Ressurected a TVROM game (p0rn included)

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Ressurected a TVROM game (p0rn included)
by on (#215797)
Sometime ago, I got some unfunctional games.
One of them was Rad Racer II.
So, I took a pirate Return to the Earth board and made a "transplant".
Here is the end result:
Attachment:
File comment: Component side
6f163715-a6ed-435c-99ea-b13439b3fd21.jpeg
6f163715-a6ed-435c-99ea-b13439b3fd21.jpeg [ 111.54 KiB | Viewed 7462 times ]

Attachment:
File comment: Solder side
af168afc-cc17-41d7-940c-97ecce47903a.jpeg
af168afc-cc17-41d7-940c-97ecce47903a.jpeg [ 101.59 KiB | Viewed 7462 times ]

So far so good the game worked!!
Attachment:
File comment: In game
20180325_145106.jpg
20180325_145106.jpg [ 852.45 KiB | Viewed 7462 times ]

This seems to be a problem with the original PCB, so I totally disassembled it and I'm sharing some board p0rn:
Attachment:
File comment: TVROM-Componentes
NES-TVROM-Comp-S.png
NES-TVROM-Comp-S.png [ 1.21 MiB | Viewed 7462 times ]

Attachment:
File comment: TVROM-Solda
NES-TVROM-Solda-S.png
NES-TVROM-Solda-S.png [ 1.14 MiB | Viewed 7462 times ]

Since in other cases disassembly, clean and reassemble made the game work again, what chances I have that this happen again, this time with an original board?
Should I post the pictures on Bootgod's site?
Thanks in advance!!
Re: Ressurected a TVROM game (p0rn included)
by on (#215801)
There's already an entry for Rad Racer II. The board type silkscreening (HVC-TVROM) on yours is identical to the one there pinout-wise, aside from some minor PCB differences (nothing major, seen this type of thing before). I don't know if BG's DB allows for raw (i.e. not populated with ICs/parts) PCB photos, but yours are higher res though.
Re: Ressurected a TVROM game (p0rn included)
by on (#216537)
Now that you talked, I started to think a bit more.
It doesn't makes much sense to strip a well known board naked.
At least the well documented ones as this don't!

Other than curiosity there's no more valuable information to be gained from these.
But on pirate or unknown boards it does!
Specially if you don't want to miss any connection, wich is possible if you're with an exotic board and don't test all the possibilities.

At least the game is working and I have a nice board.
Probably it's a mapper IC problem, but I'll never be sure if I don't try to make a repro with this board.
Re: Ressurected a TVROM game (p0rn included)
by on (#216552)
Couldn't it be the electrolitic capacitor which got in short-circuit state ? Just a random educated guess.
Re: Ressurected a TVROM game (p0rn included)
by on (#216676)
Nice tip! Thanks!
I've checked all the capacitors and even tested the board with them removed before stripping it.
I'll try to make a repro with it, maybe Megaman6...

I think a circuit to invert the PPU A13 is needed to be built, since this pin is missing on this board.
Originally the CIRAM /CE is pulled high, disabling internal PPU RAM, correct?
A simple inverter should do the job fine, maybe even a transistorised one.
A demux will be needed too, because I only have access to 2mb flash ICs right now.
I'll post the results as soon as I have a little more free time to do these stuff.

If I do everything correct and still get an non-functional game, probably it's the MMC3 that has gone.
Any place I can find a substitute that fits, if that's the case?
The Aliexpress' clones seems too big for this, but I think this can be worked around...

Or maybe I should try the "Holy diver Batman!" first.
I think Tepples renamed it, but right now I don't remember the new name... :oops:
Re: Ressurected a TVROM game (p0rn included)
by on (#216679)
Fisher wrote:
Or maybe I should try the "Holy diver Batman!" first.
I think Tepples renamed it, but right now I don't remember the new name... :oops:

Holy Mapperel (formerly Holy Diver Batman)
Re: Ressurected a TVROM game (p0rn included)
by on (#216799)
Unfortunatelly I didn't tried the Holy Maperel first.
But I was lucky and everything just worked!!
I simply don't understand why...
But well, seems that the disassemble / clean / reassemble routine just worked!! :lol:

Here's some (badly taken) pictures:
Attachment:
de834022-f306-44d6-91c7-73a0d8f12544.jpeg
de834022-f306-44d6-91c7-73a0d8f12544.jpeg [ 143.96 KiB | Viewed 7088 times ]

Attachment:
6be9e19b-d8c2-4ffd-a9c5-21a4f636a7b2.jpeg
6be9e19b-d8c2-4ffd-a9c5-21a4f636a7b2.jpeg [ 133.92 KiB | Viewed 7088 times ]

The inverter circuit I used:
Code:

                         +5V
                          |
                          \
                          / 470R
             470pF        \
            +--||---+     +------ PPU /A13
            |       |    |/C
PPU A13 ----+--/\/\-+----| BC548
               10K       |\E
                          |
                          |
                         GND 

And the final result:
Attachment:
0220b19d-48fb-4bb7-9846-a76b8deb9fb1.jpeg
0220b19d-48fb-4bb7-9846-a76b8deb9fb1.jpeg [ 289.19 KiB | Viewed 7088 times ]

How could I improve the inverter? Is an improvement needed at all?
I was thinking in using some BF494/BF495, but I just didn't find one around.
So I used a BC548, wich I'm not sure if it's cutoff frequency is adequated / enough.
Could this became a source of problems in the near future?
Thanks in advance!!