NES-001 cap replacement guide for the av power module

Discuss hardware-related topics, such as development cartridges, CopyNES, PowerPak, EPROMs, or whatever.

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jcarlos
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Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Thu Feb 04, 2021 11:17 am

PPU Pin 18: Not change
Attachments
PPUPin18.jpg
Last edited by jcarlos on Thu Feb 04, 2021 11:24 am, edited 2 times in total.

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Thu Feb 04, 2021 11:18 am

PPU Pin19 A: measured in DC (Not change)
Attachments
PPUPin19.jpg
Last edited by jcarlos on Thu Feb 04, 2021 11:23 am, edited 1 time in total.

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Thu Feb 04, 2021 11:19 am

PPU Pin 19 B: measured in AC
Attachments
PPUPin19AC.jpg

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Thu Feb 04, 2021 11:20 am

PPU Video out:
Attachments
PPUPinVideo.jpg

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Thu Feb 04, 2021 12:00 pm

In summary, it seems that everything is the same except for pin 4 of the CPU that now does not give a signal but a kind of noise. However I have not changed anything about that part of the mainboard.

lidnariq
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Location: Seattle

Re: NES-001 cap replacement guide for the av power module

Post by lidnariq » Thu Feb 04, 2021 12:25 pm

jcarlos wrote:
Thu Feb 04, 2021 11:11 am
Pin 4 CPU:
This shows a oscillation of approximately 30MHz (probably 26.6MHz) of 20mVp-p superimposed on an oscillation of approximately 4MHz (???) of 10mVp-p. That's bad. This pin (A0) should be going from roughly 0V to 4V regularly, at least every 600ns to 3µs.
PIN 4 CPU before changing the PPU:
Yeah, this is approximately what you should see.
jcarlos wrote:
Thu Feb 04, 2021 12:00 pm
In summary, it seems that everything is the same except for pin 4 of the CPU that now does not give a signal but a kind of noise. However I have not changed anything about that part of the mainboard.
Please check what happens to CPU pin 4 immediately after you release the /RESET button.

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Fri Feb 05, 2021 2:47 am

I have reviewed the connection between CPU and PPU and there was a broken connection, between D0 (Pin 28 CPU) and D0 (Pin 2 PPU). There is already a signal on pin 4 of the CPU, a 593.8 Khz signal:
Attachments
CPUPin4Fix.jpg

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Fri Feb 05, 2021 2:50 am

Although pin 19 of the PPU is still high, not giving a 50Hz signal. I don't know if this is normal. What I do observe is that the PPU does not get as hot as before. It may be that the signal from pin 19 of the PPU depends on the memories ?, which one is missing and the other is damaged.

lidnariq
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Location: Seattle

Re: NES-001 cap replacement guide for the av power module

Post by lidnariq » Fri Feb 05, 2021 12:10 pm

jcarlos wrote:
Fri Feb 05, 2021 2:50 am
It may be that the signal from pin 19 of the PPU depends on the memories ?, which one is missing and the other is damaged.
It should not depend on whether the PPU RAM is damaged. It definitely does depend on the cartridge. It may or may not depend on the CPU RAM.

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Sun Mar 28, 2021 11:28 am

I have tested the mainboard with the new PPU, the two new memories and the repaired RF module and this is the image I get. A little disappointed but from seeing nothing to seeing something is already a step. What could it be? From the videos I've seen, could it be the memory of the PPU, is it new, but could it be badly welded? It is an attempt at the Super Mario Bross game.
Attachments
IMG20210328194254CCC.jpg

lidnariq
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Location: Seattle

Re: NES-001 cap replacement guide for the av power module

Post by lidnariq » Sun Mar 28, 2021 11:51 am

That's awfully close to correct. Do you have another cartridge to test with?

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Sun Mar 28, 2021 12:35 pm

The cartridge is fine because I have tested it on another NES and it looks perfect. Right now I only have this one, the others are at my brother's house.

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Sun Mar 28, 2021 12:40 pm

I have a mainboard that works correctly and this one you can almost see. But I do not observe welding error. The bridges that I have put, due to connection cuts, seem to be correct. All compared to the good mainboard.

lidnariq
Posts: 10435
Joined: Sun Apr 13, 2008 11:12 am
Location: Seattle

Re: NES-001 cap replacement guide for the av power module

Post by lidnariq » Sun Mar 28, 2021 12:58 pm

I'd tentatively suspect the cartridge connector at this point? Or ... maybe the 74LS373?

jcarlos
Posts: 66
Joined: Mon Dec 21, 2020 11:38 pm

Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Sun Mar 28, 2021 1:01 pm

I have played a game and you can see the enemies and Mario jump and it can be heard perfectly. What is more deformed is the background decoration.

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