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I think I am going to check the IC RP5 which is near the two PRAM batteries. I did have some corrosion near there from the batteries. RP IC chips lead to the ROM socket according to the bomarc Mac II schematic. (image is of another Mac IIx board of mine).

There appears to be an issue with my ROM. I checked voltages on my good working Mac IIx and the non booting one. I had steady voltages on the working one and many of the ROM pins on the non working unit were jumping. Not too much, just a couple of tenths of volts - like 1.8v to 2.2v. They just...

Yes. I have attached an external speaker and do not get a chime at boot. I do get a crackling sound as I plug in the speaker, so there is sound being produced. When I also check the sound chips for voltage, I get the similar crackling sound from the internal speaker when I touch one of the pins...

I have been working on a Mac IIx motherboard that will not boot. I have repaired the startup/ shutdown circuit and it will turn on by pressing the power button. However, I do not get a boot chime nor video. There was slight battery corrosion and slight capacitor corrosion near C9. Nothing major...

I have a similar issue that is mentioned in the PowerBook 140 Display Blue posted by Powerbook27364 recently. I've successfully recapped several PB screens, but this one is bugging me. At first I got a full display but the top half was broken and dithered. I went back cleaned everything...

My first soldering station was the Weller WE1010NA. It's a nice entry level station. I've purchased a much better Weller unit, but I still have it handy as a secondary station...

True or actually very were old. I searched Digikey and Mouser for that value of capacitor. Mouser has them now. They don't match the small through hole currently on the board. All of them are tall axial versions, which is why I had to bend them into place. The ones I purchased on eBay were from...

There are only two caps that need to be replaced on the inverter board. They are 8.2uf 80v. They are kind of hard to find at that size and measurement. I found some on eBay that were much taller. I ended up bending them to fit. It worked out okay. Clean the contrast and brightness switches as well.

Pretty cool. I have a 512k. Nice to have some documentation.

There are a couple of 3D print files of battery cases that could work if you have issues with your original case. I haven't printed any yet, but plan on rebuilding a couple of batteries soon and it's nice to know there is an option just in case. https://www.thingiverse.com/thing:5231825

The This Does Not Compute video was very helpful. I printed up the same files to repair my PB145b and used the Loctite glue. You need to make sure the case is sanded down flat because the glue works quickly. The pieces will need to to be slightly trimmed to fit or sand the area to fit. These...

I used ceramics for the nine 3.3uf capacitors. I will look into some tantalums instead. I don't have any breaks in the ribbon flex cables along the side of the screen.

Were you ever able to resolve this issue? I have the exact same problem after a recap on my PB165. I checked the new caps and searched for any broken traces. I also cleaned up all the remaining cap goo, but the screen has remained the same. I have recapped several PB165 and this is the first one...

Years of scanning eBay daily. Someone finally listed one and I won it beating out a lot of bidders. I set my top bid at $350. Thankfully it did not reach that and sold for $244. It's tough to find one.

Thanks. I was about to replace all the RAM sockets. I did replace the top two. I found a lot of battery vomit underneath them. I had not considered the pins. Great advice.

The MacIIFX has the two Nand Gates for the startup/ shutdown circuits located near the RAM sockets on the edge of the board. They are UI18 (shutdown) and UJ18 (startup). There are two capacitors (C24 and C27) that usually leak and eat up the traces of the Nand Gates. Here's a image of the...

I got a 3D printer for Christmas and one of the first things I printed was a hinge support for my PowerBook 145b. The plastic on these old laptops are so brittle. My previous fix of using some epoxy around the standoffs was messy and ugly. These hinge supports are so much better. Just use a...

I was finally able to buy a replacement motherboard and now have a working Mac IIFX. I am guessing there is some battery damage to an inner layer of the board that is the issue. I have shelved my two FX boards for the time being. I will probably attempt a repair again some time in the future. I...

@PotatoFi thanks so much for such a great design. I just bought a 3D printer and this was my first project to print. My print needs a bit of finesse with the Cura slicer program to clean it up, but it fits the BlueSCSI perfectly. Thanks.

I just finished repairing several PowerBooks 180,170, 165 and now working on a 145 all with no power issues. I found that they all are similar. Remove the board. Either the main fuse F1 near the battery terminal is blown (check for continuity) or a diode (D15 or 16) on the back of the board near...