Apple Monitor II recently stopped working

6 posts / 0 new
Last post
Offline
Last seen: 1 year 1 month ago
Joined: May 17 2023 - 19:21
Posts: 3
Apple Monitor II recently stopped working

I've had my original apple iie and Monitor II since I was a teenager.  Its been working great all these years until the other day a friend asked about it and I booted it up. The computer sounded fine but the monitor display was having issues.  I finally got it to display after tweaking the knobs and then shut it down. Now I tried to use it again and the power light is on the monitor but I do not see any video being displayed. I tried adjusting brightness and contrast but do not see any image. I thought it might be the video port or the cable, but I tried changing the cable and connected it to a old iic I have that is known to be working and same result, no display whatsoever.

 

Any ideas on anything I can try to fix it or at this point should I just congratulate it on its long life and move on and try to find a replacement?

 

Online
Last seen: 48 min 59 sec ago
Joined: Jun 18 2010 - 13:54
Posts: 765
First test would be to see if

First test would be to see if there's any high voltage. Does the face of the screen feel staticky? Any high pitch noise?

Offline
Last seen: 1 year 1 month ago
Joined: May 17 2023 - 19:21
Posts: 3
No static feeling. Very

No static feeling. Very slight hum when powering on the monitor.  Monitor power light  comes on but that is about it.

Online
Last seen: 12 min 47 sec ago
Joined: Feb 27 2021 - 18:59
Posts: 554
notes

I don't have time to search for the schematics, but they may exist online and would be important to refer to.

If the monitor is not producing EHT ("extra-high tension", the 10 kVDC or more that is on the CRT second anode), it can be because the horizontal deflection circuit is not working, because the way the flyback transformer works is by storing energy from the horizontal deflection to convert to high voltage. This can be caused by a bad HOT ("horizontal output transistor") or by other passive components in the horizontal deflection circuit, or instead by a missing horizontal sync signal that should be coming into that circuit from upstream. The flyback transformer itself (also called the LOPT or "line output transformer") can also be the source of the problem, or it can be caused by cracked solder joints between the LOPT and the circuit board. These solder joints should be carefully inspected.

Any kind of work inside a CRT requires special precautions, and some special tools like high voltage probes. I've posted links to Sam Goldwasser's Q&As before but as they are hard to search for, here they are again:

Notes on the troubleshooting and repair of computer and video monitors

TV and monitor CRT (picture tube) information

Notes on the troubleshooting and repair of television sets

Offline
Last seen: 1 year 1 month ago
Joined: May 17 2023 - 19:21
Posts: 3
I managed to buy a

I managed to buy a replacement Monitor II online but it did not do well in the shipping process. The monitor works and the display is fine, but the case front cover cracked and it looks like the power lamp got dislodged and is inside the case. Anyone have any idea how difficult it would be to swap the cover from my original monitor ii to the replacement?  I can probably live with just replacing the front cover if that is an option. I tried to find some videos of monitor ii disassmblies but could not find any.

Online
Last seen: 1 hour 58 min ago
Joined: Jun 6 2020 - 10:50
Posts: 438
jerryrs wrote:I managed to
jerryrs wrote:

I managed to buy a replacement Monitor II online but it did not do well in the shipping process. The monitor works and the display is fine, but the case front cover cracked and it looks like the power lamp got dislodged and is inside the case. Anyone have any idea how difficult it would be to swap the cover from my original monitor ii to the replacement?  I can probably live with just repl

There are copies of the apple technical procedure manuals on archive.org (and probably elsewhere, Google can find them). While they don't cover things like schematics for monitors, they do cover disassembly and reassembly of them. That should help you in the process. It looks like from the copy I saved, you want volume 2, part number 072-0229. 

Log in or register to post comments