Case won't fit on my repro :-(

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Fisher
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Case won't fit on my repro :-(

Post by Fisher » Sun Jul 31, 2016 11:04 am

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:
Repro front
Repro front
An this is the back side:
Repro back
Repro back
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.

lidnariq
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Re: Case won't fit on my repro :-(

Post by lidnariq » Sun Jul 31, 2016 12:42 pm

Fisher wrote: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?
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.)
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.
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.

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Sun Jul 31, 2016 1:04 pm

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?

lidnariq
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Re: Case won't fit on my repro :-(

Post by lidnariq » Sun Jul 31, 2016 1:25 pm

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.

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Sun Jul 31, 2016 3:12 pm

Cool!!
Ready for some board porn??

Here is the assembled board. Bootgod has a better picrure than this, but sice it's offline...
Assembled Cosmo Carrier
Assembled Cosmo Carrier
Naked componnent side:
Cosmo Carrier - component side
Cosmo Carrier - component side
Naked solder side:
(not very useful...)
Cosmo Carrier - solder side
Cosmo Carrier - solder side
I'll insert the schematics on my next post, since I can't post more than 3 files...
Last edited by Fisher on Sun Jul 31, 2016 3:18 pm, edited 1 time in total.

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Sun Jul 31, 2016 3:17 pm

Finally the schematics I have drawn.
It's done on Eagle. I find the symbols weird... any way to fix this??
Holy Diver Mapper.png
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... :wink:
https://drive.google.com/open?id=0B0OtM ... 3hITHhGQmM

lidnariq
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Re: Case won't fit on my repro :-(

Post by lidnariq » Sun Jul 31, 2016 3:37 pm

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.

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Mon Aug 01, 2016 4:10 pm

Well...
It was a lot of work, but fitted nicelly!!
20160801_160146.jpg
20160801_160227.jpg
20160801_160255.jpg
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.

lidnariq
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Re: Case won't fit on my repro :-(

Post by lidnariq » Mon Aug 01, 2016 4:49 pm

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:
invoke.png
invoke.png (2.02 KiB) Viewed 6587 times
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?)

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Tue Aug 02, 2016 3:03 pm

Have Invoked the power supply pins, plugged all them on the VCC and GND track according to it's functions.
Schematic.png
Then switched to board and they were not plugged.
Board.png
What I'm doing wrong?
Should I add the pins on the IC's symbol??
Eagle version is 6.5.0 Light Edition.

lidnariq
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Re: Case won't fit on my repro :-(

Post by lidnariq » Tue Aug 02, 2016 4:20 pm

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.

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Fisher
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Re: Case won't fit on my repro :-(

Post by Fisher » Tue Aug 02, 2016 6:30 pm

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.
Board2.png
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!! :lol:

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