Tempest and I made an agreement for him to send me 2 broken Mac II's (one somewhat gutted) in exchange for repair and recap of his IIfx logic board. I basically paid to have the stuff sent to me and Tempest paid for the return of the repaired IIfx logic board. I thought it sounded like a good deal.
I talked about the IIfx logic board repair in another thread. It was successful and I sent it out this morning. I received the board, fixed and recapped it that day, and sent it back the next. If anyone else is interested in making such a deal with me, talk to us to see how it went and make me an offer if you like.
So now I have these two Mac II's sitting in my apartment. I opened them up and found severe capacitor leakage which has lead to some trace corrosion in certain areas.
Neither would turn on. So I did a trick to force the power supply to turn on. I took a current-controlled voltage source, hooked - to ground, and touched +5V to the sense wire on the power supply. This technique works even with dead batteries or no batteries. Both Macs fired up but neither Mac chimed.
Nevertheless, I picked one of them, removed all caps, washed, and recapped it. Still nothing. So I waited until today and tried again, and I got a death chime! WOOHOO! So I added some RAM and it booted off of my external SCSI drive and everything. It must have still had some moisture somewhere. I was psyched. The damaged traces seem to have to do with the power on/off circuit. The Mac will not turn on with good batteries. So I'll be poking around with that. Thank goodness for Gamba's power circuit schematics. Maybe I can get this Mac back to a fully-functional state.
So I think I might recap the other one and then see if we can get them both to work! The other one has damage in other areas that may affect it differently, but we'll see. There is also one very old floppy drive, looks to be double-density, and that will need some work as well. It does not physically accept a disk currently.
So as more stuff happens, I'll post here.
I talked about the IIfx logic board repair in another thread. It was successful and I sent it out this morning. I received the board, fixed and recapped it that day, and sent it back the next. If anyone else is interested in making such a deal with me, talk to us to see how it went and make me an offer if you like.
So now I have these two Mac II's sitting in my apartment. I opened them up and found severe capacitor leakage which has lead to some trace corrosion in certain areas.
Neither would turn on. So I did a trick to force the power supply to turn on. I took a current-controlled voltage source, hooked - to ground, and touched +5V to the sense wire on the power supply. This technique works even with dead batteries or no batteries. Both Macs fired up but neither Mac chimed. Nevertheless, I picked one of them, removed all caps, washed, and recapped it. Still nothing. So I waited until today and tried again, and I got a death chime! WOOHOO! So I added some RAM and it booted off of my external SCSI drive and everything. It must have still had some moisture somewhere. I was psyched. The damaged traces seem to have to do with the power on/off circuit. The Mac will not turn on with good batteries. So I'll be poking around with that. Thank goodness for Gamba's power circuit schematics. Maybe I can get this Mac back to a fully-functional state.
So I think I might recap the other one and then see if we can get them both to work! The other one has damage in other areas that may affect it differently, but we'll see. There is also one very old floppy drive, looks to be double-density, and that will need some work as well. It does not physically accept a disk currently.
So as more stuff happens, I'll post here.
The second one has not successfully booted just yet, and actually it corrupted the external HD half way through booting! Could be improper termination. I didn't use a terminator at all!
