Mighty Monarch of The Air - Page 15 - Videokarma.org TV - Video

old_coot88 · #**211** 06-27-2011, 09:05 PM

Woop. Hi Phil. Looks like you were zeroin' in on the same thing.

Phil Nelson · #**212** 06-27-2011, 09:55 PM

Well, there are so few things connected to the 1X2. At this stage, I'm scratching my head thinking, What is left besides the socket??

Phil Nelson

roundscreen · #**213** 06-27-2011, 10:14 PM

VTS1134. Try turning down the horizontal drive control and see if the arcing goes away or calms down. If it is a tuning cap that would be counter clockwise but try turning it in both directions. The sides of the screen should cave in and the picture will loose brightness. I thought I saw a drive control in the schematic. Also do you have a signal going into the set? Is the picture normal and has vertical and horizontal sync? If you are going to keep working on vintage TV a HV probe is a good idea. At some point you may want to restore a color set and a probe is a must.

old_coot88 · #**214** 06-27-2011, 10:30 PM

Quote:

Originally Posted by Phil Nelson

Well, there are so few things connected to the 1X2. At this stage, I'm scratching my head thinking, What is left besides the socket??

Nothing except whatever the socket mounts to that could sustain a leakage path to ground. Hence the suggestion that he remove the mounting(s) if possible and 'float' the socket for a test.

vts1134 · #**215** 06-28-2011, 02:21 PM

Quote:

Originally Posted by Phil Nelson

If you also want to replace the 1X2 filament loop, I believe that needs to have HV-rated insulation.

Is this a locally available material? I tried the local electrical supply house that we have an account with but they don't have anything like this. I'm not sure what to call this and therefore google it and get online results. Any thoughts?

Phil Nelson · #**216** 06-28-2011, 02:51 PM

I guess I would call it high voltage wire. Surplus Sales of Nebraska has 40KV-rated wire for $2.90 per foot.

http://www.surplussales.com/Wire-Cable/HVWire-1.html

I don't know what's available in your locale. Electronics supply stores are practically nonexistent around here, so I buy everything online.

Phil Nelson

vts1134 · #**217** 06-28-2011, 02:58 PM

Thanks Phil. I'm going to try a couple more places in my area before resorting to ordering 25ft of the stuff.
I found out the pfffssst sound was corona discharge from the filament loop so I'm going to start with that.

miniman82 · #**218** 06-28-2011, 03:16 PM

Just rob it from a newer set. I get mine from BPC stuff, just cut the anode lead off the flyback and discard the HV cup.

vts1134 · #**219** 06-28-2011, 03:51 PM

Quote:

Originally Posted by miniman82

Just rob it from a newer set. I get mine from BPC stuff, just cut the anode lead off the flyback and discard the HV cup.

Bingo. Never thought of that, we throw tube TVs away almost daily!

vts1134 · #**220** 07-03-2011, 06:36 PM

Update.
I've replaced the filament loop wire with 50kv rated wire. I've also got a third 1X2. Those haven't solved the problem. I also now have a high voltage probe and am getting some interesting readings. The 16GP4 has a maximum anode voltage rating of 14kv. I can't get the input voltage on the set over 95v before I am above 14kv on the anode. Anode voltages above 14kv is also when I start to have problems with the 1X2 sparking and glowing.
I've also adjusted the horizontal drive as per roundscreen's suggestion. Turning the drive up increases the anode voltage and subsequently makes the 1X2 spark and glow when voltage reaches over 14kv. As long as I keep the anode voltage below 14k I can run the set as long as I want with no 1X2 problems.
Any thoughts on why my anode voltages are so high with the set on 3/4 power? Sounds like this might be the whole problem, but what could be the cause?

ChrisW6ATV · #**221** 07-04-2011, 12:37 AM

Yes, I definitely agree that you have found the problem with the rectifier. Regarding the cause, I would test other voltages in the power supply and horizontal circuits with the AC input set at 90 or 95 volts.

bandersen · #**222** 07-04-2011, 01:39 AM

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 · #**223** 07-04-2011, 07:28 AM

Quote:

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 · #**224** 07-04-2011, 09:24 AM

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 · #**225** 07-04-2011, 10:20 AM

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