Saturday, 28 April 2012

Old yoke, fresh tube

I've been wanting to try this for weeks now: transfer an old Philips yoke onto a new "black matrix" Philips tube. I love the look of the black matrix tubes but whenever I try to hook up older Grundig boards the image is too wide and the geometry is distorted. I figured that a full yoke swap might fix those issues...

I finally gave it a try today and it worked perfectly!

I used the Philips 28GR5775/30B (chassis G110) that I found recently as a guinea pig. The tube (A66EAK51X03) on that is an older type that looks quite grey. Contrast is nothing compared to the tubes used in brands like Loewe. So, I used a knife to slice through the silicon that holds the yoke steady and I unscrewed the clamp on the neck. The yoke slid straight off and I put it onto a newer tube (A66EAK71X01) that I kept from a non-working Blaupunkt. Fired it up... wow! So much more contrast and the colours were vivid. While the yoke was loose, I rotated it to line the picture up perfectly with the top of the shadow mask. Very cool.

Next, I tried the same trick on a black matrix Philips tube (A66EAK071X01) from a Loewe CT1170 television. After playing with the Screen and Focus pots I got the image looking superb. With this 1989 chassis and Philips tube circa 2000 I've got another great looking MAME TV! The Philips actually has a trimpot for vertical size and horizontal hold. I can resize for Street Fighter 2 (224 lines) and Mortal Kombat (256 lines) without any problems. Nice! Haven't nutted out the service menu yet. Either need better batteries for the original remote or the terminals need cleaning. There's some slight pincushion that prevents the image from being classed as perfect.

Can't wait to upgrade my customised Blaupunkt to a black matrix tube!

Philips G110 chassis in test position (i.e. the floor)
GroovyMAME running Willow

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