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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: jjans on September 24, 2003, 05:41:44 AM
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I wish to remove some ram chips that are soldered onto an old A500 motherboard.
I'd like to reuse them by installing them into my A590.
Any ideas on how to do this without damaging the chips?? :-?
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Use a 'Solder-sucker' or de-soldering braid.
This is one job that I'm really good at! ;-)
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Yeah, get a "solder - sucker", it makes it much
much easier.
If you have room, try attatching
a small metal clip to each pin before you
desolder, that will help divert some of the heat
away from the chip. A moist piece of tissue
can work in a pinch, but obviously a metal
sink is better. "Radio Shack" sell them cheap.
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If you didn't know what a solder-sucker is, then you probably aren't an experienced solderer. If that's true, you stand a good chance of damaging the chips no matter what you do. To take out soldered-in chips you need a steady hand, a fine iron at exactly the right temperature, a solder-sucker, and lots of patience and practice.
You could always practice your technique on junk and stuff. If you see discolouration of the PCB or chips, then you've burned it. If it was real life you would have destroyed your ram chips. Be very careful.
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@ KennyR
I had to do loads of soldering when I was doing the first year of my Audio technology degree (I switched courses tho), and all we had was the braid stuff that you drag through the molten solder. I didn't know a 'solder-sucker' existed till recently...
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If the leads are terminated straight-thru (not bent over) than vacuum desoldering is the way to go. Apply liquid flux to the joint. Tin your iron. Heat joint until solder liquifies and suck it away. You will find there wil be a sweat joint left anywhere the lead actually touched the board. An orangewood stick (The pointed sticks women use for manicures) will easily break these if all the rest of the solder is gone.
Once you are done the chip should simply drop out. If not check all the pins.
To replace, tin all the pads by applying solder and sucking it away. Should leave a smooth shiny surface. Apply liquid flux and solder the new chip in place. when done clean the board with rubbing alcohol.
With practice its not to bad. Mind you I cheat as I have access to a Pace rework station at work :-D .
Things you need:
20-25 Watt solder iron with small chisel tip.
Liquid RMA flux
Small diameter 70/30 (better yet 63/37) tin/lead solder
Solder Sucker
Orangewood sticks
Small needlenose pliers
Rubbing alcohol or aerosol flux remover.
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KennyR wrote:
If you didn't know what a solder-sucker is, then you probably aren't an experienced solderer.
A solderer of fortune?
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:lol:
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I had to do loads of soldering when I was doing the first year of my Audio technology degree
Hopefully that was nothing like the education some people I knew from school received in soldering. They used to stab each others' hands with soldering irons.
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In an old issue of Byte, I read about this technique... It sounds wacky, and it does destroy the board, but it does work. .. You clamp the board in a vise.. grab the chip the long way with a pair of locking pliers (vise-grips) and heat the solder side of the board with a torch. If you do it right, you can pull the chip out at one grab, before melting it. :-) Naturally this is something best done outside, for safety and fumes. I tried this a couple of times, but I used a 1000 watt heat gun instead of the torch. It worked, but I never got around to using the chips for anything.
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JimS wrote:
In an old issue of Byte, I read about this technique... It sounds wacky, and it does destroy the board, but it does work. .. [/quote]
Hey I LIKE that technique! Sort of similar to my original 'Red Green' style of using a hammer, a chisel, and a plier(and a case of beer). This technique works GREAT on WINDOZE machines...
Thanks for the suggestions, I'll try them on some old PC cards I got first...
JJ
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the torch is the way i removed the chips i wanted, the mother board is toast but the ram chips were perfect when installed in my rev.6 A500 mother board.
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@JimS
I believe that is called "non-destructive removal" :-D
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Yep solder sucker or wick..the wick is actually faster
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jjans wrote:
Hey I LIKE that technique! Sort of similar to my original 'Red Green' style of using a hammer, a chisel, and a plier(and a case of beer). This technique works GREAT on WINDOZE machines...
Yeah, there is a certain satisfaction to torching a pc motherboard.... ya just have to add in a little Tim Allen-style grunting... :-)
I've used the solder sucker method too... one thing I've found is that boards vary quite a bit. Those multi-layer boards drain a lot of the heat out of the iron... at least a cheap one like mine. :-)
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@ MikeyMike
That reminds me of school chemistry lessons - blow down the bunsen tap to put everyone's burner's out, sabotage other people's experiments by dropping sweets, pain killers, indigestion tablets in the beaker when they weren't looking - or my personal favourite:
there would be four rows of benches in the labs, each with three sinks sunk (unsurprisingly) into them. At the end of each row you could turn off the supply. So, turn the supply off, turn all the taps on - when the teacher's back's turned, or when people are standing around at the start of the lesson - turn the master tap back on....fat soaking!!!!
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KapitanKlystron wrote:
I believe that is called "non-destructive removal" :-D
It's more emotionally satisfying. :-)
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Well I bought the solder sucker and it worked great. Thanks to all for the advise. I also gotta blow torch for an old PC card for fun...
I removed the 4 x 20 pin RAM DIP chips from an old A501 expansion card, and installed them onto my A590's card, and it worked great.
Still having a couple of dip sockets still open, I got even more exited, and ripped open another A501 card (and discovered a leaky battery...) and also discovered that this one used 16 pin RAM DIP chips.
I now know the difference between the 2 A501 cards: Rev 5 (64 Kb chips) and Rev 6C (128 Kb chips) .
Both my A500's are REV 6A motherboards, which also mount 20pin 128 KB dips.
For my UFI fill for the day, does this mean the REV 5 motherboards mount the 8 x 16pin 64 KB Dips?
Better still, you think one could sew them together some how, in order to use them in the A590???
I know what you are thinking...
What a freakin' 'DIP-CHIP'
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jjans wrote:
Both my A500's are REV 6A motherboards, which also mount 20pin 128 KB dips.
For my UFI fill for the day, does this mean the REV 5 motherboards mount the 8 x 16pin 64 KB Dips?
The Rev 5 A500 uses 16 256Kx1 drams... that's your 512K. The Chips in the Rev 6 motherboards are 256K x 4 bit drams.
I doubt there's an easy way to use the older rams in the 590.
... unless you want to glue them on the case for decoration. :-)