Typically I tend to refurbish (read about the RIFA capacitors...) or getting new additional power supply to my various system, but since I just received my Apple IIe (PAL-version) 2 days ago I just wanted to quickly fire it up and test it and believe that after good 15-20 min I saw the smoke from the power supply and simply turned off the computer.Unmounted the power supply to check the pcb to find the RIFA capacitors and looking of the whole pcb by itself didn't really show any thing:
and a closer photo of the RIFA capacitor and I could only find one:
A bit puzzled about were did the smoke come from and also the brown residue came from and then I noticed the additional Rifa capacitors soldered directly to outlet and what a mess:
Now, most likely I could either replace these Rifa capacitors but or are there other work arounds to avoid resoldering a new capacitor in such way that the above has been done?
The solution is very simple, as those components should not be there (neither the Rifa nor the 610K resistor). They are not factory spec.
It's not clear why they were added, but they are redundant and should be removed. By soldering them directly to the power inlet, the shrink insulation over those wires was also broken.
You should also take the PSU apart and use alcohol to clean as much of the “Pepsi” coating as you can. Otherwise it’s going to stink every time the computer runs for more than 10 min and the PSU heats up.
Right, but don't clean the lacquer off of the transformers (T1, T2, T3). It's there to provide isolation and prevent hum.
Yes, I was suprised to see both the capacitor and the resistor soldered in such way as I initially was just eyeing down on the pcb and was wondering what generated both the crackling noice and smoke until I flipped around the casing and noticed that components soldered directly to the outlet. As far as I can see it's original from factory since the PSU has never been open and the screws were still sealed on the inside of the casing. So seems to be a bad fix from Apple. Here are the details on the PSU if someone wants to check:
Apple_IIe_psu_label.jpeg
Oh you bet, I'll need to clean that sticky coating off with some IPA and while it's a mess it wasn't a total mess and concetrated just around the sockets and wires.
About the Rifa 0.1uF replacement; been looking at various brands among other Kemet but just way too big and doesn't fitt the rm on the board. Anyone have a suggestion for good brand since I want to avoid anything which comes from aliexpress.
WIMA is a pretty good brand. Look for polypropylene X2 and Y1 caps of the same capacity and same or higher rated voltage as the originals. They are inside a plastic jacket, which protects the epoxy from cracking, filling with moisture, shorting and exploding.
Thanks, was thinking about WIMA or KEMET and found KEMETs that fits for the purpose, so hopefully by end of the week the PSU have been de-Rifa'ied or simply debombed. :-)
The rifa and resister connected to the iec socket was possibly done by the factory. This is a user made schematic/diagram, but the fact some one else also found the same parts in their supply means there is a good chance it was done by the factory.
http://www.appleiioz.com/AppleIIoz/Projects/Entries/2019/12/21_Apple___e,_II_europlus_240V_115V_ASTEC_AA11040C_PSU_Circuit_Diagram_files/AA11040C%20PCB%20overlay%20C%20v2.0.pdf
It does look like other units with the "-C" designation had these components added: Mark Cummings documents one here. I can't figure why they would do that; perhaps there were some markets with particularly bad harmonics on the power lines at the time.
I would still not use them, because as he observed, being ahead of the power switch creates a fire hazard.
Dodgy power supplies these days I generally just do a Mean Well PT-65B conversion or if you aren't that adventurous go with the ReActive Micro kit. The MW is not really difficult and the RM one is super easy.
And you get essentially a new power supply that should be reliable for years and higher output than the original.
Just a blown RIFA cap doesn’t make it dodgy, nor is it a reason to gut it. All my Apple machines are with their original PSUs and working perfectly.
That's true, and I have several that I have only swapped out the RIFA caps for new ones. What I mean by dodgy is ones where stuff has been hacked on as mentioned in questionable manners like the cap before the power switch soldered directly to the plug. Even if that was done at the factory as someone else mentioned it might be a safety issue.
But if it is blown and it isn't something obvious, like just replacing a melted RIFA doesn't get it going again, it is easier for me to just put in a Mean Well than it is to try to re-cap or troubleshoot it. I've seen too many people do a lot of work re-capping and still have a power supply that doesn't work. The AE supply I put a Mean Well in that I posted about here for example, I got really cheap off eBay because someone else had tried re-capping it and it was still no bueno. I have a couple Apple branded Astec or Dynacomp supplies I've done the same thing. I've had a few that just replacing the RIFA that was blown when I got it made it work again, but others I just swapped the board out after the RIFA swap didn't get it going again.
And like I said, the Mean Well or ReActive boards put out almost twice the power of the originals and it is pretty likely they will provide many years of trouble free service. With the originals even if it works fine now, those parts in there are still 30+ years old and you never know how long they will last. Might be another 30 years, or might quit next time you turn it on.
Safety caps before the switch are often found in modern electronics, but they put them inside a metal enclosure. This one just needs to be removed along with the resistor. A new modern X2 cap on the PCB is more than enough.
Based on that the 470nF X2 capacitor is not included on the schematics for the ASTEC Model AA 11040C power supply was this due to that it's an US PSU which was adapted for the European 230V market were there was requirement to have the additional X2 capacitor? And was this X2 capacitor later on removed from newer machines using the ASTEC Model AA 11040C PSU init?