Hi everyone, I own a broken n64 (NUS-CPU-(P)-01) that I'm trying to fix. I buyed it for a very low price some months ago and it never worked. When I turn it on the led turn red and nothing else. I can't get any signal on TV, neither audio or video, neither a black screen, I just have constant tension on the video output. I know the problem is in the motherboard it self, because games, ram expnasion pack, controller and PSU are all working. I already opened up the console and tested different things. I suppose from my tests that the problem is located before the DENC-NUS integrated, and from what I see it seem that the PIF is not working correctly. Also tensions seem to be ok, I have both 12v, 5v and 3.3v in different parts of the motherboard. Traces are fine too. What I really need is help from technical people that know very well how the n64 should work in every point of is hardware. Many thanks in advance to everyone who will help me in this difficult journey.
this might help, on this system it had corrosion on the cpu? Did you check the RAM pack? Did you remove the card edge connector and clean it? Is the power and rest switches working? If reset switch is damaged, it could be holding low
Already checked both the reset button circuit and the power switch and they are both working as they should. The ram pack is OK cause it's working on another n64, and I also made few checks on the actual console ram and it seem fine too. The card connector was really dirty but I removed and cleaned it, and already tested all the pins of the connector with their ends on the motherboard. When I was saying that I think the PIF is not working good it s because I don't have a tense on the output clock pin, I also don't have any tense on the 3rd and 4th input pin of the DENC but they are connected with the GPU well.
My reset button is actually broken now, in the way it's not closing the circuit with the ground when you press it so not in the bad/constant reset way. When I tested it last week it was working so this is not the issue. I tested again the tensions on all the pins (in and out) of the DENC, PIF and on the audio circuit 3,3V line vcc = 3,6V 12V line = 12,3 V 5V line = 5,5 V Vterm= 2,7V Vref= I can't understand where it is Spoiler: DENC tension Referring to the image above I got Input 1:0v 2:vcc 3.6V 3:vcc 3.6V 4:0v 5:0v 6:0v 7:0v 8:vcc 3,6V 9:0v 10:gnd 11:clk 2.15V 12:gnd Output 13:gnd 14:0,4V 15:vcc 3,6V 16:gnd ??? (This should be sfreq) 17:5,4V (5Vline) 18:3,35V 19:3V 20:3V 21:1,35V 22:1,35V 23:2,7V 24:gnd Spoiler: Audio converter tension Referring to the image above I got: Output 1:2V 2:1,8V 3:gnd 4:2,3V Input 5:vcc 3,6V 6:0V 7:0V 8:vcc 3,6V For the clock circuit of the quarz X1(the one used by DENC and RCP ) I have an exit tense of 2,1V Spoiler: PIF tension Referring to the image above Note in this test vcc= 3,7V 1: sometimes 0V sometimes vcc measured while turning on the console 2:3,65V 3:vcc 4:3,5V 5:0,01V 6:vcc 7:vcc 8:vcV 9:0V 10:gnd 11:vcc 12:gnd 13:vcc 14:gnd 15:vcc 16:vcc 17:vcc 18:vcc 19:vcc 20:vcc 21:vcc 22:vcc 23:vcc 24:vcc 25:vcc 26:3,65V 27:3,65V 28:vcc Also all the fuses are working P.S. both the CPU and RCP heat up a little but I running them fine without heatsinks for long sessions without getting them over 40 degree for the cpu and 50 for the rcp
I don't know if this helps but I repaired a N64 with no audio/video by reflowing the pins that goes from the jumper pack connecter to the mother board. One of the pins weren't making contact. After a reflow everything worked.
I just repaired the reset button and cleaned the board with alcol and again same results, no signal. Does anyone know if my tensions are good or if one chip is acting wrong? I need an idea to where to look at.
Massage the board to relieve any excess "tension" maybe? (I just cannot get over this guy calling "voltages" "tensions"...) No signal on the clock pin would be something to look into imho. You sure the PIF generates a clock signal, instead of receiving one and driving a reset line on another pin until "unlocked"? Either way, don't expect a constant voltage there (or at the xtal, for that matter). To look at signals, better use an oscilloscope.
lol yeah sorry you're right: voltages Anyway the PIF chip should both send a clock to the CIC and EPROM inside the cartridge on pin 1, but also receive an input clock form the quartz (I think) on pin 9. I have problems on both because I have 0V on the input and sometimes also 0v on the output. Unfortunately I don't have an oscilloscope to get more accurate informations. Edit: pin 9 it's not from the quartz but it's directly from the RCP Edit2: I opened a working n64 and tested some voltages on there, the result it's that all my voltages are not normal also the ones that I thought were. I will check the board another time for continuity problems, bridges, broken pins etc. and if I can't find anything I will assume either the CPU or RCP or PIF integrated are somehow broken, unless any of you have some ideas.
