UPDATE, AUGUST 19, 2019, DAY 380
Author: The “cooking” process started and the first skeletons appear …
From Mike:
“Hi Marshall. I have been running the set from time to time when I am in the shop. Tonight I noticed that one of the damper tubes had no filament. The tube tested fine so the issue is either a bad socket or connection somewhere. The set has qty 2 damper tubes in parallel and it will work with only a single tube but it was designed with both in order to handle the current in the flyback properly. Glad I saw this. Not a show stopper, just another “skeleton” that I am glad I found.
More later,
OK, there was in issue with one of the damper tube filaments going dead. The problem is the way the ground takes place on the socket. The method is standard design and the problem is from age and poor soldering techniques during production. Pin 8 (filament) of both of the damper tubes are grounded by virtue of a rivet and solder connection at the mounting point of the socket. This method works fine for a while, usually through the “warranty period”. LOL. Then, the electrolytic action caused by the difference between the two metals causes some corrosion. As long as the solder connection between the two is good then everything is fine. But that was not what was happening in this case. The parts were not cleaned well enough and the corrosion, even though a small amount, was enough to cause enough resistance to keep the filament current from flowing. So, the fix is to install a wire from pin 8 of each of those tubes to ground and soldered well at both ends. This fixes the problem forever.
Pix #1 Pin 8 and the rivet in the center of the shot. You can see the poor soldering job and the circle around the rivet proves that the solder did not flow properly.
Pix #2 The other damper tube pin 8 soldering job also doomed to fail.
Pix #3 The repair. The black wire connected to both pin 8’s and terminated to the chassis at a good solder point.
Stay tuned. Mike.”
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