Magnolia, DE
Thanks Grumpy. Wasn't sure if we were still taking the step since the PSU is new. Excuse my ignorance, but what is the 5 volt TP and ground TP?
(Topic ID: 169546)
Quoted from djreddog:Excuse my ignorance, but what is the 5 volt TP and ground TP?
On the CPU board there is a metal stud between U-21 and U-22 that is for checking the 5 volts that is on the board. And just to the left of the battery pack the is another stud marked ground. Its important that these are used for testing. Testing the power supply 5 volt doesn't mean that it actually made it to the CPU board. The CPU board is what is causing the resets so you need to know what the voltage is on the CPU board when it happens. It could be heat related so you need to clip on to the test points and close the insert panel and have someone watch the voltmeter while you play games until it resets. Let me know what the voltage was just prior to the reset.
2 weeks later
On I have a small update. I had a guy come over and look at the game. He tested voltage at the necessary places and received either 5.0 or 4.9 on all test points. He checked the giant cap that’s mounted to the bottom of the backboard, tests good and it’s actually not the original one, it’s already been replaced at least once. The next thing he discovered was the remote battery install. It was a 4 slot battery holder filled with 4 batteries. He said the “RAM” chip was very hot. His belief is the batteries are/were delivering to much voltage to the CPU board and thus causing the RAM to overheat. He replaced it with a 3 slot battery holder. Time will now tell. We did not have time today to test the game with leads on the TP connectors. Does this make sense and could be the possible culprit?
I'm not buying it. 4 batteries x 1.5VDC equals 6VDC. This passes through diode D2 which causes a .7VDC drop. This equates to about 5.3 VDC...under the max 5.5VDC rating. Now the RAM very hot, or failing could certainly be a problem.
The giant cap in the backboard is for the controlled lamp voltage, and has nothing to do with the logic supply voltage.
Quoted from wayout440:I'm not buying it. 4 batteries x 1.5VDC equals 6VDC. This passes through diode D2 which causes a .7VDC drop. This equates to about 5.3 VDC...under the max 5.5VDC rating. Now the RAM very hot, or failing could certainly be a problem.
The giant cap in the backboard is for the controlled lamp voltage, and has nothing to do with the logic supply voltage.
Thanks for the feedback. My plan tonight is to play with the DMM hooked up to see what happens.
Another update. I put the DMM on the two TP's on the CPU and played several games. Watched the DMM the entire time and the voltage stayed at 5.0 or 4.99, 99% of the time. Once in a great while I would see it dip to 4.98.
I played 3-4 games on it. All great games by the way. First game was 3.5 million, no issues. Second game was 2.2 million no issues. Third game I got 2 extra balls on ball 1, and made it up to 5.4 million on ball 2 when the game died. I was not in Multiball or anything and the DMM never dipped below 4.9.
Thoughts??
Quoted from wayout440:I'm thinking that this isn't a power problem based on those readings. If you found the ram IC to be unusually hot, I'd replace it.
So I didn’t find the RAM hot, that was the guy I had look at it. Now, throughout gameplay I kept feeling the RAM, including when the game died, and it didn’t feel hot to me. Chasing a damn needle in a haystack.
Quoted from djreddog:I was not in Multiball or anything and the DMM never dipped below 4.9.
Thoughts??
If it were me I would replace every diode on the coils. This is a cheap and easy thing to do. I also had game resets from a bad U-27 ROM socket, but this is a much harder thing to change and I don't recommend doing it unless you know for sure that its causing a problem. On my board I could apply light pressure on U-27 and it cause CPU reboots.
1 month later
Quoted from GRUMPY:If it were me I would replace every diode on the coils. This is a cheap and easy thing to do. I also had game resets from a bad U-27 ROM socket, but this is a much harder thing to change and I don't recommend doing it unless you know for sure that its causing a problem. On my board I could apply light pressure on U-27 and it cause CPU reboots.
Diodes replaced. So far so good.
1 year later
I'm just seeing this thread 657 days later. While I'm not having any issues with my GL, I'm wondering if the diode replacements fixed your issues long term (since I assume you still have this game, since the GF said you had to keep it "forever")
Quoted from dyopp21:I'm just seeing this thread 657 days later. While I'm not having any issues with my GL, I'm wondering if the diode replacements fixed your issues long term (since I assume you still have this game, since the GF said you had to keep it "forever")
Never figured it out. Ended up selling the game and bought a better condition GL with new boards, upgraded speaker system, proto backglass, LED displays, etc. I've owned the "new one" for about a year now, zero issues!
Promoted items from Pinside Marketplace and Pinside Shops!
Reply
Wanna join the discussion? Please sign in to reply to this topic.
Hey there! Welcome to Pinside!
Donate to PinsideGreat to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!
