Firepower/Rottendog question

brypten

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I have a Firepower that I am trying to repair. It has the Rottendog replacement MPU (sys 3-6 only). When I press both flippers at once, the machine resets. It does not do this with the original board in it.

Any ideas?
 
I have a Firepower that I am trying to repair. It has the Rottendog replacement MPU (sys 3-6 only). When I press both flippers at once, the machine resets. It does not do this with the original board in it.

Any ideas?

Have you done any work to the power supply or connectors? Could be that the new MPU is more sensitive to the voltage drop that happens when you press both flipper buttons at the same time and there is too much voltage drop due to a weak power supply or bad connectors. Could also indicate a bad coil diode at a flipper.
 
Start by tracing your 5v from the power supply all the way to the CPU board.

Resets are more often a power issue than a CPU issue.

-Hans

If the filter cap for the +5V is original that alone could possibly solve the problem but there are probably some connector issues as well. Agreed, definitely more likely a power supply or connector related problem.

If you have a new filter cap for the +5VDC on hand you could connect it in parallel with the original with alligator clips and see if the problem goes away. I won't be surprised if it does.
 
I re-pinned most of the connectors, I do not think that this is an issue.

Why do you guys think it's the +5 cap? I am asking out of curiosity, not challenge ;)
 
Why do you guys think it's the +5 cap? I am asking out of curiosity, not challenge ;)

That cap will discharge, compensating for the voltage drop that will happen due to the huge current draw happening at the flippers. If that cap isn't storing enough electrons to perform that function effectively it could cause an MPU reset. That's why I asked if the cap was original. Even if it's not originally it could still be a problem if it's old or underrated.
 
That cap will discharge, compensating for the voltage drop that will happen due to the huge current draw happening at the flippers. If that cap isn't storing enough electrons to perform that function effectively it could cause an MPU reset. That's why I asked if the cap was original. Even if it's not originally it could still be a problem if it's old or underrated.

Makes sense to me.

The cap is not original; I will add another cap in parallel to it tomorrow morning.

The wiring is also sketchy going to the cap (it's not on the pcb), that needs to be rectified as well.

I will repost tomorrow, thanks :)
 
When you say that you re-pinned most of the connectors, I assume you mean the wiring harness side of them, correct? From experience, the power supply boards (well, ALL the original boards really) have problems with cracked solder connections on the male header pins. If you're taking the board out already, it wouldn't hurt to take a closer look... or even just resolder the 5v header if you have the tools/abilities. Don't just re-flow it, 30 year old solder doesn't do too well with the process, remove the old solder and apply fresh.


Now, you said the cap isn't on the board? the cap is wired in, and the wiring is sketchy? My honest opinion would be to get a proper 12,000uf radial cap and install it properly, and clean up the power wiring / boards of any improper repairs.

-Hans
 
When you say that you re-pinned most of the connectors, I assume you mean the wiring harness side of them, correct? From experience, the power supply boards (well, ALL the original boards really) have problems with cracked solder connections on the male header pins. If you're taking the board out already, it wouldn't hurt to take a closer look... or even just resolder the 5v header if you have the tools/abilities. Don't just re-flow it, 30 year old solder doesn't do too well with the process, remove the old solder and apply fresh.


Now, you said the cap isn't on the board? the cap is wired in, and the wiring is sketchy? My honest opinion would be to get a proper 12,000uf radial cap and install it properly, and clean up the power wiring / boards of any improper repairs.

-Hans

You are correct about the cracked solder connections. I reflowed all male headers on all the boards (exactly as you said; removing the "old" solder).

The re-pinning was done to most wiring harnesses.

Are there any advantages/disadvantages to not having that cap on the board? Maybe EFI/EMI?

By sketchy I mean that someone ran wires from the power supply as well as wires from cap and held them together with electrical tape.
 
Not having the cap physically mounted on the board isn't the issue, it's all about how it's installed. The quality an size of the wire, the quality of the connections, the length of the wire... all those things can have an effect on the performance of the cap. A twist and tape job just isn't going to be sufficient here. It also has me wondering about the value of the cap, if it's installed that way.

-Hans
 
i am willing to bet the reason the cap is wired off the board is someone who does not know how to solder probably ripped out the plated through holes, and or burned up some traces, and instead of trying to repair that he did a quick patch job with wire and ran the cap off the board. I know this because I have done it myself, all the connections were good after but still had resets, what the other guy said about lewngth and thickness of wire could have been the only remaining weak link. Do it once, and do it right.
 
Having the same problem with mine after two days. It's not the power supply or the connectors. Guess I'll be sending my Rottendog board back.
Glennon
 
Anybody have any opinions on this that have not already been discussed?
 
I put in old boards no problems. I put in new Rottendog board and the game resets when you hit both flippers?
Glennon
 
i am willing to bet the reason the cap is wired off the board is someone who does not know how to solder probably ripped out the plated through holes, and or burned up some traces, and instead of trying to repair that he did a quick patch job with wire and ran the cap off the board. I know this because I have done it myself, all the connections were good after but still had resets, what the other guy said about lewngth and thickness of wire could have been the only remaining weak link. Do it once, and do it right.

Sounds like a typical +5 v rail drop to me. Have someone run the multi meter and watch the voltage before and after the flippers are pressed. I'd bet she's sinking down past 4.7V and causing the reboot. I think Lindsey is right about the newer stuff being more sensitive to voltage drops.
If the board looks failry roughed up, I'd verify every single components ratings that looks like it was replaced.
 
I'm hoping it's the power supply or just a week connection. I just get tired of shaking wires. Lol
 
I had the same exact problem with my firepower. I have the rottendog mpu as well. It turned out to be a connector. They all looked fine upon my first inspection. Then I went through them again and noticed one wasn't snapped in all the way. Make sure they are all seated tightly.
 
Sounds like a typical +5 v rail drop to me. Have someone run the multi meter and watch the voltage before and after the flippers are pressed. I'd bet she's sinking down past 4.7V and causing the reboot. I think Lindsey is right about the newer stuff being more sensitive to voltage drops.
If the board looks failry roughed up, I'd verify every single components ratings that looks like it was replaced.

I don't doubt what Lindsey said either,but this board is supposed to be plug and play not plug , replace power supply and play. I'll go through all the connectors and check the and check voltages and report back
 
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