ToToTEK.COM

madman · Joined: 07 Jul 2006 Posts: 598

Did you check for any accidental solder bridges?

Mystic_Merlin · Joined: 15 Oct 2007 Posts: 533 Location: Bangkok

jmlp · Joined: 20 Aug 2011 Posts: 13 Location: France

I had a solder bridge.I tought there was a bad chip but not.
Unfortunately i unsolded this chip and i have damaged the card.I add "personal connections" and it works.It will be difficult now to have 32M with 2 other chips...

jmlp · Joined: 20 Aug 2011 Posts: 13 Location: France

I added the last 2 chips (bottom) and since I have 0 in Dram.
I followed the scheme "tcdev" :
http://members.iinet.net.au/~msmcdoug/consoles/SMD_DRAM_schematic.pdf
I add same capacitors (blue) while the tcdev 's scheme does not provide.
Should I remove the blue capacitors or remove two last 2 chips to have 24M?

elrobertocarlos · Joined: 15 Mar 2012 Posts: 2

Hello,
I'm trying to repair a damaged memory board for my regular Pro Fighter replacing the first two memory chips with KM44C1000BJ giving me 8Mb of available memory enough for running some small games but the loaded game doesn't start then I performed a little experiment:

Make a dump of SMW game to the floppy
Select the copy recently created file from the tools menu (this will load the ROM to RAM)
Change the disk
Compare the two files

Comparing the files I noticed the second file (copied from RAM) has small differences from the original one but curiously only 0x7F bytes where randomly changed to 0xFF. Only a few times the game starts but with very few glitched graphics.

The left file in the photo is the good dump of the SMW game and the left is the bad one, all differences are just random 0x7F bytes changed for 0xFF.

My theories are very obvious, the chips are damaged or the chips aren't fast enough. What do you think?

MottZilla · Joined: 08 Sep 2004 Posts: 765

It isn't speed related. It could be as simple as a bad solder joint or connection point somewhere. You can buy a new 40 pin pro fighter ram board from Tototek if needed.

elrobertocarlos · Joined: 15 Mar 2012 Posts: 2

MottZilla · Joined: 08 Sep 2004 Posts: 765

I have a 40 pin 32M pro fighter ram board but I'm not 100% sure that it is free of defect and I don't know where you are. But from what I heard there isn't much to these ram boards. Problems are generally only caused by defective/damaged RAM chips which can be replaced if you track down the right DRAM chips, or if you have a bad connection either solder or maybe if the connector that plugs into the copier is dirty. Hopefully you can sort it out. It probably isn't a big issue.

I don't think the circuit for the RAM boards is very complicated. It's possible to make your own as long as you have good RAM chips which can be harvested from old computers.