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General discussion

Short-circuit causing RAM-memory?

Dec 29, 2010 10:18PM PST

Dear readers,

A few weeks ago I upgraded the RAM-memory on my MacBook (1st gen, DualCore 2gHz)with two new units made by TakeMS. The specifications of the modules were correct. After installing, I started the laptop, but I didn't get any image on my screen and nothing was working except the processor, HD and fan (I could hear the sounds). The 'sleep' light was on constantly. I re-installed the old memory, and nothing changed. Completely suprised by what happened, I brought the laptop to a Mac-reseller for a diagnostic-check. After a few days they phoned me and told me a memory bank was dysfunctioning, and same was going on with the video-chip. The complete logic board had to be replaced. I didn't opt for this choice and was suspecting the RAM-memory of being the cause. Yesterday I brought both upgrades to a computer-specialist, and he checked them in another laptop. The first one worked, but the second one caused the same symptoms on his machine: no image on the screen and only the sound of the fan etc. being working.

As you could imagine now, I'm fully suspecting the RAM-module of being corupt and the cause of two motherboard-failures. Short-wiring is the first thing that comes into my mind. I contacted the salesman of the memory, and he told me he didn't have the correct materials to give me specific information on what's actually wrong with the memory. I'm not going to contact the producer, because I'm not expecting them giving me specific information on what's wrong with the memory, especially when it's causing a short-circuit on the motherboard. Purely because they would place themselves in a dangerous position.

My question to you folks is: does anyone of you know what to do now? I have the following plan myself: some of the 200 pins on the memory are for the electric supply, and when the resistance over the plus- and minus-pole is 0 Ohm, there is a short-circuit. This can be measured with a voltage-gage. The only problem is: I don't know which ones are responsible for the electric supply of the memory. Does anyone of you know this?

Thanks a lot in forward for your replies!

Discussion is locked

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I believe I would be asking the place your purchased
Dec 30, 2010 2:34AM PST

this memory from to be coughing up for the board replacement, although I have never heard of bad memory killing a board before.

guess it could be possible.

was this RAM cheap?


P

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reply
Dec 30, 2010 6:54AM PST

Well, it was about 10% cheaper then the Corsair Value-RAM memory-units. So not very cheap, but one of the cheaper ones, yes.

As you could read in my first message: the place where I bought it doesn't have the proper equipment to do a detailed diagnostic test of the memory. Especially since these units appear to short-wire the motherboard, they can't just install it in a laptop (or won't) and rum Memtest. I'm going to do some impedance-measurements tomorrow, since I found the pinout for 200-pin SO-DIMM memory online. I'll post later.

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If this is a 15 or 17"
Dec 30, 2010 12:04PM PST

If this is a 15" or 17" model, it may be subject to an extended repair program for the issues with nVidia video chips.

It might be worth a quick call to Apple to see if your system falls under the afflicted. The repair program is valid for up to 4 years after the original purchase date.

I am also going to say that the odds of RAM killing the board seems a bit dubious. Fact is, as things get older they tend to break down. Those metal connection pins will start to oxidize, become brittle... Solder joints start to go bad, dust and other garbage builds up inside the system. It might just be that installing the new RAM was the proverbial straw.

Take the system to an AASP. An Apple store is likely going to tell you that they aren't trained on such old systems, and apparently downloading the service manual for them is beyond their "Genius" intellects. They can run the nVidia graphics chip test on your system, and if it passes by failing, then you get a free logic board replacement if the system is under 4 years old. Just don't let them charge you for the repair, because it's an extended repair program that's covered by Apple. The AASP gets labor reimbursement from Apple, not you.

Anyway, it may be high time to be thinking about a new laptop anyway.

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reply
Dec 30, 2010 8:15PM PST

It's a 13 inch 1st gen Macbook. So the chip isn't the issue. You certainly have a point with the aging, but the other laptop which had a broken motherboard wasn't that old and I know the odds are against me, but this doesn't have to mean I'm wrong. Testing the impedance on the circuits was a hell, and I finally stopped because there is almost no information on what plus-pole is connected with which minus pole. All measurements are not reliable this way. I'm planning to send the memory back to the producer and try to get a specification of the problems with the unit. Does anyone else know how to research short-wiring within a SO-DIMM unit, before I do this?

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The spec is an open on
Dec 30, 2010 9:25PM PST

The spec is an open one, and the group that is responsible is called JDEC: www.jdec.org

You're still likely wasting your time trying to find a bad pin or two on the modules. Just test each module in each memory bank on the laptop. If it fails to boot each time, it's the logic board. If it boots with only one module, then make sure it will boot with that module in either memory bank. If that's the case, you know you've got a bad memory module.

Put simply, a lot of places that advertise fixing computers don't hire very competent people to do the job. And even places like Best Buy or Fry's can be a real crapshoot as to whether you get a competent in-store tech or not. Once had a system come to me, and the writeup said the customer took it to Best Buy who told them it was a HDD failure. It was the logic board, one of those that had the failed nVidia chip at that. And as a side note, sorry, I was a bit jet lagged after getting up at 2AM to catch a plane, then going 2 time zones east. I missed where you said MacBook, and not MacBook Pro. Only the Pro models were affected.

I also took a quick look at the service manual for this system, and it states if the SIL (sleep indicator light) stays on then the RAM is either bad or not inserted correctly. So, start by just reseating the RAM, and make sure you push them in pretty good. Some of those old MacBook models can have pretty "stiff" memory banks.