For the most part, I've always restored arcade cabinets from the early 80's. Later in that decade, it seems the industry began to move from linear power supplies, to the smaller, switch mode power supplies common today in almost everything. I can't pretend to know why, likely for cost reasons. These can be purchased now for about $20. Many collectors just chuck out the old power supply and replace it with a cheap Peter Chou knock off. Seems to make sense, but on the other hand, often the new product has been made in such a way as to extract every fraction of a cent profit conceivable. As I said in an earlier post, the game works, and actually plays fine. Which is a testament to the design quality of the power supply. It's voltages were correct when tested with a multi-meter, but I could hear a loud hiss coming from the base of the cabinet, and I'm willing to bet the capacitors in there are dried up and bulging or leaking.
Since I now own an oscilloscope, and I'm just beginning to learn how to use it, I decided to take a look at the 5V output. The display should be a nice flat line, what you don't want to see is AC ripple passing through. I got this:
Yikes, not good.
Once I opened up the case, I could see most of the caps were bulging on the tops, and two were leaking.
So, after discharging those nasty capacitors, I decided to give it a bath, yes with soap and water:
I like that it has the year 1987 printed on the board, and Peter Chou. Again, I'm no expert on switch mode power supplies, but this would have to be one of the earliest original Peter Chou models. So I did a quick inventory of the caps, and jumped on Digi-key's website to place an order.
Meanwhile I cleaned up the enclosure, being careful not to scrub away the labels. You can see it's a nice shiny blue, and it cleaned up really well:
I ordered the best quality Nichicon caps I could find, and had them by Wednesday evening:
A few months ago I was doing a lot of work on an old Vectorbeam monitor chassis, and I picked up a used panavise on ebay. It makes working with these boards so easy:
To keep this post from getting really wordy I'll just say I swapped those caps out and got it looking spiffy. As David L. Jones would say, "Ah, she's a real bobby dazzler"!
Then I connected it to the oscilloscope again and as you can see, the signal is excellent, no AC ripple this time, and that annoying hiss is gone:
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