Tube swap questions

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    • Tube swap questions

      Hey, I’m about to acquire a Toshiba PF D29C051 (tri-sync) monitor from a Sega New Net City cabinet that has some burn-in. I’m thinking about doing a tube swap.

      The tube inside is a Toshiba A68LTF356X.

      I’ve looked on craigslist and found someone offering a Toshiba 27AF62 (a “pure flat” model so I’m assuming the shape is identical). I googled the service manual and determined the tube inside should be a Toshiba A68LUW696X01.

      Now, before you say it, I _know_ the yoke of a 15khz consumer display will not work in a 31khz chassis for my tri-sync. But my question is whether the tube itself would be compatible if I swapped the yoke out.

      If the pin-out on the neck board is the same am I ok in assuming it should work? Do I need to get out a multimeter and check the voltage levels on the pins for the heater or something?

      Are there any fundamental differences in the _tube_ of a 31khz screen vs a 15khz one or all of the differences found in the chassis and deflection yoke?
    • ninjaz0mbie wrote:

      Now, before you say it, I _know_ the yoke of a 15khz consumer display will not work in a 31khz chassis for my tri-sync

      Actually, if it's a 100hz set, the original yoke could compatible. Get a LCR meter and measure the yoke.

      Yoke and tube specs for monitors

      If the pin-out on the neck board is the same am I ok in assuming it should work?

      That's right.

      Are there any fundamental differences in the _tube_ of a 31khz screen vs a 15khz one or all of the differences found in the chassis and deflection yoke?

      Mostly it's just the yoke and chassis. However, some tubes are paired to their yokes, so a yoke swap won't work. Tubes manufactured by Philips can be like this.

      The post was edited 1 time, last by nem ().

    • nem wrote:

      Actually, if it's a 100hz set, the original yoke could compatible. Get a LCR meter and measure the yoke.
      I don't think 100hz sets are very common here in the states, but worth checking out I suppose.

      What's the tolerance range on these things? Do I aim for something within 10% of the Lh and Rh values of the current yoke, or will anything with a lower resistance work?

      Would testing it out risk blowing up the chassis, or would it merely not work.

      I want to be extremely careful with the chassis because I understand how difficult they can be to fix and replace.
    • Just making conclusions based on yoke specs I think for Lh you want to be in around 10% for a stable pic. Lv can be off more.

      I haven't played around with out of spec yokes that much, however, my thinking it's actually worse the other way around, so a lower resistance yoke connected to a chassis that's expecting higher resistance. I connected a Sanwa PM1745 yoke (0.405mh) to a 27e31s chassis (0.300mh) by accident (the yokes and tubes look identical), and the picture just looked like garbage. No damage was done by it.