EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: Zenwizard on August 28, 2018, 11:21:55 pm
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The attached is the output wave form from a Tektronix type 106. I have checked out the power supply section and all seem to be with in spec. My question is about the massive over and undershoot pulse at the end of the waveform. The power supply voltages all are good and the fast rise pulses look flawless. Is there a fault in the high amplitude side that I need to look at and repair?
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How are you connecting the generator to the scope?
The Rigol has 1 meg impedance inputs and the generator has 50 ohm outputs. And the 106 has those GenRad connectors.
Can you go ahead and zoom in to one waveform's spike so we can see its detail shape?
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Scope connection is through a 16 inch tektronix 50 Ohm bnc cable the to get the BNC on the front of the 106 I am using GR to BNC adapters 50 ohms. I have checked the adaptor on the fast rise output and they are clean. There is also a Rigol 50 Ohm BNC through terminator right on the front of the scope input. I should also mention triggering is on the rising edge and this is the falling edge where the noise is.
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Well, the hookup sounds good enough and that waveform definitely isn't an inductive ringdown caused by stray hookup inductance.
And it definitely isn't getting its advertised falltime.
Have you swapped tubes around, or tried banging on them (gently!) with a wooden tapper?
How do the capacitors look?
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I did tap the tubes lightly. they did cause some jumpyness with the scope though something interesting happened. The symmetry or oscillator is not stable. It is jittery, here is the negative edge of the square wave triggered on the negative going edge it is a lot more stable. I am starting to suspect some weirdness in the symmetry circuit. I am starting the think the symmetry circuit is fluttering.
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But adjusting the symmetry control does not effect the waveform.