Of course not! Caps don't do that. If you're looking to rectify something, you need a diode.
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Big Blue Failure. Have you experienced it?
- Thread starter Phetishboy
- Start date
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EVB
Well-known member
My Tempest had a bad big blue. It would fire up but would not play and the spot killer was on. This was after rebuilding the blown monitor that probably failed due to the main board failing due to the big blue. It's like the trunk of a tree. If it's dead the whole tree falls down.
I think it's unusual though and I don't replace them as a habit.
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Lindsey
Well-known member
That was funny.
As far as replacing components goes... call me crazy but I like to troubleshoot things and know why I'm replacing parts rather than just throwing parts at a game until it works. I know... I'm crazy...
That said... I do have one on hand for testing
I think I've replaced...around...four "big blues" over the years in Atari games. They are easy enough to test with a descent meter. Here's my rundown with bad ones...
Check the 10VDC lug on the Audio/Regulator Board. This will usually read 12-15VDC. If it's low (say...8.5VDC or less), big blue is probably bad.
Next, set your meter to AC volts....and check the 10VDC lug again. This time we're looking for AC on the DC rail. This is where a good meter comes in handy. Those cheap $15 meters usually can't read AC on a DC line....they just get "confused" and spit out some impossible reading...like 13VDC. A good big blue will give a reading (approximately) .150VAC...give or take. If it's bouncing around all over the place, the big blue is bad. Other times it will read high...and this is where some guess work comes in to play. How high is too high? Well, my experimenting has given me this rough template. Any reading of .300VAC is borderline. I've had games work fine at .300VAC....and I've had games have issues with .300VAC. I've never had a game act up with AC voltage under the .300VAC mark. In addition, I've never had a game work properly with the voltage much over the .300VAC mark.
And as Lindsey stated....it doesn't hurt to have a good one around to toss in when in doubt
Edward
Check the 10VDC lug on the Audio/Regulator Board. This will usually read 12-15VDC. If it's low (say...8.5VDC or less), big blue is probably bad.
Next, set your meter to AC volts....and check the 10VDC lug again. This time we're looking for AC on the DC rail. This is where a good meter comes in handy. Those cheap $15 meters usually can't read AC on a DC line....they just get "confused" and spit out some impossible reading...like 13VDC. A good big blue will give a reading (approximately) .150VAC...give or take. If it's bouncing around all over the place, the big blue is bad. Other times it will read high...and this is where some guess work comes in to play. How high is too high? Well, my experimenting has given me this rough template. Any reading of .300VAC is borderline. I've had games work fine at .300VAC....and I've had games have issues with .300VAC. I've never had a game act up with AC voltage under the .300VAC mark. In addition, I've never had a game work properly with the voltage much over the .300VAC mark.
And as Lindsey stated....it doesn't hurt to have a good one around to toss in when in doubt
Edward
Since I've been a route tech since about 1985 I've replaced thousands of these caps. I only replace them when they are bad though. I dont just shot gun the cap because some "news group" or "web site" said I should.
BTW, I'm also including the filter caps in Midway games of the era. For some reason those MCR power supplies went through caps.
Matt
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All my Atari machines get a new big blue. Some may not be needed, but it is one less thing to worry about causing issues that mask as something else.
BTW, look in the bottom of the SW cab -- you will find one there too.
Again, it might be because of my back ground in the industry but its pretty easy to tell when you have a bad filter cap. Some times you dont even need to open the game up.
Matt
modessitt
Volunteer: Encyclopedia Submission Moderator
I don't normally change the Big Blue unless I have problems that could be due to unstable voltages.
Doesn't mean they never fail, though, as I've worked on lots of games that came to me with bad Big Blues in them....
Doesn't mean they never fail, though, as I've worked on lots of games that came to me with bad Big Blues in them....
Franklin
Well-known member
I liken it to changing the oil in my car, I prefer to change it while it's still good rather than wait for it to go bad. Running a car with old, broken down and possibly dirty oil will, even though the car will seem to run fine, only lead other parts to fail quicker. A new Big Blue is only a few bucks, bad ones have proven to many to be the cause of problems and since the power to many other parts goes through it, what is the reason to wait until it actually fails? Another car analogy would be, why drive with bald tires - sure your car will run but eventually (and probably when it's raining and your 50 miles from home) they will go flat. How many times do you hear people talk about all the games that break down during their gaming parties?
Lindsey
Well-known member
Would you replace the engine or the seats before they wear out?
Same basic analogy applies.
Franklin
Well-known member
Is there currently a model of engine that has a reputation for failure (like the Big Blue does)? I'd say the CPU or main pcb is the engine in a game anyway. But tell me, when do you change your oil? Do you wait until it's proven to be bad, and causes the whole car to stop running?
Having a seat wear out isn't going to strand you on the highway. I don't think the 'same analogy applies'.
Having a seat wear out isn't going to strand you on the highway. I don't think the 'same analogy applies'.
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Lindsey
Well-known member
I said seats. SEATS. It was a stupid analogy. Intentionally.
The 2.7L engine used in Dodge Intrepids has a reputation for failure, though it's still not analogous to anything on an arcade game... that's kind of the whole point.
I change my oil at a regular interval. However... If my oil would last for 30+ years with the only consequence being some basic troubleshooting and dumping in new oil I would never change it.
FWIW: The "reputation for failure" in the big blue is largely overblown. This thread proves that. If you're going to replace every part that has a "reputation for failure" on Atari games you might as well rebuild the whole machine. It's not like the thing explodes overnight or something.
Just my opinion...
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mrsell
New member
I've replaced several "big blue" filter caps on my machines - all because it was necessary.
In fact, somebody hacked in a switching power supply on my Crystal Castles simply because the filter cap was bad. After replacing the cap and removing the switcher (and "unhacking" the wiring harness) the game played perfectly fine.
The power supply is the foundation for the game - I've been burned too many times by wasting hours troubleshooting logic problems with a boardset only to find that "dirty" power was the true culprit.
I'd like to say that I always check power first, but I'm close. It's been surprising to find how many problems can be traced to a faulty power supply.
In fact, somebody hacked in a switching power supply on my Crystal Castles simply because the filter cap was bad. After replacing the cap and removing the switcher (and "unhacking" the wiring harness) the game played perfectly fine.
The power supply is the foundation for the game - I've been burned too many times by wasting hours troubleshooting logic problems with a boardset only to find that "dirty" power was the true culprit.
I'd like to say that I always check power first, but I'm close. It's been surprising to find how many problems can be traced to a faulty power supply.
Lindsey
Well-known member
Let me clarify... I didn't say "don't replace it"... I said "check it first then replace if necessary".
Big difference.
An oscilloscope is your friend
Big difference.
An oscilloscope is your friend
mrsell
New member
A decent multimeter with *True RMS* AC measurement capability will handle this task well.
I happen to work for a company in the Pacific Northwest that makes such meters...
I use the DMM for this since it is what is in my hand when I'm checking voltages - a quick flip to AC will give an indication of how clean the power is.
But yes, an oscilloscope gives a much more definitive answer.
ScopeMeter to the rescue!
I happen to work for a company in the Pacific Northwest that makes such meters...
I use the DMM for this since it is what is in my hand when I'm checking voltages - a quick flip to AC will give an indication of how clean the power is.
But yes, an oscilloscope gives a much more definitive answer.
ScopeMeter to the rescue!
Lindsey
Well-known member
Absolutely!
Actually a meter with max/min is more useful than RMS. Especially with linear supplies. What you really need to know is how far the voltage is drooping. I.e. the minimum voltage. It's not too hard to think of common situations where DC and RMS readings would indicate an ok filter voltage which is in reality causing havoc.
But your best bet is an oscilloscope as others have mentioned.
But your best bet is an oscilloscope as others have mentioned.
Yeah...scopemeter. Wish I had one!
mrsell
New member
The typical handheld DMM (using DC MIN/MAX mode) does not have a high enough sample rate to accurately measure ripple, unless you leave it connected for quite a while.
The point of using the AC measurement function is to obtain a ripple measurement. The greater the ripple, the worse the filtering or rectification.
MIN/MAX mode *will* catch an inability of the regulator to provide constant voltage during periods of high load. Good examples of high load might be the Death Star explosion in Star Wars (monitor PS, not game PS), or sequences where loud noises or music is playing.
In some rare cases I've actually seen shorted windings on transformers reducing the input voltage to the regulator causing it to drop out under load.
The point of using the AC measurement function is to obtain a ripple measurement. The greater the ripple, the worse the filtering or rectification.
MIN/MAX mode *will* catch an inability of the regulator to provide constant voltage during periods of high load. Good examples of high load might be the Death Star explosion in Star Wars (monitor PS, not game PS), or sequences where loud noises or music is playing.
In some rare cases I've actually seen shorted windings on transformers reducing the input voltage to the regulator causing it to drop out under load.
Yeah, you're right. Add another notch on my "hates digital equipment" gunbelt. I've been working around sampling limitations in the lab long enough I don't even think about them in most simple cases. I use work arounds by default. I'm glad I have you around to keep me honest!
i've replaced the big blues on all the atari games i've owned, but mostly just as a precautionary thing. i've never really had a problem with a game that i could safely trace to a big blue issue.
