Supermodel Forum

Do you have any recommendations for SMD rework soldering stations? There are some cheap ones on Amazon but I don't want to get something that I'll end up hating to work with.

There is a Step 2 board on eBay but the seller is clearly inexperienced with electronics and found it as part of their deceased uncle's lot of stuff. They took apart a Model 3 PCB because they don't want to bother shipping the whole thing and are selling it in pieces as-is untested. It's a risk but it could at the very least supply the parts (assuming they aren't broken there either).

Something we've never had confirmed: is there really a Step 2.1? Or will any Step 2 board work with Daytona USA 2 (which some sources claim is a Step 2.1 game)?

model3man wrote:M5M4V4169CTP-15
The important searchable bit is M5M4V4169, the other numbers may change according to production batch or exact variant which I don't think is important

Where would old RAM like this be sourced? None of the big US electronics suppliers carries it (they often carry old CPUs and MCUs, though). It's not on eBay (which I've used to find EPROMs). Tried Alibaba as well just in case. I guess the next step would be to identify old graphics cards that use this RAM and search for those.

I have never seen "Step 2.1" appear in any official Sega documentation, but I haven't looked closely.

There are however certainly two different revisions of the Step2 video ASICs. The actual bare PCB itself is the same partnumber.
However some of the ASICs have slightly different part numbers. I have one of both, just can't dig it up right now. It might've been the Venus/Earth asics. I swapped them between Daytona2 and both worked fine. However, I don't know if using one in place of the other causes jtag errors where it wouldn't otherwise.



I dug out my extra video board, which has some weird failures. The 2d layer works perfect, except it's too bright (probalby MSB of all bits stuck high). The 3d layer is completely corrupted, but oddly enough I can see faint traces of cars on the track moving in the noise! So I think there may be some weird failure in the Jupiter chip. Self-test reports Texture memory 00 error, just like yours. Here are the jtag errors on my board: https://i.imgur.com/4KuxjD1.jpg



As for repairs,
You're looking at around $180 for a hotair station that wont light your house on fire (Aoyue 968+, and half that again for a passable iron. Basically, you'd hot air in a loop over the ram pins and carefully lift it with tweezers. Then you'd get some decent solder wick and clean off the old pads so they're flat but without lifting the pads off the FR4 or ripping traces.
Finally, make sure the new chip's leads are completely flat (can be fluxed and wiped off with the iron) and then flux the preped pcb pads. Then place the chip on, tack the 2 corners and drag solder.

Chip packages are designed to withstand a fixed number of reflow/heat cycles. Typically for modern chips that's 3 cycles.1 bottom reflow, 1 topside reflow, and allowance for 1 rework cycle. After that it's all up to fate, usually you will be ok, but the fewer the heat cycles, the better.

I would get some old trash video cards and try hotairing the old ram chips off, cleaning the pads, fluxing and cleaning off the TSOP chip pins, soldering back on and cleaning. Flux and 91% alcohol.
I can do it for you no charge if these donor chips I got off ebay end up working - will try swapping them onto one of my working boards.

My boundary scan test passes without any errors.

That's an interesting idea regarding old graphics cards for practice. There are numerous hot air stations on Amazon in the sub-$100 category. Aoyue branded ones run about $175 and include a soldering iron and some other tools. I won't be able to attempt this until October at the earliest as I have to return to California temporarily next month.

One source of replacement chips would be the Step 2 board being offered on eBay but its condition is completely unknown and the seller is extraordinarily unhelpful. I doubt they'll even ship it with ESD protection. But it's possible the chips would survive. I think I will put in a low-ball offer tomorrow.

Where are you based? I may take you up on your offer in a month or so if I don't feel confident with my ability to rework an SMT part

I think I’ve found a source for the RAM chips. Minimum order is 100$, 16 units. That’s on par with a new Step 2 board. Might order them and keep them around.

I think that step 2.0 and 2.1 are compatible, I did some conversion between games and it worked, but I cannot affirm 100%.
I have two 2.0 boards, Video and CPU, I remember that they had some fault like the sound that was mute, but maybe I can get some replacement chip. If you want I can send to you.

Sorry to read about your Videoboard issues Bart.
This is the reason why Supermodel is so important!

Step 2.0 and 2.1 are interchangeable.
As far as I'm aware is just a hardware revision, no functionality added and none removed. I've encountered no issues.
The power supply is very important, a power supply with adjustable voltage is a must.

Did you buy your board from a Chinese seller or a US seller?
I've not had much success buying Model 3 (Or Chihiro) from China, other items have been fine though.

You could try asking Ken at irepairsega.com about your issue.
If you explain you are the author of Supermodel emulator I'm sure he would help you.
http://www.irepairsega.com/

Abelardator2 wrote:I think that step 2.0 and 2.1 are compatible, I did some conversion between games and it worked, but I cannot affirm 100%.
I have two 2.0 boards, Video and CPU, I remember that they had some fault like the sound that was mute, but maybe I can get some replacement chip. If you want I can send to you.

If you have a working video board you would be willing to part with, I would be interested in purchasing it at some point after September.

icuk7 wrote:Sorry to read about your Videoboard issues Bart.
This is the reason why Supermodel is so important!

Step 2.0 and 2.1 are interchangeable.
As far as I'm aware is just a hardware revision, no functionality added and none removed. I've encountered no issues.
The power supply is very important, a power supply with adjustable voltage is a must.

Did you buy your board from a Chinese seller or a US seller?
I've not had much success buying Model 3 (Or Chihiro) from China, other items have been fine though.

You could try asking Ken at irepairsega.com about your issue.
If you explain you are the author of Supermodel emulator I'm sure he would help you.
http://www.irepairsega.com/

Mine was a US seller. I'll reach out to Ken! Thanks for that information. I haven't yet built a power harness by the way but my old one still works. I have all the connectors I need now, though. It's just a matter of finding a PSU that should work with a sufficiently beefy 3.3V rail. I've no plans to do so this month because I have to tend to some business in California but I may look into it in October again, when I plan to resume playing around with my Model 3 board and building an interface board that lets me load up code from a PC.

There is a guy can repair this pcb's but sadly is in japan.
https://www.youtube.com/user/lukemorse1
I really enjoying watching all is videos, we learn just a bit about this.