Dragon Breed sprite issue....

[MLew]

I have a weird sprite issue on my Dragon Breed. Made by Irem, it runs on the M-81 hardware. The dragon/player/enemies are all partly transparent and the colors that are present are off. I reseated every socketed chip on both boards as well as cleaned the legs with a pink eraser. (Though didn't look like it needed it, board in tip top shape visually)

See pics...

This is what it's SUPPPOSE to look like..




This is what it looks like..note the off colored explosion as well.






Here is a pic with all the lightning right at the start of the game, to show the transparency/color issue better


This is the only problem. The BGs are great, sound is killer (love the music in this one), and its quite playable as is, but obviously want to tackle the sprite issue. Thoughts?

[cw]

just the old standard of reseating chips and checking voltage...

[SavannahLion]

Did you run the diagnostics?

[MLew]

Did you run the diagnostics?

Yes. Ram/rom check ok. But character screen shows the problem/transparency:

[lilshawn]

if you have the ability, pull the ROM chips and do a checksum/compare with a known good copy.

system tests are sometimes fudged to make it look like it's actually checking...wherein the are actually just doing a basic connectivity check. (IE no CRC or check summing the contents.)

[MLew]

Unfortunately I don't. Nor do I hav much understanding of it either. Never messed with pcb repairs

[lilshawn]

would you know anybody (friend/business or otherwise) who would have an EPROM programmer you could borrow?

if not maybe invest in one off ebay. one could be had for about $30 http://www.ebay.ca/itm/Universal-EPROM-pic-flash-mpu-Programmer-27C256-27C512-/170929104559?pt=LH_DefaultDomain_0&hash=item27cc2b26af#ht_12493wt_1397

what you will need to do is dig up the rom for the version your game is, off the internet. The software the programmer comes with should have somewhere you can load the downloaded rom data to and compare if it's the same as the data contained inside the ROM. if it doesn't match, you'll need to program it again.

to program ROMS depending on the type you have will determine how you will need to erase it.

one you will need a special UV light to erase it. they can be had on ebay for around $10 http://www.ebay.ca/itm/UV-Eprom-Eraser-Erase-Ultraviolet-Light-Erasable-Timer-/130569404459?pt=LH_DefaultDomain_0&hash=item1e668b002b#ht_2987wt_1163

the 2nd kind you can just erase with the programmer. also known as an EEPROM (Electronically Erasable Programmable Read Only Memory)

lastly there is a kind that is WRITE ONCE. also known as a PROM (Programmable Read Only Memory) or OPT (one time programmable) you would have to find a compatible chip to replace it with...this chip can't be erased.

likely you have the first kind....it will have a sticker over the rom...if you peel it off there is a window on it.

The purpose of this window is to allow the ultraviolet light to reach the transistors which compose the EPROM memory array and dissipate the electrons trapped on the transistors. This is how it erases.

this is where the issues come in. because the window lets in UV light to erase the ROM...if your sticker/label whatever covers the window has fallen off... parts of the code contained inside can be erased. an open window on an EPROM can be erased with normal room light (although it could take a few years to be 100% erased...it can happen to small portions in a short amount of time.)

 There is actually an issue with some STERN pinball machines where the EPROMS are directly behind the fluorescent light in the backbox. the UV light from the fluorescent light causes the glue to fail and the labels fall off...then they start getting erased.

[SavannahLion]

if you have the ability, pull the ROM chips and do a checksum/compare with a known good copy.

system tests are sometimes fudged to make it look like it's actually checking...wherein the are actually just doing a basic connectivity check. (IE no CRC or check summing the contents.)

According to the manual it does an all 0x00 and 0xff check. Though I admit that isn't very thorough. At the very least, you can still learn something about the system even if it does "pass".

I was kind of hoping the test might reveal evidence a broken trace or a cold solder joint or busted ram.

[lilshawn]

likely it requests the values from x00 to xFF and if they get returned then it says it's good...regardless if the data is wrong or not.

query - response

x00 - 9A 34 9A 56 FA 12 5A 0F
x01 - 45 82 A8 32 42 33 AA 34
x02 - etc
.
.
.
xFD
xFE
xFF

did we get a response every time we polled the ROM - yes? good! must mean it's working. This is good for a basic test...but no good against data corruption. the system can read all the data...but we have no way of knowing if it's good or not. I'd bet dollars to doughnuts a blank rom would check good on that test.

You need to compare the data against a known set. They do this usually with a CRC (which basically takes all the data runs it through a whole mess of complicated maths to get a basic number...if the basic number doesn't match what it's supposed to be...the data is bad.) or by a Bit for Bit comparison (which you would do with an ROM programmer and a known good set of roms.)

a bad scratch ram chip would probably cause either random mess...or a boot fail. (not work at all)

this seems pretty regular. I'm leaning to corrupted RAM data. This is why people are suggestion cleaning the legs of the chips and checking voltages. both can corrupt the data streaming out of the chip on it's way to it's destination.

have you checked the voltages (particularly the 5 volt line?) some machines can get pretty picky. check at the ROM chips too. usually the 5 volt input on them is opposite of the pin 1 (opposite sided pin of the dot marking pin 1 or to the right side of the "notch") they all should be 5.00 volts or more. never anything less.

[MLew]

Wow. Thx for the great info! I'll check the voltage this weekend. Is there any other mechanical failures I can test/look for --BINGO! Either that, or I was attempting to say "before" but it was too many letters to type-- I start jumping into reprogramming roms?

Also, how do I know what roms are what and what version my board is?

[lilshawn]

the stickers on the ROMs should say the version. If not, sometime during boot or system tests it should say a version.

[MLew]

It looks like I'm gonna have to reprogram a/some chip(s). The voltages are fine everywhere. My next question is, how do I know which one holds the sprites? Can I remove one, then power the board to check to see what changes? Or do I  not want to run a board with a chip removed?

[ChadTower]

Did you check the voltages?  Slight undervoltages can still run the board but cause all sorts of minor random issues.

Nothing else is worth doing if you haven't verified the voltages coming into the PCB and then on the PCB itself.

[MLew]

Yes, i checked all the chips, and coming into the board. It all checked out. I will do it again tho, jus to verify, any other points of measure I should be looking at?

[JasonRain]

just the old standard of reseating chips and checking voltage...


_________________
WoW Gold Kaufen|Diablo 3 Gold|Runescape Gold|GW2 Gold