EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: elliott on May 16, 2014, 02:41:00 am
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I recently got my Hitachi V-1150 running again and went to give it a good test before putting it to use. When comparing the output to my Tek I noticed something strange.
(http://i.imgur.com/ZMZWDDol.jpg)
Full Size (http://i.imgur.com/ZMZWDDo.jpg)
I'm assuming the Tek is right, that is a 100% duty cycle sawtooth wave from my function generator. I know I didn't get the X backwards on the CRT when I put it back together since the text is displayed properly. Any ideas where to begin?
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put them both on there slowest scan speed and see which way its moving, it almost looks like the Y is upside down, and could be the invert button for the channel
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It's an Aussie scope, turn it upside down so the electrons fall back into place.
Tim
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put them both on there slowest scan speed and see which way its moving, it almost looks like the Y is upside down, and could be the invert button for the channel
It is scanning left to right just like it should. I can only invert channel 2 on both of them, that signal is going to channel 1.
I think you are right that it is upside down instead of backwards. It can't be just the Y+ and Y- to the CRT switched since the text is fine. I could just swap them and it would be usable, though the menus are bad enough when they are right side up.
I pulled the Y board to look for any signs of damage first. That is some high quality 1986 bodging.
(http://i.imgur.com/XGhIVqwl.jpg)
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One would assume the invert button on the Hitachi is on. ;)
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Want to be sure? DC couple the channel, and apply a DC voltage and observe which direction the trace moves.
If one of them moves in the wrong direction, and there's no invert function, then it's possible that someone was working on the scope and reversed the connections to the vertical deflection plates on the CRT.
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One would assume the invert button on the Hitachi is on. ;)
One would, but I can only invert channel 2, it is like this on all 4 channels. Inverting channel 2 makes that one right.
I need to study the service manual some more.
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Apparently whoever made a mess of the power supply trying to recap it before I got it also reconnected something wrong.
PEF-735C is quite happy being plugged into the vertical switching board in either direction. There is even a nice little cut out in the board to the left of it that allows that cable to pass conveniently under it, which is where it was when I got it. Rerouted the cable and turned it around and it is all good.
(http://i.imgur.com/l2mPrhHl.jpg)