Debugging a dumpster find: NEC MultiSync JC1401P3E
Channel: peterderhalbemeter
Date: 2021-05-12

This monitor caught my eye at a local recycler, since its connector suggested that it can display CGA video signals, and I brought it home. In this video, I'll fire it up, give a quick tour about the monitor, and attempt to repair horizontal misalignment of the display. I've filmed the entire journey of debugging the issue, including following dead-ends, so this is not a quick "How To Fix" video. Follow along if you're interested in seeing that process - will I be able to fix it or not? :)

I also share some of my strategies for keeping screws organized, not chewing out screw holes on reassembly, and questionable tools for protection against electric shocks.

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*** SPOILERS BELOW ***
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If you want to take your own guesses, don't read on until you've watched the video to the end. :)

*About the monitor*
It can display CGA/EGA/PGA and various other early video formats given the right (custom) cable. It was one of, if not the first monitor to support a range of different horizontal frequencies, instead of a few fixed frequencies.

*Related links*
These are external weblinks, open at your own risk (ads, tracking, malware etc).

* InfoWorld review from Oct 1986: https://books.google.ch/books?id=mTwEAAAAMBAJ&lpg=PA61&pg=PA61
* Wikipedia on multisync monitors: https://en.wikipedia.org/wiki/Multisync_monitor
* User's manual: https://manualzz.com/doc/51871047/nec-multisync%C2%AE-jc1401p3e-benutzerhandbuch 
* Service manual: http://www.bitsavers.org/pdf/nec/monitor/NEC_MultiSync_%20JC1401_Service_Manual.pdf -- the relevant PDF pages here are 12 and 17.

*Table of contents*
00:00 - How I got it
00:31 - The problem and first impression
03:19 - A tour of the monitor
09:01 - Taking the cover off
13:34 - First look at the insides and "high voltage = scary" warning
15:27 - Lead #1: Taking off the controls board
18:34 - Understanding the controls
22:28 - Measuring and coming up with a plan
25:32 - Lead #2: Scrap the plan, find service manual and check for other controls
28:45 - Looking for the controls mentioned in the service manual
33:49 - Found 'em!
35:10 - Partial reassembly, and waffling about how to replace screws without chewing out the mounts
36:48 - Controls board cleaning and reassembly
45:03 - The new plan
46:37 - Tuning the controls
48:18 - Quick intermission: A discovery about CRT radiation
48:57 - Tuning part 2, this time with knowing what I'm doing
51:17 - Great success!
53:05 - Vertical hiccup
53:45 - More tweaking
55:53 - Final tests of the reassembled monitor