Dead Tovis/Happ Vision Pro MTG-1901CN similar to K7302

Jed1963

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I have a Tovis/Happ Vision Pro model MTG-1901CN chassis.
The previous owner installed a new cap kit recently with Nichicon caps and said the monitor ran a while and just died. No blown fuse. I cannot get high voltage/raster. I have no heater voltage or glow. I DO have all 3 SMPS voltages as shown. B+ is right on the money at 122.9 volts and I also have the 12v & 24v. I lifted D361 to bypass the shutdown circuit but no change. The flyback is new from APAR. The HOT checks fine along with the 2.6W ceramic resistor. I even changed the neck board. I used Randy Fromm's flow chart and checked R562 & R401 like it said. The board used to take about 10 seconds to build up to the 123 volts B+. I changed Q801 as it looked charbroiled and checked all surrounding components. Since then, the B+ only takes a second to build up so apparently Q801 was weakened by heat. That's the only damage I could see. I checked the board for any bad connections and really didn't see anything out of the ordinary. No heater voltage either. I am assuming the heater voltage comes from the flyback. I don't mean to sound ignorant but what triggers the flyback to powering up or does it just happen on its own? Can I use my o-scope to find any clues here? I have found very little info on the monitor other than what the late and great Ken Layton and Ohmerone post
I am missing something somewhere. Anyway, any help with this would certainly be appreciated. I am stumped on this one! This model always gives me fits with repair.
 
I think we got it! T401 primary is testing open. I looked at this T401 1000 times but never checked it! I can't thank you enough! I've pulled
my hair out with this. Now the task of finding a replacement...Thanks so much!!
 
I think we got it! T401 primary is testing open. I looked at this T401 1000 times but never checked it! I can't thank you enough! I've pulled
my hair out with this. Now the task of finding a replacement...Thanks so much!!
SOLVED! Robbed a T401 from a donor chassis. Fired right up and works great! Thanks so much to Arcade2007 for the time and effort you took to send me some places to check by highlighting it on the schematic. Your help is well appreciated!!Bad Transformer 1.jpg
 

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SOLVED! Robbed a T401 from a donor chassis. Fired right up and works great! Thanks so much to Arcade2007 for the time and effort you took to send me some places to check by highlighting it on the schematic. Your help is well appreciated!!View attachment 716797
You are most welcome - and glad you got it going! :)
 
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