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Old 25 January 2019, 16:38   #21
xnopasaranx
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awesome advice, I am going to try lowering the clock then first and see if it runs stable then.
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Old 26 January 2019, 13:42   #22
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okay I have some more info now. I have let systest hammer away at the chipmem, with the ACA removed. It took about 3 hours and the memory errors appear also without the accelerator. when continueing the tests after the first error, it immediately fails and shows errors. I did this several times and the memory ranges shown slightly differ some of the time.

maybe this is a thermal issue after all? I'll take a look at the solder joints of the RAM chips under my microscope and will try to touch up the solder, to see if that already helps. reflowing might be an easier solution than replacing, but I am not sure if it'll help or if the chips are just giving up the ghost.

some more screenshots attached
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Old 27 January 2019, 22:06   #23
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okay so the story continues... I tried to research how to repair chipmem faults on the amiga 1200 but didn't really find a lot of info. What I did find and realized when opening my amiga again, the RAM chips are smt, and a steep angle at that. So no reflowing with a microsoldering iron.

I do have a hot air station (858D atten clone), but I haven't done much work with it yet. So I figured I'll practice on an old laptop motherboard I have in my scraps bin... yeah the hot air station died on me, almost right away. The freaking air blower in the handle does not start up anymore. FML

I don't feel competent enough to repair a potentially dangerous china hot air station, before I can try to fix the RAM. thinking about getting a quick 861dw...
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Old 28 January 2019, 11:01   #24
d3cka2d3pwood
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I feel for you mate!
Keep persevering, it will be worth it!
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Old 28 January 2019, 12:16   #25
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Ugh, it's a strange one alright. Once the errors occur, they can be reliably reproduced, right? That would sound thermal to me. You could see if it's a solder joint by pushing down on the chips and re-running the test, see if the pattern changes or it goes away.
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Old 28 January 2019, 15:25   #26
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I have a pcmcia incompatible memory expansion card and a gayle reset fix chip.totally freaked out my 1200 and kept resetting and black screening.took me a while to work out the reset/pcmia incompatibility issue.removed gayle adapter and 1200 is running sweet.if you have an expansion board that doesnt like pcmcia and a hardware reset adaptation then issues will follow.....
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Old 28 January 2019, 23:15   #27
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Quote:
Originally Posted by Daedalus View Post
Ugh, it's a strange one alright. Once the errors occur, they can be reliably reproduced, right? That would sound thermal to me. You could see if it's a solder joint by pushing down on the chips and re-running the test, see if the pattern changes or it goes away.
Yeah I tried to do that today, but no dice. I pressed the chips while running systest, but could not really find out anything. Once the error has occurred, the memory check will fail almost immediately afterwards, also when each chip is being pressed.

Quote:
Originally Posted by jpm2901 View Post
I have a pcmcia incompatible memory expansion card and a gayle reset fix chip.totally freaked out my 1200 and kept resetting and black screening.took me a while to work out the reset/pcmia incompatibility issue.removed gayle adapter and 1200 is running sweet.if you have an expansion board that doesnt like pcmcia and a hardware reset adaptation then issues will follow.....
thanks, but that's absolutely not my issue. The reset problems I had were fixed days ago by attaching a new PSU. Now I am having issues with faulty chipmem RAM.

BTW: Has anyone on here ever had to replace their chipmem? I am really not sure if I can do this on my own, so it would be helpful to get some pointers on how to proceed. Like, what methods were used/necessary (hot air? solder paste instead of regular solder?), what temperatures should be used in order to protect the new RAM... etc.
And: Could this be related to budgie as well? maybe there is a cold solder joint there...

Last edited by xnopasaranx; 28 January 2019 at 23:28.
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Old 29 January 2019, 01:28   #28
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I haven't had to replace the RAM on an A1200, but have had similar soldering jobs. Hot air is the way to go to remove the chips, ideally with a square nozzle that matches the width of the chip. The chips are designed to be soldered in an oven so they can take a reasonable amount of heat - 280 degrees for a short time shouldn't do any harm. Solder paste can be used for resoldering, as can other techniques such as tinning the pads first and reflowing the joints with hot air to melt them all - drag soldering and soldering individual pins is slightly trickier because they're PLCC chips, but it's still possible. Practice on an old PC graphics card or something similar first, as it's possible to damage the board if you're not careful!

The fact that you're getting errors across the whole bus is strange, since it means all the RAM chips are affected by whatever's going on.

Yep, it could also be an issue with Budgie - possibly even the CPU. There's also a slight chance it could be an issue with another custom chip that's pulling bus lines high/low, or one of the related passives.
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Old 29 January 2019, 14:36   #29
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hmm I am thinking about trying to drag solder budgie again. The guy who reworked parts of the board did this already, but under the microscope, some of the solder joints look a bit dull. So maybe he didn't quite get every connection to bond decently. He did remove and resolder some of the chips, because he found some other quirks, and removed a piece of metal shaving under one, which must have caused a short under rare circumstances. Looks like the previous owner has cut some of the shielding to fit an HDD in some exotic place and the piece of metal probably found it's way under one of the custom chips because of that. The other solder joints look fine though.

I'll get practice on another board today, and will try to dragsolder the budgie chip first. I don't have a hot air station right now anyway. Maybe I can get somewhere like that and if not, I'll wait for the quick hot air station and try to reflow the RAM.
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