Electrolytic Capacitor replacement

Hi Ross,

The rule has a lot of merit. Personally I would not mess with the capacitors unless you are having a problem or if you can see evidence of leakage from the capacitors.

John

that said, the electrolytes in the Philips oscilloscope's switch mode power supply of that era are known to be bad. 

Symptom: the device will switch on and work for a time. Then smoke, and the rectifier bridge (typically a flat package on these scopes)  dies. No visible leakage before and after dying.
These are Philips capacitors. They were excellent, and did their duty for the specified life. But the Philips ones used in the power supply *are* bad by now.

I strongly suggest replacing electrolytic caps when you are in maintenance or repair mode

Electrolytics absolutely have a limited operational (and shelf) life and will eventually require replacement. And I prefer to err on the side of replacing before they fail so they do not take out other stuff with them. In general, if a device is more than 10 years old and I have my soldering iron out for any reason, I take the time to re-cap it.

Leaking electrolytics are not always obvious and dead caps are not always buldging. These reasons are why I do not put faith in the "if it ain't broke" mentality. Like all preventative maintenance, you want to perform it before the "breaking" action happens.

That said, I do not recommend re-capping as a first (or near first) soldering project. There are enough unique situations that properly removing the caps may take some soldering skill.

By the way, I did a video on HOW to select electrolytic replacements once you have them out.

Hi James, thanks for the response. I was hoping I might snag your opinion. I’ve seen just about all of your workbench Wednesdays. That’s what prompted me to come over here and make an account. I will go ahead and replace them. It makes sense to do so while I have the scope pulled apart. Thanks for the input and I look forward to more workbench Wednesdays. 

Yea I think you are both right. A lot of times one can end up messing something up that wasn’t broke trying to do maintenance, but as you said, Jan, even if the scope is working, the caps are probably dried out and will fail sooner rather than later. As I said to James, I will go ahead and replace them. Makes sense, being that the scope is already disassembled. Thanks for the input. 

Glad to hear that!

Let me or others in the community know if you need help.