NESRGB install troubleshooting

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Aerik72
Posts: 8
Joined: Mon May 09, 2022 11:28 am

NESRGB install troubleshooting

Post by Aerik72 »

Video of issue with photos of install:
https://imgur.com/a/PM6Di5Z

Hi all, I'm looking for some help troubleshooting a faulty NESRGB installation. It was me that did it, this weekend, so I get the dunce award.

Stuff I installed:

-Replaced all capacitors with kit from Console 5 (tested after this step and console worked)

-NESRGB v3

-Voultar's quick solder board with flat flex cable

-Voultar's expansion audio board

-Laser Bear AV multiout

For the PPU, I used a manual solder sucker, then solder wick, then a heat gun. This led to a mishap, where I melted part of a plastic spudger onto some components near the 1 pin of U9. After backing the heat way off, I reapplied it and got the plastics off no problem, but also desoldered a ceramic cap and component Q1 A937, but soldered those back in without issue.

I followed Voultar's tutorial and skipped the socket, and just soldered all the pin headers in place, being careful to leave some gap between each PCB and components on the next layer down.

The PPU seemed all good, and I had no more problems until I discovered that the QSB for the FFC should have gone under the NESRGB before I soldered it in place, so I soldered it upside-down on top of the board for clearance.

The video above is my result. Any idea where I should start looking for problems?

I'm afraid if I have to undo the NESRGB soldering, I'm going to need to get a desoldering gun, as my heat gun won't cut it with those plastic pin headers.
unregistered
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Location: cypress, texas

Re: NESRGB install troubleshooting

Post by unregistered »

Aerik72 wrote: Mon May 09, 2022 11:37 am…The PPU seemed all good, and I had no more problems until I discovered that the QSB for the FFC should have gone under the NESRGB before I soldered it in place, so I soldered it upside-down on top of the board for clearance.

The video above is my result. Any idea where I should start looking for problems?

I'm afraid if I have to undo the NESRGB soldering, I'm going to need to get a desoldering gun, as my heat gun won't cut it with those plastic pin headers.
hi Aerik72,

I have no idea about the meaning of QSB or FFC, but I’ve boldened a part of your post that stood out to me.

A small question: Did you adjust the wires (seems like 2 wires from your pics) for the inverted board?


When inverting a circuit board, all pin numbering is reversed. The pic’s wires don’t look long enough to reach the east, as shown, side; maybe you thought out all this turning the board upside down; however, it also seems possible that you soldered those wires to the wrong pins.


This was just a thought I had :); and I don’t have any experience with hardware changes, involving solder, inside a NES.


Ooh, heat gun == soldering iron?
unregistered
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Location: cypress, texas

Re: NESRGB install troubleshooting

Post by unregistered »

Hi again,

If I’m correct and those wires are too short to properly reach, it would be easier for me to:

1.) desolder the wires using my soldering iron
2.) trim the end of the wires off; strip the new ends
3.) grab 2 new, long enough, wires; trim them appropriately and strip their ends
4.) solder both of the original wires’ ends to one side of each of the new wire ends (twist ends together before soldering them)
5.) slide 2, appropriate sized, pieces of heat shrink tubing over the new wire ends; slide them down over the soldered wire sections; apply heat close to them so they shrink and cover those exposed wire solderings
6.) solder the other ends of the wires to the appropriate pins on the east side of that upside down circuit board


It would be easier, for me, to do all of that with my soldering iron than unattach the upside down circuit board, unattach the RGB piece, and reattach both. 🙂

God bless your efforts.


EDIT: 4.5.) Before adding the heat shrink tubing, I’d test each soldered section with a multimeter; set it to check continuity; test the sections and be joyful if you hear a beep. 👍 Using a multimeter isn’t mandatory, but testing those soldered sections for continuity, before applying the heat shrink tubing, allows you to determine if the soldering needs quick adjusting.
Joe
Posts: 650
Joined: Mon Apr 01, 2013 11:17 pm

Re: NESRGB install troubleshooting

Post by Joe »

Aerik72 wrote: Mon May 09, 2022 11:37 amVideo of issue with photos of install:
https://imgur.com/a/PM6Di5Z
That pattern looks an awful lot like open bus. I would start by checking pin 24 between the NES and the NESRGB.
Aerik72
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Joined: Mon May 09, 2022 11:28 am

Re: NESRGB install troubleshooting

Post by Aerik72 »

Hey unregistered!

Okay, I was unfamiliar with these before this project but QSB is a quick solder board, and FFC is flat flex cable. Basically, it just means there is a nice flat cable with PCB headers at either end, instead of a dozen individual wires soldered in place. It makes it easy to detach the motherboard from the AV output mounted at the back of the case.

As for the wire orientation... Hmm, this is hard to explain in text. It's not turned 180°, it's just kinda folded back so that the top sides of each board are facing each other, rather than being stacked. (It's like when you're sewing a seam in fabric with the right sides together.) The pins line up the same way.

Those particular wires are audio A and B, and that's one of the only things I'm sure is working. I had the TV turned down quiet, but if you raise the volume way up on the video you can hear the Zelda music and sound effects are all working properly.

Oh, and a heat gun is like a hair dryer turned into an electronics tool... You can set a high temperature and blow air so hot it melts solder, which is useful for stuff like surface mount components.

(Though, of course, in retrospect I think it was a bad idea using it to remove the PPU, as I'm about to have to order a desoldering tool already, and I'm afraid I may have toasted the PPU like a dummy.)

I've made a lot of mistakes and learned a lot about all these tools and tech, so in that sense I guess this project is a success. :P
Aerik72
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Re: NESRGB install troubleshooting

Post by Aerik72 »

Joe wrote: Tue May 10, 2022 11:25 am
Aerik72 wrote: Mon May 09, 2022 11:37 amVideo of issue with photos of install:
https://imgur.com/a/PM6Di5Z
That pattern looks an awful lot like open bus. I would start by checking pin 24 between the NES and the NESRGB.
Yeah... I'm starting to narrow down my suspicions to the solder joints between the PPU and the NESRGB board. I thought I tested all the connections for continuity, but that's really looking like the issue.

I'm going to reflow all those joints with some extra solder, then test them for continuity again. If that doesn't work, I've ordered a budget desoldering gun, and I'll desolder and then resolder the PPU.

If that fails, it may mean I roasted the PPU with too much heat from my heat gun, so I suppose I'd need to buy another NES off eBay and start swapping parts to isolate what's broken. Le sigh.
calima
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Re: NESRGB install troubleshooting

Post by calima »

Please consider using clone parts from Aliexpress before gutting a working NES.
Aerik72
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Re: NESRGB install troubleshooting

Post by Aerik72 »

calima wrote: Wed May 11, 2022 12:47 am Please consider using clone parts from Aliexpress before gutting a working NES.
Oh, I'm hoping I won't need to gut a working NES, just use it to help swap known good parts to isolate my problem.

But if my PPU ends up being bad, I'd be very interested in a replica PPU! A quick search on AliExpress doesn't turn up anything, though... What should I be looking for? Do you have a link to an example?
Aerik72
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Joined: Mon May 09, 2022 11:28 am

Re: NESRGB install troubleshooting

Post by Aerik72 »

Ahh, found it with a bit more googling. UA6528, right?

Are these generally accurate and reliable? It looks like they're all from no-name manufacturers, but is one any better quality than others?

(Still hoping it doesn't come to this, and I just need to re-seat my PPU, just waiting on desoldering gun to come in the mail.)
Fiskbit
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Re: NESRGB install troubleshooting

Post by Fiskbit »

(Caveat: I am not a hardware expert.)

Based on the video, I'd be surprised if the PPU were damaged. It's showing an open bus pattern, which means when it's fetching data, the data it's receiving is the address that was last on the data pins (since the data pins are multiplexed with the low 8 bits of address). I'm not sure what PPU failure could cause it to see such a pattern instead of data. I guess if its /RD output were damaged such that it never went low, this could happen because VRAM would never know to respond to the access. Are you able to see if this goes low when a game is running?
calima
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Re: NESRGB install troubleshooting

Post by calima »

The clone PPUs should work just as well as the originals. The clone CPUs had some minor differences in sound, but nothing game breaking.

They were all made by UMC years ago, who the seller is doesn't really matter.
Aerik72
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Re: NESRGB install troubleshooting

Post by Aerik72 »

Fiskbit wrote: Wed May 11, 2022 7:14 pm I guess if its /RD output were damaged such that it never went low, this could happen because VRAM would never know to respond to the access.
Fiskbit, I think you might be on to something!

I pulled up a schematic of the NES-001, and saw that /RD on the PPU is pin 24. It should be connected to pin 20 (OE) on the VRAM. I checked continuity: none. It should also be connected to pin 21 (read) on the cartridge connecter. I checked: no continuity.

Continuity is good from the pin header up through the NESRGB to the PPU itself. (This is what I checked when testing, because I assumed any problems would be between the board and NESRGB.) This all points at a lifted pad on the top side of the board around pin 24, something I easily could have done while desoldering the PPU without good equipment.

Unfortunately, because I soldered the NESRGB in place, instead of using the socket, I don't have good access to that pad, and the connections are in quite awkward placements for bodge wire.

Fortunately, my desoldering gun came in the mail today, so this weekend I'll desolder everything and see if I can fix it, and report back if that was the issue! :D

Either way, thank you!!
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Ben Boldt
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Re: NESRGB install troubleshooting

Post by Ben Boldt »

You can also run an additional wire to connect the 2 points that aren't connected properly. It may not look quite as pretty but it will work. You may find that you create another problem just by removing/reinstalling the NESRGB, so using an extra wire is safer because of that.
Aerik72
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Re: NESRGB install troubleshooting

Post by Aerik72 »

Ben Boldt wrote: Fri May 13, 2022 8:23 am You can also run an additional wire to connect the 2 points that aren't connected properly. It may not look quite as pretty but it will work. You may find that you create another problem just by removing/reinstalling the NESRGB, so using an extra wire is safer because of that.
I think you may be right, so I added a bodge wire, and look! Partial fix!

https://imgur.com/a/f53Ssle

Clearly it's much better, but I've still got a problem somewhere with reading character textures. After work today, I'll continue checking continuity from the PPU to the rest of the board, following the schematic, unless anybody can eyeball this and point me at a particular PPU pin.

Thanks, y'all, I'm hopeful I can get this fully working! :)
Joe
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Re: NESRGB install troubleshooting

Post by Joe »

Aerik72 wrote: Fri May 13, 2022 10:50 amunless anybody can eyeball this and point me at a particular PPU pin
Looks more like a loose cartridge than a soldering problem to me. PPU A5 is forced to 1, but the PPU uses a multiplexed bus where A5 and D5 are on the same pin, and I don't see anything wrong with D5. PPU A5 is pin 24 on the cartridge connector.
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