Hiya All I have acquired a Game Doctor SFII for the Snes, When I power up the snes I just get a grey screen and the Game doctor light flashes once. If I disconnect the floppy drive the light stays on, but still grey screen, All contacts have been cleaned with Alcohol, Does anyone know much about these and any common problems? I The voltage reg just gives out 12V and has 2 grounds which I find a little suspect, also the floppy drive is a slimline with 26 Pin IDC connector and no seperate power connector, anyone know where I could get one? Any Help Appreciated DJH
The voltage regulator should have two grounds (middle pin and heatsink), an input and a 5V output. You probably won't be able to get another floppy drive for it, they have been out of production for many many years. There are very few part scalpers with them and they will want nearly $100. Fortunately you can modify a normal 34 pin slimline floppy. See here: http://www.tototek.com/phpBB2/viewtopic.php?t=1334 There is a very good chance that the unit is permanently damaged, GDSF1/2s are very electrically fragile; I have 3 or 4 and none of them operate fully. Don't do anything with the floppy unless you can get the "BIOS" on screen and successfully backup a cart to memory and run.
Right, so even without a working floppy it should display the menu from the Rom? I thought it should, but wondered if it checked for a signal from the floppy on boot, I May start looking at what parts for the board I can still get, I should be able to change a few of them apart from rom image. I could not find hardly any info on these at all on the web DJH
Right ok, just did a bit more investigation, when I said that the power light stays on with floppy disconnected, and flickers on once when it is connected, this is because it is not getting power, If I unplug the power it still happens, so is obviously using power from the Snes. Now the only Power components I can see is the voltage reg and a few SMD resistors. Now taking the voltage regs middle leg as ground, one side gives 12V which is obviously the input line, the other outer leg gives nothing and acts as a ground, until it is plugged into a switched on snes, where it gives out 2.6V or 0.9 if floppy is connected, so I am going with a dodgy voltage reg first as it's the quickest to replace. Just have to find an equivilent with the same specs. DJH
Hmm, voltage reg had no effect other than making sure it is getting voltage and has now fixed the led problem, so just a grey screen Anyone have any other ideas? Voltage reg was obviously a problem, but looks like it may have taken something else out with it. DJH
Yes you should get a menu despite the floppy. Do you now get 5V from the new 7805? The only components which can be replaced aren't necessary for starting up the unit; the ASIC is what gets damaged.
Yeh, constant 5V out of the reg now, Resistors and caps all seem ok, so I guess I may as well put this on a shelf to look pretty then on the offchance I get another one with a different fault. Ah well, Thanks for your help tho DJH
GDSFII are very pretty to look at but functionally they're eclipsed by later Game Doctors which still only cost $30-50. GDSFI/II (pretty much the same thing): -load MGD2 binary files (no header) -can't backup HiROM games -can't properly backup games which aren't a valid ROM size (ie 10,12,20,24M games) -can't play HiROM games over 16M -can't save in HiROM games (I think...) -no SRAM limiting to break copy protection, so games must be cracked
For actual play the GDSF7 is ideal because of relatively low cost and great functionality. I love the SF7. And it was definitely superior to my old SF3. The floppy drive in my SF3 died too when I was gonna go and show someone some rom dump or something with it.. On that note, Calpis, you know Mega Man X featured I think some kind of ROM mirroring protection right? Something about it trying to read beyond the length of the ROM which on real hardware should just repeat the ROM again, but some backup devices wouldn't handle that right. And it wouldn't stop you from playing the game, it would just take away his Armor Power-ups making the game extremely difficult. The reason I ask is I backed up my Mega Man X to the DRAM on the SF7 and then turned off, removed the cartridge, and then played and never lost my power-ups. Which either means it does support that rom mirroring, or maybe the game was detected and pre-patched? Just curious if you know anything about it.
I don't know anything about that particular protection but it sounds neat, I'll have to try it out sometime. GDSFIII-7 do correctly detect mirroring and through their bankswitching hardware can choose to map/unmap 4M chunks and mirror duplicate areas. It's not 100% efficient though since it can't simulate a 10M game solely in hardware since the smallest block it can bankswitch is 4M. Most copiers map the DRAM in a static way, it can only be enabled or disabled just like a ROM. Pretend that the (theoretical 32M of) RAM is initially 00s or FFs, when the copier copies the Mega Man X ROM to the first 12 megabits of DRAM, the remaining 20M is blank. The game will know it's being played on a copier because normally in cart, there will be either nothing mapped after 12M or the data after 8M will be mirrored twice until 16M (and then mirrored again and again) depending on how the ROMs are decoded. When you read unmapped memory, you will get "open bus" which is the last value on the bus. One sneaky way you could get past this protection is to pad the game to the nearest power of two ROM size by tacking the mirroring or open bus values onto the end of the ROM
