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Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.
Just purchased Mac 512k
- Thread starter lumpydog
- Start date
JDW
Well-known member
Correct. The only BOMARC schematics I have are of the SE/30. But I also have Apple schematics of the SE/30. I've compared them in many places, and they appear to be the same (which is reassuring). BOMARC does a great job.
Man. Your link to those Beck-Tech schematics have me drooling now. Anyone know someone who used to work there who could provide us readable copies?
Man. Your link to those Beck-Tech schematics have me drooling now. Anyone know someone who used to work there who could provide us readable copies?
Charlieman
Well-known member
Beck-Tech sold the schematics so there should be a few copies around.
Mac128
Well-known member
You have to wonder how accurate they are and why Apple would allow them to be sold contemporarily with their technology.
lumpydog, my apologies for hijacking your thread, but at least we know that C16 may be suspect and should be easy enough to replace, before you go looking for an RTC replacement. If not that, then I think you have to really start suspecting that clock.
Having said that, this seems as appropriate a venue as any to post this. I found this ebay auction for a 820-0086-F logicboard. The seller confirms the part number, though he has not confirmed the picture or whether it has 128K or 512K RAM installed. BOMARC likewise shows a 128K/512K 820-0086-C/F board, but does not show a 820-0141-A hybrid board, which is the only 512K variant I have seen.
So what is going on here? Is the "F" variant actually the original part number for the hybrid "Fat" Mac board? If so, why change the part number? Was the hybrid board further redesigned? Or did Apple decide the redesign was more significant than to be labeled a mere revision of the original? The only other reference I find to the "F" board is this website which also shows the same picture of a hybrid board as the eBay seller does. Not enough to ensure both are not using the wrong picture, but seems unlikely.
Mac 128 - this thread has covered so many different things, I don't think it could be hijacked...
Update on my Mac 512K: Still no luck with the clock. I did de/resolder the RTC chip. No luck. I purchased a 512Ke on eBay (arrived Friday) and swapped logic boards. Clock worked. So it confirms it's something on the logic board. I'm still focusing on C16 as it looks damaged.
JDW - I did de-yellow my Mac 512K AND 512Ke cases in the solution this weekend. This time, the mix was 1/3 Hydrogen Peroxide - the rest was water (and Oxi powder). Used a big plastic clear storage bin (I think my wife bought it at Target). Six hours in the sun. Results were the same as the other parts - incredible. The plastic model number sticker on the back - undamaged. The Apple Logos and Labels - undamaged (I did not remove them - watched closely). The serial number label - some water seepage/absorption around the edges but it dries out.
Another thing to mention - after the plastics come out of the solution and are dry, I've been using "Aerospace 303 Protectant" on them. The 303 Aerospace Protectant has a UV block.
Update on my Mac 512K: Still no luck with the clock. I did de/resolder the RTC chip. No luck. I purchased a 512Ke on eBay (arrived Friday) and swapped logic boards. Clock worked. So it confirms it's something on the logic board. I'm still focusing on C16 as it looks damaged.
JDW - I did de-yellow my Mac 512K AND 512Ke cases in the solution this weekend. This time, the mix was 1/3 Hydrogen Peroxide - the rest was water (and Oxi powder). Used a big plastic clear storage bin (I think my wife bought it at Target). Six hours in the sun. Results were the same as the other parts - incredible. The plastic model number sticker on the back - undamaged. The Apple Logos and Labels - undamaged (I did not remove them - watched closely). The serial number label - some water seepage/absorption around the edges but it dries out.
Another thing to mention - after the plastics come out of the solution and are dry, I've been using "Aerospace 303 Protectant" on them. The 303 Aerospace Protectant has a UV block.
Mac128
Well-known member
Since we've determined the C16 directly interfaces with the power supply into the RTC it is definitely worth replacing if it looks suspect anyway. However, I don't think you can conclude it is not the RTC without actually swapping the known good RTC for the bad. Try the C16 first (perhaps borrow the one from the good board), then swap the RTC if that doesn't work.
The 512K and HD20 had entirely different logos from the picture that showed the corrosion (and LC?). I wonder if the diamond-cut inlaid logo was stamped out of a steel alloy while the square 3-D logo was stamped out of something less reactive with the H202 like aluminum.
Interesting stuff. I can remember using something like it to clean my mom's patio furniture in Florida. It must leave some kind of film on the case in order to work, though I assume it is undetectable? As such, it would seem necessary to reapply to maintain effectiveness. This is a good solution since it should allow for repeated dunkings as the unit yellows from heat and chemical breakdown. Would be nice to leave it on display in a sunlit room without having to worry about the UV degradation which seems to be ironically both the Mac's main nemesis and savior.
The 303 Protectant is nice because it does not make the plastic look wet or feel slick like Armorall does. It gives the plastic a "new" look.... The UV block is a bonus. Not sure how long that lasts, but after the H202 dunk and the 303, the plastic looks brand new. I'm pretty pleased.
JDW
Well-known member
I appreciate those photos, Charlie. And I am very curious how the compact Mac cases will fair in light of the gray colored spray on the inside of the plastic case. Mac128 mentions that metal under the Apple logo could have resulted in the destruction of the colored paint on that same logo. Hence I wonder what will happen to that gray paint. Because doesn't that gray coating contain metal flakes in it?
JDW:
I'm not sure about the content of the gray paint used on the interior.... Mine looks fine after being dunked.
I promised some pictures - see: http://www.flickr.com/photos/33624199@N08/3301745527/ you can move through the series by clicking to the right (you know the drill with Flickr as I've seen pictures posted by you there).
The first series of pictures is of my 512Ke - which has been treated in the H2O2 solution and then wiped down with 303 Protectant.
The last six pictures show a keyboard after it had been washed in H202. The first three are before 303 had been applied - the last three are after. It's hard to tell the difference up close - but the protectant does make the plastic look slightly newer. More of a satin finish - but not wet (like Armorall) -and it does not feel slick or slippery/greasy.
Let me know if you have any more questions.
Oh - one other observation. I think the Compact Macs can get away with such a low percentage of Peroxide because the plastic is relatively soft/porous. I put the yellowed plastic from my MacEnhancer case in the solution - 3 days so far and it's only slightly changed.... Also - you will notice in the pictures that the spacebar on the keyboard of my 512Ke looks pretty good - that took 4 days out on the sun and 1/2 to 1/3 3% solution to get it looking that close to the other keys - it's a harder plastic...
I'm not sure about the content of the gray paint used on the interior.... Mine looks fine after being dunked.
I promised some pictures - see: http://www.flickr.com/photos/33624199@N08/3301745527/ you can move through the series by clicking to the right (you know the drill with Flickr as I've seen pictures posted by you there).
The first series of pictures is of my 512Ke - which has been treated in the H2O2 solution and then wiped down with 303 Protectant.
The last six pictures show a keyboard after it had been washed in H202. The first three are before 303 had been applied - the last three are after. It's hard to tell the difference up close - but the protectant does make the plastic look slightly newer. More of a satin finish - but not wet (like Armorall) -and it does not feel slick or slippery/greasy.
Let me know if you have any more questions.
Oh - one other observation. I think the Compact Macs can get away with such a low percentage of Peroxide because the plastic is relatively soft/porous. I put the yellowed plastic from my MacEnhancer case in the solution - 3 days so far and it's only slightly changed.... Also - you will notice in the pictures that the spacebar on the keyboard of my 512Ke looks pretty good - that took 4 days out on the sun and 1/2 to 1/3 3% solution to get it looking that close to the other keys - it's a harder plastic...
Mac128
Well-known member
The gray paint has a metallic content. The whole point of it is to prevent RF interference. Given that the RF shield is aluminum and the Apple III used a solid aluminum chassis, my guess is, it's an aluminum based paint. Aluminum is not particularly reactive with H202.
As for the spacebar ... that explains a lot, in particular why it tends to discolor and the other keys do not. Clearly supplied by a different manufacturer. Did you dunk all of the keys as well as the spacebar? If so, how long did they take by contrast?
I did notice that any screws put unto the H202 solution suffered from minor corrosion (steel?) I think you may be right about aluminum. Also, I am using a much lesser percentage of peroxide - compared to the solution that ate the Apple logo in the earlier picture that I linked to.
I did not dunk any of the keyboard keys - with the exception of the spacebar, which was clearly yellowed in comparison to the rest.
Apple would have to be careful with any aluminum - based paint. If it came into contact with steel parts/screws - Galvanic corrosion.
JDW
Well-known member
Lumpy, so how many cups/tablespoonfuls of that OxiClean powder are you using versus the total volume of Water + H202 again? (For example, 1 cup Oxiclean to 1 gallon of H20 + 1 gallon of H202 @ 3% concentration -- 2 gallons total liquid, with 1.5% H202 concentration?)
It also seems that you are just leaving the plastic items in the solution, out in the sun, until your eyes see a physical change in the color of the plastics, correct? That explains why you removed some items after several hours in the sun, while others were not removed for 72 hours or so (which includes sunlight and darkness at night).
It also seems that you are just leaving the plastic items in the solution, out in the sun, until your eyes see a physical change in the color of the plastics, correct? That explains why you removed some items after several hours in the sun, while others were not removed for 72 hours or so (which includes sunlight and darkness at night).
JDW:
The solution's percentages have been pretty approximate... but here is what I've used:
First time (Mouse): 100% Bottled Hydrogen Peroxide (3% concentration), 0% Water. For each gallon of this solution, a tablespoon of Oxi... maybe a little more
Second time (HD20 Case) (Needed more fluid to fully submerge larger plastics in larger tubs): 50% Bottled Hydrogen Peroxide (3% peroxide concentration), 50% Water. For each gallon of this solution, a tablespoon of Oxi...
Third time (Mac 512 Case) (Needed even more fluid to fully submerge larger plastics in larger tubs): 30% Bottled Hydrogen Peroxide (3% peroxide concentration), 70% Water. For each gallon of this solution, a tablespoon of Oxi...
Yes, I've been eyeballing it - I don't think there is a "too long" in the solution - the plastics don't get any lighter after a certain point, when the yellow is gone.
The diluted H202 seems to be just as effective as the undiluted. I've been cleaning out my local Wallgreen's supply of bottled H202. At less than $2 per bottle, I've purchased about 15 bottles to date. The recycling truck must think I'm nuts.
If you're concerned, try it on your mouse first - you wont need much solution or a big container... Use a clear plastic container to get max UV penetration.
I used the 303 Protectant, because I reasoned that it would protect the plastic and replenish it/keep it from drying out. The protectant improves the result.
The solution's percentages have been pretty approximate... but here is what I've used:
First time (Mouse): 100% Bottled Hydrogen Peroxide (3% concentration), 0% Water. For each gallon of this solution, a tablespoon of Oxi... maybe a little more
Second time (HD20 Case) (Needed more fluid to fully submerge larger plastics in larger tubs): 50% Bottled Hydrogen Peroxide (3% peroxide concentration), 50% Water. For each gallon of this solution, a tablespoon of Oxi...
Third time (Mac 512 Case) (Needed even more fluid to fully submerge larger plastics in larger tubs): 30% Bottled Hydrogen Peroxide (3% peroxide concentration), 70% Water. For each gallon of this solution, a tablespoon of Oxi...
Yes, I've been eyeballing it - I don't think there is a "too long" in the solution - the plastics don't get any lighter after a certain point, when the yellow is gone.
The diluted H202 seems to be just as effective as the undiluted. I've been cleaning out my local Wallgreen's supply of bottled H202. At less than $2 per bottle, I've purchased about 15 bottles to date. The recycling truck must think I'm nuts.
If you're concerned, try it on your mouse first - you wont need much solution or a big container... Use a clear plastic container to get max UV penetration.
I used the 303 Protectant, because I reasoned that it would protect the plastic and replenish it/keep it from drying out. The protectant improves the result.
Mac128
Well-known member
The screws would most definitely be steel, cheapest of all the screws and no reason to use anything else. Actually you may be onto something re: the aluminum reacting with steel. The coating is judiciously applied and no metal parts come into contact with it at all. Of course they couldn't for electrical reasons. In fact, the only part that does come in contact with it is a specially designed aluminum strip mounted to the case that comes into contact with an aluminum patch on the analogue board left exposed through the vinyl. As Apple's tolerances were ridiculously tight, they later added a plastic liner that ran the length of the logicboard extending from the RF shield to prevent any contact by the chassis or logicboard caused by misalignment. I believe the steel chassis is further coated as well, though the sharp edges certainly defy any protective coating.
JDW
Well-known member
My yellow-capped 24oz tub of Oxi Clean "Versatile" arrived recently. While this product is clearly being used outside its intended purpose in restoring classic computing plastics to their original pristine color in combination with H202, I did find it interesting that the label recommends "warm to hot water" (apparently to dissove the OxiClean powder). And yet they recommend rinsing in cool water. Not sure why cold is required for the rinse. Here is the exact text off the label:
I asked Lumpy about "tablespoonfuls" of this powder in a previous post, but the instructions talk about "scoops" with the included plastic scooper. Since the scooper holds more than a tablespoon, I assume you meant "1 scoop" instead of "1 tablespoon" correct? But even at 1 scoop per gallon, it is still less than the "SOAKING" and "HARD SURFACES" instructions recommend. Those instructions say 2-4 scoops per gallon of water.
JDW:
I was using the scoop to dispense the powder, but the amount I was using was roughly a tablespoon - albeit a heaping one. I didnt pay much attention to water temp - the Oxi dissolved pretty easily. You can see from my pictures that it was set outside in 30 degree temps.
In one batch I added too much Oxi and the surface got pretty foamy - not a big deal, but it did obscure some of the sunlight in the tank of water. My recommendation is to start with less - and strengthen if you're not seeing results. Otherwise, you're just wasting materials and subjecting the plastic to a stronger than necessary solution.
On the vintage-computer.com thread that I link to, I believe they mentioned that the solution stays useful for about 4 days...
In the 3-4 batches that I washed, I was not scientific in my measurements - all of the results were the same though. As I mentioned, start out with something small (your mouse) and see what you think. Harder plastics (keyboard keys) take longer and de-yellow more gradually. Softer plastics (most Apple case materials used in compact Macs) seem to de-yellow in diluted solutions in about 6 hours.
I was using the scoop to dispense the powder, but the amount I was using was roughly a tablespoon - albeit a heaping one. I didnt pay much attention to water temp - the Oxi dissolved pretty easily. You can see from my pictures that it was set outside in 30 degree temps.
In one batch I added too much Oxi and the surface got pretty foamy - not a big deal, but it did obscure some of the sunlight in the tank of water. My recommendation is to start with less - and strengthen if you're not seeing results. Otherwise, you're just wasting materials and subjecting the plastic to a stronger than necessary solution.
On the vintage-computer.com thread that I link to, I believe they mentioned that the solution stays useful for about 4 days...
In the 3-4 batches that I washed, I was not scientific in my measurements - all of the results were the same though. As I mentioned, start out with something small (your mouse) and see what you think. Harder plastics (keyboard keys) take longer and de-yellow more gradually. Softer plastics (most Apple case materials used in compact Macs) seem to de-yellow in diluted solutions in about 6 hours.
Charlieman
Well-known member
For durability when inserted by machine tools and/or idiots, most computer screws are steel and have a bright plating which serves no engineering function. Case screws have coarse threads because their security is unimportant and the female thread may not be well formed. Some screws are japanned (ie given a gloss black coating) for aesthetic reasons, similar to plated screws. In the early days, Dell and other PC clone manufacturers used plain steel screws. PC motherboards are secured by brass mounts which use fine threads -- I don't understand the reason for this, unless it is just copying what IBM did donkey's years ago.
Inside a compact Mac, the RF paint is probably aluminium and carbon suspended in acrylic. The paint is too grey to be aluminium on its own.
The chassis is painted for rust protection. It was almost certainly brought into the assembly plant from an external supplier, in the same way as a floppy drive or CRT tube. It was probably dipped rather than sprayed -- if you were spraying it seriously, you would perform a second pass to cover the rounded corners properly.
Having looked at a few photos of naked compact Macs, I am impressed at how little steel is inside them.
Mac128
Well-known member
Are you trying to wash your colored laundry or restore your Mac? LOL
The manufacturer is covering its ass. Cold water will not cause colors to bleed or set as badly as warm water. If there is any bleed, the cold water rinse will help prevent any bleed from setting and prevent further bleed to transfer to other garments which the dryer would then permanently set. H202 is commercially used to encourage the setting of dyes in a new garment, thus a similar situation could occur in your laundry. None of this of course is a concern with your Mac, unless of course you throw your MacTV in the same bucket as your SE/30. :beige:
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