Update: I finally had success by switching the solder tip from a blunt chisel to a pointed tip. I held the tip perpendicular to the board and pushed it into the hole on the bottom side and had my solder sucker ready on the other. At first it seemed pointless because the tip was obviously not going to get hot enough to melt the solder, but after turning my iron to around 700F it suddenly melted and pushed through all that old solder. This is the first time I was actually able to get the solder sucker to work!
Thanks for everyone’s help! Now I just need to test all the connections, then clean it up and put it all back together to see if I’ve got sound!
I cleaned the ROM chips and I already resoldered J4 pins on the analog board some time ago, but I got these results: I still got the same checkerboard screen, but the speaker did a little “thud” sound when it switched from checkerboard to the gray screen and the speaker screeched a bit when the diskette icon appeared. I have very little experience with electronics but this makes me think that certain parts of the circuit are not getting enough voltage to operate which results into checkerboard and silent speaker.
Having some 400k drive issues and hoping a resident expert here can help ...
A few weeks back I got out a classic old Mac boxed game (Dark Castle, if you’re wondering) and decided to play it from the disk on my 512k. Annoyingly, the disk wouldn’t read, and suddenly neither would any other disk, so I took a look at the disk - the disk medium looked 100% fine. I decided the 400k drive head must be dirty, opened up the 512k and thoroughly cleaned the head with isopropyl alcohol. Still won’t work or recognize any disk at all (attached video shows what it does when I insert any disk on startup), and will fail to initialize anything inserted. Now I make a mistake and decide, somewhat stupidly, that the disk is probably fine and I just had a weird sudden drive failure ... so I try the same disk in an external 400k drive. All the same things happen. Suddenly I’m worried I’ve ruined two of my drives with this bad disk! Again, cleaning the drive doesn’t help. So I open up the Dead Mac Scrolls and google around for help — I see various mentions of a “track zero alignment procedure” (the Dead Mac Scrolls, p. 274, says if you can’t even initialize a disk, it’s not a stepper motor misalignment but possibly a track zero sensor misalignment) but no good photos or specific instructions for a 400k drive (the Dead Mac Scrolls diagrams are for an 800k drive only, I think). But anyway - how would I very suddenly experience track zero sensor misalignment only after using this particular disk?
By the way, I did something risky and tried the same disk again in a disused 800k drive I had lying around ... it also failed to read, and AGAIN the next disk I inserted couldn’t be read either ... however, in my 800k drive, running a normal cleaning disk with alcohol through the drive a couple times got everything back to normal and it’s now 100% fine. Again, though, head cleaning didn’t help my 400k drives at all.
So - here are my questions:
1. What the heck could possibly be wrong with this disk that it can ruin any 400k drive it touches (but again, looks entirely OK - it’s not like it’s shedding dust or the disk medium is visibly scratched or anything)
2. What’s the proper and official way to clean the head of my 400k drives? Since head cleaning fixed my 800k drive, I’d think that cleaning the 400k drive heads should work, but it doesn’t seem to ... do I need to do anything other than wipe the little white shiny head guy with alcohol?
3. Is there anything else I should try, like this track zero sensor alignment procedure? Is there a clear set of instructions for that somewhere, specific to a 400k drive?
Thanks for any help!
Quick update, got impatient and decided to just take some 70% ipa and clean the leak by the adb ports as it seems that is a common issue for soft power and it booted right up!
Will start removing the old caps this weekend, but always good to know its in a working state before you start.