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Double Pro Fighter bug

Kaneda - Feb 18, 2004

		Kaneda		Feb 18, 2004
			I currently own a Double pro fighter but have some problems.. no sound, mixed screen, etc... i'm trying to repair it to debug some of my demos (see my other post) this a link... to a more detailled description of the problem and of the DPF... if you see something strange, let me know! Kaneda

		Arakon		Feb 18, 2004
			looks like the ram is damaged. check the pins of the ram board and board connector. I'm guessing the ram chips themselves are partially shot, tho.

		Kaneda		Feb 18, 2004
			i tried WITHOUT the ram (and w/o the floppy) and same problem... i mean even playing a cartridge directly won't work... so it's something else...it's seems i have to use my testmeter ... Kaneda

		ExCyber		Feb 18, 2004
			I'd check the cart slot for shorts/opens (specifically pins A10, A12, A14, A16, and B6-B11), and if that turns up nothing try resoldering and/or replacing the 74245s. edit: I'm assuming that the 74245s have something to do with address buffering by their number, it may be that they have nothing to do with it (I have no chance of tracing the connections with only a zoomed view of the front).

		Kaneda		Feb 19, 2004
			in fact, i don't know what is the black thing on the cart adaptator...someone knows ? i'm even suprised by the adaptator schematic....(some some pins aren't connected,in back) well...thanks for hint... i'll test it deeper later... Kaneda

ExCyber

Feb 19, 2004

	
	
		
		
			in fact, i don't know what is the black thing on the cart adaptator...someone knows ?

They seem to be pulldown resistors. I can't tell 100% what they're connecting to but from their positioning they're most likely terminating the !LO_MEM and HS_CLK signals, which the DPF probably uses internally.

	
	
		
		
			i'm even suprised by the adaptator schematic....(some some pins aren't connected,in back)

The MD/Genny cart interface has a lot of pins that are not used by a typical cartridge, really a typical cart only needs access to about 43 signal pins plus something like 4 or 5 power pins, so that leaves about a quarter of the pins unused. Most of these are either for test/debug or for advanced peripherals like the 32X.

		Kaneda		Feb 20, 2004
			i checked the cartridge port pinout available on the net... you think it's the direct Adress access which can be faulty so... since the gfx are messed up, i think it was something like word/byte selection... anyway, i'll check for shorts and see what i have thanks again

ExCyber

Feb 20, 2004

	
	
		
		
			i checked the cartridge port pinout available on the net...



you think it's the direct Adress access which can be faulty so...



since the gfx are messed up, i think it was something like word/byte selection...

There's nothing special about graphics data from a cartridge access POV, it's just data coming off of the ROM like anything else, so any problem should affect graphics, code, data structures etc. equally. However if the problem only occurs at higher addresses, the main code for the game might be unaffected since it is likely that it is at the beginning of the cartridge. That's why I think it's an address bus problem. Any other problem within the DPF should either be crashing the game very early in its initialization (i.e. before the Sega logo) or only occur when playing a game from RAM.

It occurs to me that as a somewhat better test of this theory you might want to try playing Columns, since it should only use the same address range as the DPF BIOS (it's twice as large, but on an 16-bit bus rather than 8-bit, so the pins should be the same)...

edit: based on the fact that sound and joypad are not working, I'd check pins B09/B10 first (these correspond to the A22 and A23 signals, which distinguish between VDP, RAM, and the Z80/IO area). Particularly, pin B10 could be floating (edit: or maybe shorted to pin B11). However, this is still just a guess. :huh

		Kaneda		Feb 25, 2004
			i made a standard check tomorrow...no resistor or capacitor dead it's harder.... but it seems i need to make all the pins check with dpf connected on the Genny... some pins are ok (like +5V/GND/CART_IN) but the adress and data pins must be tested connected

ExCyber

Feb 25, 2004

	
	
		
		
			but it seems i need to make all the pins check with dpf connected on the Genny...



some pins are ok (like +5V/GND/CART_IN) but the adress and data pins must be tested connected

Why would they need to be connected to the genny?

		Kaneda		Feb 25, 2004
			since the DPF stop the data through the 74LS245(? or other bus) i need a signal to open all the gates... i tested all...as i can i got something strange with B11 (address 23)... i need to trace...and it's hard with the 2 sides PCB edit: if must be something else...Puyo2 is 2MBytes so adress23 is always 0

		Kaneda		Feb 26, 2004
			(my msg wasn't save?) I finally was able to dump Puyo : ALWAYS think to do the "unplug/plug-chip" method when you have problem! it's a perfect SMD file without problem so no cartrige port problem, something else... do you know if it's normal my PALCE20 is quicly hot (REALLY hot) ?

		ExCyber		Feb 26, 2004
			I really doubt that this is normal. PAL chips usually operate at a fairly low frequency. You should probably check all pins of the PAL for Vcc/ground shorts.

		Kaneda		Feb 27, 2004
			the palce16 are normal...but perhaps it's for the SNES func.... it was also strange for me, it's why i asked... i'll see this side thanks again for your help!