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Old 19 December 2004, 03:07   #1
Uplink7
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Amiga A1200 Paula chip

I think I screwed up!. I was working on one of my A1200's. I had a intermittent wire in the mouse cable. I shut the A1200 off and proceded to resolder the wire for the right mouse button (older version mouse). I think I heard a snap. The 1200 was off but the mouse was still plugged into the mouse port. When I finished and turned the 1200 back on, now it won't boot just a flash and then black screen. I checked a bunch of stuff and then checked the schematics and found the that pin connects directly (sort of) to the Paula chip. I may have popped it. Is there a source ofr these chips or does any one else have another idea?
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Old 19 December 2004, 14:59   #2
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You've knackered a chip on a board that uses SMT? Time to get a new motherboard.
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Old 19 December 2004, 17:40   #3
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It IS possible to remove and replace an SMT chip, you just need lots of time and patience, a really fine 12W soldering iron and a steady hand. A magnifier and strong light source will help too.

I can't really see how you've damaged a chip by doing what you've described unless the soldering iron tip isn't earthed - which to be honest is unlikely unless your iron has a twin core flex.

Did ytou take the normal anti-static precautions?
Have you tried to boot the Miggy without the mouse you repaired connected?
HAve you checked your work to see if you've made a really simple (ie, hard to spot) error?
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Old 19 December 2004, 17:48   #4
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Are you sure that it's the Paula chip that fails? I seem to remember Denise is responsible for mouse ports, parallel ports etc.
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Old 19 December 2004, 19:11   #5
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First of all the tip IS grounded and that is what I think may have done it. I have had that happen before with a grounded tip soldering iron but the part was on or had some power to it. I still can't figure out why though as the 1200 was turned off. I have tried pulling everything, mouse, hard drive, floppy. It doesn't want to pass the first hardware test. The snapping leads me to believe something else like a chip cap or surface mount diode/transistor etc. I am going to look further before I try to swap it out.

Paula does't look that bad to remove but I'd like to have a new chip rather than pull one form another bad mb and have to do it twice. Are there any sources for these chips? I hav e seen some on EBAY but not lately.
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Old 20 December 2004, 12:56   #6
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If necessary, You could always try piggybacking. Cut the leg that supplies power to the current chip, then solder a new one directly ontop to the old one and then flying lead to the power. Saves removing the chip and possibly causing more damage.

You can get Paula's for $12 dollars (~£7) from Centsible

NOTE: Despite Centsible saying that they are ECS only I am sure they are compatible the A1200 (But they are DIP rather than SMT, you sure the Paula in your A1200 is SMT?)

Last edited by alexh; 20 December 2004 at 13:10.
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Old 20 December 2004, 17:26   #7
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A1200 Paula chip

The paula in a 1200 is a PLCC type. That's why I'm haveing trouble finding one. What I planned to do was the PLCC chips have the leads that wrap around the chip. I can nip them with a good set of fine dykes then easily desolder the remaining leads from the solder pads. This is a trick I've done before. But then I'd prefer to use a new chip to replace it. I do have a good chip on another bad motherboard but its a pain to remove and keep it reusable. I try Censible and see if they have any PLCC type. I've bought from them before. Any other sources would be greatly appreciated.
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Old 20 December 2004, 18:07   #8
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I did a little more research after I mailed you last.

The A1200 Paula is indeed a PLCC

Paula 8364R7PL
P/N 391077-01

They have them advertised for what I think is 11 Polish Zl (~£2)

http://animart.webpark.pl/aprt.htm

The website was last updated in September this year so you stand a chance of this list being upto date.

This part is also on an Amiga A600, so you could get one very cheap to butcher
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Old 21 December 2004, 21:51   #9
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They definately sell Paula Chips for the A1200 at Vesalia for ~£5 plus postage.
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Old 22 December 2004, 03:24   #10
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A1200 Paula chip

Thanks for that info. I wish I had found it sooner as I ordered one from Softhut here in the states. Even with shipping and tax I could have gotten 2 for what I paid for one practically. Or for 50% more I could have gotten a new motherboard.

I have never bought from them before is Vesalia a good firm to buy from? We have had some problems with some suppliers of Commodore/Amiga stuff here in the states.

Thanks for all the help I'll post when I get the chip changes out.
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Old 22 December 2004, 11:52   #11
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Vesalia are sound. They are one of the last big-ish Amiga shops left.

Plus they take PayPal.

I dont like SoftHut
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Old 28 December 2004, 05:02   #12
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Amiga 1200 Paula Chip

Well Success !!! I got the chip on friday and during our snowstorm yesterday I removed the old chip using the cut the pins method and tonight I installed the new chip. A lighted magnifying glass that is mounted on an arm mounted to the workbench was a big help. Not something I want to do ever again but with a great deal of patience I got it changed out ok.
I then booted up the board and it came up just fine. I'm going to do a burn in test later but I wanted to thank everyone for the help. There is one less 1200 motherboard in a landfill.

Last edited by Paul; 28 December 2004 at 17:41. Reason: deleted a direct signature
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