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tbenbrahim
December 20th, 2006, 06:44 PM
I am trying to pull cards out of an IMSAI 8080 system, and seems to be having no luck, after applying moderate force. Am I missing something obvious, or does this require applying more force? I am afraid to damage the boards. This sytem has 10 boards, and I want to test it from scratch, first trying to find a good memory board.

Thanks in advance

Tony

chuckcmagee
December 20th, 2006, 09:15 PM
I have seen some cards that have little levers right on the corners to help lift the card straight up. Otherwise, nope, no secrets. I suppose the tin leads on the boards could be somewhat corroded in place. That's about all I can think of. Can be like pulling a gear in a transmission, meaning you have to pull both sides up at the same time. Otherwise, it rocks back and forth and jams after moving a short distance.

alltare
December 20th, 2006, 10:21 PM
Of course you have read all the warnings about turning off the power before you pull S100 boards, I hope. If you don't kill the power, you WILL damage something.

Sometimes they can be pretty tight, but there are no latches or locking mechanisms involved. Perhaps you can insert an improvised "crowbar" under the cards, on either side of the S100 connectors, and gently pry them out.

nige the hippy
December 21st, 2006, 02:57 AM
there's also often a couple of holes in the top corners of the board, to fit levers in if you have them. If there's some room at the end of the card cage, you can put a (chunky) jeweler's screwdriver through each hole, and use something across the cage to lever on. a quick dusting of WD40 on the edge connectors will ease the situation for next time.

alltare
December 21st, 2006, 01:21 PM
Sorry to disagree, Nige, but it's never a good idea to use oil or WD40 on electronic stuff. Although it can temporarily make pots work better and contacts work more smoothly, it is also a dust magnet. Eventually, the dust and crud will collect to the point where you may have high resistance leakage. In high voltage circuits (like antique radio volume controls and switches), arcing might even occur. I know a lot of old-timers swear by WD40, but before you take their advice, look at the equipment that they sprayed several years ago.

If you want to lubricate, use something made for the job like contact cleaner with silicone. S100 connectors shouldn't require any treatment beyond simple cleaning.


a quick dusting of WD40 on the edge connectors will ease the situation for next time.

nige the hippy
December 21st, 2006, 01:47 PM
Well, we could argue till the cows come home, I swear by the stuff - but yes it does collect dust I've seen plenty of boards in wooly jumpers, it can carbonise in high temperatures / voltages, and it is worse than useless on printer guide rails, however SILICONES are HORRIBLE things anywhere near electrical bits, there were tests done a few years ago, where they found silicones crept for inches along wires until they came to a switch or relay contact whereupon they sat on the end of the contact and turned into rock spikes in the little arc.

I never lard the stuff on unless using it for it's almost original purpose, and have found it to be somewhere between pretty benign and really good... but I'll have to do an investigation into the official line on recommended contact lubricants.

I also have to concede that I am a fairly old timer!:blush:

mbbrutman
December 21st, 2006, 02:03 PM
I'm with Alltare. WD40 is not a lubricant - it stands for Water Displacer, and the thin layer of whatever it is that is left behind doesn't last long.

Radio Shack has (or used to) have a product called 'tuner cleaner' which dates back to the days of televisions and radios with tuning knobs. It is safe for electronics, and might help.

alltare
December 21st, 2006, 02:05 PM
That's interesting about the silicone. Actually, I hardly ever use lubricating products of any kind on contacts, but isn't silicone what they put in the contact sprays "with lubrication"? Maybe we should use graphite powder. (that's a joke).

By the way, I'm an old timer too.


Well, we could argue till the cows come home, I swear by the stuff - but yes it does collect dust I've seen plenty of boards in wooly jumpers, it can carbonise in high temperatures / voltages, and it is worse than useless on printer guide rails, however SILICONES are HORRIBLE things anywhere near electrical bits, there were tests done a few years ago, where they found silicones crept for inches along wires until they came to a switch or relay contact whereupon they sat on the end of the contact and turned into rock spikes in the little arc.

I never lard the stuff on unless using it for it's almost original purpose, and have found it to be somewhere between pretty benign and really good... but I'll have to do an investigation into the official line on recommended contact lubricants.

I also have to concede that I am a fairly old timer!:blush:

nige the hippy
December 21st, 2006, 02:45 PM
Electrolube is now silicone free.

The IEEE say that polyphenylethers are the thing. (although it's probably all "secret formulae" so finding that in a product data sheet is probably difficult)

"contact cleaner" used to be a killer on vintage gear, as it un-lubed all the switches and stopped the mechanisms from flipping, and ruined (probably cleaned off!) what was left of the carbon tracks on potentiometers, but that was 15 years ago, I daresay things have changed a lot since.

Anyway rambling off topic a bit, so I'll shut up,

Best wishes...


Just re editied....

Polyphenylethers are used as lubricants in vacuum systems, so they're probably slippery!

chuckcmagee
December 21st, 2006, 09:44 PM
Radio Shack still sells "contact cleaner". I purchased some about 4 months ago. I still own a Marantz receiver and use it to clean the "pots". Works great. I have used it since the manual tv tuner days.