TJBChris | TRS-80 Model III Restore - CRT Repair and Calibration - Part II @TJBChris | Uploaded March 2022 | Updated October 2024, 19 hours ago.
Part two of my TRS-80 Model III restoration. In this video, I try to diagnose the source of the issues preventing my Model III from displaying video. I test the computer using the CRT and driver from a Model 4, ultimately leading to the installation of a spare video driver board I had lying around and repairing a break in the horizontal deflection coil. The CRT is then calibrated, the system reassembled, and some brief testing is performed. Enjoy!

Stay tuned for Part III: Upgrading the RAM to 48K

Music: There is no music. Just me jabbering for 28 minutes.

Chapters:
Intro & Spare Video Driver Board (0:00)
Discharging the CRT (1:37)
Removing/Inspecting the Video Driver (2:41)
Video Board Comparison and Installing Model 4 Board (4:31)
Testing With Model 4 Video Board (5:35)
Testing With a Model 4 CRT and Driver (7:05)
Musing And Pontificating - Narrowing Down the Problem (7:50)
Model III Deflection Coil - Overview and Testing (9:45)
Deflection Coil Repair and Meter Test (13:40)
Deflection Coil Test in the Model III (16:01)
Whiskey Celebration (17:36)
CRT Adjustments (18:21)
CRT Safety Spiel (18:59)
Checking Out the Assembled System (24:43)
Outro (27:10)

I do these videos unscripted, so I apologize if the in-the-moment descriptions of things are a bit scattered. If you have any questions/comments about this video, you can find me in any of these fine locations:

The Tandy Discord Server
The CoCoTALK! Discord Server
The TRS-80 Color Computer (CoCo) group on Facebook
The CoCo Crew Podcast group on Facebook
On the Vintage Computer Forums (vcfed.org)
The TRS-80 Models I-4/4P Group on Facebook
Tandy / Radio Shack Model II /12 / 16 / 16B / 6000 Owner's Group on Facebook
Twitter (I'm TJBChris there, too...)

Thanks for watching!