How dangerous are RIFAs?

[liamur]

I've got a Mac Plus that appears to be stock (aside from 4MB of RAM) and I'm wondering about the RIFA caps. First of all, do I really need to replace them? I'm not adverse to soldering---the analog board probably has cracked joints anyway---but I don't like waiting for parts (and paying $10 shipping for $5 worth of caps). Also, I know that when the RIFAs go bad, they explode and make lots of smoke. How much of a threat is this to the wall supply, the computer, and/or me?

From what I've read on here and r/VintageApple, my current understanding is that it's okay to run with old RIFAs, but not ideal, and that when they explode, it's pretty nasty but harmless.

 

[3lectr1cPPC]

First of all, do I really need to replace them?

Replace? No. Remove? Yes. Just clip them out of the board, no fancy soldering needed. They will blow up at some point, and from what I've heard, RIFA smoke smells absolutely awful. It isn't dangerous when they blow, but that stuff stinks and probably isn't great for the lungs either. No hard in leaving them out, worst that could happen is that it trips the wall supply breaker, but I haven't ever heard of this actually happening. I'd replace them at some point, but at least get them out now.

 

[Byrd]

Check the RIFA caps for cracking - most will already have deep groove in them suggesting replacement, but you might be lucky. And yes, you need to replace these eventually otherwise the stink the fills your house - it won't give you many fans.

 

[liamur]

Ok, then. Thank you both. I'll check for capacitor cracks (I highly doubt they've been replaced), and if they're bad or old I'll desolder them completely. I want to go over the analog board anyway to check for and reflow cracked joints.

If I have a DigiKey order for another project, I'll grab some replacement RIFAs and solder them in.

 

[Phipli]

Cracks are a sign of age rather than imminent failure - they will have cracks. I've never replaced X and Y line filter caps unless they're already failed. Sorry to contradict.

 

[cheesestraws]

You should replace them. The machine will work without them, but you're introducing high frequency noise back into the power lines, which may have a deleterious effect on other devices, which may be your neighbour's rather than yours. They are protection devices in that they are protecting other devices from this one, not protecting this one from other devices.

This comes under the same heading as RF shielding. It is there for a reason, you should respect that.

 

[Phipli]

What @cheesestraws said too. Meant to say that as well.

 

[joshc]

+1 for what @cheesestraws said. They are there for a reason and should be replaced.

 

[3lectr1cPPC]

Yeah, that's about what I've heard. Replacement not strictly necessary, but should be done just in case. Short term it should be fine but I'd agree that they should be replaced.

 

[liamur]

Well, fortune is on my side. It seems that somebody got to this analog board before I did and installed film caps in place of the RIFAs.

Picture for reference, see the red caps next to the small transformer and the blue/green/white toroid.

 

[3lectr1cPPC]

Some shipped like that.

 

[68kPlus]

I replaced mine, as I couldn't bare with leaving the Plus and then one day the RIFAs explode and I'd have to open it up to clean things and remove the RIFAs. Easier to just replace them and get it over with.
Note: I had no experience doing this and it was all a learning experience, but I did it anyway and learned a lot!

 

[Corgi]

I have two SEs of unknown condition and I was about to plug them in and see if they work and then I remembered this thread. Do SE systems have RIFAs? I couldn't find a good answer other than this page that basically said "maybe" – without showing where to even look. Also, it's been trying for me to find what I am meant to replace them with. Is there a resource I should be looking at?

One is a standard SE, and the other is an SE FDHD, if that helps.

 

[smrieck511]

You should replace them. The machine will work without them, but you're introducing high frequency noise back into the power lines, which may have a deleterious effect on other devices, which may be your neighbour's rather than yours. They are protection devices in that they are protecting other devices from this one, not protecting this one from other devices.

This comes under the same heading as RF shielding. It is there for a reason, you should respect that.

This is interesting to me. I replaced the RIFAs in my SE (Astec) Power Supply with 4700pf film capacitors (when I recapped the entire PSU). Ever since there has been a very subtle (but annoying) scan line going down the screen. It goes away when the analogboard/psu is oriented at a different angle or distance. I've suspected this is some kind of RF interference due to using the wrong caps to replace the RIFAs. I've definitely isolated the issue to something on the analog board/psu. Does this sound like the culprit?

 

[dcr]

So . . . I think this is the first I've heard of this issue. Are the RIFAs on the analog board or in the power supply? Where? How many? And does anyone have DigiKey links for the appropriate replacements?

 

[smrieck511]

As far as SE's and SE/30's, RIFA's can be found in the Astec Power Supplies (The ones with the beige plug/switch). There are three of them in there (4700pf)....The Sony CR44 Power supplies (black plug/switch) do not have RIFA's.


As far as 128/512/Plus, I *believe* there are RIFAs on some of the analog boards in the power supply section.

 

[3lectr1cPPC]

Certain 128/512/Plus analog boards do have RIFA caps, I can confirm that for sure. Many instead shipped with red non-rifa caps, I'm guessing film or polypropylene or something of that variety. No way to know which a board would have without having a look at it.

 

[smrieck511]

And does it seem logical that missing/incorrectly replaced RIFAs could cause interference in the form of a scan line on the CRT?

 

[3lectr1cPPC]

No clue.

 

[smrieck511]

After swapping some stuff around last night, I can confirm that removing or incorrectly replacing the RIFA's (in at least the Astec SE/SE30 Power supply) can and will cause interference on the CRT.