Search found 10 matches

by akokun
Fri Apr 09, 2021 8:02 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Thanks, those were great reads / watches. I've always wondered how exactly the PPU1/2 worked on a physical level as opposed to in the software realm where you just think of them as some registers that you upload stuff to at certain times.
by akokun
Thu Apr 08, 2021 4:47 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Oh hey I didn't realize this got a page 2. I don't know much about it, but I don't suppose FPGA will ever help us with 5a22 replacements since they're all on 3.3v or some such? Also, I suppose I should look into getting a logic analyzer. I feel I could figure lots of things out if I knew where my ga...
by akokun
Wed Apr 07, 2021 1:53 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Sure sounds like the S-CPU is toast there. You might find this: http://www.projectvb.com/nss/logs.htm informative That was an interesting read, and it reminded me... I should put the burn-in cart on my everdrive. The first snes is still totally dead but at least this super famicom can seemingly boo...
by akokun
Wed Apr 07, 2021 12:34 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Indeed, but no matter what I do all 24 address lines seem to always be 0. I just thought it was odd how I was getting something on the data pins for whatever reason. And that's seemingly the only activity I get off of this thing other than clock waves and such. And alas, I have temporarily boxed up ...
by akokun
Wed Apr 07, 2021 10:24 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Actually my super famicom arrived just now. Also currently blackscreening but this one seems to have a much easier to diagnose cart connector issue. Poking around inside of it, I see the expected activity of lots of digital stuff on pins such as address 0 / 1 / 2 off the CPU after boot which I wasn'...
by akokun
Wed Apr 07, 2021 7:19 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

I've simply moved the SNES into a place where the scope can reach it now. I noticed I'm getting some actual readings off the cpu data pins after power on CPU D0 60 HIGH CPU D1 61 LOW CPU D2 62 HIGH CPU D3 63 LOW CPU D4 64 HIGH CPU D5 65 LOW CPU D6 66 HIGH CPU D7 67 LOW (AA with game Cybernator in) C...
by akokun
Wed Apr 07, 2021 2:47 am
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

You probably need a powered usb hub, not a better extension cable. I had a similar issue, and hooking a powered hub at the end fixed everything, otherwise the voltage was too low for things to work. Ie comp -> 5m usb extension cable -> powered hub -> usb device. After a lot of reading on this stuff...
by akokun
Tue Apr 06, 2021 2:56 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

My USB scope is acting up and crashing the software (I'm guessing it's because of signal loss in my USB extension cord. stops acting up when plugged directly) so I just reverted to multimeter for this one. Those 3 pins give 4.90V which I'm assuming is what we want. Also tried powering on without the...
by akokun
Tue Apr 06, 2021 1:03 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

Re: SNES oscilloscope readings?

Okay thanks guys I should have known to check that first. Also hey lidnariq, when doing some research I think I saw a thread of you helping someone with a similar problem for like 10 pages, lol... I think it was a broken stack register or something which sadly was unfixable. Be back at some point.
by akokun
Tue Apr 06, 2021 12:49 pm
Forum: SNESdev
Topic: SNES oscilloscope readings?
Replies: 30
Views: 1112

SNES oscilloscope readings?

I am trying to diagnose why this snes sits on a black screen and doesn't boot. Got it off ebay, and the first obvious issue was no power. Replaced the fuse with the correct type and I get a nice 4.81v off of the output of the voltage regulator, light turns on, and so on, so I really doubt it's a pow...