Concerning tube swapping

[ncflagg]

I've been eyeing televisions for tubes to put my WG4600 and WG4900 chassis. I keep seeing perfect tubes (size-wise) that are manufactured in 1989-90 but the Wells Gardeners were made 82-83. Is there any chance these newer tubes will work?

[SirPeale]

Consult a cross reference chart.

[ncflagg]

I don't think a cross-reference chart will help me while I'm standing in Goodwill deciding if I want to buy a TV or not. I'm just curious if there is any chance it will work so I don't buy a bunch of tubes that I'll have to take to the dump later.

Are you talking about a chart that shows which tube types are interchangable? Where might I find such a chart?

[grantspain]

you can get good results and bad results by swapping tubes,normally you would have to swap the yoke at the very least
you need to look at the neck for the shape and the amount of pins
the same size tube or close is very important
and sometimes all this is correct but you can never get the convergence just right

[qrz]

a63 xxx series crts are 25" and work just fine as a cheap replacement . plenty to be found on trash day !
direction of mounting tabs is the minor problem  (use  1" spacers when needed )

as long as size and pin out are correct , most tubes can be swapped .  bonded yokes are another matter....

may use donor yoke and conv rings if monitor is 15khz/60hz scan freq.
 otherwise, mark the position of the purity ring on the donor. so it may be reinstalled in the exact position after installing the orig monitor yoke.  this reduces the need for adjustments.  ok , i'm lazy.  just never liked an extended
"dink" session w/purity-convergence rings .  have changed many a crt over the years .

qrz

[Pac-Fan]

Most TV tubes from TV's made from 1980 to 1988 that you find will be compatable with both chassis (10 pin type 23 pinout), however a vast majority will not have the correct yoke impedence for either one.  1989-90 tubes are going to be a mix of 10 pin/CR23 pinout or the newer 8 pin/CR31 pinout that won't work with either of your chassis.

K4600's have a very low impedence of 8 ohms. K4900's have a high impedence of about 50 ohms. Neither are compatable with the other, and most TV sets have yokes with a 15 ohm impedence. A 15 ohm on a K4600 results in a square and highly pincushioned image, while it will fry a K4900's deflection circuit.

So unless you're willing to attempt to swap yokes and reconverge, which is hard as most 25 year old arcade yokes cannot get fully converged correctly on most TV tubes unless you find the exact matching tube # or direct sub, you're best off buying a new monitor -- you won't be happy with the results or time spent on your (near) 'free' tubeswap.

[qrz]

Most TV tubes from TV's made from 1980 to 1988 that you find will be compatable with both chassis (10 pin type 23 pinout), however a vast majority will not have the correct yoke impedence for either one.  1989-90 tubes are going to be a mix of 10 pin/CR23 pinout or the newer 8 pin/CR31 pinout that won't work with either of your chassis.

K4600's have a very low impedence of 8 ohms. K4900's have a high impedence of about 50 ohms. Neither are compatable with the other, and most TV sets have yokes with a 15 ohm impedence. A 15 ohm on a K4600 results in a square and highly pincushioned image, while it will fry a K4900's deflection circuit.

So unless you're willing to attempt to swap yokes and reconverge, which is hard as most 25 year old arcade yokes cannot get fully converged correctly on most TV tubes unless you find the exact matching tube # or direct sub, you're best off buying a new monitor -- you won't be happy with the results or time spent on your (near) 'free' tubeswap.

spent the last  25+ yrs repairing consumer electronics, and have replaced 20+ crts this way for a local arcade route operator . mostly 25's  but, a few 12 and 19's here and there.    its really not terribly difficult to do...
  perhaps i 'll remember to document and post pics from the next one i change.    it might be "entertaining "    ?


qrz

[ncflagg]

I went to a local thrift store and bought 3 TV's one day for the purpose of swapping two burned-in monitors. Being my first two attempts were completely successful, I would have to say it is not as hard as it might look. On the Nintendo 20" swap I didn't even have to swap yokes! It was actually an old 83 Sanyo TV. 

But here's another question. If one yoke doesn't match (say a high impedance yoke on a low impedance chassis or vice versa) would it be possible to add/remove some resistors to make them compatible. I picked up some old wg 4900/4600 chassis but with no yokes and am trying to think how I'm going to bring them back to life....

[Pac-Fan]

It's NOT hard at all if you don't have to swap yokes. Its when you have to swap yokes that it gets harder. I've swapped numerous tubes (100+) to test on chassis. I've tried to swap yokes about 10 times. Only 2 of the 10 were anywhere near successful and got back in anywhere close to being converged. Problem was, due to availability and low burnin, I was using mid to later 80's tubes not the original late 70's to early 80's RCA tubes, and for some reason the yokes just aren't as compatible. You can even see slight differences in the bell of the tubes when you look on the ones that have issues.

More power to you if you can converge one perfectly to not have purple and green pixels hanging off the pacman dots on one side or the other!

As far as adding resistors -- no. Impedence is not simply resistance, it's a makeup of the entire winding wire size, length, composition, position and number of windings, as well as placing of windings.  Your Sanyo swap worked perfectly since it probably was the exact same tube and yoke that was used at the time.

Some chassis like Hantarex really work well with mid-80's tubes+yokes (drop in and you're done), others like the 4600 require their own yoke and specific tubes to align properly, same goes for the G07.   4900 seems to have a bit more leaway.

Good luck