NES-001 cap replacement guide for the av power module

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jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Tue Jan 12, 2021 4:13 am

I have unsoldered the PPU and the memory, and I have soldered pin strips for both. I have had to solder two jumpers for two connections that have been cut while desoldering. I have measured continuity of all the affected connections and I think everything is fine.
Attachments
IMG20210112120555.jpg
IMG20210111090804.jpg

jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Tue Jan 12, 2021 4:33 am

The PPU has an expected delivery date between January 22 and February 3, and the memory between January 16 and January 20

Memory: https://es.aliexpress.com/item/40006961 ... 63c0xYVeyM
Attachments
PPU
PPU

jcarlos
Posts: 56
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Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Tue Jan 12, 2021 4:37 am

When they arrive, I will tell you if there is a problem or everything is fine. I am very grateful for your indispensable help. I can only hope and pray that the CPU is good, because otherwise it is difficult to find and expensive despite being second-hand, also they do not give you guarantees and they do not return the money even if you have not used it. Unless there is a cheaper and easier to find clone for the CPU, according to your page it would be the UMC UA6540, would it be interchangeable with the RP2A07A that I have?. A greeting.

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

Post by lidnariq » Tue Jan 12, 2021 2:14 pm

Yes, supposedly the UA6540 should be compatible.

You may also be able to use other CPUs with varying levels of compatibility.

jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Wed Jan 13, 2021 12:41 am

lidnariq wrote:
Tue Jan 12, 2021 2:14 pm
Yes, supposedly the UA6540 should be compatible.

You may also be able to use other CPUs with varying levels of compatibility.
But the most compatible is the UA6540, right?

lidnariq
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Location: Seattle

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

Post by lidnariq » Wed Jan 13, 2021 1:13 am

Yes. But if you can't find one for whatever reason, you may be able to use some other famiclone CPU.

jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Wed Jan 13, 2021 5:57 am

Another question I ask myself, about the old non-constant transformer is if I can power the NES with a continuous source (DC)? Only two of the four diodes would conduct and the other two would remain inversely polarized and the input of the 7805 will have the DC supply voltage minus 1.4V approx. which would drop across the diodes, if the source was 9V DC it would be 9V-1.4V = 7.6V DC. The 7805 will receive less voltage, at the input, than with the alternating source (AC) approx. 9V AC * root of 2, which would be approx. 12 V - 0.7 V = 11.3V DC (through the filter, with a little ripple). Therefore the 7805 would heat up less, but the two diodes would suffer more than with an alternating signal, these diodes I think are 1A and all the current of the NES, which I don't know how much it is, I think approx. 1A, will pass through the two diodes constantly, I think they would be very tight, if they are really 1A. Also looking at the circuit of the RF module I see that this signal not only goes to the input of the 7805, but also goes with a 150 ohm R24 1/2W to the RF module and I wonder if this circuit would be affected (it would not work correctly) with the voltage drop, when applying the continuous source of 9V DC. A solution would be to raise the DC source to 12 V DC, although the 7805 and the two diodes, will suffer more, the latters may be destroyed. I also wonder the average consumption current of a NES, its original transformer is a maximum of 1.3A, I suppose that the NES at full performance, will draw less current, around one Ampere.

I think it is better to feed the NES with 12V DC instead of 9V DC, To keep approx. the same voltage in the RF circuit (R24), although not how this circuit works. It would be necessary to see what happens with the rectifier diodes, because if they are 1A, as I think, due to the size, they would be supporting approximately 1A. at the moment that the NES consumes more than 1A, I think they would be destroyed, they could be replaced by 1N5404 diodes of 3A. These are all assumptions, because I do not know the mission of the circuit as of R24, with the help of a simulator. I'm not totally sure what would happen in the real circuit, but it gives me an idea, when it comes to getting rid of the old original transformer.
Attachments
Measurements 1: Input voltage 7805 and R24 10.73V (yellow signal, with ripple). NES power by original transformer (9V AC)
Measurements 1: Input voltage 7805 and R24 10.73V (yellow signal, with ripple). NES power by original transformer (9V AC)
NES power circuit powered by 9V DC continuous source
NES power circuit powered by 9V DC continuous source
Measurements 2: Input voltage 7805 and R24 7.13V (yellow signal). The voltage drop, around 4V DC, can be observed at the input of the 7805 and R24. I don't know how this can influence the RF circuit, starting from R24.
Measurements 2: Input voltage 7805 and R24 7.13V (yellow signal). The voltage drop, around 4V DC, can be observed at the input of the 7805 and R24. I don't know how this can influence the RF circuit, starting from R24.
NES power circuit powered by 12V DC continuous source
NES power circuit powered by 12V DC continuous source
Measurements 3: Input voltage 7805 and R24 10.13V (yellow signal). R24 returns to approximately the same voltage 10.13V DC as with the original transformer that was 10.73V DC with ripple. The two conducting diodes carry just 1A.
Measurements 3: Input voltage 7805 and R24 10.13V (yellow signal). R24 returns to approximately the same voltage 10.13V DC as with the original transformer that was 10.73V DC with ripple. The two conducting diodes carry just 1A.
Last edited by jcarlos on Wed Jan 13, 2021 12:27 pm, edited 1 time in total.

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

Post by lidnariq » Wed Jan 13, 2021 12:26 pm

jcarlos wrote:
Wed Jan 13, 2021 5:57 am
Another question I ask myself, about the old non-constant transformer is if I can power the NES with a continuous source (DC)? Only two of the four diodes would conduct and the other two would remain inversely polarized and the input of the 7805 will have the DC supply voltage minus 1.4V approx. which would drop across the diodes, if the source was 9V DC it would be 9V-1.4V = 7.6V DC.
The US NTSC AV modules use four 1N400X diodes in their bridge rectifier, but at least some PAL AV modules seem to use prepackaged rectifier bridges. The 1N400X diodes have a typical 1V forward voltage, not 0.7V, but I don't know if that's also true for the rectifier bridge.
Therefore the 7805 would heat up less, but the two diodes would suffer more than with an alternating signal, these diodes I think are 1A and all the current of the NES, which I don't know how much it is, I think approx. 1A, will pass through the two diodes constantly, I think they would be very tight, if they are really 1A.
My NES seems to take around 350-450mA at 5V. You're not near any current limits, although there may still be some thermal ones.
Also looking at the circuit of the RF module I see that this signal not only goes to the input of the 7805, but also goes with a 150 ohm R24 1/2W to the RF module and I wonder if this circuit would be affected (it would not work correctly) with the voltage drop, when applying the continuous source of 9V DC.
That's only used for the external RF switch. Do you care?

jcarlos
Posts: 56
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Re: NES-001 cap replacement guide for the av power module

Post by jcarlos » Wed Jan 13, 2021 12:32 pm

So I can feed the NES with a source of 9V DC and 1A or more quietly?

lidnariq
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Location: Seattle

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

Post by lidnariq » Wed Jan 13, 2021 12:33 pm

Other people have.

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 » Wed Jan 13, 2021 12:36 pm

And is it better than the original transformer?

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

Post by lidnariq » Wed Jan 13, 2021 12:37 pm

Only if you're using a modern switcher so that the output voltage doesn't rise under low-load conditions.

jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Wed Jan 13, 2021 12:40 pm

lidnariq wrote:
Wed Jan 13, 2021 12:26 pm
jcarlos wrote:
Wed Jan 13, 2021 5:57 am
Another question I ask myself, about the old non-constant transformer is if I can power the NES with a continuous source (DC)? Only two of the four diodes would conduct and the other two would remain inversely polarized and the input of the 7805 will have the DC supply voltage minus 1.4V approx. which would drop across the diodes, if the source was 9V DC it would be 9V-1.4V = 7.6V DC.
The US NTSC AV modules use four 1N400X diodes in their bridge rectifier, but at least some PAL AV modules seem to use prepackaged rectifier bridges. The 1N400X diodes have a typical 1V forward voltage, not 0.7V, but I don't know if that's also true for the rectifier bridge.
Therefore the 7805 would heat up less, but the two diodes would suffer more than with an alternating signal, these diodes I think are 1A and all the current of the NES, which I don't know how much it is, I think approx. 1A, will pass through the two diodes constantly, I think they would be very tight, if they are really 1A.
My NES seems to take around 350-450mA at 5V. You're not near any current limits, although there may still be some thermal ones.
Also looking at the circuit of the RF module I see that this signal not only goes to the input of the 7805, but also goes with a 150 ohm R24 1/2W to the RF module and I wonder if this circuit would be affected (it would not work correctly) with the voltage drop, when applying the continuous source of 9V DC.
That's only used for the external RF switch. Do you care?
What is the external RF switch?

jcarlos
Posts: 56
Joined: Mon Dec 21, 2020 11:38 pm

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

Post by jcarlos » Wed Jan 13, 2021 12:53 pm

I had seen this power supply, but I do not know if it has that switch for low loads that you tell me, it is an Amazon Spain page, sorry. I think the diameter of the connector matches 5.5mm on the outside and 2.1mm on the inside. The polarity I think is + on the inside, although I think this doesn't matter. To you okay?
https://www.amazon.es/Aukru%C2%AE-1000m ... 052&sr=8-5

lidnariq
Posts: 10264
Joined: Sun Apr 13, 2008 11:12 am
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Re: NES-001 cap replacement guide for the av power module

Post by lidnariq » Wed Jan 13, 2021 1:02 pm

jcarlos wrote:
Wed Jan 13, 2021 12:40 pm
What is the external RF switch?
This thing:
https://images-na.ssl-images-amazon.com ... L1024_.jpg

The thing that lets you use a TV that doesn't have a SCART or A/V cinch jacks.
jcarlos wrote:
Wed Jan 13, 2021 12:53 pm
I had seen this power supply, but I do not know if it has that switch
One of these: https://en.wikipedia.org/wiki/Switched- ... wer_supply
I don't see the polarity, but I think it doesn't matter.
Polarity indeed doesn't matter because of the bridge rectifier inside the AV modulator unit.

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