Getting the Agnus chip off an A500 rev6a motherboard

[Sim085]

I am trying to get off the Agnus chip from an A500 rev6a motherboard. I have bought one of these to do this; https://www.ebay.co.uk/itm/Motherboa...72.m2749.l2649

However it is not coming off and I have stopped trying as I am afraid I am going to break something. It looks like the tool does not want to fit in and when I try to pull I end up simply scratching the chip.

Do I need to buy a specific Extractor Puller Tool? Or the one I bought should be ok?

[Daedalus]

That looks like the correct tool, albeit a slightly cheap one. But it should do the job. It should fit into the two slots on opposite corners of the Agnus socket, and when you squeeze the sides together it should grip the chip tight from the bottom with the metal hooks while putting pressure on the top surface of the socket. If it takes a reasonable amount of force but then pops out, it sounds like the chip is stuck. Commodore fitted the Agnus chip on some A500s with a sticky pad to secure it in the socket. Earlier ones had a metal clip to hold the chip in place, while others simply had the chip inserted into the socket without additional securing measures. I'm not sure if it was to do with certain sockets being looser / more prone to working loose, but when they used a sticky pad, it's extremely difficult to get out without damaging the socket.

You can take the motherboard out and if you're lucky, holes in the bottom of the board correspond with holes in the Agnus socket, allowing you to insert things and push Agnus out. I suggest something like chopsticks, but try to avoid hard metal things like screwdrivers. If the holes don't match up, your only option without damaging things might be to remove the socket, break it apart, and replace it with a new socket. Which is a fiddly job...

[Sim085]

In my case when I try to use the tool as should (i.e. - as I saw on youtube video) it simply jumps off and scratch the chip. Would you suggest a place from where to buy a good Extractor Puller Tool?

Originally Posted by Daedalus

That looks like the correct tool, albeit a slightly cheap one. But it should do the job. It should fit into the two slots on opposite corners of the Agnus socket, and when you squeeze the sides together it should grip the chip tight from the bottom with the metal hooks while putting pressure on the top surface of the socket.

I did manage to take it off in the end but not by using the tool as should, I simply inserted the tool from just one side and unhooked the chip from that side only and then with the gap I got a better grip and it came off pretty easy. So does not look like it was glued or anything. Simply the tool does not want to work as should.

Originally Posted by Daedalus

If it takes a reasonable amount of force but then pops out, it sounds like the chip is stuck. Commodore fitted the Agnus chip on some A500s with a sticky pad to secure it in the socket. Earlier ones had a metal clip to hold the chip in place, while others simply had the chip inserted into the socket without additional securing measures. I'm not sure if it was to do with certain sockets being looser / more prone to working loose, but when they used a sticky pad, it's extremely difficult to get out without damaging the socket.

I will check this one. When I got it off I did not really look too much at the socket. But I don't think in my case it had a whole. I would have noticed. But it is good to know, should I do it on another Amiga I will first check the bottom of the motherboard

Originally Posted by Daedalus

You can take the motherboard out and if you're lucky, holes in the bottom of the board correspond with holes in the Agnus socket, allowing you to insert things and push Agnus out. I suggest something like chopsticks, but try to avoid hard metal things like screwdrivers. If the holes don't match up, your only option without damaging things might be to remove the socket, break it apart, and replace it with a new socket. Which is a fiddly job...

[Jope]

When the chip has been in the socket for 30 years, you can't just insert the tool and squeeze hard.

What works for me: I insert the tool and gently squeeze it together, making sure that the hooks are definitely under the chip. Then I add squeezing force and start rocking the tool in a circular motion. Add more force, more circular motion and the chip should work its way out.

.. and that's what she said.

[Daedalus]

Yeah, that's true, sitting there for 30 years untouched can cause problems too, especially if there's been corrosion for any reason. I've found with the cheap tools that the metal hooks bend easily when they encounter a tight chip, and once that happens, they're more likely to slip off the chip in the future. I can't remember where I got mine, but probably one of the usual electronics / tool suppliers like Farnell.

Glad you're sorted anyway!

[DarrenHD]

Try some isoprophyl alcohol to act as a lubricant to loosen it a bit ?

[Sim085]

Since the subject cropped up I thought of going ahead and ask; most of the legs on the chip are dark in colour - far off from the that shiny silver colur.

Is there a way how to clean these up?

[torsti76]

Originally Posted by Sim085

Since the subject cropped up I thought of going ahead and ask; most of the legs on the chip are dark in colour - far off from the that shiny silver colur.

Is there a way how to clean these up?

For that kind of work I highly recommend a glass fibre pen. Push the fibres out to make it look more like a small brush than a pen and gently rub the ends of the fibres along the pins of the chip. Ground yourself while doing this!

[dalek]

Electrical contact cleaner / de-oxit is also handy here, both before removal to breakdown corrosion holding the pins to the socket, and afterwards providing lubrication and preventing further oxidisation down the track.

[Daishi]

Both suggestions from torsti76 and dalek will get your chip legs clean. However the socket on the motherboard will probably also need some cleaning also. Can I ask what you were doing removing it.

[Sim085]

I am replacing the Angus with a mega chip to try the 2mb chipRam mode on this rev6 motherboard.

Originally Posted by Daishi

Both suggestions from torsti76 and dalek will get your chip legs clean. However the socket on the motherboard will probably also need some cleaning also. Can I ask what you were doing removing it.

[johnnybarker]

Does the Rev 6A motherboard have holes under the Agnus chip to push it out from the bottom?

[Sim085]

When I rechecked, mine had two small holes. My connector is brown.