I've been working with Psikyo boards a lot, and recently noticed the audio quality differed greatly between the two PS5-pcb-layout games, Gunbird 2 and Strikers 1945iii/1999. Gunbird 2 suffers from what seems like video interference. This issues has been mentioned before on AP and elsewhere, but I wanted to pull this into its own thread since I've made some progress to improve it.
While recapping both boards I noticed the audio sections were populated differently, Strikers routing to a Yamaha YAC516 D/A converter and Gunbird instead using a YAC513. Both use a JRC 4741 op amp. Datasheets are linked in the previous sentence. Trouble is, I'm not capable of understanding or diagramming this circuit to see what could be fixed. That didn't exactly stop me, but I don't think my results are perfect!
Here's a Strikers 1999, you can see the empty YAC513 on the right hand side.
And a close-up of Gunbird 2, where those are populated (and you can't see it here but the YAC516 is not populated)
Armed with little knowledge, I just took a shot and replaced C22 and C19, previously 222K, with 104K film caps that were used everywhere else. That made a large improvement to me. I also installed a C0805,100pF±5% 50V C0G on C12. Possibly that's helpful, but possibly not -- you see I took off my C12 and damaged it while trying to take its value, so I don’t actually know what should be on there. I saw that value in the op amp datasheet so I went for it.
More photos: https://imgur.com/a/WmpEs9Z
So while I'm happy with the results, it would be awesome for someone to look at the chips involved and see if there's an actual factory error... and if there's something more suitable for a solution. I'm convinced that the YAC513 circuit is misbehaving. Anyone with the pcb want to take a look? Anyone without the pcb want me to get more photos of anything? If helpful I documented the electrolytic caps already too.
While recapping both boards I noticed the audio sections were populated differently, Strikers routing to a Yamaha YAC516 D/A converter and Gunbird instead using a YAC513. Both use a JRC 4741 op amp. Datasheets are linked in the previous sentence. Trouble is, I'm not capable of understanding or diagramming this circuit to see what could be fixed. That didn't exactly stop me, but I don't think my results are perfect!
Here's a Strikers 1999, you can see the empty YAC513 on the right hand side.
And a close-up of Gunbird 2, where those are populated (and you can't see it here but the YAC516 is not populated)
Armed with little knowledge, I just took a shot and replaced C22 and C19, previously 222K, with 104K film caps that were used everywhere else. That made a large improvement to me. I also installed a C0805,100pF±5% 50V C0G on C12. Possibly that's helpful, but possibly not -- you see I took off my C12 and damaged it while trying to take its value, so I don’t actually know what should be on there. I saw that value in the op amp datasheet so I went for it.
More photos: https://imgur.com/a/WmpEs9Z
So while I'm happy with the results, it would be awesome for someone to look at the chips involved and see if there's an actual factory error... and if there's something more suitable for a solution. I'm convinced that the YAC513 circuit is misbehaving. Anyone with the pcb want to take a look? Anyone without the pcb want me to get more photos of anything? If helpful I documented the electrolytic caps already too.