Tron MCR power board issue

scottz29

Member

Donor 2024
Joined
Sep 1, 2006
Messages
732
Reaction score
21
Location
Macomb, Michigan
I've been working on my Tron MCR power board for some time now and finally fixed it to the point where I get +5 and +12 adjustable by the pots. Board is capped, and many other parts replaced like voltage regulators and some transistors.

However, when I boot the game, I get a screen of garbage, and if I wait long enough, the game reboots and eventually works. Manually cycling power a couple times sometimes does the trick.

I have a Satan's Hollow, and when I swap in that power board, Tron boots immediately without issue.

The +5 is set to around +5.1 on both boards.

I've been waiting to get this fixed before I install the SRAM (http://forums.arcade-museum.com/showthread.php?t=90255) and I see alot of other people have this problem.

Any ideas on what to check, or what causes this?
 
I've been working on my Tron MCR power board for some time now and finally fixed it to the point where I get +5 and +12 adjustable by the pots. Board is capped, and many other parts replaced like voltage regulators and some transistors.

However, when I boot the game, I get a screen of garbage, and if I wait long enough, the game reboots and eventually works. Manually cycling power a couple times sometimes does the trick.

I have a Satan's Hollow, and when I swap in that power board, Tron boots immediately without issue.

The +5 is set to around +5.1 on both boards.

I've been waiting to get this fixed before I install the SRAM (http://forums.arcade-museum.com/showthread.php?t=90255) and I see alot of other people have this problem.

Any ideas on what to check, or what causes this?


Check for cold solder joints on the connectors of the Power board.
 
wasnt there a wire somewhere to bypass this reset ciurcuit krap??? like you cut it and all was well again?
That's the purple wire, but I don't believe that would cause the garbage on the screen. I think it just reboots the game when the line voltage is low.
 
Where are you measuring the 5.1v? If your not measuring it at an IC on the pcb stack itself, it'll be too low. Tron has a filter on the power lines that drops the voltage a bunch.
Test your power at the bottom left corner and top right corner of one of the eproms on the SSIO (top board on the stack), and set it for 5.0 volts at that point, and i'll bet your game boots. If that doesn't take care of it, then i'd look at the reset section of the power supply.
And, while cutting the purple wire works on some MCR games, every Tron pcb set i've seen requires the purple wire to go from low to high, after powered on before the game will boot.
 
My Tron was working perfectly for a while, then came up one day to a solid screen with some garbage... I looked and the purple wire was still there, so I cut it, and it's been working ever since. If you still have your purple wire, IMO, I'd cut it.

DogP
 
Have you tried your Tron Power supply in your Satan's Hollow?
Yes, same result. Won't boot, garbage on the screen.

Where are you measuring the 5.1v? If your not measuring it at an IC on the pcb stack itself, it'll be too low. Tron has a filter on the power lines that drops the voltage a bunch.
Test your power at the bottom left corner and top right corner of one of the eproms on the SSIO (top board on the stack), and set it for 5.0 volts at that point, and i'll bet your game boots. If that doesn't take care of it, then i'd look at the reset section of the power supply.
And, while cutting the purple wire works on some MCR games, every Tron pcb set i've seen requires the purple wire to go from low to high, after powered on before the game will boot.
Great tip, duly noted - I was measuring the +5v on the MCR board. I measured at one of the EPROMs and it was low, around 4.9. I adjusted to 5.02 or so, which now measures 5.2 back at the MCR board, plus or minus.

On the bad board, I get a voltage on the reset line (P4, pin 15) that jumps around from .2 to .8. On the good board, it reads +5v.

I'd guess something's up with the reset circuit of the power supply board.

Edward
Good call Ed. When I was working on this board trying to get the 5 volt line fixed, after I achieved success there, the game still didn't boot, at which point I noticed my reset line was dead. I put a logic probe on the LM3900 at U3, which is used in the pump charger as well as the reset circuit. Many of the pins were pulsing. On the good board they were not. However, as I mentioned, sometimes a cold restart makes this board work, sometimes it even works on the first boot. Could that LM3900 be bad, or could something else upstream cause those pins to pulse like that?
 
Yes, same result. Won't boot, garbage on the screen.


Great tip, duly noted - I was measuring the +5v on the MCR board. I measured at one of the EPROMs and it was low, around 4.9. I adjusted to 5.02 or so, which now measures 5.2 back at the MCR board, plus or minus.

On the bad board, I get a voltage on the reset line (P4, pin 15) that jumps around from .2 to .8. On the good board, it reads +5v.


Good call Ed. When I was working on this board trying to get the 5 volt line fixed, after I achieved success there, the game still didn't boot, at which point I noticed my reset line was dead. I put a logic probe on the LM3900 at U3, which is used in the pump charger as well as the reset circuit. Many of the pins were pulsing. On the good board they were not. However, as I mentioned, sometimes a cold restart makes this board work, sometimes it even works on the first boot. Could that LM3900 be bad, or could something else upstream cause those pins to pulse like that?

First, was there a lot of battery corrosion? The LM3900 could be bad....It could be anything in the reset circiut. Likeliest culprit....any of the 2 or 3 IC's (some boards have two...later revisions have three), D201/D202/D203....and I find Q201 bad (a lot).

Edward
 
Great tip, duly noted - I was measuring the +5v on the MCR board. I measured at one of the EPROMs and it was low, around 4.9. I adjusted to 5.02 or so, which now measures 5.2 back at the MCR board, plus or minus.

On the bad board, I get a voltage on the reset line (P4, pin 15) that jumps around from .2 to .8. On the good board, it reads +5v.

Good call Ed. When I was working on this board trying to get the 5 volt line fixed, after I achieved success there, the game still didn't boot, at which point I noticed my reset line was dead. I put a logic probe on the LM3900 at U3, which is used in the pump charger as well as the reset circuit. Many of the pins were pulsing. On the good board they were not. However, as I mentioned, sometimes a cold restart makes this board work, sometimes it even works on the first boot. Could that LM3900 be bad, or could something else upstream cause those pins to pulse like that?
Just wanted to close this thread. I replaced the pulsing LM3900, and further adjusted the MCR board so that the board was receiving +5.1v. Tron now boots every time, and I haven't lost high scores yet (replaced 6116 with an ST M48Z02-150)
 
Back
Top Bottom