68kMLA Classic Interface

This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.

Click here to select a new forum.
Macintosh Plus won't boot. Just clicks.
Posted by: mpfjr on 2020-02-06 10:20:00 Hi there. Clicking coming from the speaker. youtube links at bottom... With the floppy plugged in it makes noise in time with speaker click. I unplugged the floppy and rebooted. Now I don't hear the floppy making noise but the speaker still clicks. Nothing appears on the screen. No chime. Sanity check, I put my 512K motherboard into the Plus chassis and it boots up just fine. That means the analog board, which I have re-capped is fine. All cables from analog board to crt and to mobo work just fine. This isolates the issue to the motherboard. I had a system where it was giving me vertical lines but the floppy icon center screen was fine. I thought it was capacitors. I looked at the mobo and saw a round circle of yellow under one of the capacitor ends. So i ordered a kit and went in there to swap them. Turns out the yellow circle that I thought was capacitor goo came off like masking tape. Well it peeled off with no issue. I went ahead and replaced the capacitors. I did not remove the leads going through t he board. Instead I snipped the wire close to old capacitor and soldered on new caps and snipped off the excess. I made sure that they were in the correct direction and I used a pre-made kit. One of them ( reference this link https://www.classic-computers.org.nz/blog/2015-05-14-mac-plus-checkerboard.htm The cap that is up there closest to the keyboard RJ11 connector is a 50V 1uf and I replaced it with a 100V 1uf. The rest are 16v 33uf. Curious if I messed something up, I referenced this site http://recapamac.com.au/macintosh-plus/ was able to confirm I did it correctly. So as I was saying, I snipped off the resistor, one end of it anyways, that controls the memory type. I then had swapped out for 4x1MB 70ns At some point I had a bong chime but it was a checkerboard pattern so that is how I found the link above. But that checkerboard was only one time. Now it doesn't do anything but click click click from the speaker. I put the original memory back in thinking the memory was bad. Re-soldered the resistor. Still the same result. click click click. I took precautions. Anti-static pad with grounding straps. But we have really dry air and its been very windy here in SoCal. I wonder if it just wasn't good enough. I wonder if I STILL managed to zap something. What else can I check? Per that blog above I tested the voltage of the floppy port. The voltage is all over the place. Not a steady 12v Here is a video of the clicking. https://youtu.be/2YEfFjJQ03U Here is a video of a 512K board in the same chassis. https://youtu.be/DKW8AZCezFM Oh and just in case one of the caps was bad, I re-did them this morning. I also re-flowed the solder around the white plug that comes from the analog board down to the motherboard just in case. According to the link above I should remove the solder and re-do it. That will be my next step. But wanted to check with you guys first.
1