Mighty Monarch of The Air

[bandersen]

The maximum peak inverse voltage on a 1X2 is 15kv so I think you found the rectifier problem too.

Are you measuring the HV with the 16GP4 installed ? If not, it might be to high because there's no load.

[vts1134]

Originally Posted by bandersen

The maximum peak inverse voltage on a 1X2 is 15kv so I think you found the rectifier problem too.

Are you measuring the HV with the 16GP4 installed ? If not, it might be to high because there's no load.

I'm measuring with the 16GB4 installed. Thanks for asking/pointing out obvious things, helps folks like me greatly.

[vts1134]

After some measuring I found that my "Y" and "Z" voltages are too high as measured directly on pin 5 and 7 of V19 (the lv rectifier). Is it possible to remove the leads of the transformer from V19, give the set voltage, and measure the output directly without harm? If it is and it still measures too high is the transformer at fault? There is not much in front of the transformer but a couple of filter caps.

[old_coot88]

Vts1334,
It seems very doubtful that three 1X2s are all gonna be displaying an acring/sparking problem such as you describe, even with the driving voltage being a little over spec. The tubes should have enough 'headroom' to be able to handle it without a problem.

As was suggested back in posts 210 and 214, what you describe sounds more like something under the 1X2, not the tube itself, is doing the arcing/sparking.. like maybe a leakage path from the socket to ground.

As a test of this theory, if it's possible to temporarily 'float' the socket by removing whatever it's mounted to, that would eliminate a leakage path as the problem.
oc

[vts1134]

Originally Posted by old_coot88

Vts1334,
As was suggested back in posts 210 and 214, what you describe sounds more like something under the 1X2, not the tube itself, is doing the arcing/sparking.. like maybe a leakage path from the socket to ground.

As a test of this theory, if it's possible to temporarily 'float' the socket by removing whatever it's mounted to, that would eliminate a leakage path as the problem.
oc

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

Originally Posted by old_coot88

It seems very doubtful that three 1X2s are all gonna be displaying an acring/sparking problem such as you describe, even with the driving voltage being a little over spec. The tubes should have enough 'headroom' to be able to handle it without a problem.

How much head room do you think they have? 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 haven't measured anode voltage when the 1X2 is at it's fail point but I suspect it's a good deal over 14kv.

[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.

[jeyurkon]

If the focus coil were open or disconnected maybe the +255 would be too high.

Anyhow, here's the power supply section.

John

[vts1134]

Originally Posted by old_coot88

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.

Ha, just wait. This is only the latest problem, I haven't told you that I still don't have a picture yet. It might be a while until this is over. I know I've said it before but I can't thank you all enough for teaching me what I know refer to as my crack addiction. I can't wait until I can show you a picture on this bad boy, take a 5-7 minute break to admire it, and start the next one .