21fbp22 red gun advice
 

hey all i have this silvertone roundie with a weak red gun and the brightness is limited to the red gun to match the other colors. so what would be the best route to go to try to get more from this weak red gun, run the red gun on the crt tester for a few hours and see if it comes up but using the set didnt get results from that, or should i try to rejev the gun , or i have a single gun brightener for the red, which way would anyone think is best to go at this point. and with a weak gun and the other drives low to match up with the bad gun would this effect the contrast in a way that one way its soft and the other way things seem to take on black and get really dark, and the pic gets really lousy. i do remember the cutoff on the red gun was not good.

I don't think you can use a brightener for just one gun. The heaters are all connected in parallel.

Have you already tried increasing the heater voltage on the tube? What were the results? How much do you have to increase the voltage before your red gun shows good on the meter?

If increasing the heater voltage brings the red gun up pretty quickly, then you have a good chance at correcting your problem just by letting it sit there for a while with the increased voltage.

Do you have a "clean" or "balance" feature on your crt tester? I would try that first. The rejuv function should always be your last choice since you can possibly do more harm than good with it.

well i have 2 boosters and its wired for only one gun and the 2 i have is for the red and one for green as it only has the red wired thats boosted. on the crt tester 300 is good but the rde is only 260 which is low but raising the heater voltage to 7 volts brings it up nice.

If you have to clean or rejuv the tube, use a Beltron. Some of the others are "kill or cure" machines.
I have had very successful results from a Beltron on roundies.

yes i know some of them kill crts like the bk 440 that i have, it can be harsh im told on crts.

the single gun brightener i think takes out the red gun and leaves the others alone and increase the red to whatever it does because it is for a single gun marked for the red gun and the other i have is for the green gun. so its how its wired and i think it may be isolated incase of shorts as well.

My sencore CR-70 is pretty good too, and a lot safer than the older units.

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Timmy, as mentioned all of the filaments are in parallel so all a "CRT Booster" will do is increase (and isolate) the filament voltage and thus increase emission on all three guns. There's only one point of connection at the socket. What are you referring to?

OTOH is great to see the emissions jump up with the increase of filament voltage. Do you have a life test? I'd be curious how the other guns do just for observation initially, but you need to concentrate on that red one for sure.

im not sure how itworks but i do understand that the heater voltage is one wire or one point of connection but it looks just like any other booster but one red wire no green or blue so i dont know how it works but it s in the wiring some how.

Timmy, just for shits & grins, could you please post a photo of the device you are speaking of? I'm kinda curious about this.

Ya know, if ya crank that heater voltage to about 8 volts for an hour, and then let it cool, and then check that red gun again at 6 volts, you should have a good idea if it will hold up for a while.

But then, if the booster you speak of does indeed correct only one gun, then perhaps that's the way to go. Of course, the rest of us want to acquire one of those as well!! :)

Timmy, a booster or isolation type booster only act on the filament wires of a CRT by inserting a transformer in between the heater supply of the set and the heater of the CRT. All other wires of the socket are merely jumpered from the male to the female connector of the booster. A regular booster just steps up the voltage to the heater which increases cathode emissions due to the increased heat boiling off more electrons from the cathode. An isolation transformer is used to eliminate the DC path between the heater supply of the TV and the CRT heater to cure the symptoms caused by a heater to cathode short inside the tube. An isolation booster merely combines the functions the booster with that of the isolation transformer.
All roundy color tubes(and all color and monochrome CRTs that I know of) have only two filament pins.
Given this and the fact that there is only one filament circuit loop through the socket(meaning that the filaments for all three guns have to be wired together in series or parallel for all of them to light) there is no way for a booster, isolation type or not, to act on only one gun in a color tube.

What you describe is impossible unless it operates on vastly different principles from the vast majority of, if not all other boosters made.

You are either remembering wrong or you posses an extreme rarity that many folks here(myself included) would very much like to know the operational principles of.

I'd like to see a picture of this device as well.

Well, I DO remember. My recent hospital stint did NOT in ANY way damage my memory.

NOt sure if I have seen one myself, but I* THINK I have. I KNOW I have read about them. They seem to be a small, rectangular device, that connects to the CRT in some way to boost the emissions and NOT just raising the filamant voltage. i know They were advertised in radio--electronics. Jack Darr reviewed one, and talked about how good one did for a tube with a weak red gun. The device had a control on it that would adjust to how much "boost" was needed for the bad gun.

Seems that I remember reading they were made by someone like "Oneidea", or something like that.

I think you mean AC path. there are no DC filament voltages

By "DC path", he means the fault condition that occurs when there's a heater-cathode short. When this happens, it kills all luma (B&W signal) displayed by the CRT, while leaving the chroma display unaffected. Rapping on the neck of the CRT will usually reveal the condition, causing the luma to flash in intermittently.

An isolation booster will eliminate the "DC path" but introduces a new problem: the parasitic capacitance between the secondary and primary windings of the isolation xfmr. causes smearing-out of fine detail in the pic.

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Ditto. The CTC-9 that I have had a booster on the CRT. That thing measured absolute zero. You would think that the filaments were open. The Sencore CR-70 didn't do squat to it...

Well ok here they are i only have the 2 red and green but the red is what i need right now and i dont know if it boosts heater voltage or something else here and it does have the adjustment pot on it.

Looks like an adjustment on the bottom.... does it say what that adjustment is for?

It's a little difficult to read the lettering on the package... can you tell us what it says on the label? I'm wondering if that is a brand name at the top left above ColorRite.

Sounds like something that RCA2000 mentioned earlier..Now I'm curious as what you have there..

You can always hook it up and report back to us!

Ok the brand name is telematic and under that it says colorite and it says also single gun booster model 336 for red and 337 for green. And i hav voltagee to tell you it works really well adjust the pot on the unit and the red gun came right up and after getting the red back i had to readjust the other drives and now the picture is much brighter. I dont think there is a transformer in this unit because it is so light i would say a few ounces, that light. So i think it just boosts the emission some way without bringing up the heater voltage because like the way its wired in paralle so not just one heater can be boosted so this way this type of boost wont speed the death of the tube.

Better image of his boosters from eBay: http://tinyurl.com/color-boosters

hey timmy, whered you get those?

It appears he got them from ebay... it's the same set... look at the top corner tear on the red package.

So now, we have to determine what the dang thing does. Is it simply increasing the screen control even higher than the set does, or is it adjusting the kine bias for just that one gun?

Obviously, this device can't be too hi-tech... I am sure it can be easily made from spare parts in our kitchen junk drawer (yeah we all have one of those).

Timmy: Just to confirm, you are placing this device between your CRT and your tester, and as you increase the pot, it brings the emissions reading up for that one gun on your tester? Also, you are pleased with the visual results you see with the set operating?

One thing is for sure... the package says it's foolproof!! I like foolproof! :D

yes that is the 2 i got from ebay and yes i am pleased with the result its great as i could not even get any red line in service mode for setup but now i turn up the pot on this unit and raise the red drive and wala, there is the red. i still got issues with this tube because i get one reading on the crt tester on the red gun and the blue but when i up the heater voltage the emissions actually go down rather then up so this tube im sure is tired.

Not trying to change the subject... but that same seller has a really cool 70's LED watch for auction... and it works! Man I wish it was a man's watch... I'd be on that like stink on sh!t. Those are so cool!

so get it and start a collection of those,lol,lol:D

Seriously... I am thinking about getting it for later... a Christmas present for my daughter!!

maybe he has more of them as i asked if he had anymore of these type brighteners but he didnt,lol..

Since you're not using the green one, why don't you disect it and let us know what's inside and how it's wired?

THIS one is much more like I remember in the old days::

http://www.ebay.com/itm/Vintage-Onei...item4ac0bd5b21

That thing must do a little re-biasing of the G1, a little more positive and possibly even boost the heater voltage a little.... Simple resistor network off one of the more positive going pins, couple meg-ohm resistors, a slider pot, and there ya go.... Accomplishes the same as a brightener and resetting the screen bias, but sold to home owners for a profit, so no real need to learn them anything about those 50 little turnie things back there. Almost like the thigh-blaster from the 80's that also came with a fitness and diet guide..... Guess what actually got the weight loss done.....

I happen to have one of the Oneida units with the 3 sliders as shown in the auction link that RCA2000 posted. The patent number on it is 3967314. Here is the description from the patent document:

"A means is disclosed for selectively increasing the emission of the several color guns of a color picture tube by placing a variable resistance between the control grid and the screen grid corresponding to each said color gun. This provides a source for increasing the voltage on the control grid of that color gun. As the voltage on the control grid is increased, the emission of that color gun is increased, thereby making it possible to blend the colors of the several color guns."

"The unit disclosed herein is constructed of three slide resistance controls. The controls are 5 megohms each with a 100,000 ohm stop. Each control is connected between the control grid and the screen grid of the three guns."

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