Axial caps NEVER need recapping?

[JDW]

You'd be wrong about that.

Through the years I've read many people talk about what things they THINK need recapping and what they don't. Most of that goes beyond their own personal machine usage experience and also ties in with what they read online, or more accurately, what they DON'T read online. If you tend not to read lots of reports about certain boards having issues, you tend to ASSUME those boards are OK and don't need recapping. Same with floppy drives which have electrolytic capacitors on board. I talk to a lot of people who've recapped Analog boards, but floppy drives? Nope. Only a tiny number, myself included, seem to be doing that.

I've said this so much my head is ready to explode, but because so many out there still misunderstand the fundamentals of fluid-filled capacitors, it must be repeated until the end of time:

No electrolytic capacitor has eternal life.

Technically speaking, NOTHING lasts forever, not even ceramic or film capacitors. But we're talking about things that will last or fail during our life times. And when you ponder that, fluid filled caps are the most vulnerable. No electrolytic capacitor datasheet makes promises beyond 20 years or so, regardless of how many years of life you may calculate using the capacitors Hour rating for a given ambient temperature. Capacitor packing and gaskets degrade over time, electrolyte leaks and dries up, and your capacitor slowly becomes a resistor.

I was going through photos today and found my stash of Macintosh 128K Photos. One in particular shows something that inspired me to create this thread in the first place. Two axial caps had clearly leaked (note the greenish substance below, and bear in mind that photo was taken back in 2012):



That's not a one-off either. I've had axial on my analog boards spout leaks like that over time.

And this is precisely why I did a video about recapping the very boards most people say don't need recapping:

So yes, motherboards for the Mac 128K, 512K and Plus do in fact need recapping, regardless of them "working just fine."

Someone might say to me: "Yeah, James, but I'm not adept with a soldering iron and my destroy the board!" But that's beside the point because again, no fluid filled cap has eternal life, and now with it being 40 years or so since the time of manufacturer of the earliest Macs, it's now time to either do the recapping job yourself, or find a low-cost guy in your area who can do that for you.

Others may say to me: "Yeah, James, but I want my 128K motherboard in stock condition forever." Well, I guess if you never intend to switch on the machine, that's fine. Because hey, see that 128K motherboard photo above? A guy approached me about buying it some years back, telling me his sole aim was to mount it behind glass on his wall. I kid you not. And I sold it to him for that purpose.

But here's the thing. I suspect most 128K machines are not put behind glass. Someone out there is powering them on. And for that very reason I get private emails all the time from people asking me about a Sad Mac error code that inevitably leads them to a bad RAM chip. You know the kind. The Apple-logo RAM chips which are notorious for failure. Now keep in mind that most 128K owners treat their machines with a delicate and contemplative hand. Even so, these same folks often proceed to have bad RAM chips swapped out when they see the Sad Macs. Swapping out the bad chips for new chips that exactly the same? Of course not. They swap them out for chips that look different than the Apple logo chips. And a chip that looks different is quite easy to spot. So if somebody who cares a lot about keeping their motherboard stock is willing to do that, making their board NON-STOCK as a result, it behooves us to consider what else needs maintenance on that board. The answer is, the electrolytic capacitors. In fact, I'd say it's a world easier to swap out the axial caps on a 128K board than to PROPERLY desolder one or more RAM chips and then solder in new ones.

I aim being a pest about this topic because it needs to be done. Some people will read this, shake their heads, and just keep using the machines as is in the stock condition until they suddenly stop working. And because the manner of leakage from the axial caps isn't nearly as severe or damaging as say the SMD caps on an SE/30 motherboard, most people feel content. Doing nothing is easy and saves you money, right? Sure!

But there are others of you out there who do understand the nature of fluid filled capacitors and the need for maintenance on these old machines. My post merely serves as a reminder to you to do the right thing. Swap out those caps and make your Mac HAPPY again...

You'll sleep better at night too, knowing he's happy.

HAPPY RECAPPING, FOLKS!

 

[phipli]

Yeah, never say never.

I've not noticed people saying axials never need replacing, it is certainly less frequent, but what I tend to say to people is that machines with SMD "tin can" electrolytics from between 1988 and 1992 are recap on sight. Everything else is recap based on condition - i.e. have a look, perhaps measure a sample capacitor.

I replaced one of the axials in my SE/30 a couple of weeks ago. I had the board out and noticed it had leaked some electrolyte. Luckily I had a spare on hand. They're more tricky to get out than the SMDs because they tend to be thermally coupled to a big ground plain.

The big problem I find is that people not used to doing this have an idea of what they think cap damage and bad caps look like, and it isn't inline with reality. They expect to see rust or big bulging caps I think, rather than mottling and dark patches, and black marks on the edge of pads. What I tend to go by is the shine of the solder. If it is bright and shiny like chrome, that cap hasn't leaked. If it is slightly dull, be suspicious. If it is a dull grey, black, green or white and fluffy, a recap is probably needed. At this point, there is generally more harm in not recapping than in an un-needed recap.

Buuuuut. Never work in absolutes as above.

Everyone's machines are different, but at this point I haven't needed to recap anything past 1993 (yet - I expect to). I did have to do one badly stored beige G3, and some stuff from the capacitor plague in the 2000s (mainly video cards).

One thing I don't think you mentioned in your post is that the caddy CD drives all seem to need doing. 3 of mine have stopped working due to bad caps. Also, cards. NuBus cards often have at least one tin can electrolytic next to the main board connector, while first gen PPC PDS video cards have been having more leakage issues than the main logic boards in those computers - I've had to recap two HPV cards due to leaking caps. They were actually already quite far gone (I had to reflow one of the QFP chips on one), if I'd left them they would have been pushing pretty bad.

Oh, one last thing. LaserWriters! My LW Pro 630 was in a horrific state. Worst cap (not battery) damage I've ever seen in person. Some of the pins on chips were BLACK from corrosion and there was electrolyte literally pooling on the board.

 

[phipli]

Only thing I'd say is if you are trying to save money or keep a machine as original as possible, invest in a cheap component tester. They work surprisingly well and with a little guidance you can do things like check every cap in a PSU and verify the condition. This can be a real money saver with, for example, the huge mains side capacitors in powersupplies which are expensive, or even not readily available.

All you need is something like this for $10 :

https://www.ebay.co.uk/itm/326258860593

or...

https://www.aliexpress.com/item/1005005590533196.html

I'm not promoting those specific listings. Please search for the best deal in your country. They're also great for checking the pinout of transistors, matching diodes for your ring modulator and all sorts of things. They're not equivalent to a high end tester, but they are way better than I would have ever expected despite appearances. Anyone about to scoff at them, given the low price, I suggest you buy one and compare the results, with consideration given to the difference in price, to your fluke or Peek LCR. It isn't about replacing the high end kit, it is about giving a capability to people who wouldn't otherwise be able to justify owning something that could do this.

 

[JDW]

You make a lot of good points and I do not wish to diminish the importance of what you wrote in any way whatsoever. But I feel it important to repeat myself. I put the key sentence in orange color in my opening post:

No electrolytic capacitor has eternal life.

If a fluid-filled electrolytic capacitor is about 25 years old or older (which is easy to figure out if you know the model year of your electronic machine), it should immediately hit your radar as a recapping candidate. That's pretty much it.

Yes, it really is that simple. You can do all the DE-5000 ESR meter testing in the world, but that only gets you so far. I've measured ESR on caps that seemed fine, but when put under a load, they didn't do their job.

I've encountered many people with the philosophy: "if it ain't broke, don't fix it." That's flat out wrong when it comes to fluid-filled capacitors because you may not know what is really broke and what isn't. Your machine may run fine and all the while your SMD electrolytic caps are spewing their guts all over your board.

Recapping is a vital part of this hobby even though I personally hate it. That's right. I hate recapping like most all of us do. I just want to use my darned old Macs! I don't want to spend 90% of my valuable time on REPAIR! And yet, getting into this hobby immediately initiates you as a member of the Repair Community.

Even if you aren't immediately thrust into repair due to a non-functional machine, just wait. It will happen. And I feel for people who hate the repair part as much as I do. That's why I make video walkthroughs to make it a little bit less painless. I do that because I wish somebody out there had taken my hand and walked me through the process, step by step. Believe me. I need a lot of detailed help AND repetition too. So I try to give that to other people whenever I do a video walkthrough.

I personally don't try to look for bulges, calculate operating hours, take a guess on ambient temperature, or otherwise try to scientifically determine if a give fluid filled cap needs replacing. If it's 30 to 40 years old, it absolutely does need to be swapped out. I don't care if it is SMD, radial or axial, so long as I know it is electrolytic. But getting some folks in our hobby to do that important job, either on their own or by paying a pro to do it, is sometimes an uphill battle. I've had know-it-alls in the EE community (think EEVBlog) who come along and say old electronics should almost NEVER be recapped! I kid you not.

We all need to be prodded now and then to be mindful of important things to do. Recapping in this hobby is a significant part of the experience. And Gosh! There are so many caps to replace. Analog Board... Motherboard... Floppy Drives... Keyboards... Power Supplies... Mice! One SE/30 system is a huge amount of work! Wish we didn't have to do it, but we do.

Some machines are worse off that others, as @phipli nicely pointed out. But again, you don't have to wrack your brains about the details. Just find out how old the caps are, then consider how the recapping job should be done, then do it. (Do it based on videos and/or recapping lists or Console5 recapping kits. The knowledge is out there, and readily available.)

Yes, there are other important things to repair too, but that's beyond the scope of this thread. My words are exclusively focused on fluid-filled capacitors in vintage electronics.

That's all I'm trying to say.