Amplifone Tube Swap ...

[m_mcgovern]

Been wondering about that too, I think a set with the same number of rings and same diameter should work.

My uncle told me that the permanent magnets (which these rings are) could loose their magnetism (or it gets less strong) over time.

However, when adjusting purity, this is still not the issue....

I spoke to a local guy when sourcing some convergence rings for my 25" monitor. He basically said that they are made for the tube neck diameter. So I guess this goes under the "if it fits it is okay". He sounded like an older, craggly, wizened veteran of CRTs, so I will defer to his judgment on this one...

 

[Level42]

Mmm, dug up an old thread on BYOAC:

http://forum.arcadecontrols.com/index.php?topic=91217.0

 

[kentmurphy]

thanks guys .... so I guess the next steps are


1. degauss the entire tube, front and back
2. degauss the metal tabs
3. perform the purity adjustment procedure

right?

Kent

 

[jetusenet]

Hi;
I have a Rauland with the same issue, it was shipped from OH so I am wondering the outcome of this thread as I would like to know if I should even attempt to take corrective action or just use it as a "test" tube...
Jeff

 

[ixtlann]

Agreed 100% with everything Komodo writes.

Here's the simple frame I built for a 25" tube:

Crude and simple but effective and amazingly firm.

Crude you say? nah, looks more finished and complete then most the Mame machine projects i see for sale for one billion dollars

 

[Level42]

LOL !!

Well, my wood-working skills are not the best, and this just needed to be functional.
Actually, once the tube is installed it's amazingly sturdy. Not a second doubt that it wasn't stable.

I still have it.....for future use...

 

[kentmurphy]

Years ago I dropped this project and put the original tube back in the game. Now after more than 4 years I'm thinking about resurrecting this project

My problem may have been that I didn't rotate either the yoke or the convergence magnets to create a horizontal green band in the center of the tube. I came to this conclusion after reviewing the purity adjustment procedures once again and one of the videos I shot when I attempted the swap. Read step 14, the note immediately below it, and then view the video below.

https://www.youtube.com/watch?v=TcDv-nquGiE

It's pretty obvious the green band is diagonal and I believe the band should be centered and straight up and down.

Anybody want comment?

 

[dezbaz]

Looks like the tube in the video needs a degauss

The purpose of the sliding the yoke forward and back is to find the midpoint of the yoke.
The clamp gets tightened on this midpoint

Once tightened the "yoke tilt / add wedge" procedure starts to get the horizontal convergence done

 

[Smitty420]

Convergence and purity in a nutshell

Get to a red, green, or blue cross hatch pattern.
Move yoke in and out till you get a solid color and lock it down.
Then adjust the rings on the purple cross hatch to get alignment in center.
Then adjust yellow crosshatch to get alignment in center.
Then check the light blue gopr allingment.
Then redouble and yellow till they all line up and then check white.
Then using the white go for the corners and you can move the yoke around a bit for allingment, and you could place a couple of wedges.
Lastly use the strips to manipulate the lines n the edges. If the yoke is set right the fewer strips are necessary.

Give this a try and see what happens.
You will find a meathod that works for you.

 

[kentmurphy]

Looks like the tube in the video needs a degauss

The purpose of the sliding the yoke forward and back is to find the midpoint of the yoke.
The clamp gets tightened on this midpoint

Once tightened the "yoke tilt / add wedge" procedure starts to get the horizontal convergence done

Thanks Debaz!

I did degauss the tube ... As a matter of fact I degaussed it several times ...

 

[kentmurphy]

Thanks Smitty!

This is where I got stuck ...

Move yoke in and out till you get a solid color and lock it down.

I could never get a solid color across the entire tube. I'm guessing I need to rotate either the yoke or the convergence rings to follow the procedure exactly as outlined in the amplifone manual. Do you think rotation of the convergence rings will help?

Convergence and purity in a nutshell

Get to a red, green, or blue cross hatch pattern.
Move yoke in and out till you get a solid color and lock it down.
Then adjust the rings on the purple cross hatch to get alignment in center.
Then adjust yellow crosshatch to get alignment in center.
Then check the light blue gopr allingment.
Then redouble and yellow till they all line up and then check white.
Then using the white go for the corners and you can move the yoke around a bit for allingment, and you could place a couple of wedges.
Lastly use the strips to manipulate the lines n the edges. If the yoke is set right the fewer strips are necessary.

Give this a try and see what happens.
You will find a meathod that works for you.