Cap kits - Store them or order ad-hoc?

There's no way that quality caps are going to fail in anything under 10 years I would think.

As mentioned by @andrewb a Variac is indespensible In this endeavor I believe, and I would add to that an ESR meter.

Having well labeled parts bins also is critical to this, as overflow from other projects will become valuable in the future.
I'm still ordering double what I need for parts because I still suck at this stuff and make a mess sometimes.

I asked recently in another thread for a "suits most" list of components for this kind of thing. And i'm still hoping someone comes up with one!
 
Having well labeled parts bins also is critical to this, as overflow from other projects will become valuable in the future.
I so need to complete this. I bought a parts organizer. I've accumulated a lot of overflow and have more than once put in an order for something only to later realize I had what I needed already!
 
Very interesting! I've never heard of this, and it sounds like it's used in the audio world too (another vice of mine). So install the the monitor back in the cab with the board and everything connected and plug the cab in? Or are you just talking about the monitor only?

Jason
I've used this technique, but without a lot of confidence in the exact way I've been doing it. My variac has a built in meter for current draw, so I always power questionable gear through it... at least if I notice the current draw surging, I can kill power and limit the damage.

Do you start at zero volts and gradually move up to normal input voltage? And how long a time would you spend doing this before calling it ready for normal service?


I'll plug the whole cab into the Variac (just for convenience, so you're powering the monitor through the ISO if it has one). But I'll unplug the game board and marquee light, since they aren't going to work anyway when undervoltaged.

I go very slow. 10 volts every 10 minutes. I'll just set a timer and dial it up while I do other stuff around the shop. That's probably way slower than necessary, but it's just what I do, and I've never had a problem.

I do it for new-to-me Atari bricks too, to reform the big blue.

If you don't have a current meter built into the Variac, you can plug the Variac into a Kill-A-Watt (another handy tool), to show the current.

 
To have spare parts or not to have spare parts.

Depend on the collector's habits and the availability of the parts.

In my case.
All of my arcade machines, typically get the standard preventative treatment in repairs. So my up time is normally long. This is a must when dealing with a collection that is on the large size. Waiting for something to break is more expensive just doing maintenance repairs. A cap, few connectors, some thermal grease extents the up time on these machine.

I am more proactive in my repairs this way I dictate when the machine goes down and not the other way around,
Sometime it a time issue, We are all getting older way quicker than we should.

My parts collecting habits changed since dealing with MOP. I no longer look for bulk deals. In fact I have given away some of my parts away to fellow repair techs.
 
I was thinking about this more, and how is it that caps on game boards rarely need to be changed? On "any" game board, since caps start to go bad after an undefined period of time, you'd think that 40+ year old caps on a game PCB would be completely rotten and create all kinds of problems, yet they still just work on some boards. I'm not gonna lie, I've actually started thinking about replacing game board caps since APAR supplies kits, just for peace of mind.

Thoughts?

Jason
 
I was thinking about this more, and how is it that caps on game boards rarely need to be changed? On "any" game board, since caps start to go bad after an undefined period of time, you'd think that 40+ year old caps on a game PCB would be completely rotten and create all kinds of problems, yet they still just work on some boards. I'm not gonna lie, I've actually started thinking about replacing game board caps since APAR supplies kits, just for peace of mind.

Thoughts?

Jason
Game pcbs run off regulated 5v mainly. It's the way the capacitor is being used in circuit, in a power supply or monitor every cap is constantly being stressed running greater amps of power through it. Not a bad idea to recap something like a dig dug pcb or donkey kong though with age.
 
I was thinking about this more, and how is it that caps on game boards rarely need to be changed? On "any" game board, since caps start to go bad after an undefined period of time, you'd think that 40+ year old caps on a game PCB would be completely rotten and create all kinds of problems, yet they still just work on some boards. I'm not gonna lie, I've actually started thinking about replacing game board caps since APAR supplies kits, just for peace of mind.

Thoughts?

Jason


Get an ESR meter, and measure all the caps you want. You'll learn which brands are still good after 40 years, and which aren't.

You don't even need to remove them, as most caps can be measured for ESR in-system.

Also, electrolytics on game boards can be bad in a lot of cases, with no detriment to the board. Many (but not all) caps are just redundant filter caps on power rails, which are added as precautions. In many cases they don't do much, because the power is already filtered at the PS. You could cut those caps off and the board would still work fine. That's not all of them, but it's many of them.

So it isn't a matter of 'replace caps or not'. To make a really informed decision, you just need to measure the ESR of the cap, and that will tell you if it's still good or not, and how good. And you can look at what any given cap does, and how critical it is to the overall operation of the board.

There's no need to guess, when you can measure. I learned this firsthand, when I got a meter and started measuring. That's when I realized that we replace far too many caps in this hobby. And a lot of it was just because people could make $10 a bag, selling caps.

Some caps do need to be replaced. But when you start actually measuring them, you realize a majority of them don't.

On many boards, you're far more likely to have a TTL chip go bad, than a cap. But we don't go replacing every TTL chip to prevent that, do we?
 
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