Model 2609 Resets itself/freezes/etc.

+-^CrossBow^- · April 22, 2020

Received an original 2609 for some AV upgrade work. Found it was dead as a doornail when it arrived. Would only give me the black screen when switched on with occasional flashes or colored bars when pressing reset. Since the original 3904s looked pretty cooked, I replaced them out with some 4403's I had on hand. Spec wise they are the same only the 4403s look to handle twice the incoming current as the 3906s. Once I did this, the system sprung to life and I thought everything was good go as the 201 test cart would pass..etc. Then while using the a philly classic demo on loop for burn in. I noticed when I came to check on the thing about an hour later, that it had apparently reset itself because I was looking at my LTO menu screen with the rom selected highlighted. I didn't think much of it at the time and just powered it off the night.

Today, I fired it up again and it seemed to test fine as it did the night before. I turned it off, and recapped the entire system both power supply and main logic. Put it back together and test it..and it all tests out good once again. I again put my demo loop on for burn in and noticed while sitting there looking over some other things, that it again reset itself and went back to my LTO menu. Only now the menu would occasionally reset and re-read the directory etc. Then eventually stop and just stay where it was. I then tried a few games like Beauty and the Beast, Frogger, and the MTE-201 test cart I have. The test cart again seemed to pass and both beauty and the beast and Frogger seemed to play okay. I put the MTE-201 back in for another check and this time the system just froze up right after the initial graphics test screen that first comes up with just a solid yellow up on the screen.

Before someone yells at me for testing the power...that has been done. I'm reading a constant 5.09 off the +5 regulator and 12.13-18 on the TP indicated. I even left my probes connected to each while waiting for the system to do this reboot/lockup issue to see if the VRs were shuttind down or something. No change at all from them. I then did power testing from the ribbon connection areas and again all voltages are where they should be and never waiver when the system is on and even when it does the odd reset/lockup bit. I can get the system to stay stable longer if I let it cool down for a few min each time. The only chips getting warm are the ones we would expect with the heatsinks on them. Q1 and Q2 do still get blazing hot and you don't want to touch them if the system has been on for any real length of time. I'm beginning to suspect a CPU issue but not sure if there is a specific way I can test that without a spare system and parts on hand? I know I can hook up my scope to check for activity off the pins that connect to those two transistors, but I'm not sure that is enough.

Anyone ran into this or have any other ideas on where I should look? Again, it appears the main DC power supply board is 100% so it has to be something on the main logic PCB at this point.

+-^CrossBow^- · April 23, 2020

I think I got this sorted now. Looks like the 4403s I was using was the issue. I used my Intelly 2 as a chip swapper and found that I still had the same issues regardless of which IC I changed out. So..I took out the 4403s I had in Q1 and Q2 and put in 2709s instead that I also happen to have on hand. I then ran it through the Castle demo from the Philly classic for over 2 hours without any issues so I'm calling that good for now.