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. | |
| Triple IIcx | |
| Posted by: petteri on 2020-05-29 22:51:44 I went to pick up ROM chips for my Plus project and came back two Plus logic boards and three IIcx units. So, only one of the IIcx is working without sound. It has a display adapter (Macintosh Display Card 8•24 (670)), RAM, PSU and floppy drive and other two are empty cases with only motherboards and some RAM. I was told these two did not boot at all. Based on quick look the boards are somewhat ok but would need cleaning and recap. I am hoping to get one perfectly working unit and maybe second one if I manage to source missing bits for it. The photo is from a non-working unit.   | |
| Posted by: petteri on 2020-05-30 19:36:14 The working IIcx has some startup issues, the keyboard start doesn't work every time. Also, if I have the mouse plugged to the IIcx instead of the keyboard the startup seems to fail. Is this PSU issue or just yet another symptom of bad capacitors? | |
| Posted by: petteri on 2020-05-31 07:21:48 Recapped the worst looking IIcx board first. I didn't try it before hand as I was told it being totally dead. After recapping it starts up fine but no chime from loudspeaker or headphones, no video, no disk activity. The corrosion on pads was pretty bad and I two caps fell off during the initial wash. It was pretty difficult to find some clean metal but I managed to do all electrolytic SMD caps. I guess there are some broken traces as well. Edit: Where is Nubus controller on this board? | |
| Posted by: petteri on 2020-06-02 22:37:24 Some update: On machine A (soldered CPU, recapped and washed now) I found two broken traces to near audio circuits, that would explain no audio at startup. But I haven't seen anything related to video issue. Maybe I'll fix the audio traces first and then I might be able to head some dead mac chime. On machine B (socketed CPU, washed once, not yet recapped) I get chime from headphones and it seems to start up. But only if I hold the power button down all the time and event then the startup fails sometimes with clicking. On machine C (socketed CPU, washed once, not yet recapped) there are some professional looking jumper wire fixes and sticker indicating some service work. The board seems to be made in a different factory as the silkscreen printing differs a bit from other two. Also blue "blob" filters used instead of green "worm" ones. This one requires startup from power button of the board but doesn't require holding it down all the time. | |
| Posted by: petteri on 2020-06-03 16:23:18 No clue why machine A is not working, I haven't found any broken traces yet... The machine B was much easier to recap and it is now in working condition. In addition of new capacitors it requires a sketchy jumper wire to bypass corroded trace. ADB, soft start, floppy, video and sound all work nicely. I haven't tested SCSI yet. Unfortunately I ran out of SMD tantalum caps so Machine C has to wait a bit.    | |
| Posted by: trag on 2020-06-05 07:10:59 Nice work. I am enjoying reading about it. | |
| 1 |