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Dynamic_Computing

by Dynamic_Computing posted Mon Jul 30, 2018 1:46 pm

Set a desk fan to blow cool air on it for now!
You are right about version 3.0 of that board. It is a bit flaky! Is there any heat sync or fan on the CPU itself?

I am serious about that desk fan - as it would at least prove or disprove the overheating theory.
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dalek

by dalek posted Mon Jul 30, 2018 5:20 pm

Also bear in mind if you are going to sell it then you won't get back the money you spend getting it in to tip-top shape. If you are doing it for the love or fun of it then that's great, but don't be surprised if you end up not getting a price that you think reflects the cost and effort of repairs you'll put in to it.

There are plenty of buyers that can get the rework done themselves if you are upfront about what work you know needs doing.

As for the airflow, the fan is a good idea for troubleshooting.

The mask of the CPU (version number) will be an important factor - what are the numbers printed on your big 040 CPU? See here for more detail

Simply swapping the 040 for a newer mask if you have an old version will reduce a lot of heat. Since you are in the US they might be easy to source. An 060 CPU in an adaptor will run even cooler (as it will run at 3.3V rather than 5V) but you will need to burn and install a modified kickstart.

But the better option is to do all the work you want to do and keep it for fun :)
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Jimbo99

by Jimbo99 posted Mon Jul 30, 2018 8:28 pm

Hello Dynamic and Dalek,
I appreciate both your suggestions. Running cool air across the unit should determine whether my observation about overheating is right or not. Dalek, your advice about the profit/obsession trade-off is right on, and I will have to decide as I go a bit further. My A4000/040 system is almost certainly 1992 vintage, which doesn't bode well for later revisions of the CPU which run cooler. My system has only a heat sink, no special fan for the CPU. In order to check the model number, I would have to remove the heat sink, correct? I've been meaning to do that anyway in order to refresh the conductive paste between heat sink and CPU. I did this once on my HP laptop. I don't have any tools for pulling out large chips, but using care and common sense might work? Any tricks or warnings about my doing this?
Thanks again, fellows,
Jim
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dalek

by dalek posted Tue Jul 31, 2018 12:06 am

yep you will need to remove the heatsink to check the markings on the CPU. If the fan works then adding a regular heatsink mounted cooling fan after refreshing the thermal compound sounds like a quick win! You don't need to remove the CPU from the socket, just the heatsink, which (depending on type) should just be metal spring clip(s).

As for if you really do want to remove the CPU, there was a chap on Amibay selling extraction tools for 040/060 chips which look like a little rake. If you are careful you can get away with gently working your way around between the chip and the socket with a flat headed screw driver, but be gentle.
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Jimbo99

by Jimbo99 posted Tue Jul 31, 2018 7:37 am

Thank you, dalek,
No trouble taking off the metal clip and heat sink. The white, pasty compound doesn't seem as efficient as the modern "polysynthetic silver thermal compound" I will replace it with. The model number is XC68040HRC25M, a heater from the 1989 or so era. I like very much the idea of mounting a small fan on top of the heat sink. Do you have any good source in mind?
Thanks again,
Jim
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santidarkg

by santidarkg posted Tue Jul 31, 2018 12:58 pm

Welcome to the forum.... Do a recap as soon as possible.

The audio section of the Amiga 4000 is very fragile.....

My Amiga 4000 was looking great, but once my friend started removing capacitors here and there, you will see how the "dark side" is taking over, in pure silence. My advices is...... do a recap right now :)
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santidarkg-Amiga4000-AudioCaps.jpg
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Jimbo99

by Jimbo99 posted Tue Jul 31, 2018 8:32 pm

Great advice Santidarkg!! Your pictures are worth a thousand words. So far I've seen two companies that do the motherboard and the A3640, both on AmiBay which I registered for. One is from Denmark, named tbtorro, the other from Finland, named hese. Tbtorro does beautiful work as shown by his video, but claims to be overloaded with work. I plan to contact these guys soon.
Thanks very much for your help,
Jim
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dalek

by dalek posted Wed Aug 01, 2018 6:03 am

There are good guys in the states that will recap (Try Acill - Paul Rezendes), though both tbtorro and hese are great options but will involve overseas postage.

For the fan, if you have the older large heatsink you might be struggling for height - see if you can get a low profile 60mm fan with a molex connector that will plug in to your a spare hard drive power connector - that's probably the easiest. To attach, find some screws that will wedge nicely into the fins of the heatsink. Worst case since you have the metal clips you could cable tie it down. Any other 5V or 12V fan would be fine but will require you to cut the end of the connector and solder the wires somewhere convenient (like a molex connector ;) ).
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A10001986

by A10001986 posted Wed Aug 01, 2018 6:14 am

My $0.02:

XC-040s run notoriously hot, any MC-040 would do better. There are versions (mask versions, that is) of the MC040 that can be used even without a cooler, these are K63H and L88M. The bad news is that those are impossible to get, and if there is one up for grabs, it's probably even more expensive than a 060.

However, I wouldn't bet on the CPU being the culprit. The GALs on the 3640 should be warm, at best, not hot. There is something else going on. Hard to tell from a distance.

As regards your FZ-357A, I think there are SMD-caps on those that tend to leak.

That guy from Denmark is technically good, but insanely expensive.
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intric8
Seattle, WA, USA

by intric8 posted Wed Aug 01, 2018 6:21 am

For recapping just contact Paul. He's even a member of this site. If you only send the motherboard it would be $80. Shipping to the EU would be painfully expensive. Just know that his work load might put your board behind several other folks, so you might not see it for a while.

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