GO7-CBO Sparks from yoke.

[sabrewulf69]

I got a GO7 with a bad chassis in a cabinet the other day, I put a good GO7 chassis on the tube in the cab for testing but upon power on a large spark shot out from under the yoke and blew one of the fuses on my good GO7 chassis. I removed the yoke and inspected it for damage but I couldn't really see anything obvious and the windings read in spec (2ohms HORZ, 53ohms VERT). What made it spark? I would have thought if it were shorted the ohm reading would have been significantly lower, asking for educational purposes.

 

[Richard48]

It is possible that static electricity from the CRT discharged to the board.
Was the ground wire from the CRT aquadag coating/frame connected to the neck board ground?

 

[sabrewulf69]

It is possible that static electricity from the CRT discharged to the board.
Was the ground wire from the CRT aquadag coating/frame connected to the neck board ground?

I believe so, but may be worth testing again, I may have thought i attached it but didn't. I have several spare fuses so its worth trying.

 

[sabrewulf69]

I think I figured it out. I tested again and I believe I didn't have the flyback anode fully secured, I noticed when I put it back in that it didn't want to stay in the hole and I had to bend the prongs back apart to make it work. So it probably just ran across the aquadag and it looked like it came from the yoke. Its now functional but I believe it damaged something in the sync section because it will no longer lock in.

 

[Mattspad]

adjust the sync check the headers, also just thinking if you truly did send the hv around the tube into the yoke you may have damaged something in the deflection circuits causing a loss of sync but idk

 

[sabrewulf69]

View attachment 857839
adjust the sync check the headers

Mmmhm... I already reflowed the sync pins yeah... just rolls horizontally, mmmhm.