Mega-Drive Switchless, please help! [SOLVED]

Hello!

I am attempting to install a switchless mod to my Mega-Drive, motherboard revision IC BD M5 PAL VA4. I'm using a PIC16F630 flashed with the hex from dforce3000.de (which seems to be down now).

I have wired it according to the diagram here:

http://retro-magic.de/sites/default/download/Mega_Drive_Switchless_D4S.pdf

It's partially working, holding the reset button cycles through modes as it should, except that I am not getting any light from the LED. I swapped it out with another LED just in case it was a faulty one, but still nothing.

Has anyone come across a similar issue when installing this mod? Is there anything I should check that might be causing the issue?

I'd appreciate your help, as I'm a bit stuck!

 

wath kind of led are you using? think the d3000 mod calls for a common cathode bicolor led if im not misstaken?

 

I believe that's what I'm using. I can't remember where I got this bag of LEDs from, but they're labelled Red/Green/Diff and have three legs.

I do have some other multi-coloured LEDs I could try, but they have four legs and I wasn't sure they'd work with this.

 

you could try testing the led with a cr2032 battery. Just hold the middle leg to negative and first one then the other leg to positive. if it lights its common cathode. if not its common anode (or broken).
You could use a rgb one commen cathode. just leave one color out. and you might need to adjust the resistors to get the best color mix.

and your sure your using dforce3000s code? and not Sebs. cause that one calls for a diffrent LED.

 

I just tested the LED I have in place in the MD with a CR2032 and yes, it lights up. One side red, the other side green, so it looks the LED is good and of the correct type.

It's definitely dforce3000 code I flashed. It's really bugging me because I can't figure this out, but I am very much a newbie so it's probably something really obvious.

If the chip is working and switching regions then I assume it must be getting power, and it's switching modes when I hold reset so that part must be wired correctly. I've checked all the points from the chip to the board with a multimeter and they all have continuity, there's no kinked or broken wires or anything like that. I wired the common base of the LED to ground via a 220ohm resistor as instructed, and I even wired it to a different ground point just to test and I still couldn't get the LED to light.

I've spent long enough on it today, maybe sleeping on it will bring new ideas, but honestly I'm stumped.

 

That version motherboard uses 5v on reset rather than ground. I don't know if the code you are using is compatible, but I know that seb's code isn't.

 

I am certain I am using the d3000 code, I chose it specifically because it addresses that issue and should work on all variations of the console. I downloaded the hex from this page: http://retro-magic.de/Download. I downloaded "Mega Drive von D4S".

Like I mentioned though, the mode switching is working so the chip seems to be getting power and is intercepting the reset button as it should, it's just the LED that won't light up.

 

Some of the points in the install doc are wrong. If memory serves a ground and 5v point are inverse on one of the models.

I would just verify power connections with a multimeter, rather than following a guide.

Also try using meter to measure the lead points on the pic with no led connected. You should see them change when you swap modes.

Also, pics of install.

 

Thanks, I'm still learning as I go along with this stuff so I'm not confident with veering away from the documentation yet, so please excuse any daft questions!

I've measured with a multimeter, but it's a cheapish one so I can't vouch for it's accuracy.

Pin 1 is measuring 5.06v, Pin 14 is 0.00. So, I guess the power and ground are as they should be?

Pins 5 and 6 change as I hold reset. They are either both 5.06v, or just one or the other is and they cycle through until reset is released.

Pin 10 (language_out) measures 5.06v.

Pin 13 (reset) measures 0.10v.

I'm going to just double check my wiring and then I'll take some pics. Constructive criticism on my soldering/wiring is welcome, but please remember I'm self-taught and still learning, so please go easy on me!

 

Right, here we go, pics of the install. I know it's a mess, but like I say, I'm still learning. It's much better than my first attempts at soldering, believe me!

Anyway, I tested with the multimeter while the LED was connected and the legs of the LED are getting the same 5.06v as the pins they connect to. I really don't know why this isn't working.

 

if everything is as you describe. It should work! And dforce code handelse both types of resets. im betting at a bad/wrong resistor ont the common cathode. that would be the only component not tested by now.

 

I've swapped out the resistor too, and tried it without the resistor entirely. Pulling my hair out now, haha!

 

Sounds to me like your LED is incorrect type.

What your multimeter is saying - a common cathode LED will work. Maybe you have picked up a common anode.

 

Drat.

I guess so. So frustrating. Off to eBay I guess, unless anyone can recommend a next day delivery place that sells what I need?

Thanks for the help everyone. I'll pick up some new LEDs and report back.

 

just for fun, if you have more than one LED, swap polarity of the led and cycle the modes with one far end dissconnected. thats all i can think of. It will light or it wont and might smoke.

 

So, my new LEDs arrived this morning and... you were right! I must have been using common annode LEDs before. The new common cathode ones work perfectly and the mod is complete. I took it out and rewired it all so it's a bit tidier, and yeah, working like a charm.

Thanks for all the help guys, really appreciate it. I always learn so much from this forum!