10 replies to this topic

[DistantStar001]

This is mostly for my grandfather's //e (for which I've posted before), but I also have a Mac Classic that gives me nothing but checkerboards.  So I have to ask, has anyone ever tried putting a motherboard in a dishwasher?  I've seen several youtubers who swore by it, and I've reached a point of desperation where I'm finally willing to try it.  However, I have a few questions before I do it.  Do I use detergent? And if so, what kind?  Also, heat, or no heat dry?

 

Any advice would be appreciated.

[Keatah]

When it comes to classic computers and vidyahgamez I just use some Dawn dish soap on a brush and manually do it. Foam it up. Then I rinse and blow it off with an air compressor.

 

In the dishwasher I also use Dawn, just enough to foam up. Too much and it absorbs all the water and makes suds that the pump doesn't move. Half a teaspoon at most. 1/4th is good.

 

With home dishwashers you need to blow the water out or it will leave mineral deposits. Heat or air dry is not a good choice at home. Must use Industrial washers use a brief highly-purified rinse and air dry. We don't really have that option at home.

 

You may also want to spot-clean any problematic areas with chemicals and abrasives as needed.

 

(A friend of mine made a centrifugal dryer from a washing machine with hi-speed spin.)

 

If washing an Apple II mobo, all the chips need to come out first. This to ensure everything gets cleaned. Then you methodically blast-dry each socket from several angles working across and down. You'll be surprised to see nearly 2/3 fl. oz. water come out.

Edited by Keatah, Fri Aug 31, 2018 1:26 PM.

[OLD CS1]

What I have done in the past: all chips removed, old toothbrush or soft bristle shoe brush where needed, mildest detergent possible, no rinse aid, rinse thoroughly with distilled water, heat gun or hair dryer to completely dry or my more recent favorite is to hang with fans blowing on board. Some have spoken of using an oven to dry, even to re-flow solder -- I am not totally sold on that but have tried it once or twice with no ill effects, but I am paranoid about any heated option.

[Osgeld]

IMO your better off with a tub from dollar tree and a can of denatured alcohol from the hardware store

 

its going to do more and not linger wicked under chips for god knows how long, while promoting dendritic growth due to flooding the entire thing in chlorinated mineral water piped to your house in iron or lead mains pipes 

[DistantStar001]

OK, so I've washed it.  I removed all the IC's (the Motorolla MC1741CP did not survive extraction, and had to be replaced) and used some dish soap lukewarm water, and a new toothbrush, and lightly scrubbed the whole thing.  I used a towel and compressed air to dry it off, then when I couldn't get any more liquid out, I placed it under a fan for 24 hours to make sure this thing was dry.  Visually, this board is as clean as it has ever been in decades.

 

I put all the IC's back and hooked it up to a power supply, monitor, keyboard, and speaker.  When I flipped the switch, all I got was a white screen with blue rectangles (no beep), which is similar to what I got before, however, the rectangles are shorter, and there are more of them.  Other than that, the image is stable and no longer flickers like it did before.

 

There is a problem, however.  The chip at LS154 gets extremely hot, as does the area of the board just to the right of it.  This happens within seconds, and obviously, and as soon as it did, I cut the power.  This is the only area of the board that gets hot, and I'm guessing that there's a short somewhere in the socket that's causing it.  I still haven't figured out what the screen means, or why there's no beep.  The RAM chips are all new...  I've already tried contact cleaner and alcohol (which is how I got here in the first place).  I suppose I could try a good soak in alcohol, but I'm not sure if it will help.  I wish I could take a picture of the screen, but this thing really heats up quick, and I'm afraid of frying that chip.  

 

So, does anyone have any ideas as to where to go next?  

Edited by DistantStar001, Mon Sep 3, 2018 11:44 AM.

[DistantStar001]

Out of curiosity, and because I figured that it couldn't do any more harm, I sprayed some contact cleaner into the affected socket, and then blasted it with compressed air.  The chip at LS154 still overheats, but the area of the board immediately to the left no longer does (I know I said to the right in my previous post, but I'm dyslexic.  Sorry).  How the chip overheats also has changed, as before the heat was concentrated to the middle and upper left of the chip.  Now the chip only overheats in the upper right (yes I wrote that right, it's the right) corner of the chip.  The heat is also more concentrated in that area, and it takes almost twice as long before I can feel it.  There is, however, no corresponding change on the screen, and no beep on power.

 

I'm pretty sure now that the overheating issue is a short somewhere in the socket, otherwise, why would the contact cleaner have changed where the chip was overheating?  I'm guessing the same is true for the screen issue and the failure to boot, however, I'm not sure where that short might be?  

 

Also, the MC1741CP chip that was lost in extraction?  The replacement was generic, marked simply 741, and I'm curious now if that was truly the right part?

 

Note: I'm orienting my board as it would be in the //e, RAM to the front and expansion slots in the back, just so I'm clear as to what right and left are.  

 

Also, I think Osgeld was right, an alcohol bath would probably have been more efficient, and caused me less followup.  I just didn't have enough alcohol or anything to submerge it in.   I was being impatient, and I'm paying the price.

Edited by DistantStar001, Tue Sep 4, 2018 5:59 PM.

[DistantStar001]

Another two blasts of contact cleaner and LS154 no longer overheats, but the screen remains unaffected.  

[Osgeld]

shit happens, its not permanently dead, its just a chance to learn more 

 

make a truth table pop out the LS154 and check resistance on the each combination of pins of the socket, as far as changes there might have been something shorting it, killing the chip, contact cleaner displaced it, now its just showing up where the chip crapped itself ... or it could have just damaged itself further as its burning up 

 

as far as the MC chip, motorola has a chip on its shoulder (see what I did there) with TI so a 741 op amp is functionally identical to a MC1741, almost all moto chips in the past use a MC part number just cause 

 

as far as the root cause of the machine not functioning, IMO its not worth magic tricks and swears from youtubbers getting something to work on camera with sheer luck, the electrolytic capacitors are most likely shot and cleaning their snot off the board is not going to magically put the snot back inside the caps 

 

I have the opposite problem, my SE mainboard works perfectly fine but the HV section for power supply and monitor are crap so I get wiggles of the screen all the time 

Edited by Osgeld, Tue Sep 4, 2018 7:12 PM.

[DistantStar001]

make a truth table pop out the LS154 and check resistance on the each combination of pins of the socket, as far as changes there might have been something shorting it, killing the chip, contact cleaner displaced it, now its just showing up where the chip crapped itself ... or it could have just damaged itself further as its burning up 

I'm getting a couple of new boards in about a week.  If one of them checks out, then I should be able to test the chip to see if it failed.  As for the socket, I'd like to test a working one to compare if anything's wrong.  Unfortunately, this chip is soldered in my current functioning board.  The good news is that the chip appears to be generic, and can be easily replaced.

 

I have the opposite problem, my SE mainboard works perfectly fine but the HV section for power supply and monitor are crap so I get wiggles of the screen all the time 

I haven't even tried the Classic board yet.  I know I need to replace one cap that I saw leaked, and as for the rest, why leave defective parts when you know they're going to cause a problem.  Also, my screen flickers as well, so the analog/power board needs a recap too.  That Classic is going to be all kinds of fun!

[Osgeld]

 That Classic is going to be all kinds of fun!

 

yea .... I am an electrical engineer and I have not recapped that machine for a reason (besides once it warms up it tends to settle down)

 

its just a PITA and its big caps with big voltages and its just a mac SE that mostly functions the 4 times a year I turn it on

 

its not that big of a deal to do one just has to put a bit more care in doing it, big caps make big booms 

Edited by Osgeld, Tue Sep 4, 2018 8:14 PM.

[DistantStar001]

OK, so I just got two new motherboards (one enhanced, the other not) and swapped the chip at LS154 with the un-enhanced board (because that's the one that's socketed).  I ran the internal diagnostic, and got "KERNAL OK".  I guess that means the chip is good unless the diagnostic doesn't test for that chip?  So I guess my next steps are going to be swapping all the ICs, one by one, to see if any have failed, and then test for shorts in all the sockets.  Or maybe reverse that.  Either way, wish me luck, this is going to take a while.