Tube replacements - question on ohms

Bullwinkle

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I've been searching the forum and have come across some great information. I need a new, "unburned" tube for my Missile Command. Any tube is ok for the first 8 waves, but once you hit the bright blue background...the burn, any burn, is extremely annoying. And forget playing Super Missile Attack as the 2nd screen requires a clean tube.

So I tried a new monitor ... lets not get into that though... I've moved on...

I'm now reading up and my best choice is to swap a tube into one of the old monitors I have (I have a few G07s, WG4600 and a few others..all with nasty screenburn). So, reading up on things (and a special thanks to Orion3311 for his site and tube swap writeup... just missing the yoke swap..which I think I'll most likely need to know) ...I notice he mentions on one of his donor tubes, that a Panasonic CT-9010 tube is an exact match to a G07 except the ohms are about double the value of a G07. The suggestion is to use a 50 ohm resistor in parallel across the vertical wires to bring it into acceptable levels.

I'm just curious, if this does indeed work, couldn't we adjust almost any low impedance tube to fit a low impedance chassis (and high for high) provided we can come up with an appropriate resistance? This assuming that the resistance level of the donor tube is higher than the original and can be adjusted down.

for reference, when I say tube, I'm probably referring to the yoke..not the tube itself :) I'm still learning...

Also, if the ohms are the same, what happens when you match up a 20" tube with a 19" chassis? just curious. My guess is that you'll have a black border around the screen.

Thanks

-tom
 
The reasoning seems right for the resistor idea, but in fact ohming out a yoke is only a vague indicator of compatibility.

The short answer to the resistor question is 'no'

For a longer answer, you can query some of the monitor gurus - it's been discussed before on a few other threads.

My vote for a tube swap - find a better donor for the G07.
 
Thanks for the props! The resistor trick may or may not work and honestly I wouldn't use it as gospel, in fact I should remove that note. I think it depends on the chassis. I know Wei-Ya recommends using a resistor to adjust some yokes to their specs though, but I'm curious to know if anyone has actually done that to know if it works or not.

In regards to the 20in tube on a 19in chassis...it may work and even be compatible, however in all the cases I've tried it, it physically didn't fit. The mounting tabs of the tube wont line up to the frame, and the tube may sit farther forward or back causing it to hit the chassis or not line up to a bezel. In addition, unless you're using the yoke from the actual 20in tube, you'll prob never get it to converge properly either.
 
Or just use the G07 yoke and converge it.
Peale, that's what I'm leaning toward. The question then becomes, is a tube a tube as long as the neckboard fits on the 10pin (or 8pin) connector and the yoke fits properly on the neck?

Thanks for the props! The resistor trick may or may not work and honestly I wouldn't use it as gospel, in fact I should remove that note. I think it depends on the chassis. I know Wei-Ya recommends using a resistor to adjust some yokes to their specs though, but I'm curious to know if anyone has actually done that to know if it works or not.

In regards to the 20in tube on a 19in chassis...it may work and even be compatible, however in all the cases I've tried it, it physically didn't fit. The mounting tabs of the tube wont line up to the frame, and the tube may sit farther forward or back causing it to hit the chassis or not line up to a bezel. In addition, unless you're using the yoke from the actual 20in tube, you'll prob never get it to converge properly either.
orion3311, well. i have a Wei-Ya that I might be able to try it with (screwed it up ..see other thread :( ) ..it's supposedly a 20" (2620HR), but it measures at 19"... I'll look at the zenith tube that came with it tonight for the tube number (hopefully it says 48...could I possibly be that lucky..probably not). It's going into a missile command, so I can probably get it to "fit" properly in the cab as it's in a type 2 frame. but the measurements I took last night mirror my 19" and it may just fit right in the frame I have. I'll find out tonight and post results.

thanks guys.

tom
 
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Peale, that's what I'm leaning toward. The question then becomes, is a tube a tube as long as the neckboard fits on the 10pin (or 8pin) connector and the yoke fits properly on the neck?

Yes, in most cases, a tube is a tube. As long as the neck socket is a match, and the tube is a 90 degree tube (90% or more are), then you should be good. Check this chart, and find your 2 tubes on it. Make sure the heater voltage and neck pinout match. If they do, then you should be golden. http://www.bkprecision.com/support/downloads/pdfs/CRT_Setup_Chart.pdf Be sure to keep the purity ring assembly with the tube, not the yoke & chassis. Mark the ring assembly with a sharpie to ensure you remove and replace it correctly, other wise you'll be learning how to converge a tube ;)
 
Yes, in most cases, a tube is a tube. As long as the neck socket is a match, and the tube is a 90 degree tube (90% or more are), then you should be good. Check this chart, and find your 2 tubes on it. Make sure the heater voltage and neck pinout match. If they do, then you should be golden. http://www.bkprecision.com/support/downloads/pdfs/CRT_Setup_Chart.pdf Be sure to keep the purity ring assembly with the tube, not the yoke & chassis. Mark the ring assembly with a sharpie to ensure you remove and replace it correctly, other wise you'll be learning how to converge a tube ;)

Great!..thanks for the info! Here's hoping for a successful evening messing with tubes!
 
Yeah the yoke swap part...I have to put some thought into how to explain that as simply as the rest of the article without getting technical. Its a lot less cut-n-dry than the actual tube swap. (plus I'm not an expert on yoke swapping...I've done a couple successfully but I think luck plays a huge part in it lol)
 
YES! .. Tube on my so called 20" monitor ... LG Phillips A48QAD220X. it's a low impedance monitor, so I won't be able to swap it right in, I'll have to swap out yokes to use it with a G07 chassis, but at least all is not lost with the new tube :)
 
Thanks for the props! The resistor trick may or may not work and honestly I wouldn't use it as gospel, in fact I should remove that note.

Inductance is what matters... resistance is just used as a cheap proxy for inductors for people who don't have the correct tools to measure it, since wire if a certain guage should have approximately the same resistance per foot, and if the yoke is wound the same way with the same wire it should require the same length of wire to get the correct inductance to convert the current into a magnetic field to deflect the electrons.

There's no way adding a resistor is going to 'help', since it's not going to add to the inductance... you're just going to get FAR less magnetic field and beam deflection than you should.
 
Inductance is what matters... resistance is just used as a cheap proxy for inductors for people who don't have the correct tools to measure it, since wire if a certain guage should have approximately the same resistance per foot, and if the yoke is wound the same way with the same wire it should require the same length of wire to get the correct inductance to convert the current into a magnetic field to deflect the electrons.

Just wanted to confirm Mark's explanation (not that he needs it) and to reiterate the advice that ohms alone cannot tell compatability. Mark's comment that they must be "wound the same way" is correct. I can tell you from experience that standard and medium resolution yokes are not wound the same way. Even though they both have the same ohm reading, you cannot get a decent picture trying to pair one chassis with the other yoke...
 
I figured as much, and actually removed the note earlier today right after I posted. I'll double check and make sure there's no other notes like that on the list or the tube swap writeup.

(As a side note while I waited for some patches to load at work I cleaned up the writeup a bit, and fixed some wording/grammar/typos. It still isnt' perfect but better now.)

Hey whats the make/model of your donor monitor? I'll add it to the list!
 
The monitor I "was" going to use was a Wei-ya Huai M2620HR. Turns out that the chassis was fine but shut down due to turning the tuning pots to a position the chassis couldn't handle (coupled with the wrong sync signal).

at least I know the tube is decent and if needed, I can probably use it as a donor if the chassis dies.

that being said, looks like i'll still be doing tube swaps on some of my other screenburnt monitors starting with a dump run for donors this weekend. I'll have your list with me as well as a dmm :)
 
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Write down makes/models even if they're 20in donors, just so I can put them on the new "do not use" portion of the list. Actually I think the Nintendo Sanyos use 20in tubes so having a list of them wouldn't be all that bad either.

If you have G07 and K7000s you may find that the tube w/yoke drops right onto one of those chassis. At the bottom of my list are some factory yoke readings that you can use to match up the yoke to a chassis.
 
you could just get a wie-ya from aa and use a doner 19intv.i have just replaced 2 of my burnt tubes with 100% sucsess for $71(each) shiped to my door(tv,s were free).i know a go7/wg with a clean tube is best but for the price of the working zero burn tube its to easy.i almost forgot to thank ken layton for all of his help.

I might do that if I run out of chassis. At current, I have plenty of working G07 and WG chassis to mess with..so the dump run for tubes on Saturday should provide some matches... Out of curiosity, which Wei-Ya chassis did you order from aa?
 
Well..first endeavor into tube swapping. A neighbor had one outside, so I figured I'd give it a go even if I couldn't use it as it was right there.

Orion3311, here are the specs

TV Brand: Sharp
TV Model: 19CM100R
Size: 19"
Tube Number: A48AAB26X
Horiz - 3.11ohm
Vert - 15.92ohm

pins: 9 (dammit..should have checked this first before testing anything. From what I can tell, I want to start with either 10's or 8's for arcade monitor swaps)

9 pin connector.jpg

If I'm incorrect, please let me know, but I can't find anything compatible here in my chassis collection.

Thanks,

-tom
 
That tube should work. It is a CR23 neck pinout (fat neck, 10 pin compatible) and a heater voltage of 6.3 according the B&K setup guide:

http://www.bkprecision.com/support/downloads/pdfs/CRT_Setup_Chart.pdf

It should work perfectly with that chassis. You will need to swap the yoke over from your burned tube, though. The TV's yoke isn't bonded, right?
 
I guess I'm confused. I can see the reference on the chart, but it's only got 9 pins (missing the last pin if counting clockwise not including the one inside the triangle) G07s have 10 pins, is this a pin that isn't used?
 
I believe that's correct. Take a look at the foil side of your neck board pcb to confirm - there shouldn't be anything connected to the spot where that 10th pin goes.
 
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