Trying to FIX: Earthworm Jim SEGA Mega Drive (Genesis) Game
Вставка
- Опубліковано 13 кві 2020
- Hi, in this video I attempt to fix a Sega Mega Drive (Genesis) that fails to start.
Remember that this is just for entertainment and I am not an expert in these repairs. The processes in the video may not be the best way, the correct way or the safest way to fix these things.
I do love fault finding and trying to fix broken things so I hope that comes across in this 'Trying to FIX' series.
Many thanks, Vince. - Навчання та стиль
Shame, I looked forward to seeing earthworm soccer and sensible Jim.
The first of those sounds like an interesting idea for a game, the second sounds like the name of a racehorse or greyhound...
Haha
The two ROMS are in "parallel" except for one or two control lines. It could have been sorted with a bigger ROM chip with enough capacity. But probably not possible at this era or it was more expensive compared to using two half capacity chips. So they fitted two of them. Still the console need to "select" the one from the top or the one from the bottom, based on what portion of the data is willing to read. NAND chip sure is helping to this task so the console just see the cartridge as single ROOM chip with the NAND taking care of picking the right chip (TOP or BOTTON) based on the console signals sent to the cartridge. A2 is and Addres LINE, the more Ax the bigger the ROM is ROM is as big as the biggest Ax pin. To get the size do 2 power Ax. If you happen to have A15 its a 64K ROM (2 pow 16). Lines are numberes from 0, so A15 is actually the 16th line. If you have twin 64K chips, they add, so the cart has 128K ROM.
There you go :) parallel bus with the nand doing chip select.
Exactly!
The reason there are two chips is that Earthworm Jim is a 24Mbit game and ROM chips are normally made in sizes that are a power of 2 - if you used a single chip it would have to be 32Mbit with 1/4 being wasted - so they split the game over 2 chips, one 16Mbit and the other 8Mbit as that was cheaper at the time.
Always a Pleasure to stop by and watch your work my friend!
Just watching your videos helps keep me sane , Thanks for all you do
So nice to the fellows from the Genesis / Sega days, all around 40's or over.. Thumbs up for all you lads!! Keep it going!
Great video Love these challenging trying to fix videos
You tried everything you could Vince. Very interesting to watch, as usual.
I like your profile picture That's from one of my favorite music videos
Evelyn Madill
:)
Another comment that shows at the top ruining the video before it starts 👍🏻
@@IronWarrior1316 I had that same problem with a rap battle I was watching Rayman versus Earthworm Jim and the top comment spoiled it, who even thought it was a good idea to move the comments for the bottom to the top in the first place?!
Evelyn Madill happens on A LOT of videos. I did not like the comments being moved in the first place, this issue makes it worse. It’s like a reaction to read the comment as the video loads or during the initial ad.
Thank you. Watching your videos is a great distraction in these times.
Wow Sega Megadrive that brings back memories. Looking at my x box one x and all the fancy 4K graphics of today I now have a hankering for a good game of earthworm Jim or sonic. Unlucky Vince but you got further than a lot would!
C1 to C3 seem to be buffering caps for the chips. The switching action inside the chips can cause voltage drops if the caps do not work properly and therefore the chips can fail. In 12:16 and 12:49 you can see that the ESR of the caps is 16 Ohm which is in my opinion to high. A ceramic cap should have less than 1 Ohm. If you do not have a wired ceramic cap you could use a smd one with a jumper wire. The capacitance is not critical 100nF should also work. But check for the voltage ratings.
I think these testers does not measue the ESR correctly on capacitors below 0.47 or 0.1uF. But you're right, it's worth a try.
Those magic testers are notorious for inaccuracy on really high precision or low capacitance caps. I saw that too though and scrolled down to see who else spotted it.
The game is split over 2 ROM chips, the address and data lines will be connected in parallel, with OE pins driven by that smaller IC. Best way to compare pin readings there (in case of failed pull ups or failed clamping diodes) - is to remove one chip, then compare readings on data / address bus pins between the chips, but I see you did that =D Still watching =D With regards to programming two eproms, you would split the game down the middle I think, and you have to byte swap the ROMs too before programming up the chips. Thanks for the mention again =D Much appreciated =D Loving the videos!!!
❤
Love this channel very cool to watch and learn.
Great video Vince. Shame about the game not working but at least you tried. We are only human after all. No one is perfect.
hey Vince the topic you are missing here is called 'multiplexing'. the 2 chips are wired up together on the same pins and then they are 'multiplexed' with the NAND chip acting as a controller by toggling the cable select pin of the active chip. the nand is set up to invert the pin from the system between the 2 rom chips - when one is selected the nand sets the other one low
If you need me to burn some new rom chips, let me know. I have a load of eproms etc for mega drive
I love fix it videos from u ive watched them all! U should do another xbox one controller trying to fix. I recently bought a lot to try and fix! Its just so fun and satisfying fixing things
Love the videos as always, iv learned afuw things.
Even if we were not successful we learned a lot from your videos, I am very grateful, I have some games that do not work I will test 💪💪
Good videos vince ....all the way from SOUTH AFRICA💯✌
I've only skimmed through the video but assuming that the connector pads are also clean (and I note that you buzzed them though too as corrosion can be an issue) you probably have a corrupt mask ROM (they are the two 42-pin chips). I'm not familiar with the MD carts but the smaller chip (I see you noted it down as a 74HC00) is just used to select between the two chips as and when their data is required by the MD. You could try checking which outputs are used on the 74HC00 and verify that they are toggling as required based on the inputs. However it's most likely that, as already mentioned, you have a mask ROM fault. The only way to verify is with a suitable EPROM programmer and a dump of the mask ROMs (no doubt they are online somewhere). If one or both of the mask ROMs are corrupt then you could program up a suitable EPROM (if you had an EPROM programmer and the required EPROMs). BTW, assuming there's enough 'head room' in the cart then use sockets for the mask ROMs instead of soldering them back in, it makes life easier for any future repairs and even when testing (I mention 'head room' because sockets will of course raise the height of the chips which could foul on the cartridge shell if it's a slim fit).
I don't know the pinouts, maybe pin 42 is NC, but when he did a diode test between ground pin and pin 42, it tested as open. the reading was done at 18:42 . So either that pin is already NC or there's a break somewhere under the package.
ah, I'm mistaken. I was wrong about how the diode test works. That reading shows that the ESD protection diode for that pin inside the package has failed short, so the game probably got a nice little shock in the past.
always great to watch you :)
Sorry to hear that you couldn't get the game to work once again. I did learn as you did about how things from that era work. I hope the other games are of more success in fixing.
hey Vince, I really like your videos, you should continue and show us how you program the new eprom and install it in your cartridge.
Hey Vince, sorry you didn't fix the game, looked like you tried practically everything, still an interesting video, thanks mate for keeping us sane, stay safe.
a NAND gate is an AND gate combined with a NOT gate. So if both inputs are 1, the output of the AND gate would be 1; the NOT part then inverts that.
Nice job with the desoldering of those big ICs!
This is a great game bro!
Sat here bored, and wondering what to watch. And then I see another VINCE video! Boredom cured. Thanks!
You should do a review of your top 5 fixes Vince. :)
Hi i really enjoy your videos! Thanks for making them. I used to love taking electronics apart when i was kid (used to get me in trouble lol) the thing i wanted to ask is i would love to start tinkering again and hopefully fix some basic faults but dont even know where to start in equipment needed. I dont soppose you can do a list, make a video or provide some links on whats needed please? I know there is some obvious equipment,there is quite a few that im not familiar with. Thank you for reading! :)
Back in the day happened sometimes when the cartridge was accidentally removed with the power on 😫 Uh sorry owner of that James Bond game I borrowed!
Sounds like a tragic story honestly.
I've known that to kill the console as well. We used to get them in for repair when they were still new. Had a few dead 68000 CPU's, probably caused by hot plugging a cartridge
Hey Vince, get a minipro, it will allow you to test logic chips like the nand on this cartridge and also program eproms for this. It will come in handy with a lot of other repairs too, so well worth the money! I have on and used it for so many things now...
love earthworm Jim, great game
You're doing god's work
Hey Vince, just wanted to say:
The reason the two ROM chips (the 42 pin chips) are connected together is because they share a "bus"; a bus usually has some address pins (the A pins you noticed), which are used to select which data to read out, then some "data" pins, where the actual data comes out. Since they use the same physical lines, both chips can't be active at the same time, so they have another line, usually a "chip select" or "output enable" line as well; this is likely what those two pins that the chips *didn't* have in common were for. Most likely the NAND chip would be used to select between them based on an extra address line from the cart slot (since most likely the cart slot has more address pins than these chips).
To touch on the NAND chip, indeed you are correct that NAND means "Not AND" or easier to understand "inverted AND". An AND/NAND chip will usually have several individual AND/NAND "gates" within it, and each one is usable independent of the other. Each gate only has a single output, with multiple inputs, but it only ever outputs a 1 or high state when both of it's inputs are high/1, in the case of an AND, and in the case of a NAND, exactly the opposite is true; it always outputs a 1/high unless all of it's inputs are high, in which case it outputs a 0/low. These chips are common and you should be able to look up a data sheet for them. There are also a couple other types of gates; a Not gate (or inverter) which is where the name NAND comes from, because it's just a Not and an AND gate hooked together, then there's also an OR gate, which I bet you could figure out how that one works easily (and you guessed it, a NOR gate too) and then an XOR, which is "eXclusive OR" (and again, XNOR does exist as well); these little circuits can be wired together to create most of the circuitry needed to make an entire CPU! There's a guy on UA-cam (Ben Eater, though there really are a bunch of these tbh) who walks you through a lot of this stuff in a really simple and easy to understand manner; you should look him up :)
Hopefully this was helpful, and thanks for the awesome content as usual!
EDIT: also, I've just remembered this: nandgame.com/
It takes you through building an entire simple CPU from the ground up using these components!
greetings from india ,love u videos😊😊😊 a good time pass in this lockdown
Nice relaxing video
👍👍
That’s why I like it! 😊
The game would be split by default so one bin (dump file) per chip would be easy , geat video
Thanks for the video, gutted it didn't work.
The NAND gate is there to do a chip select (or chip enable) from either ROM. It is usually done because of either too many address lines for that processor to handle, or the correct size ROM chips worked out more expensive than two smaller ones. Therefore the NAND chip has to switch one on and the other off instantaneously to fool the processor. It is also known as "bank switching". It is well known on the Sinclair and Amstrad computers with 128K of RAM as the Z80 processor can only handle 64K with 16 address lines.
Sweet, interested to see how you get on :-)
Oh I love the Sega Mega Drive! I would marry it if I could 😀😀😀
Hi vince dont give up hopes yet i think you're going to make a revisit and you might fix it on that video but at least you tried to fix it Good luck on the revisit if you make one. :)
Hi Vince I’m the one who commented this just to let you know in case you see this account in other videos you make but once again at least you tried
Hope you and your family are okey! Miss your videos, but just worried today!
Going to like before I even watch it! Love MMV!
Think I would have tried the resister trick on the bottom chip as the top chip may have been working right and the bottom one needed the resister ? ?
With an update to the switching of you able to change the controller layout so now it’s easier to use those other consul controllers
The nand gate iis a chip select. It allows the compute to choose which chip. It needs. Could be connected to wo address lines. And the needed chop. Is pulled low when needed.
well, at least you can always clean it up and make it a display only piece :)
What type of multimeter and soder iron do you use?
This video was great
No video without rolling on the floor checking stuff 👌🤣
You probably need to program a new ROM. I suggest chatting to Gadget...
As for how to program a game onto two chips, it doesn't have to be two chips, it just has to be big enough to hold the entire game. But if you do use two chips, it's as simple as splitting the ROM file into two files and flashing each half to one chip. Remembering which one is which and making sure they are soldered on in the correct spots, of course. One of those universal flashers would probably come in handy more than once, might be worth investing in one.
Ohh, enjoyable, let's see... :)
What’s poppin’ V-Squard!
As you suspect, one of these mask ROMs is prob bad. This would have been a good opportunity to break out the O-scope and look at each parallel address & data lines, along with the NAND chip's decoded chip select lines. Some might have looked a bit messy (you have to get used to looking at tri-state signals) but by lifting each leg on each IC, you may have been able to find the chip that was unable to drive / receive. Still a good experience though. The scope lets us do less guessing ....
What’s been one of your favourite fixes that you’ve looked forward too, thinking it will take a while but you were completely surprised how quick it took.?
You don't split the game your self. Each chip has a separate file which is programmed on to it. I doubt that you could get the file from Sega. Therefore you would need a working game and take the chips off and plug each chip one by one into a chip programmer. Which is a USB device which you can get of Ebay. Although I wouldn't recommend you buying one since the cheaper ones seem to be specific to a range of chips. Anyway you use the programmers software on a computer to read the chip and make a file. Then put the blank chip in and write the file to it using the software. Then repeat for the other chip.
There are two rom chips because earthworm jim is a huge game. They are connected in parallel because the system bus has only a limited amound of address and data lines available. The way this works is the smaller chip will enable only one of the rom chips while the other sleeps.The switching depends on the requested address.
You put a lot of work into that. You eliminated everything. Hopefully you might come back to it and naill it.
Even though I don't know what the fuck your on about I find this very interesting
Hello Vince, do you know how to fix the av multi out on ps2? It’s broken and it isn’t showing up on the tv.
You would need a eeprom programmer to compare the eproms to a known good dump off the game of the internet. Really easily done. This is often done when repairing arcade pcb's using ROM's from MAME.
Coming on a week that we have seen you vince hope you are well mate.
Where did you get that resistance tester from with the green LCD looks neat!
The small chip is an address decoder. The big chips are memory chips. Both memory chips share the data bus and the address buss. The chip select of both chips comes from the address decoder (built with NAND ports).
Will donate $20 US to see you keep working on this. You can do it!
can you tell us how to connect 3 screen to one gaming pc using hdmi
The Sn74hc00n Is a demuxing chip. The main processor of the sega can only access memory in chunk files of a certain size. Say 64kb and the 74hc00 Allows the processor to switch between memory banks. So say you had 512kb of memory the Processor needed to access it would split it up into 8 ports allowing the system to access 512kb of memory when in theory it's only capable of calling 64kb at a given time. This is the same memory setup used throughout a lot of the 80's-90's and was prevalent in the much acclaimed HP 48GX Expandable RPN Calculator.
You could also try to pull the faulty pin up to vdd with 10k? This is just a quess, don't actually know if megadrive already has pullups on bus lines. But it should not break anything. Maybe worth a try? Edit: Just thinking if the pin "up" driver is faulty inside the chip. But pin could also be stuck down or up, and in that case the resistor trick won't help...
Just a question do you have coffee at all before you repair things as I've noticed that you can be a little rough I know if I have coffee before I repair things that I can get a little heavy handed 😕
He seems a little hectic, too, at times. Coffee could def be a reason for that. 🙂 Still a great video!!
Hello, could you help me? I'm trying to fix a hyper x headset, I have to change its tip, but I was confused, because I have at the ends a green and a blue wire (which are on the right and left sides, I believe) one with two colors, green and red, I believe that be it the ground, and there is the room that is the microphone, it is divided into two one red and one orange. what do I do with the two of the microphone?
Hi Vincent how can I contact you about fixing my xbox scuf elite controller. All four of my rumble packs in controller have stopped working
Thank you for the continued fun! I suspect the NAND is handling the chip select logic. As you noted both of the ROMs (assumed) chips were in parallel, and so there is likely a chip select (CS) signal sent to enable (EN) one of the two chips at any moment in time. Also, did you check all the board vias? You mentioned checking the traces from the edge connector to various parts on the board, but wasn't sure if that probing covered all the vias.
This game! I remember the first time i tried... Was on SNES... Love it!
No new vids for 5 days? 😮
Hope everything is ok!
The sega mega drive was awesome
Maybe try to switch both of the chips with each other
i know im late but pleese help my switch have a problem so the place were you slide the joycon is started to wiggle a little bit when i shake it normally it doesnt but now it does pleese reply
First and foremost, ROM chips back in the early-mid 90s were very expensive. Getting for example a 8 MB chip would cost more than twice the price of a single 4 MB chip, and thus more than two 4 MB chips.
My calculations based on the highest Address pin count indicates that the chips are 1 MB ones (A0-A19 means addressing width is -20 bits, which is 1048576 address points available). The fact that A19 showed “open line”, however, suggests that A19 is actually not even connected.-
If it WAS supposed to be connected, then that means that there’s possibly an internal break at that point, meaning the system only has access to the lower half (or upper half, based on how the internal signal architecture works).
BUT if it was left out on purpose, then that chip is actually a 512 kB chip (meaning it only has about 19 bits of addressing space).
Honestly, I need to rewatch the video, get the specific name for the chip and see if it was meant to be a 1 MB chip or a 512 kB chip... edit will follow.
EDIT:
After poking around a bit, I have come to the theory that the lower chip is actually a 2 MB chip, and the upper chip is a 1 MB chip, yet the chip pinout corresponding to that 1 MB chip (which is 27C800-compatible) doesn’t seem to use an A19-pin (which is why it shows as “open line”), which means that it must use a different method to switch between the lower and upper halves. Perhaps that is what this NAND-chip is for? If so, that would make the NAND-chip a type of MBC (short for “Memory Bank Controller”, which was used widely in the Gameboy)...
...but this is becoming a bit much to wrap my head around... like, is it really a 27C800-compatible chip? Is it supposed to NOT have the A19 pin?
*So many questions... not enough answers...* 😓
Great attempt, looks like a bad ROM chip is likely the culprit. I'm sure someone out there could program a new set of roms for it.
The PAL version of earthworm jim is somewhat valuable as far as mega drive games go. Might be worth it if you can get a set of the eproms shipped for a few bucks.
Can you fix switch carts too?
Hi vince iv just watched this one, those 2 chips are piggy backed together, so I think the short to ground on pin 10 of one of the chips would drag that line down on both chips, you should try bending that pin 10 up out of the way so it's not connected to the other chip and see if the game boots, if not try the resistor trick on that particular DISCONNECTED pin. not sure about that pin with no reading at all, maybe it would get that line through the other chip, and since it's open and not shorted to ground it might still work without it.
You could always cut the track from that pin too on the board to save you having to desolder the chip again
I remember my sonic 1 game doing this exact same thing. Had to get mum to buy new one in the end (I was 7)
That NAND gate is a Lego part. It could be bad but it's unlikely. It handles chip selection between two parallel PROMs. You have a bad PROM. To write a split image you would need two image files because splitting it in the middle wouldn't work. You would need the correct image for each PROM.
Could be useless, but did you try to heat-up in hoven either the complete board or just the 2 main components(after desoldering them )?
This is actually a classic way to regenerate components or harden them when use in harsh conditions.
It works also for consumer products some time, i did it several time for some graphic cards for example. 100-120°C in hoven for like 10 mins, it worked several times for me (but not always, obviously it depends on the fail, but for such a basic rom, i would definitely try).
the bottom rom is the culprit its been shocked
Vince or anyone have a little forum space to share any broken items they have to help with fault finding as I am starting out getting interested in fixing things and been doing ok but now have one issue I have no clue and would like some help. So is there anywhere I could post my problem for people to help?
I converted a snes pachinko game into chrono trigger last night, then swapped it into a japanese chrono trigger shell. It's quite fun, but I only do it to crap games. Also I keep the maskrom.
As for the two maskroms in this earthworm jim, it was probably just cheaper for them to make it into two, as they need less space in each maskrom. What a maskrom is, is essentially an eprom, but the game is built into the chip as it's created, so they don't need to flash it and you can't erase it, as it's not programmable, the game is literally just built into it. I'm going on snes here, but you can get an eprom and use a program to split it into multiple files, so you can flash each one to one eprom if you wanted to replace the chips in this one. You could only do one, but realistically, there's no way to know if an image you flashed would work with the other half in the remaining maskrom. I've never tried that.
Anywho, good try Vince, looking forward to more if you got more game stuff. That's what I enjoy the most.
I personally would have applied the N64, blow on the cartridge pins. This definitely works. Although, SEGA likes to be different. 😁
In regards to how us developers break-up games you need to understand the systems limitations. So for instance the NES can only read 32k of address space (ROM) at a time (if my memory serves correct). So making larger games, lets say 128k then we use a method called bankswitching. That's 4 x 32k banks of ROM storage (so-to-speak). It's also not uncommon to have 2 or more duplicate game engines within the one game.
Fetching data when bankswitching in general is slow so it's critical to make decisions on when and where to bankswitch to make the game seamless and optimized. Most the time we try to only bankswitch during screen or level transitions ect (save machine cycles). This is where RAM plays an important part as it will remember the stored values when using bankswitching like lives/ammo/health/x&ypos ect ect. From here you can bankswitch back into the main engine loop/s like nothing happened on the users end.
There is alot more to it, however that's the quick run down of what's going on behind the scenes.
I saw the bit on Nandgates and remembered an excellent book and course I tried a few years back. From a Nandgate all computing can be built if I remember correctly, and the course was called Nand to Tetris, as it takes you from a NandGate all the way up to building a game of Tetris. It's found at www.nand2tetris.org/
I'm sure someone reading this will love to try it!
What if you try the reset button,and reinstall cartridges back a few times,?I try it first week of lockdown, something to do.It work with me with a racing game.Its like it cant read information, maybe not enough power,going into cartridge .Thats my Theory anyway?
A) it’s never the cap that’s for power filtering. It’s definitely an address not connected as if it was a data line youde get no boot. I would try the extra pull down but if not maybe the address lines need pull-ups to vcc instead I don’t exactly what is going on in those chips but ide try the extra pull down that you didn’t try then a pull-up on a19 if not
Regarding burning the roms: it is the same procedure as for one chip. The difference is: you have two rom image files.
The chip is a Quad 2 Input NAND Gate by Texas Instruments, and the variant is 14 Pin DIP
This means there are 4 individual logical NAND gates within the IC, each having 2 inputs and 1 output.
Each gate uses 3 pins (AB & Y), there are 4 gates (4x3 = 12) + 2 pins for powering the (IC 12+2 = 14)
Inputs are A and B, while the output result is Y, below is the truth table for NAND
AB Y
00 1
01 1
10 1
11 0
Dear mymatevince i have a bsod that i can get fixed by recovery mode and was wondering if i could send it to you, to see if you could repair and return (i would pay for that of course) but of course i would love to see another switch repair even if it does not get fixed or gets damaged i would still quite enjoy watching it. Sorry in advance if you happen to receive these requests often. :)
@retrorepair may have some input
Sweet