Recent content by pfinn

I have an international Mac Plus with a very blurry screen towards the edges. Center pixels seem okayish. When I adjust the R57 pot meter (focus) nothing happens on the display. Using my multimeter I can confirm that the pot meter varies resistance between about 0 to 2M ohm, so it seems to be...

Hey wow, I didn't expect that! It's not in the schematics. Is yours a revision C too? My 1070-A doesn't have that, while the C does... Thanks for checking! I wonder what engineer suggested this change and got approval. :D

Is this something that's a normal find or do I have a couple of Frankenstein Mac Plusses here? This is a different machine from the one with the resistor on the back of the analog board. Notice the transistor with the resistor doing a little dance together. It does not look factory default to...

I don't think CR21 is the problem. According to the Dead Mac Scrolls: "With the power off, check the in-circuit resistance across CR21 (IR31 D Q, R-Schottky Barrier, 40V, 6A). If the reading indicates 00/00 (not 52/53), replace CR21 with a heavy-duty MBR360 rectifier. If the in-circuit reading...

It beeps in both directions. It shall forever be remembered as the little diode that could.

Hi folks, I've got a Mac Plus international analog board here with a blackened CR21 diode. When measured it has about 40 ohms resistance regardless of polarity. This is a good indication this diode has blown right? Should I get a replacement and try again or could there be something else at...

It had weird solder blobs that stuck out from the rest. Solder wasn't shiny and evenly distributed and its pins were bent in a way to stick to the board without solder (middle pin opposite direction). I've removed the rifa caps and gave the voltage pot meter a little nudge. Measured the...

Thanks for the quick reply! Q10 also seems off to me. Weird soldering job has been done on that board. And the battery compartment is red. Haven't seen that before either, but maybe that's more common.

Hi, I've recently acquired two mac plusses which I'd like to restore to proper working condition. I've found a resistor on the back of one of the analog boards which looks very odd to me. Somebody has definitely been inside the machines before me, so I was wondering if this factory default for...