It is currently Tue May 22, 2018 6:14 pm

All times are UTC - 7 hours



Forum rules


1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.



Post new topic Reply to topic  [ 7 posts ] 
Author Message
PostPosted: Sun Mar 25, 2018 4:12 pm 
Offline
User avatar

Joined: Sat Jul 04, 2015 9:58 am
Posts: 713
Location: -29.794229 -55.795374
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 750 times ]

Attachment:
File comment: Solder side
af168afc-cc17-41d7-940c-97ecce47903a.jpeg
af168afc-cc17-41d7-940c-97ecce47903a.jpeg [ 101.59 KiB | Viewed 750 times ]

So far so good the game worked!!
Attachment:
File comment: In game
20180325_145106.jpg
20180325_145106.jpg [ 852.45 KiB | Viewed 750 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 750 times ]

Attachment:
File comment: TVROM-Solda
NES-TVROM-Solda-S.png
NES-TVROM-Solda-S.png [ 1.14 MiB | Viewed 750 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!!


Top
 Profile  
 
PostPosted: Sun Mar 25, 2018 4:50 pm 
Offline
User avatar

Joined: Sun Sep 19, 2004 9:28 pm
Posts: 3372
Location: Mountain View, CA, USA
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.


Top
 Profile  
 
PostPosted: Sat Apr 07, 2018 6:09 pm 
Offline
User avatar

Joined: Sat Jul 04, 2015 9:58 am
Posts: 713
Location: -29.794229 -55.795374
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.


Top
 Profile  
 
PostPosted: Sun Apr 08, 2018 5:33 am 
Offline
User avatar

Joined: Fri Nov 12, 2004 2:49 pm
Posts: 7432
Location: Chexbres, VD, Switzerland
Couldn't it be the electrolitic capacitor which got in short-circuit state ? Just a random educated guess.


Top
 Profile  
 
PostPosted: Mon Apr 09, 2018 6:15 pm 
Offline
User avatar

Joined: Sat Jul 04, 2015 9:58 am
Posts: 713
Location: -29.794229 -55.795374
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:


Top
 Profile  
 
PostPosted: Mon Apr 09, 2018 6:45 pm 
Offline

Joined: Sun Mar 03, 2013 1:52 am
Posts: 105
Location: Texas, USA
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)


Top
 Profile  
 
PostPosted: Thu Apr 12, 2018 7:20 pm 
Offline
User avatar

Joined: Sat Jul 04, 2015 9:58 am
Posts: 713
Location: -29.794229 -55.795374
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 376 times ]

Attachment:
6be9e19b-d8c2-4ffd-a9c5-21a4f636a7b2.jpeg
6be9e19b-d8c2-4ffd-a9c5-21a4f636a7b2.jpeg [ 133.92 KiB | Viewed 376 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 376 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!!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group