MacAttack
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Page 24 of the Dead Mac Scrolls also says to replace component CR20 on the board, right next to CR21. This component is an MBR1045 Schottky Rectifier Diode. In fact, pages 20 through 29 deal with this issue entirely. You didn't mention these steps so I thought I should point them out. Also, if you deduce that the flyback is the issue I could possibly send you one.
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Probably not, I already replaced the MUX chips with brand new Motorola chips but this next chance I get I'll test them with my logic probe to see if I scorched the chips while soldering.
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I don't have much experience as my Plus only needed a ram replace, but my 128k came from a guy who replaced the analog board due to a bad flyback transformer. Now, I know that these flyback transformers are known to go bad so I wouldn't be surprised if that was causing your issue. If this is the case, then the flup noise could be the flyback repeatedly arcing internally.
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Here, I photoshopped about where the mirrors are occurring.
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Yea, Everything appears to be mirrored three times, one on the right, one in the middle and one on the left.
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MacAttack changed their profile photo -
So, I posted here about a year ago about a 128k Macintosh that I got off of craigslist. Since then I figured out that the ram was bad and replaced it. I've got to a point where the computer functions but the video has a major issue. I have been unable to find the issue so far, so here I am again! For further reference, I do have logic probes and an oscilloscope at hand if that helps fix the issue. (Before Ram Replace) (After Ram Fix)
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So I want to replace the ram. I thought these chips would work. Any objections? https://www.jameco.com/z/4164-150-Major-Brands-64KX1-DIP-16-DRAM-150NS_41662.html?CID=GOOG&gclid=EAIaIQobChMI4JOMn5T02QIViV5-Ch09NgcCEAQYASABEgJPYfD_BwE
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What chips are the GALs/PALs?
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No, not myself so I guess it could be bad ram, but I'm just going off what the seller said. Anyways, I will test the Mac Plus board in it too.
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The ram has been socketed and replaced so I ruled that out and the Mac plus board is not compatible with the 128k case
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I tried but it gave me the same screen.
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Yeah, a plus and I’ll try that.
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Also the boot sound is gargled, forgot to mention that
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Hello, I recently bought a 128k Mac (non-functioning) and the seller told me that he thought that the 74F253 Ram Multiplexers were bad. But after replacing them with new Motorola ones, the screen still has the same issue. Here is a photo: I have no idea where to got from this point and a google search came up inconclusive. Please Help!!