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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Karlos on September 06, 2003, 01:44:34 PM
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Hi,
I'm currently dragging an old Apollo 040 card out of retirement for my A1200. It's in a bad way but I reckon it could be made to live and breath again.
One of the nuisance factors is the old fan/heatsink. The old fan sounds like a motorcross bike and the heatsink is bonded to the chip.
I have a very low profile, (and quiet) 5V fan/heatsink I'd like to install in its place, only marginally taller than the original heatsink.
Does anybody know a 'safe' way to remove the old heatsink? I'd rather not take a chisel to it :-)
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Hi Karlos,
I asked the same question a couple of weeks back on the Amiga hardware hacks Yahoo group.
The only reply I got, was to put the Apollo in a plastic bag , suck all the air out, seal the bag up and put it in the freezer for 20 mins. :-o
I haven`t worked up the courage to do it yet...I might forget about it in the freezer, and have it turn up as a pizza topping..
I know what you mean about the fan..that poxy heatsink is too small to properly take the screws to hold the fan firmly without vibrating..
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Superglue fails at extreme tempretures so as Doobrey says, freezing it should loosen the glue. I used to superglue the tyres to the wheels of my radio controlled cars when I used to race them and the only way to remove them was to boil them up in a pan of water, thought I doubt doing the same would be good for your accelerator :-P
You probably would be best to just use brute force though, if it's stuck with superglue it shouldn't be bonded too fast to it.
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Brute force, eh? I do have some scary visions of shattering the ceramic of the CPU however ;-)
I was thinking that I might be able to wedge it off...
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Hey, I got it off!!! :-D
@ Doobrey
I just got the heatsink off no problem. I simply prised it off with a pair of narrow tip pliers. Just gently ease the end vanes of the heatsink and voila :-)
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The only downside is that the nasty blue coloured glue stuff is still stuck to the CPU. I guess it's thermally conductive though, so I'm not too worried
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Now I just need to find a nice +5VDC line on the card I can tap for the fan. Either that or power it from a connector somewhere...
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how do you intend to affix the new heatsink now?
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With some thermal grease and a pair of small plastic clips ;-)
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Alchohol and cotton buds should remove the previous adhesive. And as for damaging the ceramic its pretty unlikely, i once took a drill to a dx33 and did nothing but blunt the drill bit :/
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Why cant you use the source that the old fan was wired to? is it 12v?
You would probably be best to just take the power from a molex connector on the psu if its in a tower, or from the floppy power connector if its a desktop.
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Yeah, the old fan was +12VDC. The card is going into a desktop 1200 (I already have a towered 1200 with BlizzPPC).
The fan I have is +5VDC, covers the whole CPU area and is much lower noise :-)
I am thinking to source a pair of connectors so that I can remove the card and simply 'unplug' the fan from wherever I choose to draw power (probably the floppy).
My old desktop (pre tower) had a pair of power connectors that fed power seperately to the motherboard and to the drives via a molex connector I fitted to the back of the case. The whole system was thus powered via two power cables from a 200W PSU. I might do something similar again :-)
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Just out of curiosity, is this the 040 board that you were going to sell on a while back?
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Indeed it is. I sent it to Vincent who had it for a bit but it tuned out to be wrecked and he returned it a while ago.
I wasnt able to test it myself since I had no desire to rip my 1200t apart for it so it sat idle for a bit.
I went home last week to visit the folks and grabbed a bunch of a1200 bits I had lying around to build myself a 1200 wedge again and thought I'd try the 040 card.
It is wrecked, but I think I know what is wrong with it (the cards boot ROM is physically damaged) so I'm trying to fix it...
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Incidentally, that's a good memory you have there matey ;-)
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You could stepdown the voltage from the onboard 12v source to 5v for your fan with a resistor, just use voltage/current = resistance. It'll waste a little power, but not too much.
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Yeah, I guess, but I dont mind sourcing a 5VDC line from somewhere. A power regulator to step the voltage down might be a bit better, but I'm not sure what the waste is like. Probably more than the resistor...
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Most people say I have a photographic memory, it would help if I could have remembered the useless crap that I needed for some of my final exams, but I think beer deleted all that, oh well.
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:lol: It seems I used to have one but the last few years have seen it reduced to sieve like powers of retention ;-)
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Hmm, a resistor should do the trick okay in this case. Remember that you only want to loose 7 volts not 12 too when you work out what resistor to use ;-)
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Well, V/I = R. In this case my fan is rated at 5V, 0.14A
So 7/.14 = 50 Ohms? Seems pretty low. The closest youd get is what, 47 Ohm resistor?
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Ehm... resistors ain't a good option to lower V. Sure it does the trick but for it to work it creates heat. For shorter intervalls it'll work but when you're driving a motor for longer intervalls as with the fan you will most likely burn the resistor (something you don't want to happen while the machine is rendering stuff while you're asleep).
Best option is to find 5V on the card or take it from the motherboard.
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Brian wrote:
Ehm... resistors ain't a good option to lower V. Sure it does the trick but for it to work it creates heat. For shorter intervalls it'll work but when you're driving a motor for longer intervalls as with the fan you will most likely burn the resistor
Yeah, that's what I was thinking when I worked out the resistance and it came out so low - I can imagine a lot of heat dissipation for 50Ohm...
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Hmm, Brian has a good point, with this in mind maybe you should pull out your multimeter and source 5v from the board. You may want to slap a diode in there too to stop any back emf.
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Well, the new cooling is working fine and much quiter. The card is still knackered though :lol:
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Wow, my card seems to be a prototype :-o
The rom is socketed (this is where the problems lay. I was just working on it and the label started to peel off the rom chip. Lo and behold, it is an UV erasable kind!
Man, that sure explains a lot :-)
Anyhow. a moment ago I got it to configure, saw that it was working from the early startup.
Things are looking up :-)
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Famous last words :lol:
Dead again!
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"Lo and behold, it is an UV erasable kind!"
I've pulled this type of EPROM from PC's before so I'm not sure if this makes it a prototype.
"Famous last words"
lol
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Well, it's up and running again....
I just played AB3D on it for a good 40 mins. Nostalgia overload there.
What I need to do is to desolder the socket and mount the chip directly. A couple of legs are half missing :-)
The problem is that the bloody solder contacts are minute. I get the sense that I will doubtless knack it up...
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Be very carefull not to get the tracks too hot, I've taken tracks off in seconds before by having my soldering iron turned up too high and keeping it on thew board for too long.
Is it a DIL socket?
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Yeah, it is.
The problem is that the socket adds 5mm to the height which causes the ROM chip to be pressed against the top of the SIMM when inserted. This is what has caused the gradual mechanical damage over time.
Without the socket, thered be ample space. I noticed that later revisions of the card all had the ROM directly mounted on the card.
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Shouldn't be too big a deal then, but I'm not the one holding the soldering iron :-P
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Like I said, the solder junctions are tiny and the tracks are really, really thin. I'm not totally convinced I can remove it without damaging it beyond repair.
Just now it's working, but I know that if I just so much as look at it in a funny way, its going to spit the dummy on me again.
Funny, until yesterday I wouldn't have cared about it. Now that I have a use for it, I'm a bit more cautious :-)
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>I can imagine a lot of heat dissipation for 50Ohm...
Not really. Look on the fan, it should have a label with the technical data. Small 12V 40mm fans are rated 1W or a bit above. Since you will be burning only a fraction of that in the resistor (50%?) and the rest in the fan, no problem with heat. Just get a 1W resistor for 10 cent.
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@Dietmar
No need, its drawing off the 5V line :-)
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Why not simply tap into the 5v of the floppy power cable for the fan?
Or are you trying to do a neater job by powering it from an onboard source?
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Doobrey wrote:
Or are you trying to do a neater job by powering it from an onboard source?
That was the idea, but its not a big deal. Currently its tapping the floppy 5V line.
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Just try gently wiggling the old fan off. When I overclocked my 040 I just eased the old afn off, and stuck a heatsink in place.