Zoex
Member
I've spent a whole day working on this thing and I don't feel like I'm and closer to fixing it. Typical 25" WG K7000 monitor, has the pincushion board, was working but needed a cap kit. I did the kit and installed a new flyback as well. Now the monitor powers up, I can hear the high voltage whine, tube generates static, but no neck glow and no picture or signs of life at all on the tube side. Turning the flyback up does not show any signs of raster. So I went to town pulling and testing parts (all out of circuit)
Horizontal output transistor checks out fine.
Fuse is fine, I don't think it's ever blown a fuse even with all the stuff I have been doing.
Diodes D18-D22 test fine.
C36 and C38 test fine.
R213 tests fine.
Voltage Regulator tests fine.
C55 tested fine, swapped with a known working one anyways.
R103 tested fine.
Swapped the flyback back to the old one that was working, no changes.
The entire time the B+ voltage has been low. The longer I hold my meter to the R301 test points the lower it drops starting around 40VDC and bottoming out around 20VDC on the unregulated side. Same thing but even less voltage on the regulated side. At some point it was giving me negative voltage on the regulated side.
I have desoldered, cleaned up, and resoldered various large resistors that are prone to bad solder joints, and checked for any obvious shorts where they should not be.
At this point I am at a loss and am thinking about trying a different tube or neck board just for the hell of it (I did swap this tube with another working K7000 as this one was going into a shooter that needed a strong tube). I'm going to make this post and go to bed, hopefully someone better than me can think of something and post it here for me to wake up to.
Horizontal output transistor checks out fine.
Fuse is fine, I don't think it's ever blown a fuse even with all the stuff I have been doing.
Diodes D18-D22 test fine.
C36 and C38 test fine.
R213 tests fine.
Voltage Regulator tests fine.
C55 tested fine, swapped with a known working one anyways.
R103 tested fine.
Swapped the flyback back to the old one that was working, no changes.
The entire time the B+ voltage has been low. The longer I hold my meter to the R301 test points the lower it drops starting around 40VDC and bottoming out around 20VDC on the unregulated side. Same thing but even less voltage on the regulated side. At some point it was giving me negative voltage on the regulated side.
I have desoldered, cleaned up, and resoldered various large resistors that are prone to bad solder joints, and checked for any obvious shorts where they should not be.
At this point I am at a loss and am thinking about trying a different tube or neck board just for the hell of it (I did swap this tube with another working K7000 as this one was going into a shooter that needed a strong tube). I'm going to make this post and go to bed, hopefully someone better than me can think of something and post it here for me to wake up to.
