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I did the early measurements on a Plus but I've done my experimentation on an SE/30 analog board. I found someone selling an analog board with a dead flyback transformer, which was perfect since I don't need it on the yoke driver anyway. Tomorrow I'll see if I can put together a useful...

Changing the scan rate of the analog board seems unlikely to work, and definitely won't get anywhere near 68kHz, so I thought it would be worth trying something different:   Approach   The way I'm working on this now is to run the yoke and the flyback and two completely separate circuits. In...

Just to collate some info scattered around various threads and documents (this may be old news-- and hopefully I have this all correct):   Background   The standard compact Mac resolution of 512x342 uses 22.25kHz horizontal sweep and 60Hz vertical sweep. 22.25kHz = 44.93us per scan line, of...

I'm revisiting one of the "classic" goals of compact Mac hacking: changing the resolution of the internal CRT screen. I've been poking at this for a few months, and I've finally got enough progress now that I'm reasonably confident it can be done, so I thought I would share where I've gotten to...

Yep I guess this is a lesson to be learned the hard way (once!). I previously recapped a couple SE/30s with problems but got lazy on this one because it was working flawlessly until this happened. I admit it was a pretty surprising failure mode. I'll see if a recap, wash and replacing those...

Might be. It didn't look quite as bad to me as the transistors, but who knows. At least the part number there is marked, and easily replaceable. Judging from the traces on top, I guess Q10 and Q11 are probably power drivers for the speaker, with UK3 the preamp. In which case the loud noise and...

Looks like I have literally burned out the logic board on my IIsi. I powered it up today after a few weeks in storage to test some RAM sticks, and it was behaving strangely: lots of crackling through the speaker with flickering LED, plus some chimes of death, not wanting to stay powered or...

Does anyone have drivers for the Radius display cards for the Plus and SE? I've been working on getting a Radius Two-Page Display card for the SE back up and running from a state where it was hanging the machine. See this TC thread: SE PDS card ROMs Now I'm getting somewhere with the hardware...

I don't own a CC and haven't done this modification, but I've looked at the horizontal sweep circuits of the B&W compacts in some detail. I think the CRT shouldn't be your concern here. The reason for the higher sweep voltage is to drive the horizontal deflection coil to move the beam...

I have one of these drives doing the same caddy eject thing. It probably is a cap issue. Oddly enough, the caps look fine and there's no obvious leakage on the component side of the board, but there's a real mess on the underside of the board around each set of caps. I can't quite figure out how...

For what it's worth I recapped an SE/30 recently with a horizontal line on screen-- no change after recap. The culprit turned out to be a via near UF8. From the schematic, UF8 appears to count vertical lines. The output goes to PAL UG6 which probably implements comparators at 342 and 370...