Mac Classic - will it ever run again!!

[Tomswork]

@rune.bjørge

The macs use there on video signal and would be hard to get on a compiste monitor to work. I would look to resolder all the power connectors on the analog board and the flyback. It is the most common fault on those boards. I also was give a donor clasic board. It may work needs capacitors. My advise it to reflow the soldier on the analog board first

Tom

[rubber_jonnie]

@Tomswork I have already reflowed the cable end at the analog board and recapped the power section. It'd really help if I had a good board to compare this logic board to.

I haven't done the flyback though so will try that, but get no sound at the moment either.

The whole composite video idea was just a vague hope, but the helpful thing has been being able to hook up external power and get in and probe without the board dangling off the CRT and analog board.

[stephen_usher]

Just a mo... Doesn’t the Mac Classic have soft power-on via the keyboard in addition to the power switch at the rear?

[rubber_jonnie]

Just a mo... Doesn’t the Mac Classic have soft power-on via the keyboard in addition to the power switch at the rear?

It does, but it will power up just with the mains switch, or at least it used to. I can double check but I don't recall ever using it on this machine. Thanks for the reminder, always worth a check.

[Tomswork]

@rubber_jonnie
You may find making an extention cable up for working on it really handy

I do have a classic board that works it has the caps off at the moment to stop leaking and has been us cleaned are you in the uk im in Canada but can price economy shipping

Tom

[Aeberbach]

I’ve done a fair bit with Mac video on a SE/30 recently - I have VGA output working from a MAX10 FPGA. It’s easy enough to use a scope to count pulses leading into the start of video and then to sample the pixels on each line. My setup is probably non-optimal but I just buffer each frame and then read from that buffer to display output.One bit of course, on the classic and if it is the same as the other compacts you can get a lot of info from the Burrell Smith sidebar in the Byte review of the first Mac - it’s online in several places.

I don’t know if you need 12V to boot, but you do need 12V for audio so you probably will not hear a chime even if the CPU is trying to boot. -5V is only used for serial comms.

[rubber_jonnie]

@rubber_jonnie
You may find making an extention cable up for working on it really handy

I do have a classic board that works it has the caps off at the moment to stop leaking and has been us cleaned are you in the uk im in Canada but can price economy shipping

Tom

Yeah, an extension cable is not a bad idea, that's going on my to do list!! It doesn't help that I have a really small workspace, so getting everything on my workbench, so 'scope, Mac, other tools, is a bit of a problem. if everything goes to plan, we are moving in March and I will have much more space for my workshop, so I will keep at it.

I am in the UK, so am interested if you can give me an idea of price, thanks. Replacing caps isn't a problem, so that's all good. I just wished I'd looked at the caps sooner, all my problems started when they leaked.

Luckily the battery was ok as I replaced that when I got the machine.

[rubber_jonnie]

I’ve done a fair bit with Mac video on a SE/30 recently - I have VGA output working from a MAX10 FPGA. It’s easy enough to use a scope to count pulses leading into the start of video and then to sample the pixels on each line. My setup is probably non-optimal but I just buffer each frame and then read from that buffer to display output.One bit of course, on the classic and if it is the same as the other compacts you can get a lot of info from the Burrell Smith sidebar in the Byte review of the first Mac - it’s online in several places.

I don’t know if you need 12V to boot, but you do need 12V for audio so you probably will not hear a chime even if the CPU is trying to boot. -5V is only used for serial comms.

I had read an article about something similar to get VGA out, but sadly whilst I am reasonably ok at troubleshooting and basic electronics, I have no experience with building something like you describe, though I will go and have a look at the Burrell Smith stuff you've mentioned.

I did connect up all the power lines in the end, but didn't get around to checking if there was any sort of signal on it when I booted, I just ran out of time. I think I'll build some sort of extension cable for the analog board and plug it all in together again, see what it's currently doing.

[mrbombermillzy]

Theres a book, The Dead Mac Scrolls, which covers troubleshooting and repairs for the early 68k Macs.

It may well help out. :)

[rubber_jonnie]

Theres a book, The Dead Mac Scrolls, which covers troubleshooting and repairs for the early 68k Macs.

It may well help out. :)

Ta, off to visit Google :)