Doctor V64 DRAM errors..

[phreak97]

ok, i know these things are bordering on the anti piracy rules here.. but it isnt mine, and i kinda dont want to give it back dead.. if anyone can tell me how to fix this crap please tell me!

[kyuusaku]

Um, reinsert the cards. If that doesn't work... may want to check Digikey.

[phreak97]

they got re-inserted a bunch of times (theres actually only one, but it worked with one before)

[kyuusaku]

Is the power supply well? Are you testing it connected to the 64? Do you have a cartridge inserted?

[phreak97]

i might test the power supply, i have tried with and without the n64 connected and same for cart insertion

[Vertigo]

phreak97 try asking on dextrose.com you'll probably get more help there.

Oddly, I had a RAM that tested fine but was wonky sometimes with 1 byte, but I swapped the boards over and it worked ok after that. Have you tried switching their places in the bottom of the V64?

[phreak97]

im back reviving old topics again.

the guy who owned this unit said i could keep it if i built something for him, which i did.

so now i REALLY want to fix it.


i've cleaned everything, resoldered everything, checked theres voltage to the W9925PF's ram.. and now i need outside help.

heres my error screen:



this screen is a bit confusing, and im not sure i fully understand it. the w9925pf is an mpeg-1 a/v system decoder, and it has a ram ic connected to it, which i assume is the w9925 dram, which fails.. but wouldnt that be the mpeg dram aswel? theres OK next to DRAM <--> MPEG DRAM, but theres only one ram ic on the board, and the w9925pf datasheet doesnt say anything about inbuilt ram, so i guess it has none.. just tested a theory.. this err's if i remove the ram expansion board. i guess that says the dram and mpeg ram is ok to a point:/ it also probably means the mpeg ram and the w9925 ram ARE the same thing.
dram0 and dram1 change to err 1234 if the ram expansion is removed (i only have one, theres two slots).. i guess thats the standard result for an empty slot..
i dont know what dm test is..


HELP!!

[l_oliveira]

If I understand your picture It's trying to tell you that the link from the game DRAM to the MPEG DRAM is ok. I suppose it's a DMA based device.
The DRAM connected to the W9925 is for MPEG decoding only. Last time I saw a Doctor 64 open was 1999 so I can't really say anything about it now.

Since you said you already tried to ressolder the chips, what I can suggest is try to change the chips. You can try to swap them around the ram board and see if the bad bank on the test screen changes.

In the Doctor 64 I saw back in 1999 it used standard 4 bit EDO ram chips in long boards with pins on a side.
The DRAM chips can probably be salvaged from old Pentium 1 RAM SIMMs. So it's just a matter of figure out which type of ram chip it uses and get replacement parts.

[phreak97]

alright, i have made some discoveries.
first, the dram errors are normal if there is no game in the ram, i was trying to put a game into ram with the n64 connected, but it turns out you have to plug the game directly into the unit. once i learned this the v64 passed all tests. and even let me run the game in ram, so it does work.
the problem i had initially was that the unit would restart when i was trying to load from cd. since i dont have any games on cd anymore im probably going to have to download a bunch of homebrew stuff to test it out, or (hopefully not getting too far over the edge of the piracy policy here) make backups of the games i own just for testing purposes. then i can test the parallel port link while im at it.

if it doesnt work, ill try a new cdrom drive, which is a shame.

[l_oliveira]

The power supply is really crappy on these units. Give it a look. It might be the cause of the restarts while using the CD-Rom (It draws more power thus causing the PSU to fail briefly)

[phreak97]

ah, yeah, i thought about that.. if i get the problem again ill try hacking up a pc psu