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Broken 5200 - No Power!

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More info on the one I'm working on. So using the service manual, I've verified I have +5 to all main ICs and RAM with a cart inserted and power applied. But still nothing. I swapped out the main ICs with known good ones...still black screen. Swapped the BIOS with a spare I have from a 4-port...black screen.


Only thing odd from the service manual flowchart is that when checking for +5 on the main ICs, the Pokey is stated to check for voltage from pin 1 GND, to +5 on pin 17. On this Pokey I'm getting +5 on Pin 16...not 17. Without taking another 2 port unit apart (I've haven't one on hand really) I'm not sure if that is just a misprint in the service manual?

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Got is resolved. The issue was that somehow when the PSU went out, it took out 5...yes 5 of the vram's with it?! The first 5 in fact from the top down. Only figured it out because I damn near burnt the side of my hand off them when I was taking voltage measurements on other places on the board. They were all getting crazy hot! Yanked them all out and replaced them all from a known good donor. Fired right up without issue at that point. Then I started to replace them out once by one with the originals until I found the culprits. Still trying to figure out what took out the PSU in the first place as it my primary bench testing PSU and the one I use on my personal 5200 ugh... And it is a sealed PSU so I can't open it without cutting.


Still client will be happy to get a fully working 2-port unit back with properly calibrated controllers to boot.

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