This has been documented before, but I thought I'd make a separate post because I couldn't find all the info in the same place and just had to fix one of these.
If you have a Matsushita TM-202G that the Horizontal Hold won't lock in, here's why:
1. you may have the sync on the wrong pin, this monitor only takes Negative Composite sync, and only on pin 5. Pin 6 isn't hooked up to anything. Many Atari games have two video connectors to accommodate this monitor.
2. Once you know the sync is correct, if the monitor's B+ is off, the vertical will sync and the monitor may work but the Horizontal will drift out of sync if you can get it to sync at all. At this point doing a capkit is the next step. There are 4 Bi-Polar caps on the monitor.
3. After a capkit, you may still figure out that the B+ is nonadjustable (stuck around 144v instead of 123v) because resistor R811 is burnt up. You can easily measure the B+ on either end of fuse F002 (right near the edge of the board). If the B+ will not adjust, check R811, but you have to remove it to test it. It should be a 47k 1% resistor (half watt).... if the resistor has drifted anything more than about 1k the 500ohm B+ adjustment pot it's tied to will not work. 46k, or 48k, will not work. Mine for instance was measuring 68K, way out of spec.
Once you get the B+ right and the capkit done, the horizontal hold will literally snap into place when you adjust it like it does on most monitors. Hope this helps people save this monitor, because they have great pictures if they're working.