Alright School Me Please - Nanao MS2930/31/33 Tube Swap

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    • Alright School Me Please - Nanao MS2930/31/33 Tube Swap

      I think the worst case scenario just happened. Now I am in search of a TV that I can harvest a tube from, if at all possible. My buddy works at a recycle center/landfill. He says they have a ton of CRT's going through his facility, so I might have a leg up on finding a suitable donor and will report back here what I find.

      This is a Blast City. The tube on it is A68KZN696X
      • Donor candidate #1 is 29" Panasonic TV w/tube number: M68LGL061X
      Ignoring physical fitment for now, why will this tube work or not work as a donor candidate?
    • I'm sorry to hear that. Honestly, I think it's inevitable if you're messing with this chassis on a more regular basis. I wonder how the repair shops are handling it?

      Anyway,

      tubular.atomized.org/#s/M68LGL061X

      Correct neck and heater voltage, so you're good to go to testing it.

      It will need to be yoke swapped (I don't know of any consumer TVs that come with 0.20mH yokes). Save the original convergence ring set from the Panasonic. It could work better than the ring set from the Tosh.
    • nem wrote:

      I'm sorry to hear that. Honestly, I think it's inevitable if you're messing with this chassis on a more regular basis. I wonder how the repair shops are handling it?
      Yeah, it blows. The red decided to die suddenly on the monitor. So reflowed solder around the neck and neck wires down to the chassis. Red still did not come back. Ordered some new color transistors, but my buddy wanted to get it back going before the parts came. An MS9 chassis that was also awaiting parts for repair had the same color transistors so harvested it from there. Still red did not come back. At that point, we were using a CPS2 as a video source. Decided to shut down and hook up a MAME PC running CRTEmu@15khz (known to work well with the MS2930) and poof!!! Arching near the yoke, a scary zapping sound, and a puff of smoke coming from the chassis.

      nem wrote:

      Anyway,

      tubular.atomized.org/#s/M68LGL061X

      Correct neck and heater voltage, so you're good to go to testing it.

      It will need to be yoke swapped (I don't know of any consumer TVs that come with 0.20mH yokes). Save the original convergence ring set from the Panasonic. It could work better than the ring set from the Tosh.
      Thanks! I've seen that site before in my travels. Never needed it till now.

      So how does one test the heater voltage on the TV? What is "G1" and how does one test that? I know I have to test with the TV's original chassis, but what pins are they?
    • Why do you have to test it with the original chassis? Swap the yoke from the Toshiba, you can try either ring set, connect a compatible chassis (MS-293X) and turn it on. I'm positive you'll get a picture. No idea if it will be any good.

      For measuring heater voltage, I've been led to believe there's no easy way to do it accurately. See here:

      elektrotanya.com/files/forum/2…kepcsofutes-mero_[ET].pdf

      I don't know if it will give any meaningful readings if you try to do with a regular multimeter. I haven't tried.

      As for G1:


      The control grid (G1) control the brightness of the CRT. It is generally placed directly on top of the cathode. If there is no voltage on G1, the electrons can flow freely from the cathode. If there is some negative voltage
      on G1, the electrons from the cathode are repelled somewhat, and the screen appears darker. The greater the voltage on G1, the darker the screen becomes, because more electrons reaching the screen equals a brighter image, and less electrons hitting the screen equals less brightness.


      From here: lateblt.tripod.com/bit71.txt

      The whole thing is a good read.