Recent content by Y030

My package of deadstock 74 series chips  arrived today from Poland and sure enough, it was UB8. During the wait I got a new fan in there to replace the noisy squirrel cage which made a huge difference, and a SD to SCSI card - yet to be installed. https://imgur.com/JQnyCgr Just need to find a...

Thanks Bolle. I grabbed some more time on this and checked the VADR lines, all good, so setup a second good se/30 on the bench for comparison. This has what looks like a later revision board and different and socketed PALs. Otherwise, ICs are labelled the same (except the PALs curiously) and at...

OK - tested lines A0-A15 from the mux inputs back to the PDS, all is well there too. Looking more and more likely its an IC at fault. Is there a good method to test the PALs? I was going to get a working SE/30 and compare the signals on each pin, unless there's a more obvious/simple procedure...

Thanks guys very helpful. I traced D24-D31 back to the ROM and PDS slot, everything fine there. Also fine were RA0-8 and the other lines RAS/CAS, etc back to the PAL ICs. Were there any others I should check? Unless there is something else - then I guess either the 253 mux’s or a bad PAL. Are...

Yes it’s an odd one... Hmm couldn’t upload images. (Am I doing something wrong?) So instead here are a couple of links: During POST Waiting for boot disk Board is plugged in using an atx extender but behaves the same plugged directly in.

Hi folks, this is my first post here and I’m looking for some help diagnosing yet another video issue with a Mac SE/30 - hoping that someone could point me in the right direction. Usual story, dug the Mac out of storage to find it didn’t boot, display full of stripes and noise. Removed the...