Case won't fit on my repro :-(

Hello!!
It's some time I'm willing to do a Holy Diver repro.
Now, I finally could get the parts and have done it!!

This is how the front side looks like:


An this is the back side:


So far, so good. The game works just fine!!
But I'm having trouble putting it back on the case, since the CHR ROM is blocking the hole.
I don't think the IC would survive if I made a hole on it, will it?
The better idea seems to remove the IC, put it on the back side of the board and solder all it's pins with small wires, leaving the hole free.
Since it's a lot of work and may not end on a perfect fit, I'm posting here to ask for suggestions.
Thanks in advance.

Inside the epoxy, there are a bunch of metal frames going from the pins to the center of the chip, where they are then wire bonded to the actual die. (e.g.)

It's remotely plausible that the metal frames might, just maybe, not be where you need to add that hole, but unless I either had access to an X-ray machine to find out, or was perfectly comfortable with the idea of doing little fiddly soldering on tiny pieces of metal sticking out of the epoxy block, I wouldn't take that chance.

The metal is substantially harder than the epoxy, so you can use tools to remove the epoxy and leave the metal (but be careful; the wire bond wires and the silicon die are NOT harder) (e.g.)

You could also try removing the plastic post that wants to go through that hole and add some other way to hold the PCB from sliding inside the shell.

I really would not like to damage the case...
It's a very nice Uchusen Cosmo Carrier I was luck to get cheap
Make a chip hole seems feasible... But I think I don't have the right tools
Soldering the IC under also seems a bad idea...
Looks like I'll have to cut the case and add some screws to hold the board... or find another case.
I had made some bare board scans and a mapper schematics. Should I post it here?

Maybe you could try building a new shell instead?

Mapper 78 isn't very complicated, and I'd previously described how both hardware variants work, but you should feel free to post pictures and/or schematics.

Cool!!
Ready for some board porn??

Here is the assembled board. Bootgod has a better picrure than this, but sice it's offline...


Naked componnent side:


Naked solder side:
(not very useful...)


I'll insert the schematics on my next post, since I can't post more than 3 files...

Finally the schematics I have drawn.
It's done on Eagle. I find the symbols weird... any way to fix this??

Looks correct, it took me a while to understand the mapper description.
Could instead of using 2x 74'161 use a 74'373 or other similar thing?
By the way, what program is used to make the ROM board schematics we find floating around?
Any ideas?? I think that ones looks much better!!
Unfortunatelly, all cases I have use the middle connector to hold the board.
This PCB don't helps much, since it doesn't have lateral grooves

Edit: If someone is interested in some more "board porn" here's a folder on Google docs with some boards I've come across.
I try to scan the boards I use on my repros before moding it. Hope this can help someone besides me...
https://drive.google.com/open?id=0B0OtM ... 3hITHhGQmM

You're bothered by the IEC logic symbols for the latches? Or for the OR/NAND gates?

For the latter, use the "US" or "EU" libraries instead of the "DIN" libraries.

We have been told that the old black and white grid schematics were drawn with a 1986-era copy of ORCAD.

You could use a 74'377 instead of two 74'161s. The 74'373 or 74'374 lack the required active low latch enable signal ... although maybe you could use the spare OR gate in the 74'32, since you no longer have a 28-pin 128KiB CHR ROM.

Well...
It was a lot of work, but fitted nicelly!!



I've used some old 80wire IDE cable and a low power soldering iron, I think it was 15W.

Any suggestions of readings to learn a bit more of Eagle?
The sites I've been lurking around gives tips that just don't work
I really cannot pinswap logical inputs and add the power pins...
The later just don't appear on the board... what could I be missing??
I've tried the invoke command and no deal.

Invoke should really make the power supply things appear...

For example, if I INVoke a 74ALS08D from the 74xx-us library, I get this dialog:

I can then choose the "P" gate, and click OK to make the power supply connections become placeable.

What's happening for you instead?

(What version of Eagle are you using?)

Have Invoked the power supply pins, plugged all them on the VCC and GND track according to it's functions.

Then switched to board and they were not plugged.

What I'm doing wrong?
Should I add the pins on the IC's symbol??
Eagle version is 6.5.0 Light Edition.

Try using the ERC (the icon is a magnifying glass around an AND gate). I bet that for whatever stupid reason, the junctions aren't connected despite looking so.

Try also using the NAMe command on the nets around there, too.

You'll observe that in the PCB, the ICs Vcc pins are all connected and their Gnd pins are all connected ... just not to what you want it to be.

Great!!
That was it!!
It had many nets unconnected, and I've put togheter VCC and +5v, GND and VSS.
Looks like I need to use one or other.

Thanks for helping!!
Pretty nice software!!
I'll try to draw and home produce the boards for my mods!!
So no more rat's nest inside my cartridges!!