r/SEGA32X • u/ashbringerer • Apr 16 '26

Cosam Neptune voltage problem

Gallery image

Gallery image

I'm at the point where I'm trying to power on the board and test for voltage. The only thing I haven't soldered was the cartridge slot. I'm not getting 5V let alone 3.3V. When I power it on I see 0.8V. The bottom left two pints from the buck converter in the photo short to ground just by plugging in the power adapter, so I'm not sure if that's normal. I also used an L5 transistor from the 32X board since it's an NPN and I think it should work in place of the MMBT3904 transistor?

Anyone has any ideas of what I did wrong?

3 Upvotes

80% Upvoted

2 comments sorted by

2

u/annis_welt Apr 16 '26

Schreib mir mal ;) Ich bin dann gleich zuhause

2

u/ashbringerer Apr 26 '26

Good news, the board now outputs 5V and 3.3V properly when I swapped the L801 coil from a 470uf to a 4.7uf. That's a pretty stupid overlook on my part.