MS9-29T & MS9-29SU - Static Sound but no Neck Glow or Image

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    • MS9-29T & MS9-29SU - Static Sound but no Neck Glow or Image

      EDIT: MS9-29T fixed as of 4/16/20. Project log in spoiler:

      Display Spoiler

      Symptom:
      • Dead - electrical static can be heard filling the tube upon power up, then monitor quickly can be heard discharging. No image is ever displayed on screen. No neck glow.
      Actions Taken:
      • Replaced LA7837 - still dead
      • Replaced LA7853 - still dead but at this step, I errantly removed solder around HOT and did not reapply
      • Reapplied solder around HOT and recapped vertical circuit and she fired up again!
      Jublilance was short lived as monitor would go into OCP (over current protection?) and shutdown randomly, then turn back on. Neck glow remained as monitor was in OCP shutdown.
      • Finished recapping entire chassis - monitor still randomly goes into OCP and shuts down
      • Swapped neckboard with MS9-29SU - monitor still randomly goes into OCP and shuts down
      • Swapped neckboard back - monitor still randomly goes into OCP and shuts down
      • Upon advice from gunblade, reflowed solder in high voltage area
      • Removed filter cap (C911) from MS9-29SU and placed it back in MS9-29T - monitor stayed on throughout 2-hour soak test.
      • Attempting to calibrate monitor pots on chass produced a screen jump or flash depending on what pot was touched
      • Noise on screen is observed
      • Reflowed solder on all chassis pots (including B+ pots), reflowed RGB header, reflowed visible oxidized joints
      • Grounded chassis frame properly
      • Fired monitor back on, noise is gone, image no longer jumps or flashes upon touching pots, monitor stays on throughout 1-hour soak test
      Bow tie is placed on monitor frame, not tube to protect it from scratching :D

      Upon power-up, I hear static filling the tube. But there is no neck glow. No image on screen. Reflowed solder around the high voltage area. Still nothing. I do plan on fully re-capping this chassis. But wondering if there is a quick fix for this.

      Also at CN102. Anyone know what connector and series this is? Or an alternate series with the same pitch can be used?

      The post was edited 2 times, last by acblunden2 ().

    • Interesting. The MS9-29T is chassis version 05A00675C1.

      I have another MS9 (I believe). The model number sticker is missing but the number silkscreened on the chassis is 05A00585D1. I just recapped this chassis, but it has the exact same start up and shut down issues. Should I replace the LAxxxx chip on this one was well?

      The post was edited 1 time, last by acblunden2 ().

    • Ok, so 05A00585D1 is the chassis that I recapped previously. I replaced LA7837 and there was no change whatsoever. Still same static buz on power on, then that goes away. No image on screen no matter how much I turn up the screen pot. What is the next step here? Shall I pull and replace the LA7853 or the HOT?


      I'll check the MS9-29T (05A00675C1) now to see if replacing LA7837 fixes the issue. EDIT/UPDATE: Now I get nothing on this chassis.

      The post was edited 1 time, last by acblunden2 ().

    • Could be my tube is dead too? It was given to me and said to be a bit dim and had some burn. Sat outside for a few months. So I'll try a swap tonight.

      The 05A00585D1 was semi-working. I had hooked it up to my buddy's NAC. It displayed an unstable image and I found out later one of the neck board cables had broke off the chassis. Hence the question about CN102 in OP. I soldered the wire right to the chassis.
    • I replaced LA7853 on both chassis. Both remain non-working:
      • 05A00585D1
        • At the same place where I started: static filling tube, then shut down. No image. No neck glow.
          • Previously, this chassis had an unstable image. I decided to re-cap it. As I was doing it, notice that the neckboard harness had come loose from the mainboard at CN102, perhaps explains the unstable image.
          • I'll recap this one again
      • 05A00675C1 (MS9-29T)
        • Previously was behaving just like the one above, now is completely dead.
          • Completely died when LA7837 was replaced
          • After replacing LA7853, no change from completely dead status
          • Never recapped this one

      I think I will put aside the MS9-29T for now and focus on the 05A00585D1. I only need one working for now. Will check the resistors you mentioned now before ordering parts to recap
    • Alright, some progress with the 05A00585D1 (which I have come to know now is the MS9-29SU).



      Did a full recap. The monitor no longer goes into high voltage shutdown. I get an image, but now have:
      1. Vertical size collapse
        • I did adjust VS Limit, didn't help situation much
      2. Vertical rolling image
      I will try different PCB's to see if I get the same issues. Will check VGnd on the chassis connector, frame connector, and JAMMA edge connector. Weird that would have vertical collapse after replacing LA7853 & LA7837 and recapping.

      Any other ideas?

      Here are the actions thus far:
      Display Spoiler

      1. Replaced LA7837
        • No change, still goes into HV shutdown
      2. Replaced LA7853
        • No change, still goes into HV shutdown
      3. Recapped monitor
        • This where we re currently as of this post[/spoiler]

      The post was edited 1 time, last by acblunden2 ().

    • All the resistors checked out:
      • R457 = 220.21Ω

      • R425 = 100.88Ω

      • R571 = 99.80Ω

      Reflowed solder around them and checked my installation of the LA7853 and LA7837. No bridges in sight.


      Do you think the newly installed LA7853 took a dive because it was installed before the new caps were put in? If so, should I replace LA7853 again or is there something else to check. I see no discoloration/darkening anywhere near the vertical circuits.
    • Yeah, that is good sound advice.

      Thing is that I recapped this chassis with a kit I got from a parts vendor. Before that recap, I had an image, but it was unstable. Decided to recap it. After recapping, found out later that CN102 was broken off the mainboard. After soldering CN102 right to the mainboard, I ended up where I started in OP.

      Built my own cap kit at Digikey, recapped it again, and that is where I am at now. Ok, off to replace LA7853 again. Will report back. I feel I am close. And I am swearing off of buying cap kits from parts vendors from now on.