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Title: Sega Monitor Power Issues Post by: Hooligan93 on October 12, 2016, 09:19:59 pm Hello everyone,
Need some help and advice on a sega 14" MC-2000 monitor. Originally this monitor was slowly going into Verticle collapse. Did a cap kit didn't know this was a Sega MC-2000-S monitor at first otherwise i would have gotten a cap kit from Ian Kellogg. That would have been so much easier but I ended up making my own kit from a local place who just happened to have the hitachi IC for my chassis. Double and triple checked Cap polarity before trimming the legs got it all togather now nothing comes on the screen. Checked voltages i have 107 Vac from Isolation Transformer to the chassis to the bridge-rectifier. I have 137 VDC coming out of the BR to the Voltage regulator. I have 137vdc coming out of the voltage regulator on to the fuse and first test point. From here it goes to the HV circuit, video and neckboard circuit, and the Horizontal and Vertical Deflection circuits. On the Sega MC-2000-s it does show voltage after the VR to be 105vdc. So I pulled the VR and tested it found it to be bad so ordered a replacement tested and installed it today. No change in voltage. 137vdc coming out of new VR. I pulled the two other Transistors in the power regulation circuit but they tested good but i think i am going to replace them anyway. Also The main resistor (cement encased and attached to the HOTS transistor heatsink) that feeds power to the Horizontal deflection cuircut is137VDC on one side and 45 vdc on the other and is so hot it melts the sodder to the outut wire if left on more then two minutes. I figure this is because the Voltage regulator is just letting power straight through at 137v and at 105 volt the resistor wont heat up enough to melt solder. Maybe a short on the Horizontal deflection circuit? but it isnt blowing the .8amp fuse after the VR? Any ideas? This is the first time I am working on a monitor power supply not really sure how it works but slowly figuring this out. |