Problem with SD cartridge mod using prerunnerseth's PCB

[Joery]

Dear all,

I'm trying to do my first Game Boy Zero project and I am running into some problems with getting the SD cartridge mod to work.
I'm using prerunnerseth's PCB and did the mod exactly the same (I think?) as shown in the Game Boy Zero custom parts' video by wermy.
Unfortunately, I am only getting the RP.0 to turn on the green led indicator, but it doesn't start flash nor does it boot up retropie. When I stick the micro-sd directly into the SD slot of the RP.0 it boots without a problem. I've tried 2 different SD cards without any success... I have also used a multimeter to test out the solder points and cables, but there doesn't seem to be any problem. Does anyone have any tips for me to get this working? I have included some pictures of the mod in attachment.

Thanks in advance,

Joery (from Belgium)

[WoodMill]

I found that using the Gameboy cart, and the modified Gameboy advanced card reader, the game cart has to be inserted very specifically to line up the pins.

I frustratingly spent probably 2 hours trying to narrow down why the SD card couldn't be read from the cart, but still worked in the RPi.

It came down to the pins from the card don't exactly match up with the reader. I have no idea why, or where the issue is. But it's off by microMM's.

What works for me almost every time, is pushing in the cart not from the top center of the cart, but from as far to the side of the power switch I can. Make sense?

Don't force the cart down until both sides of the cart stop moving, only push down the cart on the side of the power switch.

Disclaimer is that this works for me. I have no idea is this will work for you. But by creating this very very very slight angle of the cart when inserted, the Rpi is able to see the SD card.

I really wish I knew how to fix so that I can securely push down the cart anyway I want, but it's just not worth tearing apart to figure it out.

Oh, I also soldered together the pins on the reader just in case. If you see PRS's cart, pins one and two are tied together, 3+4, 5+6, and so on. I bridged the connection of the spare pins on the reader, to try to catch any surface space I could.

Hope this kinda helps track down your issue. Not sure if my issue is common, or just happened to me.

[Joery]

Thanks a lot for the feedback. I will try your method of "pushing it with an angle" and if that doesn't work yet I will try to solder the pairs of pins (1+2, 3+4, 5+6, ...) together and see if that helps. I will be back with the results soon.

[Pun1sh3R]

Cart.jpg (41.28 KiB) Viewed 9005 times

Are your wires on the Cartridge reader lining up under the SD Cartridge on the game card? The traces on the left side are "extra". You want the ones on the right side.

Frank

[Joery]

Yes, this should be the case I think. Please see picture below...

[WoodMill]

If you've got a multimeter, you can test to make sure a connection it happening between the cart and the reader. I stupidly got ahead of myself and mounted the reader and just assumed everything would line up.

[Joery]

Yes I tried this and (un)fortunately all connection were OK according to ohm measurements. I tested this by sliding the cartridge in for 90% and it already has connection but no booting...

[WoodMill]

All you need to test is continuity. But if all contacts are making contacts, the next thing I'd look at are the solder pads on the Rpi. Make sure there are no bridged connections, and also double and triple check to make sure wires are in correct place.

Just gotta eliminate one by one, and move down the line.

I'd take the SD card out, and test one pad on the RPi, and then test the contacts from within the SD card reader. You don't need to know which one goes to which one, just that only one contact buzzes when you have you multimeter set to continuity. If non buzz, there's broken chain somewhere. If multiple buzzes, you've got a bridged connection. Then if you 8 individual buzzes, you know that you can eliminate everything about the cart, and then start checking the pads on the Rpi for bridged connections or improper wiring.

[Joery]

Yes I will do try that somewhere tomorrow. What I just noticed is that when I pull the brown cable (ground)? more apart from all the others, the RP0 starts flashing 4 times (ACT) the green led in stead of just keeping the green led on, so this cable/rpi pad could be my first target to check. Unfortunately retropie still doesn't boot...

[Joery]

I've soldered now the even and odd pins together as you suggested to increase the chance of getting connectivity between reader and cartridge, but still no luck...I've also desoldered the brown wire (GND) and resoldered it to another ground pin... also no improvement... see pictures for more info... I also tested everything with a multimeter and all looks fine... for me the wiring to the RP0 also is correct...any feedback is welcome.

Joery