Cap kits on Game PCBs?

jonathan1138

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Hi Folks - I am sure this question has been asked before, i did some searching but it returns alot of clutter (relating to cap kits for monitors, which is not my question....).

Newb question ahead. Now that all of my Monitors have cap kits, I am next addressing some minor game / logic issues. When studying the PCB boards (Main, sound, etc) i see lots of Caps. Even though they may not be the cause of my issues, It drives me crazy that they arent new!

Has me thinking - anytime a monitor issue is reported, caps are always the first suggestion as a fix. So my questions:

Should seemingly nice looking but original (20 yr old) game PCB caps get replaced?

What do they generally drive (for example, monitor caps drive colors, position - what are game caps running in general)?

In general, can bad caps on Main PCBs lead to strange behavior on games?

Why dont i see suggestions here such as "replace the <game here> main PCB caps" as much?

Are they either less susceptible to outage or not at critical to replace? I would assume less prone to outage (compared to monitors) - why is that? Less stress on their use?


Thanks.
 
Game board caps are usually ceramic and don't dry out like the electrolytics used on monitor boards. The vast majority of these ceramics are used for filtering and can often be removed with no noticeable change to the game play.

That being said there are a few boards, and a few areas on virtually all boards (sound filtering for instance) that are heavily populated with electrolytics. I occasionally replace these if I am having problems with a board such as inconsistent sounds or random resets.

Also, some older boards did the power rectification on board and they are heavily populated with caps. Bob Roberts sells cap kits for most of those boards.
 
quick thing to keep in mind...

If it aint broke, dont fix it! If the game board isnt doing anything wrong then leave it alone. If you have sound issues or random resets like Oryk mentioned then go for it.
 
Ok - I am referring to the circular caps that resemble monitor caps - for example, my Dragons Lair and Frontline PCBs have quite a few of these. So it sounds like caps are related to sound (no pun intended) IN GENERAL.

Fortunately my issues (minor monitor issues, ruled out the monitor) are not related to sounds, so as suggested i will leave those be. Thanks!
 
Sega/Gremlin Eliminator and Space Fury sound boards are a fine example.

Often, when these audio boards have a bad or missing sound, simply replacing the capacitor in the audio circuit for the specific sound will fix it. The audio boards are populated with many 10uf capacitors, same as you find on monitor boards. When working on these audio boards, I have a capacitor map that says when sound x is missing, replace capacitor y.
 
Pacman and Pole Position are two game boards that bake the electrolytic capacitors over the years and definitely should be replaced. Zanen Electronics has a capkit for Pacman boards.
 
Neo Geo boards are well known for audio issues such as missing sounds channels, low volume, or audio suddenly getting loud or soft. I sell cap kits for these boards on my website.

Outside of those, I only replace caps as needed on game boards. I've never seen any other game boards that consistently required new audio caps than the Neo Geos.

RJ
 
Time Pilot.

If you have this PCB, be prepared to swap out the original caps responsible for sound if you'd like to keep hearing it.
 
Newb question ahead. Now that all of my Monitors have cap kits, I am next addressing some minor game / logic issues. When studying the PCB boards (Main, sound, etc) i see lots of Caps. Even though they may not be the cause of my issues, It drives me crazy that they arent new!

I would try to curb that attitude right now. It's an attitude that does nothing but cost money :)

Has me thinking - anytime a monitor issue is reported, caps are always the first suggestion as a fix. So my questions:

That doesn't necessarily mean it's the correct advice every time. Some people's troubleshooting method is throwing parts at the game until it works. You don't want to be that person.

Should seemingly nice looking but original (20 yr old) game PCB caps get replaced?

Not necessarily. If they have a problem they should be replaced. If not... then not. The appearance really has little to do with it.

What do they generally drive (for example, monitor caps drive colors, position - what are game caps running in general)?

I wouldn't really use the term "drive" to describe how caps are used in monitors but it's a subjective term. On PCBs you'll find that most electrolytic caps are used in either power filtering or audio circuits.

In general, can bad caps on Main PCBs lead to strange behavior on games?

Sure they can. There are examples where it's a good idea to just shotgun the caps. Like Pac-Man for example but generally speaking you're better off troubleshooting your problem than just throwing caps on the board and hoping for the best.

Why dont i see suggestions here such as "replace the <game here> main PCB caps" as much?

The short answer is because it's not necessary but there are cases where it is and caps do have a finite lifespan. Once that time has passed it's a good idea to replace them but this should be done as a preventative maintenance measure. Not a troubleshooting method.

Just my $.02
 
For my games, it all depends on what I know about the board, what problems the board has, and what function the caps on the boards have. I also take into account age.

Here is what I've done:
1. Any obviously damaged caps get replaced. Most of my Sega System16 boards had thier ROM board filter caps wrenched off. These were replaced.
2. Pac-Man and Mrs. Pac-Man use the caps to generate +5 from AC delivered to the board straight from the ISO. I always rebuild linear power boards first, and to me this is linear power and is needed.
3. Night Driver, see above.
4. Expensive to replace PCBs. Tempest and Omega Race. I don't know what they do, they're old and large. Be careful with Bob's kit for Tempest, it had some really cheap caps that had missing polarity ratings vs. what came on the board.
5. Spy Hunter-three or four level boardset, very picky about voltage that runs through it. It was crashing and new caps helped smooth the flow of power around the board.

If you do this, use a temperature controlled iron with a fine tip. None of that cheapo Radio Shack garbage. Use a good solder sucker and clean it out often. Patience.

I hope this helps!
 
That doesn't necessarily mean it's the correct advice every time. Some people's troubleshooting method is throwing parts at the game until it works. You don't want to be that person.
Just my $.02

Hey, I make decent money off those people... :001_stongue:
 
Here's one for you.

I flat out, straight up, fixed like a MOTHERFUCKER a Space Invaders Deluxe pcb that had video issues. The display was all wiggly and didn't have straight lines anywhere. After forever I noticed there were some electrolytics on the pcb, that the video ran through (wtf?). Replaced them, and had a rock steady picture.
 
Here's one for you.

I flat out, straight up, fixed like a MOTHERFUCKER a Space Invaders Deluxe pcb that had video issues. The display was all wiggly and didn't have straight lines anywhere. After forever I noticed there were some electrolytics on the pcb, that the video ran through (wtf?). Replaced them, and had a rock steady picture.

Those inline caps are simply blocking the DC component off the video signal. Simple enough. :)
 
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