Re: Odd display on Tektronix 577 curve tracer


Bob Koller <testtech@...>
 

Check the LV power supply for ripple. A bad cap is common.


From: Brad Thompson
To: TekScopes@...
Sent: Thursday, May 31, 2012 5:34 PM
Subject: [TekScopes] Odd display on Tektronix 577 curve tracer

 
Hello--

Does anyone recognize the nature of the possible fault shown
on the display of this up-for-auction Tektronix 577 curve tracer?

http://img.inkfrog.com/click_enlarge1.php?image=177A.jpg&username=DREDD2010&aid=138665431

It's difficult to tell from the photos, but the rightmost display
pushbuttons are pressed, the collector sweep is set for AC
the collector voltage range is set for 25 volts and the
variable collector setting is at maximum. Collector load
resistance is set for 7.5 (ohms?).

There's no device in the 177 fixture, which is set to center off'.

I'm thinking that the configuration is driving the horizontal axis
to clipping, and the vertical axis gain is set high enough to
display noise. Or else, the power supply ripple is severe.

Thanks, and 73--

Brad AA1IP



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