NES-001 cap replacement guide for the av power module

[lidnariq]

I'd say your results there can safely assume that the PPU is in fact broken.

One last one: do you a video-like signal at all on PPU pin 21?

[jcarlos]

I'd say your results there can safely assume that the PPU is in fact broken.

One last one: do you a video-like signal at all on PPU pin 21?

I am going to do the measurement you have told me. But what about the CPU, can it be assumed that it works correctly?

[jcarlos]

I'd say your results there can safely assume that the PPU is in fact broken.

One last one: do you a video-like signal at all on PPU pin 21?

I am going to do the measurement you have told me. But what about the CPU, can it be assumed that it works correctly?

PPU pin 21: Alernate square signal, frequency reading: 15.61Khz

[lidnariq]

I am going to do the measurement you have told me. But what about the CPU, can it be assumed that it works correctly?

I'd say that it's quite likely that the CPU works. Both pin 4 and pin 31 kept on changing, and that's the easiest sign that the CPU at least mostly works.

PPU pin 21: Alernate square signal, frequency reading: 15.61Khz

Oh dear, that's a valid video signal. You should be getting valid video, but not necessarily a functioning NES, on the RCA jack of the RF modulator.

Follow the video signal down the path on your mainboard. After pin 21, check the pins of Q1, R2, the ferrite bead FC2, and the lowpass capacitor C5, before finally arriving at the removed RF modulator pin closest to the RAMs.

[jcarlos]

I am going to do the measurement you have told me. But what about the CPU, can it be assumed that it works correctly?

I'd say that it's quite likely that the CPU works. Both pin 4 and pin 31 kept on changing, and that's the easiest sign that the CPU at least mostly works.

PPU pin 21: Alernate square signal, frequency reading: 15.61Khz

Oh dear, that's a valid video signal. You should be getting valid video, but not necessarily a functioning NES, on the RCA jack of the RF modulator.

Follow the video signal down the path on your mainboard. After pin 21, check the pins of Q1, R2, the ferrite bead FC2, and the lowpass capacitor C5, before finally arriving at the removed RF modulator pin closest to the RAMs.

Base of Q1 is the same signal from pin 21 of the PPU, already measured. I think I forgot to capture a DC signal that alternates with the others. It is seen below, on the emiter of transistor Q1.

Collector Pin of Q1 (GND): frequency 13.52Khz

[jcarlos]

Emitting Pin of Q1- Left R2- Up FC2: Alternate signals frequency 15.61Khz

[jcarlos]

Down pin FC2 to RF module in: Alternate signals frequency 15.61Khz

[jcarlos]

I don't know if it will help, but what I saw on the TV with this mainboard was a blinking pink screen, at the same time with the led diode of the NES, and I dare say that at the same frequency with which they alternate between one signal and anothers on the oscilloscope. When you enter the game, the pink screen is fixed, it stops flashing. I think the continuous signal is when I don't see anything and the others are the pink screen. The continuous signal and the others alternate at a frequency of approximately 1 second (1 second pink screen and 1 second without signal), together de NES's diode led, on both the TV and the oscilloscope, when you enter de game only pink screen fixed. But I only tested for the RF signal I did not test for the RCA signal. The PPU continues to heat up, especially in the central part.

[lidnariq]

The continuous signal and the others alternate at a frequency of approximately 1 second (1 second pink screen and 1 second without signal), together de NES's diode led, on both the TV and the oscilloscope, when you enter de game only pink screen fixed.

That's consistent with what the CIC does.

The PPU continues to heat up, especially in the central part.

Warm, or uncomfortably hot?

I guess it doesn't really matter. The PPU is generating video, but it seems that the game software can never enable the PPU to generate NMIs, and that counts as broken.

[jcarlos]

The continuous signal and the others alternate at a frequency of approximately 1 second (1 second pink screen and 1 second without signal), together de NES's diode led, on both the TV and the oscilloscope, when you enter de game only pink screen fixed.

That's consistent with what the CIC does.

The PPU continues to heat up, especially in the central part.

Warm, or uncomfortably hot?

I guess it doesn't really matter. The PPU is generating video, but it seems that the game software can never enable the PPU to generate NMIs, and that counts as broken.

The continuous signal and the others alternate at a frequency of approximately 1 second (1 second pink screen and 1 second without signal), together de NES's diode led, on both the TV and the oscilloscope, when you enter de game only pink screen fixed.

That's consistent with what the CIC does.

The PPU continues to heat up, especially in the central part.

Warm, or uncomfortably hot?

uncomfortably hot, burning after a while touching it

I guess it doesn't really matter. The PPU is generating video, but it seems that the game software can never enable the PPU to generate NMIs, and that counts as broken.

What is NMI?

[jcarlos]

Is there any test to test the memory soldered to the mainboard and any test that it is desoldered for?

[lidnariq]

What is NMI?

Pin 19. It should pulse low for 4.5µs-4.5ms, every 20 milliseconds, if enabled by the game, with a functioning PAL NES.

(It's the signal from the PPU to the CPU that it's time to send new data to the PPU)

Is there any test to test the memory soldered to the mainboard

Not without some way to run your own programs on the NES.

and any test that it is desoldered for?

Some part programmers (e.g. the MiniPro) include such a test. But that only works if you have one.

Otherwise, it depends on how much work you're interested in going to, and what parts you have on hand. For example, you could use a breadboard and bunch of switches to manually generate writes and reads from it and use that to find out if it's storing data reliably.

[jcarlos]

So the first thing I should do is replace the PPU and a new memory that I have ordered whose reference is LH5116D-10?

[lidnariq]

So the first thing I should do is replace the PPU and a new memory that I have ordered whose reference is LH5116D-10?

I think so. Just the PPU first. Even with bad memory you'll often get a weird crash instead of just a solid colored screen.

You didn't have to order specifically that 2KB RAM. Any 24-pin 2KB RAM that's 50ns or slower would have worked.

[jcarlos]

So the first thing I should do is replace the PPU and a new memory that I have ordered whose reference is LH5116D-10?

I think so. Just the PPU first. Even with bad memory you'll often get a weird crash instead of just a solid colored screen.

You didn't have to order specifically that 2KB RAM. Any 24-pin 2KB RAM that's 50ns or slower would have worked.

I am going to replace the PPU with the UA6541 clone that you say on your website. because it is much cheaper and easier to find (EBAY) than the RP2C07A-0