snes's wont boot.

Lately ive been getting in more and more snes systems that seem to have the exact same problem.

the power light comes on and stays on, and you get a short flash on the screen as well as some audio buzz but no games will play. On these systems no amount of cleaning will get them working again.

these particular snes systems will boot to the sd2snes menu but thats it - nothing else works. other Cartridges dont work either.

I have had 2 1-chip systems like this and would like to get them working.

Im thinking these systems have a bad ram chip but i have no idea how to know for sure.

are the ram chips from regular snes's interchangable with a 1-chip?

mvsfan wrote:

Lately ive been getting in more and more snes systems that seem to have the exact same problem.

the power light comes on and stays on, and you get a short flash on the screen as well as some audio buzz but no games will play. On these systems no amount of cleaning will get them working again.

these particular snes systems will boot to the sd2snes menu but thats it - nothing else works. other Cartridges dont work either.

I have had 2 1-chip systems like this and would like to get them working.

Im thinking these systems have a bad ram chip but i have no idea how to know for sure.

are the ram chips from regular snes's interchangable with a 1-chip?

First thing I'd do is check the ram chips and count if they have the same number of pins.  Next if you can get the part number google the datasheets and compare pinouts. Also good to see you posting again, I missed having you around.

First thing I'd do is check the ram chips and count if they have the same number of pins.  Next if you can get the part number google the datasheets and compare pinouts. Also good to see you posting again, I missed having you around.[/quote]

I remembered i had read the wiki over at console5.com and it had a cross reference on snes ram chips so i went back there.

the ram chips are pin compatible between regular snes's and 1-chips. they also appear to be electrically idential even though they have different part numbers.

It looks like im going to be doing some ram chip swapping this weekend.

In every respect these snes's should work. the power is good and they do give the flash on boot that they normally would before a game loads. and the weird thing is that the sd2snes menu boots.

Im going to try replacing 1 and see if i get any change. if not i will replace the second one. I wonder which one i should try first though u4 or u5. I guess it doesnt matter but it sure would be nice to have a good idea which one is bad first.

I believe thats because the menu isnt using the bad ram that only occurs when a game is played.

I really doubt the ram chips are dead. Don't try it on a onechip first. Find a non-onechip that has this problem and try it on that first.

Drakon wrote:

I really doubt the ram chips are dead. Don't try it on a onechip first. Find a non-onechip that has this problem and try it on that first.

yeah but these 1-chips dont work. I also have a gpm board that has the same problem.

what do you think is most likely wrong with them?

mvsfan wrote:

Drakon wrote:

I really doubt the ram chips are dead.  Don't try it on a onechip first.  Find a non-onechip that has this problem and try it on that first.

yeah but these 1-chips dont work. I also have a gpm board that has the same problem.

what do you think is most likely wrong with them?

From here I can't say, I'd need one in my possession. If you're going to try some experimentation do it on a gpm pcb, don't do anything to the onechips until you've found the issue.

Drakon wrote:

mvsfan wrote:

Drakon wrote:

I really doubt the ram chips are dead.  Don't try it on a onechip first.  Find a non-onechip that has this problem and try it on that first.

yeah but these 1-chips dont work. I also have a gpm board that has the same problem.

what do you think is most likely wrong with them?

From here I can't say, I'd need one in my possession. If you're going to try some experimentation do it on a gpm pcb, don't do anything to the onechips until you've found the issue.

Yeah id kinda like to do that problem is ive been taking parts off the Gpm for a while now.

ive got another parts board that works perfectly though its just missing the power jack. Its perfect to pick the ram chips off of.

Okay so use the donor gpm with a gpm that has this trouble. Also don't even think about removing the sop chip without using a hot air device.

Drakon wrote:

Okay so use the donor gpm with a gpm that has this trouble. Also don't even think about removing the sop chip without using a hot air device.

yeah, i was planning on using a heat gun.

another trick i just learned! for the snes that absolutely wont boot.

if no amount of cleaning will get it to boot its basically because the cleaning solution cant cut through the crud.

I took 2500 super fine grit sandpaper put it on a credit card and inserted it 3 times and it chewed through the gunk without taking the gold plating off.

that snes works great now.

but the first 1 i have still doesnt work. it has to be something more than gunk.

More sand paper then

Drakon wrote:

More sand paper then

now you just want me to take the gold off huh? :P

seriously though i know its not advisable.

Btw, i found out that the snes ram chips are still available.

these part numbers should work.

ms62256; lh52a256n; cxk58257; mb84256c; 65256blfp; hsrm20256lm; gm76c256.

Some useful information i found in case anyone else needs it.

I also found out that pin 10 on the cic is the reset line - and if you stick a multimeter on it it should read 5v when the snes is operating properly, and 0v when you hit reset.

if it reads anything less than about 5v then something on the circuit is not letting the cpu start.

either a broken trace to the cart connector, bad ram or a bad cpu.

now im getting somewhere with this.

I replaced the two ram chips on this snes with two that were known working and it didnt make a difference.

also replaced the work ram.

so that eliminates 3 things.

I dont think this has anything to do with the 1-chip itself because i have other non - 1chip systems that have the same problem.

strange.