Several Video glitches in my XVI - Bad Memory?

[hyrulebr]

Hi

Just after I made the RaSCSI work I tested 5 or 6 games and everything was fine.



I leave the XVI tuned on for a moment and when I look in the screen I saw that:



Very bad!   

I tried everything: turn it off for hours, tried another cables, without extra memory and even without RaSCSI.  Some games even didn't work the inputs (keyboard or pad didnt work ex. Alien Syndrome). I don't know what happens but is it possible to the memory faulty in a few minutes?

I have installed a Xellent30 (but no sw drive yet) and more 6MB inside (total of 8mb). As I wrote I already take down the extra memory but same results. But some games works without any flawsand some with minor glitches. Below some pictures.

I tried x68memorytest and receive A LOT of error. See picture below. Everything indicates that my main memory died in front of me!  Do you think it's is replaceable? Did someone already replace the memory? Please help me....

Super Street fighter - some glitches



see bridge



Alien Syndrome freeze after that screen and no input



Geograph seal very bad



Final fight letters and numbers



Dracula like vertical scanlines



Undeadline  score



Cotton I cannot see any glitch



Daimakaimura  I cannot see any glitch









 

[hyrulebr]

I ran mtest.r

and got error with  Text memory


Also with memory graphic test, it ran until "OK" But was weird because I could see the dos prompt below the blue columns. (I cannot see it im my other Sharp, a Super model).



I tested with Mahou Daisakusen. High resolution mode




and see what happens when I selected low res mode



Could memory only do all these vertical blue lines? It's like static interference...

[leonk]

I would remove all the extra memory and run switch to set it back at 2Mb. Then run memory test.
if you still get an error it could be one of:

- needs a cap kit on motherboard if hasn't been done already
- one of the memory chips  has a short on one of the legs due to leaking cap fluid
- one of the memory chips failed and needs replacement

if he memory test passes then one of the memory chips on the add-on pcb is bad or the pcb itself needs to be reseated/going bad on you.

[neko68k]

The trick is that TVRAM can be used as regular RAM and many games do this. Capcom is particularly fond of doing this so any errors in TVRAM would show in other data and may cause games to not run at all. :/

[hyrulebr]

I would remove all the extra memory and run switch to set it back at 2Mb. Then run memory test.
if you still get an error it could be one of:

- needs a cap kit on motherboard if hasn't been done already
- one of the memory chips  has a short on one of the legs due to leaking cap fluid
- one of the memory chips failed and needs replacement

if he memory test passes then one of the memory chips on the add-on pcb is bad or the pcb itself needs to be reseated/going bad on you.

Hi

I got this XVI as junk and a technican replaced all caps and moded an atx power supply. See the pics:












As you can see in the last image, the board was cleanead with a chemical bath (something like that) and receive a protection coat.

Anyone already exchange these memory chips with sucess? I can't believe it works for some minutes.. Is it posible to chips to go bad after warn up?

[leonk]

The "bath" the PCB got in the last picture is insane.  All capacitors (and even resistors) eventually fail.  I wouldn't want to be the poor technician trying to work on this X68K in 30-40 years .. when not only would I need to replace the now new caps, but also figure out how to break through the extra crap put on the PCB in order for the soldering iron to work!

[hyrulebr]

The "bath" the PCB got in the last picture is insane.  All capacitors (and even resistors) eventually fail.  I wouldn't want to be the poor technician trying to work on this X68K in 30-40 years .. when not only would I need to replace the now new caps, but also figure out how to break through the extra crap put on the PCB in order for the soldering iron to work!

My bad! It isn't a coat. See the board AFTER this bath. No residue at all. You can see in this new picture that he took off the battery holder and fix it in a easilly acessible place .





And this was the botton board (2nd mistake). The memory are in the tower (slot side). But all caps are exchanged, even on floppies. So I think the problem is a bad chip somewhere. I'm looking for a physical map of memories in the MB. I'm trying to OCR service manual looking for some help. If someone have this information please let me know.

[hyrulebr]

Hi

I didn´t even tried to fix my X68000. I´m not a "friend" of  a soldier iron and have to pay to someone to do it to me. Too much work and it´s not guaranteed. So today I won this auction in japan and my hope is that the motherboard is working condition and I can exchange it:

https://page.auctions.yahoo.co.jp/jp/auction/k292222863


From a very know seller and I paid a good price. But now I realize that something could be wrong with motherboard since the psu and floppies was taken off. I can understand if only the psu was take off (to exchange to a new one ATX) but the floppies... maybe the motherboard is bad and someone use it just for parts... This seller also repairs stuff... maybe he didn´t try this one because spare floppies are hard to get and the machine needs it to work...

What do you think? I know that I have to receive it and test to make sure but I start to think it wasn´t a good deal after alll....

Previous to my bid I didnt see the additional pictures below description. Someone know whats is that mod? Overclock? HD63450 chip is the DMA control. I hope the previous owner didn´t burned the motherboard trying a extreme mod!

Any hope for me?

[neko68k]

Overclock. Here is some info.

[hyrulebr]

Overclock. Here is some info.

Thanks!

I know that you don´t have crystal ball but what is your feelings about this x68000? Do you think the motherboard can be in working condition?

[neko68k]

Maybe, I don't know It looks kind of rough.

[hyrulebr]

Well, it will takes a long time until arrive and finally test it. 

[hyrulebr]

Hi

I didn´t even tried to fix my X68000. I´m not a "friend" of  a soldier iron and have to pay to someone to do it to me. Too much work and it´s not guaranteed. So today I won this auction in japan and my hope is that the motherboard is working condition and I can exchange it:

https://page.auctions.yahoo.co.jp/jp/auction/k292222863

This X68000 finally arrived and the motheboard was in working order! 

Passed in Mtest and memtest68X with no error! 

The only problem that I encounter was that I had to keep overclock mod because the previous owner took off the originals 33.33mhz  and 40mhz crystal and replace with 38, 40, 50 and 60 crystals with two switches to select. (you can see it in the previous pictures I posted). So the minimum clock that I can get is 12,5mhz too fast for some games. I tested Dragon Spirit and the audio is weird. I know other games also have problems with anything more than 10mhz. I plan to put the original 33.33 crystal back and leave it as original state.

I will keep that problematic motherboard (of first post) and if anyone know what memory I cvan exchange let me know. But now let's play some games! 

[kamiboy]

Replacing the main memory modules on X68000 models is tricky. Lots of legs, large ground planes and tiny traces are a recipe for disaster unless you are very skilled and have the right tools.

Finding replacement is not that hard, just read off the model number on the module and search ebay for replacements. If you have a schematic for the XVI motherboard and you are technically proficient you can use the memory test to trace the fault to the exact memory module that is faulty so you don't have to replace them all.

[hyrulebr]

Finding replacement is not that hard, just read off the model number on the module and search ebay for replacements. If you have a schematic for the XVI motherboard and you are technically proficient you can use the memory test to trace the fault to the exact memory module that is faulty so you don't have to replace them all.

Hi, I´m not technically proficient (I can only soldering wires, small stuff) but I can hire a technican do it for me. I did not tried to fix the motherboard because I can end buying the modules, paying the service and still can end with no success. I got the XVI service manual in the NFGgames FTP but didn´t find were TEXT memory is installed (where the memtest68x shows a lot of errors). Maybe even more memory is bad...

So in choose to buy another one (I also take a risk) but in the end everything was fine. But I imported the second X68000 to Brazil and costs a lot .I´m very interest in save it.

Please can you tell me more about how I can use the memory test to trace the exactly fault module?

Thanks!

[repoMan]

You can trace the suspicious RAM ic by looking the failure byte pattern (seems that the lowest order nibble in every word is 0); but to do this it's recommended the use of schematics if you don't want to go completely nuts.

As per the pics found in the web, the XVI has the TVRAM and GVRAM as ZIP ICs, so it could be definitely a hard task to desolder the chips. Both RAM types are organised as 4 x 128KB blocks so they could use 64K x 4 ZIP RAM ICs, I'm wild guessing here, your fault seems to affect also 4 bits in a row, a full IC.
Looking at the schematics you can also find that it could be the glue logic the faulty one...

Have you tried to check if some of the ICs is hotter than the rest?; I know, X68000 are not the more friendly machines to repair...:-P