but I really don't want to just willy nilly go replacing things until I can nail down what is really bad.
Also, I was running these tests with no cartridge installed so as to see the function of the unit. Does the unit need the cartridge installed to test proper function of the CPU? I would think the CPU would go into some type of hold until instructed mode when no cart is installed, not just turn into a space heater.
Any thoughts or opinions would be helpful.
Thanks!!
Story is he had a lightning strike in his neighborhood while he was playing the NES. After power came back on, NES only went to gray screen once he changed the power supply (original power supply was directly plugged into wall and has zero output now). He gave it to a NES repair guy who said it was the capacitors without even looking at it. The guy charged him $50 to replace the capacitors and it still is gray screening.
I step in at this point and start buy just doing a front to back eval of it. The caps the guy replaced are of the correct size and properly installed. The power supply section of the NES is functioning properly (tested both downstream and upstream of the 7805 regulator).
When I powered the board directly from my variable power supply (8.5v supplied directly to the input side of the 7805) it is consuming 1.2amps and the CPU chip is getting insanely hot (I shut it off at 109ºC and climbing on the CPU). PPU heated up and stabilized. I am leaning twoards a bad CPU, but I really don't want to just willy nilly go replacing things until I can nail down what is really bad.
Also, I was running these tests with no cartridge installed so as to see the function of the unit. Does the unit need the cartridge installed to test proper function of the CPU? I would think the CPU would go into some type of hold until instructed mode when no cart is installed, not just turn into a space heater.
Any thoughts or opinions would be helpful.
Thanks!!