Mighty Monarch of The Air

[old_coot88]

Originally Posted by vts1134

I did this. The socket was only connected to the tube and the lead to the picture tube. I still had the same problem.

Ok, my bad. I didn't realize you'd already done this.

The sparking is definitely coming from inside the tube itself. The problem I had below/around the tube was corona discharge from various locations, the "tire," the filament loop, the connection to the wire lead to the picture tube, etc...
Wouldn't it make sense that if those components are driven past their voltage limits that they would begin to show corona discharge?

Yes, now that you've done the 'float' test.

With the input voltage at 90v y and z are already at 270vdc. At input voltage of 95v and the anode voltage reading 14kv (the limit according to the 16gp4 spec) there is no problem in the high voltage area. Above 95v input, when y and z get up over 310v then SPARK!

I don't have access to the LV supply section of the schematic. But the most relevant voltage is where the flyback system itself is supplied. That would be at lug# 6 of the flyback. The print calls for 210V. If that voltage is signifigantly over spec, it could sure as heck be overdriving the whole flyback system.

The schematic shows 255V at other locations in the chassis. Is that voltage over spec too? If it is, it would suggest the LV power supply is putting out too much juice. Is there any evidence of the power transformer having been replaced?

Or if the 255V source is not over spec, could there be a miswire somewhere that's putting 255V onto the 210V line?

Maybe Phil could post the print showing the LV section.

One thing's for sure- we all gotta admire the heck outa your tenacity in rassling this critter. For a total Noob, it's truly been a baptizm of fire. When you get it whipped, you can rightly call yourself The Dragonslayer.