Search found 1163 matches

by Fisher
Sun Apr 11, 2021 6:47 pm
Forum: Reproduction
Topic: Help to find mistake for Circuit with NO SRAM
Replies: 13
Views: 2272

Re: Help to find mistake for Circuit with NO SRAM

The only time I saw something similar was when a guy suggested cutting one of the ROM pins to make it work fine with a SNES' Game Genie. In the end, I figured out that a small resistor mod would do the job better and not cause any kind of damage to the cartridges. Maybe the circuit just needs a pull...
by Fisher
Sun Apr 11, 2021 6:28 pm
Forum: NES Hardware and Flash Equipment
Topic: Short pads on certain carts
Replies: 1
Views: 212

Re: Short pads on certain carts

I remember to have read somewhere that this could probably be related to the PCBs being made at the edge of a big manufacturing PCB, but I simply can't find the place where I've read it! I had one Return to the Earth, which I used to make a repro of Double Dragon II that has a similar "feature". It ...
by Fisher
Sat Apr 10, 2021 5:58 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1214

Re: SNES oscilloscope readings?

I think pin compatible substitution packages will soon become a thing. IMG-20210326-WA0175.jpg This picture was taken ata a guy's workshop and posted on a Whatsapp group. These are the results of a few weeks of work, according to the guy. That's the result of fixing 162 consoles. He claims to have a...
by Fisher
Fri Mar 26, 2021 9:18 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

I think the eraseable windowed ones are the way to go, at least until you know exactly what an how to write it. :wink:
by Fisher
Fri Mar 26, 2021 9:16 am
Forum: Reproduction
Topic: Help to find mistake for Circuit with NO SRAM
Replies: 13
Views: 2272

Re: Help to find mistake for Circuit with NO SRAM

A good way to at least start troubleshooting is to try to read the ROM on the circuit, as it was the console reading it and compare the data you got with what you should be getting.
by Fisher
Wed Mar 24, 2021 7:06 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

The datasheet states that the windowless versions are OTP, the only version being able to be reprogrammed is the windowed one. It's eraseable with exposure to ultraviolet light with an wavelength shortrt than 400nm, 250nm typical and a power of 1200 μW/cm2, pretty much the same way as an EPROM. Unle...
by Fisher
Wed Mar 24, 2021 4:57 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

Looks like Caitsith2 has dumped then and posted here.
Please, keep us updated with your DSP "adventures". :wink:
by Fisher
Wed Mar 24, 2021 4:04 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

I forgot to post the datasheet.
Page 29 describes the programming process.
Seems pretty similar to a EPROM to me, maybe with some pins swapped.
by Fisher
Wed Mar 24, 2021 3:34 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

WOW!
I took a look at Aliexpress and the price is WAY bigger than before. :shock:
Fortunatelly EBay seems to have better prices, but not as low as it was.

If I understood correctly the datasheet, the chip should be written just as an ordinary EPROM.
Is it correct?
by Fisher
Wed Mar 24, 2021 2:07 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

A while ago I saw some "blank" upd77p25d for sale on Aliexpress. I've heard that they're common on some kinds os semaphors. Unfortunatelly I don't know how ro write these chips neither what files should be used. There are rumors that the firmware was dumped and is used on Higan (or BSNES?), but I'm ...
by Fisher
Tue Mar 23, 2021 6:34 am
Forum: Reproduction
Topic: schematic DSP-1, DSP-2, DSP-3, DSP-4
Replies: 21
Views: 4115

Re: schematic DSP-1, DSP-2, DSP-3, DSP-4

A while ago I tried to add battery backup to a pirate Mario Kart and this is what I ended with: https://drive.google.com/folderview?id=0B0OtMD7uFlqgMG9NdTVMMjJpLVU Probably the battery circuit is not correct, the other parts needs to be checked but I think it's mostly fine. Any corrections and addit...
by Fisher
Fri Mar 12, 2021 8:03 pm
Forum: General Stuff
Topic: SNES multicart worth fixing?
Replies: 18
Views: 3085

Re: SNES multicart worth fixing?

Well, I have absolutelly no idea too. And I guess that even if I had better tools to test it there shouldn't be much of a difference. I tested the ICs of the mapper and they are fine. I still get all 00's when trying to "view" the ROM, wich probably is telling that it isn't being enabled at all. Che...
by Fisher
Fri Mar 12, 2021 5:36 am
Forum: General Stuff
Topic: SNES multicart worth fixing?
Replies: 18
Views: 3085

Re: SNES multicart worth fixing?

I've found another one, slightly different, sory for the crap pictures: WhatsApp Image 2021-03-12 at 09.18.40(1).jpeg WhatsApp Image 2021-03-12 at 09.18.40(3).jpeg WhatsApp Image 2021-03-12 at 09.18.40(2).jpeg SNES Multicart 2.png Looks a lot like some NES' discrete mapper. Unfortunately, testing wi...
by Fisher
Mon Mar 08, 2021 4:04 pm
Forum: Reproduction
Topic: 74LS139 Logic inside SNES Cartridges
Replies: 5
Views: 3975

Re: 74LS139 Logic inside SNES Cartridges

Sorry for the necro-bump, but for posterity's sake - someone was asking me about this pinout and I found my 1A3B's '139 to be wired a bit differently. Interesting. I've got a pirate Super Mario All Stars + Super Mario World that's wired almost like yours, but is a little different since it uses 2 e...
by Fisher
Fri Mar 05, 2021 2:29 am
Forum: General Stuff
Topic: SNES multicart worth fixing?
Replies: 18
Views: 3085

Re: SNES multicart worth fixing?

Oh wow, that surprises me a guy like you wouldn't have one. Oh yeah, I would love to have one. It would sure make things easier if I knew what's really happening or at least could better describe what's happening. Sadly imports are stupidly expensive in Brazil, both in flat currency but especially ...