Pi-MMS Troubleshooting

[Yop]

Hello,
I have a MiSTer Multisystem (from Heber) which works fine. I recently bought a Raspberry Pi Zero 2 W (from an official dealer) and the Pi-MMs board and case (from Heber). I downloaded the software from the MT32 Pi project and tried to solder the boards. The result was ugly so I went to a professional.

Unfortunately, it doesn't work. Powering directly the Pi or plugging the Pi-MMS into the MMS changes nothing and shows nothing. Maybe I forgot a setting but I double-checked the PDF without success.
I probably have to see on Heber and MT32 Pi forums but I wanted to begin here first because I'm more used to this community.

Below is a picture of the boards, where you can see the soldering. The MMS is turned on.

[Flandango]

When first powering on the unit...do you see any lights on the Raspberry Pi?
If so, at least you got power to the RPI. Next is check your MT32 configuration. It's been a while since I built my (standalone) Mt32Pi so I can't be 100% sure, but I don't think it worked with my oled and Mister without modifying the configuration file.

[Yop]

Nothing. It looks like a brick.

[Flandango]

If you have a multimeter, I suggest you carefully check to see if the raspberry pi is getting power (at it's gpio ports) while it's plugged in to the MMS and powered up.
Now, I do see you mentioned that you powered it directly at one point....hopefully it wasn't plugged into the MMS at the time....I am not sure if the Pi-MMS board has any protection if the rpi is powered externally.
If you didn't and you are not getting voltage at the GPIO pin, then you could try removing it from the MMS and try powering it directly and seeing if any led's light up...even briefly.

[Yop]

If you have a multimeter, I suggest you carefully check to see if the raspberry pi is getting power (at it's gpio ports) while it's plugged in to the MMS and powered up.

Okay, I found a multimeter and learned how to use it.
On the RPI GPIO, from pin 39 as ground, I got 3,3V on pin 17 and 5V on pins 2 and 4.
On the Pi-MMS board, from P4-5 as ground, I got 3,3V on P5-2 and P5-4 and 5V on P5-10.

Now, I do see you mentioned that you powered it directly at one point....hopefully it wasn't plugged into the MMS at the time....I am not sure if the Pi-MMS board has any protection if the rpi is powered externally.

I didn't, I was holding it in my hand.
Also, I got no smoke.

If you didn't and you are not getting voltage at the GPIO pin, then you could try removing it from the MMS and try powering it directly and seeing if any led's light up...even briefly.

Checking the RPI datasheet, I saw it requires 2,5A but my cellphone loader gives 1A only.

[Flandango]

Since you are getting the 3.3/5v on the RPI, then it's getting the necessary power.
Double check to see if the SD card is still good (it can get corrupt if it's powered on and off repeatedly) and post the configuration file.
Only other thing I can possibly think of, to see if the RPI is good or not, is to use a mini(micro?) hdmi cable to hook it up to your tv and grab an SD card with a generic build of raspbian or whatever it's called nowadays, and boot it up (will need something more than 1A though)...if you get a display..then it's not a bad RPI.

[Yop]

The electronic shop is back from holidays. Unfortunately the Pi don't do anything : no LED, no HDMI signal, no heat…
I'll buy a new one and check it before soldering it to the board.

Thanks for your help.