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DR
03-14-2017, 12:11 AM
A random problem with my Dell Win 7 laptop, it randomly got a blue screen and rebooted. This morning about four reboots before I got a home screen. Put in a new hard drive last week and reloaded Windows, still the problem. Even did a memory test with no indication of ram problem.

My favorite used computer guy suggested bringing it in to the store so they could try exchanging memory just in case that was the problem. When the girl at the counter started looking she noticed it showed only 4G memory, but it has 2 4G sticks. A bit of switching the sticks around between slots we got it to stop randomly rebooting and recognize all the ram.

Obviously there was a contact problem... is this the sort of situation to use a spray contact cleaner on if the problem should return?

ed_h
03-14-2017, 12:20 AM
I believe re-seating is the most effective way to fix a contact problem like that. Contact cleaner is more for contacts that open and close, so using it in conjunction with a re-seating may not be a bad idea.

Ed

lakeside53
03-14-2017, 12:42 AM
You should have gold on gold.. so don't bother "cleaning". as above - reseating will be fine.

J Tiers
03-14-2017, 12:46 AM
Might not be gold, in which case it is corrosion does it. Use the cleaner then.

Evan
03-14-2017, 02:46 AM
Fingerprints can cause problems. Best cleaner if using any is ethyl alcohol. Totally non corrosive and leave no trace of anything. Next best is pure vodka.

tincture500
03-14-2017, 07:01 AM
Gold. Does not tarnish , no need to use contašt cleaner. In fact it may cau▀e plastic to weaken

achtanelion
03-14-2017, 08:28 AM
White eraser. Best computer contact cleaner, and no worries with overspray.

Leadfootin
03-14-2017, 08:48 AM
One product that does work well is Caig De-Oxit. Go to a high end audio store where they use it on connectors and noisy volume controls. Also works wonders on car electrical connectors.

Juiceclone
03-14-2017, 08:52 AM
most contact cleaners are alky, (I read the label) and even gold will get a buildup? of dust/grease/etc. so cleaning while out and re-inserting usually is the cure. Artist paintbrush for the contact area in the comp. Yes an eraser is good, but u still need to use cleaner to get rid of debris . There is also a spray product that is supposed to improve contact in electronic connections. Tried it but eehhhhh!

lynnl
03-14-2017, 10:06 AM
..... Tried it but eehhhhh!

It probably wasn't meant to be ingested.

danlb
03-14-2017, 10:55 AM
Just in case the problem returns;

a) Many memory problems will pass the tests once or more. Memtest86 is a memory tester that you can set to run extensive and repeated testing. When I have a PC that has random crashes I run the memory tester overnight and it will often show one of three results; 1) no problem 2) same block of memory failing multiple times 3) random blocks of memory failure.

Memtest86 is a good tester because it runs without an OS, so it's a very minimal memory footprint and no drivers or configurations to go wrong.

B) With laptops the problem is sometimes not memory related but is instead heat related, more specifically CPU overheating due to bad contact between the CPU and it's heatsink or fans that are clogged / stopped. Just flipping the laptop upside down may shift the laptop enough to make it work for a short time.

Paul Alciatore
03-14-2017, 12:56 PM
Heavens NO. Do not use any abrasive cleaner on electronic contacts. If they are plated with gold or anything else, you can be dead sure that the thickness of that plating is as thin as they could possibly make it and any abrasive, even the mildest, will quickly remove it, exposing the base metal under it. The device will work better for a short time and then, as it corrodes again, it will get worse and you will be stuck with cleaning it over and over again.

Take the memory sticks out and gently clean the socket with 99% pure alcohol. Do not use tuner cleaner, it contains a lubricant. Other electronic contact cleaners are probably OK. I have never seen one of them have a bad effect on any plastic used on circuit boards and I spent my entire career repairing electronics. You will not be able to actually scrub the contacts in the sockets and you should not try. Just squirt the alcohol in there with some force. Let the flow do the job.

On the memory sticks, GENTLY wipe the contacts with a cloth or paper towel soaked with the alcohol or the contact cleaner. GENTLY! You are just trying to remove any fingerprints and dust. And go over them only once or twice, not over and over.

Note: I said I have never seen alcohol or any other electronic cleaner harm any plastics on PC boards and the is completely true. The only problems I have seen were with mechanical parts like switches and relays. If a cleaner washer into them it can carry dirt and oil into them and cause all manner of problems. Computers rarely have these mechanical components so you should be OK there. If you do have a problem with a switch or relay after using a cleaner on a PC board, the only solution is to wash those components with a massive amount of the same cleaner in order to wash out the contaminant that was washed in. This could take a quart or more of the cleaner and many flush and dry cycles. Been there, done that. Not fun. No tee shirt.




White eraser. Best computer contact cleaner, and no worries with overspray.

J Tiers
03-14-2017, 01:55 PM
Heavens NO. Do not use any abrasive cleaner on electronic contacts. If they are plated with gold or anything else, you can be dead sure that the thickness of that plating is as thin as they could possibly make it and any abrasive, even the mildest, will quickly remove it, exposing the base metal under it. The device will work better for a short time and then, as it corrodes again, it will get worse and you will be stuck with cleaning it over and over again.
....

+ many.....

And I do not like even trying to wipe the tiny contacts on many boards.... especially NOT the 2 piece plug and socket type connectors. Often the boards are just plated traces, which are reasonably good, but for sure not perfect as to toughness. You can wipe those, but take it easy.

Back in the 1970's when I did electronic repair while in school, you could get away with the white erasers, usually. "Not no more", as the factory folks used to say...

6PTsocket
03-14-2017, 01:58 PM
Fingerprints can cause problems. Best cleaner if using any is ethyl alcohol. Totally non corrosive and leave no trace of anything. Next best is pure vodka.
Pure vodka is a long way from pure alcohol. 100 proof is only 50 % alcohol. I presume the rest is mostly water. You can get around 90% in the pharmacy but it is isopropal, not ethel. It works fine for cleaning contacts. Pure ethel is rather hard to obtain. Denatured is ethel with enough methel mixed in to make it toxic and undrinkable and of no interest to the ATF.

Sent from my SM-G900V using Tapatalk

Evan
03-14-2017, 02:18 PM
Here in B.C. last time I checked one can buy high quality ethanol at Saveon Foods under the Western Family brand in the pharmacy department. It is in the rubbing alcohol section in the same size bottle with half a litre for a few bucks. Look at the ingredients list and it is anhydrous ethanol 95%. The rest is water that is chemically combined with the ethanol because of how alcohol interacts with water. It does not say that it is in any way denatured either but I sure wouldn't try to drink it. It is what I use to machine aluminum.

As for the vodka, there is a brand from Eastern Canada that advertises that it is made from glacial ice water and pure triple filtered ethanol only. No idea if it still exists, I do not drink at all.

J Tiers
03-14-2017, 04:01 PM
if you want high proof, Everclear is the stuff you want.

Drinkable pure, as high a proof as is possible with regular distilling, no solvents.

Euph0ny
03-15-2017, 07:45 AM
I have had very good results for many years with Stabilant 22 contact enhancer. A tiny bit swabbed on the contacts with a cotton bud (q-tip) is enough, and a small bottle lasts a long time.

http://www.stabilant.com/sizes.html

Evan
03-15-2017, 01:25 PM
You must be very careful how and where you use Stabilant 22. It has the property of increasing capacitance across connections it bridges even though it will not become conductive at low voltages across gaps bigger than a few microns. This will particularly apply to RAM connectors since RAM must operate at extremely high frequencies. A capacitive connection can act almost like a short at such frequencies. At the least it may act to cause momentary bit errors depending on the values being read for a few nanoseconds.

I would not recommend that it be used on the RAM or any other buss connectors. S-22 is excellent for low frequency connections of all types as long as it is low voltage. Not to be used on anything at line voltage though. That will cause it to break down quickly.

S-22 should be OK on USB-2 connectors but I wouldn't use it on USB-3 connectors. USB-3 is also very high frequency.

MichaelP
03-15-2017, 01:32 PM
Just keep in mind that it is not necessarily a contact problem. This can be a soldering defect near the contacts too: either on the motherboard or on the memory boards. This kind of defect may be intermittent and manifest itself only when the board is heated while the computer is on.

I'd try cleaning the contacts, first. I feel that a simple rubbing alcohol will work just fine for this purpose, and there is no need to spend time and money visiting a liquor story to buy pure grain alcohol.

If cleaning doesn't work, I'd leave just one RAM board and try it in each slot. Then repeat with the other one. This might help pinpoint a faulty RAM or faulty motherboard slot.

I don't know what new RAM costs for your laptop. If not much, you may simply skip the step-by-step approach, and replace both sticks if cleaning doesn't work.

P.S. I wonder if your memory checking program can be run continuously for a long time and pinpoint the faulty memory bank.

Evan
03-15-2017, 01:46 PM
It very much depends on the motherboard as to what slots must be occupied with certain sizes and types of RAM. One cannot just flip the RAM to another slot in many cases. In many of the later motherboards RAM must be used in parallel pairs for smaller RAM capacities. Laptops can be a real problem and are often very particular about not just the size/type of the RAM but also the manufacturer.

mattthemuppet
03-15-2017, 01:54 PM
my wife washed my flip phone once (it was my fault for not anticipating that she would wash my trousers) and my uncle got out a can of water displacer. I usually dry stuff out in rice or the oven at ~60C, but thought I'd give it a shot. Gave it a good spray, 10 seconds later it fell to pieces as the plastic case fell apart. In very small writing on the can it said "may dissolve some plastics, test first".

Even now I take my phone out of my trousers at night, just in case.

MichaelP
03-16-2017, 12:56 AM
It very much depends on the motherboard as to what slots must be occupied with certain sizes and types of RAM. One cannot just flip the RAM to another slot in many cases. In many of the later motherboards RAM must be used in parallel pairs for smaller RAM capacities. Laptops can be a real problem and are often very particular about not just the size/type of the RAM but also the manufacturer.

I agree. Good catch.

tomato coupe
03-16-2017, 01:10 AM
my wife washed my flip phone once (it was my fault for not anticipating that she would wash my trousers) and my uncle got out a can of water displacer. I usually dry stuff out in rice or the oven at ~60C, but thought I'd give it a shot. Gave it a good spray, 10 seconds later it fell to pieces as the plastic case fell apart. In very small writing on the can it said "may dissolve some plastics, test first".

Even now I take my phone out of my trousers at night, just in case.

Sometimes "Keep it in your pants" is good advice. Sometimes it's not.

J Tiers
03-16-2017, 01:42 AM
my wife washed my flip phone once (it was my fault for not anticipating that she would wash my trousers) and my uncle got out a can of water displacer. I usually dry stuff out in rice or the oven at ~60C, but thought I'd give it a shot. Gave it a good spray, 10 seconds later it fell to pieces as the plastic case fell apart. In very small writing on the can it said "may dissolve some plastics, test first".

.

Almost certainly did not matter at all.

When the detergent hit it, the conductivity iof the water would probably have caused things to receive voltages they should not. And if that was not a problem, the hot water likely would have seriously discombobulated the battery and quite possibly have deposited conductive residue that would stay on the board. Phones are very highly integrated, but there are connections between the parts, and to the screen, etc. Very likely to have been damaged in an effectively unrepairable manner.

It likely would never have worked again regardless. I'd suppose it at around a 2% chance it could be made to work again if it was totally submerged in ion-enhanced water, i.e. laundry detergent and hot water.

Dropped in teh ocean might have been worse. I have seen electronics resuscitated after that, but they were much simpler and more rugged items.

Juiceclone
03-16-2017, 07:25 PM
advise NOT using q-tips on such contacts as they shed almost invisible strands. An artist tiny paintbrush will do the job and not create a new problem.. Also, in case anyone does not already know, NEVER use any silicone cleaner/lube/etc anywhere near electronic contacts... a lesson learned 40 years ago the hard way and confirmed by a mfg rep who told us silicone causes the most "pull your hair out" intermittent contact failures. I don't even keep the stuff around after that.