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I agree, if it plays fine then stops working and it is reporting all CPU RAM and VIDEO RAM chips are faulty its most likely some simple maintenance (5V voltage rail, harness/edge connector or dirty CPU/RAM sockets.Have you done all the basic troubleshooting steps, like checking your voltages, reseating connectors & socketed chips, etc.?
a lot of the Konami (it was really made by Konami, not Sega) games of the era have this thing where you have power coming into one board with edge connector and then the other board gets power daisy chained with 2 wires via a plug. on the Konami games they have like single +5V and ground wires, which is totally substandard for powering 2 boards. I sand the solder mask off the +5V and ground traces on both boards and solder 18 gauge red and black wires to them to go back to the power supply. that'll eliminate the voltage drop issue. a number of those old Japanese switching power supplies of 40+ year old vintage still work just fine. replacing the power supply with a new one and running it at like 5.8V and overlooking the wiring deficiencies is just a band aid.What led up to replacing the power supply?? bad voltage? 5, 12 Or was it just a guess..
I had to fix sound on some Froggers over the years. replacing the CPU and AY3 sockets seemed to help a lot. I don't know about the integrity of the original caps but I think I wound up replacing those too.Sound needs -5V, maybe you lost that.
Not sure if the rest of the boards need it too, though.
If you had sound and jacked up game and then only Switched power and now game works but sound doesn't I'd expect you are missing -5v on new PS per @Laschek above.Sound needs -5V, maybe you lost that.
Not sure if the rest of the boards need it too, though.
I don't think I over-powered it but anything is possible. I did test the PS and I believe I'm getting roughly -4.7V coming out of it. Are there test points on the board where I can measure the -5V as well?If you had sound and jacked up game and then only Switched power and now game works but sound doesn't I'd expect you are missing -5v on new PS per @Laschek above.
I would also flex ribbon, check all pins on both sides aren't corroded and clean the edge connector and put a thin film (put few drops between fingers and slide across) of deoxit across card edge.
It's not impossible that you broke something else with new power, any chance that you over-powered the board before dialing in 5v on new Ps?
Audio problems on Frogger in my experience are usually ram on audio board, then AY, then CPU then 741, last thing is amp
If you don't have an audio probe, search out pcb from @philmurr and build one, makes quick work of most audio repairs imo, especially on Frogger.
Also note, if you're working on Frogger on your bench, most Konami jamma adapter have a jumper that cuts off -5v, make sure it's in place to allow -5v through or you'll prob get hissing but. It full audio.
Also note, gremlin Frogger PCBs need a volume pot. So if you're testing on your bench and not in the cab, you can lick your finger and bridge volume pot pins to test audio.I don't think I over-powered it but anything is possible. I did test the PS and I believe I'm getting roughly -4.7V coming out of it. Are there test points on the board where I can measure the -5V as well?
I'll do some more testing and clean the edge connector also. Huge thanks for the tips!!!