silvertone roundie

[DaveWM]

Did you try more than one video out? did it make any difference at all (always does on mine, every tube has a different gain, every tube resulted in a different level of brightness, some a lot some not much but there WAS a change.

since you seem to have issues going from normal to setup did you check ALL the parts in and around the setup service switch. Are you adjusting to a just visable line? does the sams say anything about where the brightness control should be set (matters on some sets).

does the contrast control work as is should? where is it set at? Many times the contrast is set too high.

[timmy]

contrast control works fine, its at half. the problem here is hv not regulating and that it does seem that the hv is being loaded down. another video out tube i dont think will help but change little. the color lines i adjust to see then back off til just gone. and no i didnt check anything around the service switch. i think the sams did say something as to where the controls should be and i did what it said.

[DaveWM]

Why do you say its not regulating, I thought you said the shunt current changed with the brightness and was between .5 and 1.5 with a dark to bright raster and the HV held to 23-24kv all signs that HV regulation is working as it should.

Now you may indeed have a over load that exceeds the ability of the HV to supply current at excessive beam current in the CRT, but this is unrelated to HV regulation. The shunt can only regulate within a beam current operating range, go beyond that and its NOT a regulation problem, rather its a load problem, You keep saying it like those can't be separated. you could confirm this by observing the shunt current when the blooming happens, the current should drop to 0 as the KV drops to 19kv. this would indicate the regulation is working as designed and you are simply overloading.

My guess is you are simply over driving the CRT to make up for a brightness deficiency real or imagined. there could be an issue with the service switch that may be making the setup not work properly, but that can be worked around, not all set had setup switches you just do it by eye with a live signal.

I am sure you will suddenly have the solution and it will all be fine.

[DaveWM]

Originally Posted by DaveWM

My guess is you are simply over driving the CRT to make up for a brightness deficiency real or imagined. there could be an issue with the service switch that may be making the setup not work properly, but that can be worked around, not all set had setup switches you just do it by eye with a live signal.

I am sure you will suddenly have the solution and it will all be fine.

See above. from page 5 some 40 post ago.

Talked to CTC-17 says he talked to you about too much brightness range, seems like something that could be figured out if you stick with that.

[timmy]

Originally Posted by DaveWM

See above. from page 5 some 40 post ago.

Talked to CTC-17 says he talked to you about too much brightness range, seems like something that could be figured out if you stick with that.

yes it does seem now that the brightness control is driving alittle harder then it should and yes i can leave the bright reduced alittle but as ctc17 said when the sets were made no one would have wanted a new tv set that had to have the brightness lowered to fix other things. i would have thought the control was bad but it was not and the resistors as well are good. its not me overdriving anything to try to get a brighter picture, brightness was not the issue, hv and white colors and crt bias was so all these things are affected. so ill leave it for now but i will keep this brightness issue on the back burner should anything related to that crop up.

[DaveWM]

check the voltage at the plate of the 12BY7 with the service switch set to service.

[ctc17]

More myths!

i believe X-Rays go nuts over 25kv, the crt may internally arc and crack at 30-40kv. Most all of the tube sets have a hard time producing 25kv with the crt and regulator disconnected.
The 70s solid sets with tripplers could go nuts but not the tube stuff.

[timmy]

the brightness pot seems to be ok but turn it all the way down and can still see just alittle movement in the picture thats on the screen. its all crazy to me in that why does it take the hv adjust pot to be maxed to get 24kv. but what is overall overdriving or overloading this crt to cause this indirect hv thing. clearly the hv pot should not be maxed to get 24kv my other sets are alittle over the half mark at 24kv. the voltages at the crt i would think are somewhat ok since they are not reading off the charts, the readings i got are on page 2. the hvwill hold at 24kv providing there are no white scenes because the hv does drop so if its regulating the thing is now to figure out what is loading down.

[ctc17]

I would unplug the crt socket and the hv reg tube and see how high the voltage goes, then I would disconnect the hv from the crt and measure it in an attempt to verify there isnt something like a tad of air causing overloading.

But thats me, I have no fear of getting shocked or it arcing all over the place.

You changed the 3A3 right? Premium cigar rash?

Its common to fluctuate from 20-24kv, thats common and shouldnt be noticed.

Also, keep in mind how demanding modern content is on an old set. During the ntsc days they had all kinds of tricks to limit contrast and brightness. Subjects never work solid black suits on a bright white background. Thats why old programming looks washed out, that was intentional.
A strong crt+modern programming demands a perfect working chassis.

Good to use your hands, run it for 30 minutes, is the flyback hot? is the focus coil hot? the lin coil? etc

Sometimes just using a set that has been stored for years fixes alot of issues. Maybe its time to just use it gently for awhile and see if it wakes up.

[timmy]

Originally Posted by ctc17

I would unplug the crt socket and the hv reg tube and see how high the voltage goes, then I would disconnect the hv from the crt and measure it in an attempt to verify there isnt something like a tad of air causing overloading.

But thats me, I have no fear of getting shocked or it arcing all over the place.

You changed the 3A3 right? Premium cigar rash?

Its common to fluctuate from 20-24kv, thats common and shouldnt be noticed.

Also, keep in mind how demanding modern content is on an old set. During the ntsc days they had all kinds of tricks to limit contrast and brightness. Subjects never work solid black suits on a bright white background. Thats why old programming looks washed out, that was intentional.
A strong crt+modern programming demands a perfect working chassis.

Good to use your hands, run it for 30 minutes, is the flyback hot? is the focus coil hot? the lin coil? etc

Sometimes just using a set that has been stored for years fixes alot of issues. Maybe its time to just use it gently for awhile and see if it wakes up.

back when i was troublshooting with don lindsly i pulled the crt plug off and the hv came up and he had said something was loading the hv down. the flyback never gets warm and the focus coil is bearly warm and i had even checked the ohms of the focus coil and it matched the sams give or take an ohm or 2.i also had tried several 3a3 including a solid state one. i do remember pulling the reg tube cap and the hv went up alittle over 30kv and taking the anode off the crt didnt make a difference only pulling the crt neck plug made a difference but soon as putting the crt neck plug back the hv dropped. a small amount of air would do this?????

[ctc17]

An heres an observation....

I rewaxed a flyback out of one of these color sets. I boiled out moisture for over 90 minutes in a pot of wax that was 300F.
They are basically 90% paper and paper is hygroscopic and there has to be leakage through the paper at 24kv.
That very well could be your mystery load.

Speaking of hygroscopic, arnt yall about to get nailed by 3 record storms? Souldnt you be prepping for that and not worried about tvs? Making sure the car is full of gas, you have plenty of food, water, batteries a good working battery radio etc???

[timmy]

Originally Posted by ctc17

An heres an observation....

I rewaxed a flyback out of one of these color sets. I boiled out moisture for over 90 minutes in a pot of wax that was 300F.
They are basically 90% paper and paper is hygroscopic and there has to be leakage through the paper at 24kv.
That very well could be your mystery load.

Speaking of hygroscopic, arnt yall about to get nailed by 3 record storms? Souldnt you be prepping for that and not worried about tvs? Making sure the car is full of gas, you have plenty of food, water, batteries a good working battery radio etc???

well the flyback in the set was replaced and its a thordarson fly273 and its silicone potted and no arcing . so alittle air in this crt could have this affect afterall its the original that has silvertone on the neck plug. and the storm ahhh we will see if that happens even after the million dollar satillites they still cant get the weather right.

[ctc17]

Originally Posted by timmy

and the storm ahhh we will see if that happens even after the million dollar satillites they still cant get the weather right.

I wouldnt get caught with my pants down when you have a clear heads up.

I would be home watching the masses in total panic mode raid the stores of everything on my roundie totally prepared

Ok we can rule out the flyback...hmmm

You can try putting your crt tester on it in cutoff test mode, crank the cutoff voltage all they way up and see if you get blue glow in the neck. That would indicate gas/air.
The only sure way is to substitute

[timmy]

oh did i tell you i got a brand new fly273 on ebay for 10.00. he had 10 flys for sale and i messaged him if he had another fly273 he said no but he said outbid everyone then pay the full amout and ill get the fly and a refund for the difference and he would put the other flys back on ebay. it worked out great got the refund and the fly273.

[ctc17]

Everyone trips so hard on flybacks. I have never had one go bad on me, not even on the 16 I ran in a museum for 4 months the flyback held up. I have run across a few bad ones in old sets, maybe 2 in 100 sets. Not bad odds