Apple IIe memory removal and replacement

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Joined: Jul 12 2013
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My Apple IIe gives me the following after the RAM test RAM: 0 1 0 0 0 0 0 0

I am assuming that it is stating that the chip at F6 is bad. Can I unsolder and replace? Is there any special trick to doing this to avoid damaging the other components or the replacement? As far as a replacement chip goes, am I limited to what I can scavenge from another motherboard or is there a source for getting new chips? Any and all advice is most appreciated. Thanks!

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gsmcten's picture
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Re: Apple IIe memory removal and replacement

Geoff,

Specifics:

Apple IIe unenhanced?
Apple IIe enhanced?, or
Platinum IIe?

If regular Apple IIe is it a 1982, '84, 0r '86 motherboard?

If you are skilled at unsoldering and soldering chips from boards and cards, then it should not be too much of a problem as long as you don't mess up a trace.
If you are not skilled at it, you may want to find someone who is.
If you want to become skilled at this, buy yourself a spare MB and the tools and practice, practice, practice.

Quote:

As far as a replacement chip goes, am I limited to what I can scavenge from another motherboard or is there a source for getting new chips?

As of yet I have not seen individual RAM Chips for sale on eBay for Apple IIe's. Your
best bet is to find a motherboard, or a cheap apple IIe.

Now...I can tell you that folks have gone absolutely nuts up there on prices for an Apple IIe. Last year this time, you could pick one up for anywhere between $15 and $35
plus shipping. NOW, because they saw what happened to the Original Apple II that sold for $23k a while back, they think that IIe's are just as valuable and are starting to ask outrageous prices for them.

(As Keatah, Jay and several others can atest to)

Well... That's my two cents worth.

Steven Smile

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Re: Apple IIe memory removal and replacement

Are the RAM chips on the motherboard the same as the ones on the 1MB memory expansion boards? If so, I have some.

transwarp II guy's picture
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Re: Apple IIe memory removal and replacement

If your RAM is soldered on (not socketed) then it will probably be easier to just replace the motherboard. I have some experience with soldering and while it's not too hard, If your not experienced you can run into problems quick. Unless the motherboard has sentimental value then I would just keep it for parts and buy another one.

Like gsmcten has said prices have jumped for IIe's. Not surprisingly no ones paying for the ridiculous 200+ craze on computers that come with no extras and usually are not even tested OR in good condition!

However there are still deals to be had: http://www.ebay.com/itm/Apple-e-System-EARLY-REVISION-11-83-/251304215999?pt=US_Vintage_Computers_Mainframes&hash=item3a82e605bf

I figured I would post the above just in case your looking for a cheap system that is in decent shape. You can switch the motherboards out so you can still have your old system, and also have a whole spare computer for parts! It's a win-win.

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Re: Apple IIe memory removal and replacement

Is this a sentimental motherboard? And since you mention F6 as being a RAM chip, this would make it a standard Apple //e motherboard, not a Platinum board.

But, yeh, if you got soldered-in chips you'd of course need to unsolder them. If you're new to soldering, get some crap board and practice first.

They're going to be xx64, 4164, 4264, 3764. Something like that. And 200nS or faster. Most are 150nS. And that's what Apple recommends.

There are times when another chip is bad, not the one indicated. An address line or data line is overly weak or overly sensitive and there is interaction between two chips when there shouldn't be any. You hook a 'scope to it and look at the signal quality and see if anything is marginal. If so you replace it too. And chances are one of those 2 were the real culprits. It all depends. Keep in mind the built in test is simple in nature and certainly nothing like the modern-day MemTest for PCs. Well..

http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&freeText=4164&search_type=jamecoall

And for $10.00 you can replace all of them while you're at it. I always like to match my memory chips in any one bank-circuit-card. Keep them of the similar date codes. I *could* probably get you a date code to match what the other original chips are. But considering that 4116 (II+) and 4164 (//e) are turning out to be the most unreliable parts on the motherboard, it's worth considering swapping them all at once. Of course, keep the original parts in anti-static foam and in a baggie strapped to the computer if you're sentimental or a collector wanting period accuracy. Or hunt down matching dates.

I've already long ago lost count of how many dead systems I've replaced memory in. And more than one chip especially when the built-in diagnostic initially indicated only one was bad.

Even as late as the mid-1980's DRAM *still* hadn't achieved reliability like we know it today. IMHO the Platinum //e has the most dependable memory, it has only 2 chips for the entire 64K bank. And it's rare I have to dick with those.

I remember one time my II+ failed, A2-FS1 kept locking up or something would go wrong with the flight algorithms. Something. Anyway I took the computer to CompuShop and they replaced a DRAM chip at the pretty penny of $165.00 !! It took several weeks because I insisted I get an original Apple stamped chip with the same date markings. Boy was I an ass about it! It was one of the last electronic repairs I ever paid for.

There will be a time when we'll be able to repair individual chips, especially these crude ones from the 1970's, what with their monster-sized process geometry and all. Well Nvidia and Intel regularly repair and spot-patch many problems in their one-off prototype chips. Exotic nuclear beams and all that.. Believe it or not!

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Re: Apple IIe memory removal and replacement

Thanks, Steven. I have the enhanced IIe. I am assuming the memory is the same in both the regular and enhanced motherboards as there used to be a ROM set for upgrading to the "enhanced" version. I do have experience soldering circuit boards, but in the past, I was soldering sockets and then installing the ICs. I have not soldered memory directly and didn't know if I needed to heat-sink (although difficult)or take any other special precautions.

I really appreciate all the information. Thanks again.

Geoff

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Re: Apple IIe memory removal and replacement

Thanks for the info, Transwarp II guy. I have a backup motherboard that works (not enhanced, but I could swap the relevant chip set) but I may still try fixing this one to "maintain the inventory." Thanks for the advice.

Geoff

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Re: Apple IIe memory removal and replacement

Thanks for the great information, Keatah. I do have a follow-up question, though. I followed the link to the supplier and the chip looks like it is a 64K chip. So I can replace each of my 8K chips with these and not have any issues? It certainly would be nice to be able to buy off-the-shelf memory and install sockets into the motherboard and simply swap out chips as they failed.

Geoff

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Re: Apple IIe memory removal and replacement

Geoff1985 wrote:

Thanks for the great information, Keatah. I do have a follow-up question, though. I followed the link to the supplier and the chip looks like it is a 64K chip. So I can replace each of my 8K chips with these and not have any issues? It certainly would be nice to be able to buy off-the-shelf memory and install sockets into the motherboard and simply swap out chips as they failed.

Geoff

That's right, they are 64K X 1-bit. Read the data sheet.

The chips in the //e are 64K locations X 1-bit. That's 64x1. So you need 8 of them to hold 64K bytes. Think of it as 1 Character or byte being split up and spread across 8 chips.

(On its own, with a different memory access scheme, each chip would hold 8K bytes. And 8x8 = 64)

I don't see any reason why you couldn't desolder the existing chips and install sockets.

If you want to read more about memory access in the //e, why not read Jim Sather's "Understanding the Apple //e", Section 5.
ftp://ftp.apple.asimov.com/pub/apple_II/documentation/hardware/machines/Understanding%20the%20Apple%20IIe.pdf

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Re: Apple IIe memory removal and replacement

You can solder the ram chips in. As you progress through soldering, more connections are made which act as little heatsinks to the motherboard traces. When I solder these things I just do pin #1 right away. On each chip. Then I'd do pin #16 on each of the 8 chips again. This holds them in place nicely.

Then then pin #3, across all 8. Then #4 and so on. I also don't let each chip cool down entirely either, less internal expansion and contraction.

Each chip doesn't get too hot this way either. There's really all kinds of methods and ways of doing this. At the factory, all connections on the board are done instantly, at the same time, through a wave machine. And that is with new parts in a controlled environment.

At home in the shop a little extra care is warranted because we're working with crusty-old-man parts. And who knows how much "durability" is left?

You also want to use a grounded work surface, and soldering iron, and wrist strap. These DRAM fuckers are the most sensitive of all chips in the system.

Don't make the mistake of using a 150-watt Weller soldering gun with that big-ass transformer in it! I used to use one of those when I was a kid and always wondered why stuff stopped working soon thereafter. Or why it never worked again!

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Re: Apple IIe memory removal and replacement

Geoff1985 wrote:

My Apple IIe gives me the following after the RAM test RAM: 0 1 0 0 0 0 0 0

I am assuming that it is stating that the chip at F6 is bad. Can I unsolder and replace?

Geoff,
if you are absolutely sure about which chip is bad, you may quickly replace it as follows, even if you're not a skilled desolderer and don't have access to a desoldering station:

- Remove the motherboard from the case.
- With a mini cutter, cut each leg of the bad chip right where it joins the plastic body of the chip and when done remove the chip. You will be left with 16 pins holding thin air.
- Put the MB in vertical (e.g. between two piles of books), gently heat the first pin from lower side and, when solder melts, pull it with pliers from upper side. You may also try this by putting the board upside down and the pins will probably fall down by themselves.
- Repeat for each pin. You will be left with 16 holes, some may be full of solder that can be removed with a piece of desolder wick, or drilled.
- Install a socket and solder it. This will save you repeating the whole procedure in case the chip breaks again. Just plug in a new chip and it's done.

Memory chips used in IIe (except maybe later versions) are common 4164 DRAMs (different manufacturers may use slightly different names, but they're all the same), easily obtainable on the web.

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Re: Apple IIe memory removal and replacement

Ouch.. Avoid the drill, one slip and you'll be repairing traces too.

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Re: Apple IIe memory removal and replacement

Keatah wrote:

Ouch.. Avoid the drill, one slip and you'll be repairing traces too.

of course you must know what you're doing Smile
But I agree and the wick is usually enough.

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Re: Apple IIe memory removal and replacement

What I find that works for me is to clip each of the chips legs and then heat up each leg and use a solder sucker to suck out the leg and the solder at the same time. If need be, I'll add some solder to improve heat transfer. Sucking out solder is really easy.

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Re: Apple IIe memory removal and replacement

Thanks Gabriele72. I will use your method.

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