Tube transplants & 8-liners

[daeven]

I just garbage-picked a beautiful old Zenith color TV.  It works perfectly, and has a 19" Zenith picture tube.  Could it be possible to take this tube and replace the one on a G07 monitor?  Or should I just order an 8-liners chassis?

When you use an 8-liners chassis, does it include the neckboard?

[Ken Layton]

All replacement chassis include the correct neckboard.

[MonitorGuru]

The tube itself should be compatable (90%+ are--post the part number on the sticker here and I will look it up for you)

If you don't want to hassle with switching yokes and re-converging, then test the yoke to see its' DC resistance to see if it may be "within range" of compatability with a G07 chassis.  You can check 8liners page for info, but basically look for a vertical winding resistance of about 55 to 60 ohms (yellow and green wires if Zenith used standard colors), however be prepared for some geometic problems as it's almost impossible to find an exact match, but perhaps close enough.

Yes, 8liners include the neckboard.  Basically everything except the yoke, tube and frame

[daeven]

The tube part # is 19VMLP22.  It was manufactured 3/3/83.

Where would I find the wires for the vertical winding resistance?  I assume they would be on the neck board.  Everything is covered in dust - I'll blow it clean tomorrow, but most of the wiring to the neck board is via a ribbon cable.

[MonitorGuru]

I believe the MLP is the same tube that the GO7's used, I'll doublecheck later.

The yoke has nothing to do with the neck board. It is the copper windings attached to the piece of round plastic that slides onto the neck of the tube.

Check 8liners.com monitor chassis page for pictures and details about how to check.  You will need to disconnect the yoke plug from the chassis to get an accurate reading, and do it while it's off.  Or also look for the replacement chassis thread (whoo mama or something like that) here.

Look for a set of 4 wires into a single plug on the chassis in the TV... should be Red, Yellow, Green and Blue. Set your digital ohm meter at 200 ohms setting, and test against the Yellow and Green connectors with it unplugged.

If it's the odd color cables, there may be a grey, a white, a putty and some other color... if so, you'll have to just test all 4.  one pair should measure between 1 and 4 ohms [this is the horizontal windings], and the other either between 8 and 16 ohms (not usable in a G07) or 50 and 60 ohms (usable in a g07).

[daeven]

Everything was covered in so much dust that I couldn't see any wiring except that going to the neck board.  I blew the dust out and found the vertical winding wires.  Too bad my (analog) multimeter only has one resistance range, and it is marked in k-ohms.  No chance of telling the difference between 8 and 50 ohms with this thing.  I'll stop by Fry's on my way home to pick up a better multimeter.

As I looked around inside the old TV, it amazes me how much this thing looks like an arcade monitor (I know, duh).  It looks like the brackets on the tube will match up with an arcade monitor mounting bracket.  After all the threads I've read about people decasing monitors and TV, I had assumed that there was no possibility that the mounts would even come close.

[MonitorGuru]

If you have a Harbor Freight, go there. They have a very nice DMM for $2.99 most all of the time. (Normally $9.99). It's got the same guts as the $14.99 ones at hardware stores or $24.99 ones at Radio Shack/Sears.

Yes, TV's usually have the same mounting ears as arcade monitors.. a large steel band with 4 ears.  It's because the tube is 100% identical, and those mounts come with the tube.

THe only other style of mount I've seen in an old 1980 Maganvox TV is one that doesn't work... it has the metal band around the front edge of the tube, but instead of 4 corner ears, it has some hook loops and metal clothes line type thing that used to bind it to the front of the case by pretty much friction alone rather than a large bolt.  Almost impossible to mount those tubes in anything.

[daeven]

I picked up a DMM from Harbor Freight with a resistance scale of 200 ohms.  That should do the trick.  Thanks for the tip $7 compared to the $17 I paid for the Rat Shack with only a single range.

MonitorGuru: you said in your first response that I may be able to swap the tube & yoke from this Zenith TV on to my G07 chassis (if the resistance matches).  I assume the technique used would be to follow the 8liners website.  They do have the same number of pins - will check the resistance when I get home.

Thanks for the help.

[MonitorGuru]

Wow.. The DMM seems like it's always on sale for $2.99 or $3.99 at most.. you just picked the wrong week I guess to need one .  Oh well, at least you didnt waste more money at RadioShack.


Yes, swapping tubes is the same on an arcade chassis or an 8liners chassis.  Steps, in order are:

1) Unplug (duh)
2) Discharge and remove anode wire. (Most dangerous..google for the safety issues/how to do it)
3) Remove ground wire from neckboard that leads to wire touching the back of the tube
4) Check for silicone caulk or glue adhering the neck board to the tube. If so, use a SHARP utility knife to carefully cut the seal.
5) Remove the neckboard by pulling straight off the back, using as little side to side pressure as possible.
6) Find the yoke wire and disconnect from the chassis.
7) Find the degaussing coil wire and disconnect it from the chassis if socketed. If soldered you can choose to simply pull the tube out around it leaving it in place.
Remove the 4 bolts holding the tube to the TV case or to the arcade frame
9) Remove the tube from the case or frame.

Now simply swap the tube with attached yoke to the other .  Do not bring the TV's deguassing coil over. Use the original one that came with the arcade chassis. (They *should* be the same, but there is no need to swap just in case there is a difference and the original one still works)

Just reverse the order to reassemble.  Ensure you get the yoke plugged in correctly or you can fry the yoke or the circuitry.  (It should be keyed so one connection is farther than the other 3).

LMK if you need assistance.  

[daeven]

Thanks for all the help MonitorGuru.  Too bad (for now), this Zenith is incompatible with my G07 chassis.  The Zenith has 10 ohms vs. 56 ohms on the G07.  I'll soon order the 8liners for the Zenith tube, but I'll finish the repairs on the G07 chassis with the flyback and cap kit on the way from Bob Roberts.  I'll keep looking for more old TV's!

[MonitorGuru]

Well you could always swap yokes.  But you'll have to remove the convergence rings to swap them and then reconverge.

A 10 ohm yoke would work very well in a Wells Gardner K4600 chassis. (They're normally 8-10 ohms and most TVs in the low range are between 13 and 15 ohms, causing pincusion problems)

[MonitorGuru]

Actually come to think of it, the 10 ohm yoke MIGHT be too small for the 8liners chassis.  I tried to use a 8-9 ohm yoke from a WG K4600's RCA tube in the 8liners chassis and got severe pincushion.

Check this site with picture of my 5 tube swap-a-thon between a K4600 and a 8liners chassis, with yoke ohm ratings listed and tons of pics of the results:

http://www.oscarcontrols.com/chassis

I'd save the zenith yoke for a WG K4600 chassis and crack another TV and look for a closer to 13-15 ohm yoke for the 8liners, or a high resistance (50-60) for the alternate 8liners or G07.

[daeven]

Any chance the chassis from a 13" WG K4600 would work with this 19" Zenith tube?  I haven't worked with any monitor chassis other that the 19" size so I don't know if they are identical.

[MonitorGuru]

I don't know.  I know some universal chassis are sold in the 13-20 range (one size fits all) but I know others have specific differences based upon size. (13-15, 18-21)

Ken?

[Ken Layton]

The yoke on 13" monitors generally has a higher impedance than their 19" cousins. They also have a couple of different caps in the picture size generating circuitry. The 13" tube and 19" tube probably have different pinouts. Suggest looking in both the 13k4700 manual (for 13") and the 19k4600 manuals(for 19").

[daeven]

I got my hands on a K4600 chassis, but I've got a question:

The tube has 8 pins + 1 pin in the key
The chassis seems to need 9 pins + 1 pin in the key.

The neckboard does fit, just that there is no pin on one of the holes.  Is this the way the K4600 works?

[Ken Layton]

The k4600 uses a 10 pin tube. What ube number are you trying to use and I'll look it up in my B&K rejuvenator manual to see if it will work.

[daeven]

19VLMP22

Thanks Ken!

[Ken Layton]

Hmmm.... that number isn't listed in the guide. And I have the latest edition. Sounds like it may not be compatible.

[daeven]

Oops, typo.  That should read 19VMLP22.  Does that match?

[Ken Layton]

Ah... now that matches! Yes this should work.

[daeven]

Where does the degauss circuit plug in on the K4600 chassis?  I can't find it on the schematic, and I can't find a blown-up schematic that I can read.  Is there any polarity to the degauss connections?

[Ken Layton]

The 4600 degauss connector is over at the left side (when viewed from the rear). It is a 3 pin header connector and you connect to the outside pins (pins 1 & 3). There is a "B" silkscreened next to the connector.

Degaussers operate on AC power so they do not have a polarity.