Macintosh LC II Recapping and Dishwasher - please don't!

[Alex]

So this is not about the retrobrite that the 8-bit guy completed, that turned out very nice.

Instead it is about this really bad video he did, sorry I know some of you may like him but this video was wrong in so many ways that I had to warn potential viewers. I couldn't comment on youtube because they were not available for this video.

I hope this will equip you to perform any rework on your Mac or other electronics with safety to the board while ensuring a good solder job and good clean up.

 

[rsolberg]

Sometimes things get a little cringeworthy on YouTube, don't they?  I quite enjoy "Adrian's Digital Basement" and "Retro Man Cave" in their repair and restoration endeavours.  Adrian and Neil both seem to appreciate feedback from the community and both develop their techniques over time.  Adrian seems to be a whiz with through-hole components, having a lot of experience with Commodore 64 hardware and the like, and Neil has taken on some major surface mount recap jobs in recent months.

 

[AwkwardPotato]

Although I had a few issues with the video as well, I'm hoping it'll spread the word about recapping some, especially seeing how big his audience is on YouTube. It seems that a lot of people into classic Macs still don't realize just how damaging caps can be.

Re: the twisting caps method, respectfully, I don't think it's as dangerous as people make it out to be. Although a newcomer to the hobby might not know the difference, if your board is still in "okay" shape, it works fine, provided that you're gentle (based off purely empirical evidence, 5x 68k's of mine). Also bear in mind that the heat from desoldering can damage pads too. I totally agree with your points on lack of ESD safety & the dishwasher though, it was frustrating to see that in the video.

 

[nglevin]

Though I was about to blame LEM.com (again), it turns out that dishwasher advice is as old as the pickle's Low-End Mac FAQ. Although that should have only applied to cases and not logic boards.

I like that he's raising awareness of the Mac caps problem, perhaps my standards are low for YouTube exposure.  I've had bigger problems with MetalJesusRocks and LinusTechTips in the recent past.

There's quite a few people in his comments raising an issue or two about how he did the repair. Maybe that will inspire a follow up episode.

 

[Bolle]

Carefully twisting the caps off the board works just fine if done right.

I have done countless boards that way - not a single pad ripped. Ever.

I am with @AwkwardPotato here, excessive heat will put a lot more stress on the pad as will wiggling the cap back and forth while heating just one side.

For a beginner it is the way to go in my experience as you can do wrong a lot more swinging around a soldering iron or hot air gun trying not to burn your fingers or anything else while keeping calm and go slow about removing the cap. Not going to work if you haven't done any soldering before.

Been there, done that, ripped a lot of pads already doing it "by the book"

The twist method is fool proof though. The key is to push down on the cap while gently twisting and not pull up on it.

As long as there is no upwards force you won't be able to get enough torque into the pad to actually rip it off.

Just see how thin and tiny the lead it that actually goes into the cap. This is where you want things to break - and it will break there.

You are not supposed to actually rip through the solder at the pad which is of course not going to work.

 

[bibilit]

Never used the twisting method.

Cutting the top of the old cap is the less dangerous method in my opinion.

I have ripped very few pads, but to be honest most of them were very weak already.

Never used a dishwasher, but i have washed every board to remove old goo and dust.

 

[Alex]

Do not twist off caps from any logic board, it's not in the manual as it were for a reason … you run the risk of ripping of the pads that capacitors are soldered to. Once a pad is removed through the force of twisting off a cap,

I appreciate everyone's comments, I should make one correction. It was really late when I wrote this so I hope you can all forgive me but he did not twist the caps, he rocked them back and forth, which might be considered more desirable but I still prefer using heat to remove them. I should make that correction for what it's worth.

Despite this, I much prefer folks be given the advice to use heat to melt the solder as the safest method of cap removal. If your pad comes off even when using heat, a serious amount of damage to the board can simply be expected. The epoxy used to adhere pads can withstand heat of up to 800 degrees celsius or more which is way beyond the melting point of any solder so using heat should not rip off any pad unless, again, the corrosion caused by a capacitor's innards have been exposed for dangerously long periods, in extension this could also apply to the innards of a battery leak. Granted I do not know if either type of leaked material puts at risk the epoxy holding down the pad this would depend on the severity and exposure time these chemistries play on the board itself.

In any event, my original post was to simply put some perspective on his procedure which is not the advice I would have given for reworking a board, generally it is unfortunate that many youtube videos are providing out of spec instructions and I appreciate that some of you have cut off caps or twisted, rocked them without an issue. I am not saying it is luck that saved the board each time maybe you have a very good sense. I see the reason why this is the case, it's much easier and quicker to rock or twist off caps and just have cleanup as a post process but there are risks that are innate to applying physical force. As long as folks know those risks we are all free to use our own methods so I pasted those videos that provide best practice but of course doing things procedurally requires more time but yields as a little risk as possible. I should add that the PACE lessons have so much good advice that they stand on their own as a reference for so many types of soldering methods and good practice measures.

Thanks again for all your input, just take care of your boards and inspect your machine's from time to time, age can be their downfall.

Kind regards

—Alex

 

[Solvalou]

One thing that I'm a little surprised that wasn't noticed is that he left all the ROMs on the board when it went in the washer. 

When I (hand) washed my Classic II board, I made sure I removed anything removable so that it could try more efficiently. Including the ROMs. Not to mention I'm never a fan of doing this unless I feel I have to.

Overall, not a huge deal but IMHO, the less I can submerge in water, the better.

As for the twisting/rocking the caps, I watched it and immediately I was not a fan of this method either. I was surprised he even suggested this was (he thought was) the best.

If they haven't leaked than maybe it wouldn't be so bad but since they had (badly too) and has started to corrode, it's a massive risk as it's already almost certainly compromised the pads.

I've yet to get into recapping myself but I think of I did, I'd prefer to desolder them and use gravity to let the weight of the board drop (onto a soft surface) while the cap is still in the pliers. 

Still at least it still worked for David this time I suppose. However I don't think this is a "fool proof" method by any means.

Frankly is there really is a defacto right way to do these jobs? At least on vintage hardware?

I guess you got to do what works best for you, or at least what gets the best results with as few screwups possible.

 

[Bolle]

as it's already almost certainly compromised the pads.

But the much thinner cap leads itself will be as well by then. I had caps fall off while gently brushing the board using an old soft toothbrush to get the major gunk off before starting with removing any caps.

The leads were completely corroded away and the cap was only sticking to a little dab of glue they put underneath on some boards.

It may look bad when you see someone twisting caps off but once you feel how little force is actually needed until the leads snap I have no worries that this could do any damage to a pad ever.

I'd prefer to desolder them and use gravity to let the weight of the board drop (onto a soft surface) while the cap is still in the pliers. 

Any straight upwards force should be avoided. Even when desoldering a kind of a sideways twisting or jiggling motion to see wether the solder did melt or not is better than pulling up on the component.

There is no "right" way in the end I'd say. If you can try as much of the known methods to get a feel for it and just do what gets the job done for you.

 

[Crutch]

So, realizing that alcohol is to be preferred, what is the physical risk to washing boards in tap water (e.g. in a dishwasher?).  I have washed multiple cap-damaged boards in the dishwasher, followed by a quick bake (something like 15 min at 195 degrees) and 24-48 hours to dry, and to my knowledge have never had problems.  TechKnight and others on these forums have advised doing so repeatedly stressing he’s never had any problems.  Is the idea that using tap water (as opposed to distilled or something) could result in corrosive or conductive deposits on the board?  It seems to me really, really, like incredibly unlikely that a single washing with standard municipal treated water would leave enough of anything behind to make much of a difference, one would literally have to leave behind enough corrosive impurities to eat through a trace or enough conductive impurities to create a de factor “solder bridge” somewhere for this to matter, right?  That means maybe 0.5-1 millimeter of accumulated impurities which seems very unlikely.  Sure, if one washed the board daily for a month I could see that piling up some damage, but nobody does that.  And I can’t imagine damaging an IC this way.  What am I missing?

 

[Alex]

Links on cleaning PCBs … just a list of references. You can enter "pcb cleaning" in your fav search engine to find more articles. Tap water is not a good option because it leaves residues, DI water or deionized water can be an alternative. Some of the links are technical while others below are more general and useful. I think most of us have limited tools for cleaning but a brush and isopropyl alcohol is a good choice. Both are not expensive. Hope this just adds to the discussion and knowledge.

https://www.wellpcb.com/special/dirty-pcb.html

https://www.embeddedarm.com/blog/deionized-water-the-gold-standard-for-electronics-cleaning/

To sum up, tap water is a known bad soluble when cleaning boards in the electronic industry. DI water has many benefits over tap water for the longevity of the boards the customer receives. The pure water washing process will leave boards clean and free of contamination and is far superior to using dirty tap water that might possibly cause defects in the field.

https://www.ifixit.com/Wiki/Electronics_Water_Damage

https://gesrepair.com/clean-circuit-board/

https://www.kolb-ct.com/cleaning-tasks/product-cleaning/pcb-assemblies-cleaning/

https://www.kemet.co.uk/blog/cleaning/pcb-cleaning

https://www.digikey.com/en/maker/blogs/cleaning-pcbs

https://www.digikey.com/en/maker/blogs/cleaning-pcbs

 

[AlpineRaven]

I've done countless of caps and never lifted a pad by twisting it exactly 180° twist.

What people don't realise - the cap leak is actually toxic. What makes me cringe is once you've washed in the dishwasher - you're eating it on your dinner plate and drinking the glasses from your old caps!!! 

Not way to go, either ultra sonic or ISO wash it would be way to go.

Cheers

AP

 

[Alex]

 I have washed multiple cap-damaged boards in the dishwasher, followed by a quick bake (something like 15 min at 195 degrees) and 24-48 hours to dry, and to my knowledge have never had problems.

Your question was raised here but I didn't get a chance to read it all as other things are on the go.

http://www.circuitnet.com/experts/70402.html

Here is a caption from one answer given:

There are three general grades of water: tap water, distilled water and deionized (DI) water. In terms of precision cleaning, neither tap water nor distilled water are sufficiently pure to handle the job as both are contaminated, to greater or lesser degrees, with minerals and organics. So if you want to use water, you must jump to DI-water. Tap water, especially tap water mixed with detergents, should never be used for cleaning circuit boards. It generally will not remove the contamination and almost certainly will deposit soapy residues on the PCB. But DI water can be tricky. The quality of DI water usually is measured by the water's resistance to electric current (in OHM-cm). Now, how pure is that?
50 kOHM is pretty standard and can be produced easily and inexpensively by many in-house deionizing systems.
1 megaohm of resistivity is the minimum required for true precision cleaning.
In the really high-end world, such as the semiconductor industry, 20 megaohms is the norm. 20 megaohm water is so hungry for ions it will cut through steel.

If you search for "pcb cleaning" + "tap water" in your search engine you will find resistance to tap water due to contaminants that are left behind. I've done it once on a PCB for a dead Sony CRT but that was the only time. I stuck it in the dishwasher but I would never do this to a Mac logic board that I care about.

I don't have an ultra sonic cleaner so I can only use isopropyl alcohol and an ESD safe soft brush. The problem with this is that I can't get under components that's why an ultrasonic cleaner is preferred but I can only make due with what I have. An ESD brush and isopropyl alcohol is not expensive at all.

 

[maceffects]

@AlpineRaven I agree 100% that cap goo is toxic as well as any trace things found on the board like lead.  NEVER wash in a household dish washer. Just buy a cheap ultrasonic cleaner. 

 

[KnobsNSwitches]

I don't think this thread is going to come to any resolution; there are loads of people (myself included!) who have cleaned and repaired things the 'wrong' way and still had success. If this hobby absolutely required desoldering stations and ultrasonic cleaners there would be even fewer of us left. 

Just do your research, know the risks, and decide what is do-able for you.

 

[Crutch]

For the record I don’t really have an opinion and am looking to learn from people who have more experience, but basically I’ve read a lot of absolutist stuff like “washing with tap water is BAD, NEVER DO IT” and have never really seen any evidence of such (thanks @Alex for the links!  many of them basically state that an alcohol bath or ultrasonic cleaning is preferable, which seems obvious, but again my question is how bad is tap water really).  Of course, intuitively, tap water has impurities that will end up on your board and could then hypothetically cause corrosion ... but (and again I confess ignorance here) given the composition and size of the components that matter on a typical vintage PCB, it seems to me extremely unlikely that a single washing (or two, or six) with any water supply intended for human consumption could possibly leave enough of anything behind to materially damage a consumer board from the ‘80s, barring some freak circumstance.  

Of course one could argue, why take the chance?  ... and I agree, but I also like to know the facts.

I am assuming one isn’t using detergent, and do agree that getting cap goo in a dishwasher used for dinnerware is a bad idea.

 

[LaPorta]

As an aside: anyone suggest a good size ultrasonic cleaner, and some DI water to go with it? Also: do you ever worry about the ultrasonic process causing issues such as micro cracks in solder joints, etc?

 

[Alex]

but (and again I confess ignorance here)

but basically I’ve read a lot of absolutist stuff like “washing with tap water is BAD, NEVER DO IT” and have never really seen any evidence of such

I am not an expert myself but I think you could agree that there is something to be said about relying on the experts who really specialize in these areas. I believe the problem with tap water has to do with those impurities which might not wash off the board and cause problems down the road. It should also be pointed out that tap water varies from location to location for numerous reasons. I believe the overarching issue with tap water or similar has to with with pH or alkaline levels which can be problematic, perhaps not immediately but intermittent issues may arise down the road. Or perhaps this is like opening up a platter drive in a non-clean room environment. I am not sure if these are acceptable analogies but this is all I can come up with, maybe these similarities can help you find better analogs. I would tend to put this in the same ballpark as practicing ESD safety when handling PCBs to avoid static discharge. I posted a video on this way at the top. But @Crutch I do apologize for not being able to give you a solid answer on this. I posted some links, at least one tackles the question but it's one of those things. I think if you simply use isopropyl alcohol and a brush you will be fine, the results can be extraordinary. Alternatively, if you use water I would immediately (while the PCB is still wet), dip it in a bath of isopropyl alcohol as it will be pretty good at repelling the water away from the board. I hope this helps. 

@LaPorta I don't know the answer to that, I don't use one myself but perhaps this forum post on another forum might be useful? https://www.eevblog.com/forum/reviews/pcb-ultrasonic-cleaner-recommentation/. If you plan to buy one just for a single board it could be an expensive proposition. Maybe a used device could serve your purpose and save you some money and the environment in the process.

 

[Crutch]

Thanks for the info @Alex !