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Hantarex MTC900e - white screen
CathalDublin:
I’ve a hantarex MTC900e
It’s the European model that takes 128v and 220v for the degaus.
I acquired this a long time ago but hadn’t got a stepdown isolation transformer to test it.
Finally came across an isolation/stepdown the other day and plugged it in and nothing, finding some posts from grantspain I found he’d mentioned the most common issue with these chassis is corroded coil/TR20 which indeed it was corroded and broken, I repaired this and the monitor now comes on but all I’m getting is a white screen, if I plug in a game the picture does kinda roll, see video with game running. I’ve re-capped the neck board and adjusted the screen pot which just makes the black area brighter/darker. The resistor on the left hand side does get very hot.
I have only the 128v connected, I haven’t got the 220v connected but I believe this is only for degaus.
Any ideas
grantspain:
next test voltages, 200v video b+ and 12v and -5
refer to the schematic for test points
CathalDublin:
My b+(Sp4)is reading about 180ish v, my 12v(SP8)is 10v and my -5v(sp7)seems to be reading +5v, is that possible?
I’m measuring these from the neck board
grantspain:
if someone has replaced the 7905 at ic1 with a +5 reg then yes
the +12 is a bit low, you can read again at ic4
CathalDublin:
I may have read it wrong, doesn’t look like anyone’s every worked on this before, I’ll re-check them tonight at ic4
Thanks