FDS occasional graphic glitch

[ringl]

thank you for reading the post.

recently I try to experiment with the fds loader software. I have ran into problem I can't solve. below is the explanation of my testings and issue.

first

I have famicom and famicom disk system (02 powerboard, fd7201 drive chip)

I have many fds games, some original, some have been re-writed with the official diskwriter many years ago (several labels on top of each at the disk label area)

I build the ram adapter cable and it seems to work ok.. I can load games to fds ram adapter via cable, write them to disks using copymaster / disk hacker.

I have an original copy of The Legend of Zelda 2 リンクの冒険 and it works fine, i first made a copy of this disk and then made a copy of an fds image and both additional copies work fine with no errors or glitches.

But, my problem came when I tried to to load an image of  悪魔城ドラキュラ (overseas name castlevania) I got several graphic glitches (mainly the item in the itembox is corrupted and the player flashes when moving)

I tried loading different versions of this fds image (1.0, hacked etc), writing them to several disks but no combination seems to fix the issue and all have the same grapics corruptions.

If I try the same images on an emulator they work perfectly.

I have ran the famicom built in ram checker  which says ram is ok
I used the Nintendo FMC disk checker (pink disk) to verify that the disks I wrote could be read ok (all came back fine)

but the graphics corruption is there.

I tried some other games which wrote without error or glitches (クレオパトラの魔宝) cleopatras magical treasure

夢工場ドキドキパニック (Mario 2? doki doki panic) has corruption on the characters head.

Both games always have the corruption in the same places and it doesn't matter if I load to ram adapter or write to disk.

I've cleaned all the connectors and usual things too.

I suspect perhaps a fault dram chip on the ram adapter itself that the ram test does not check. scrolling / moving seems to make it worse. Disks copy fine.

in a few days I will buy another ram adapater and disk drive unit and famicom to try and isolate the problem to one specific thing (such as ram adpater). It's no real trouble but I would like to know the actual cause. I can then load a copy into both units and see what happens.

even if the ram adapater has faulty dram, perhaps it can still be used to make disk writes with. I wonder!

thank you for advice

[80sFREAK]

Try Pro Wrestling. If graphics flickering, replace CHR RAM.
/thread

[ringl]

Thank you.

Will try it soon
Post Merge: May 18, 2013, 08:04:30 am
update!

try to use the pro wrestling as suggest.

result is flashing of characters.

solution.

change chr-ram as mentioned. Problem solved.

I used the zelda 1 / 2 before to testing the ram adapters but they do not show the graphical errors.. even with something like mario bros 2 there is only minor glitches.

castlevania and pro wrestling really show up the errors quickly. <- I recommend the pro wrestinlg as good way to test ram adapter quickly.

thank you. problem fixed.

just for adition info.

the ram adapter is hvs-fmr-03.

the fault ram chip is made by fujitsu. MB8684 15L (150ns)

I replace it with same type of new old stock fujitsu chip.

[P]

Glad that you solved the problem!

This has been researched in this thread http://www.famicomworld.com/forum/index.php?topic=8512.0. This problem seems more common than I thought. Maybe I should get Pro Wrestling just to check my ram adapter as well.

[80sFREAK]

Better to use 120 or 100ns SRAM. Just in case. Manufacturer does not matter.