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Replacing a 68030 in a IIci?


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I have a IIci board which apparently had a dead 68030, which was removed leaving a clean pad.  I'm trying to figure out what I can use to replace it.

 

I know the IIci ran at 25 MHz, but for some reason 25 MHz 68030s are expensive on eBay.  However, 33 MHz chips seem to be far more plentiful.  Will a 33 MHz chip run fine at 25 MHz in the IIci?

 

This is the part I'm thinking of using:  https://www.ebay.com/itm/1pcs-MC68030FE33C-ENHANCED-32-BIT-MICROPROCESSOR/392523139565

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33 MHz parts will run perfectly fine at 25 MHz. They're identical except the 33 MHz part was tested at a higher speed.

 

I do hope that's a real part. While I got an m68882 which was, according to the markings on the package, made in 2012, sometimes newer parts from China are fakes.

 

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I did exactly that on one of my IIci boards. Works just fine at 25MHz with a33MHz chip in place.

Those chips you linked are probably fake anyways, I ordered a few of them not long ago and the silkscreen on most of them is sketchy (+they all arrived with horribly bend legs)

 

They do work just fine though, once you went through the trouble of straightening the legs and soldering it down.

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If they're fake and they work fine once installed, what does that mean?   They're not really 33MHz parts?   Surely someone isn't fabricating pirate 68030 CPUs?  

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Not going to speculate over "why" reworking those chips is a thing...

But see for yourself:

 

ri5WbyM.jpg

 

 

This is exactly how I got it from the seller linked above.

The markings on the chips do seem to be what was on there originally. On some it could be washed off with acetone, on some it stayed on. On one chip you can see signs of either a round heatsink or leftovers from grinding off the old markings.

 

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I believed you when you said they were re-marking them.  I just don't understand the why or what of it.    I could see marking random QFP packages with 68030 markings, but then they wouldn't work.

 

It sounds like it doesn't make a lot of sense to you either.

 

Perhaps they have some kind of bulk process where the desolder the pins and wash the chips and that removes the markings?  Then they must remark them?

 

Strange and puzzling.

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As for the why—the story I heard, at least, is that this is the runoff from scams involving extremely long-term support contracts that should never have been signed in the first place where everyone knows that the parts will never actually be used.  How accurate this is I don't know, but intuitively it feels more likely than it being purely targeted at retrocomputing enthusiasts who are likely to work out the fakery anyway...

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20 hours ago, trag said:

I believed you when you said they were re-marking them.  I just don't understand the why or what of it.    I could see marking random QFP packages with 68030 markings, but then they wouldn't work.

 

It sounds like it doesn't make a lot of sense to you either.

 

Perhaps they have some kind of bulk process where the desolder the pins and wash the chips and that removes the markings?  Then they must remark them?

 

Strange and puzzling.

 

Mostly to make them appear newer (fake mfg dates are frequently used) or even NOS. These rebrands have the Freescale logo on them, despite the fact they're likely pre-Freescale chips.

 

I too have heard it is to defraud second and third world countries dependent on Chinese supply chains for old equipment they need to keep running, for scientific or military use.

Though for parts that only really retrocomputer enthusiasts would want, say old C64 SID chips, they could just be honest and say they're old, pulled chips.

Most of the prices are low enough that being honest wouldn't impact sales at all.

 

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Sometimes the parts are cheaper cost variants re-screened and sold as more expensive versions.  Sometimes they're just a different brand (but same part) re-screened as a different brand -- but otherwise the exact same part.  And sometimes they're re-screened better parts of the same brand, and sold as the lower cost variant.  Sometimes the part is exactly what you ordered ... but they screen a new label on it for whatever reason.

 

So my theory is this:  all of these parts are simply recovered parts from ewaste or surplus.  They're loosely sorted into bins with other similar parts, but no further sorting beyond that (i.e. all PGA 68040s go in this bin, regardless of its MHz, feature set, etc.)  They're all cleaned and reconditioned, then all re-screened as a 68040 33MHz (probably because even if you get a 25MHz one, it might still run at 33MHz.)  Sometimes you'll get a Motorola part, sometimes you'll get a Freescale, sometimes you'll get the actual 33MHz chip, sometimes you'll get a 25MHz LC variant, sometimes you'll get a 40 MHz one ... but they're all refurbished and re-screened as a Motorola MC68040RC33.

 

Some places might do a better job at sorting, like maybe even going through the effort sorting out the LC variants from the regular ones, or the low power variants, but many don't.

 

Given that the return policies are generally really good, it seems like a decent gamble.  I haven't read any horror stories about people not getting refunded, just that they got the wrong part.  The cost of recovering these parts versus how much they sell them for must be lucrative enough to offer generous refund/return policies.  If they're recovering a SID chip for 10 cents and selling it for $25, the effort put into sorting the parts in the first place isn't a priority.  Just recondition and sell the parts in bulk, and if even up to 50% of them are the wrong part ... oh well.  Give them their refund and let them keep the part you spent 10 cents to recover, and continue on; you're still make a huge profit on the parts that just happen to be working or weren't returned.

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