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I am trying to replace a component on my Krohn-hite 1000A function generator that burnt up.

The component is connected directly to the high-impedance output. I have found a schematic for Krohn-Hite 1600, which I believe is close. (I believe) my burnt up component is the schematic symbol circled in Red.

Is this some kind of diode? I have never seen this symbol before, and cannot find anything like it online. Looking to replace this burnt component.

full schematic: http://www.waynekirkwood.com/images/jpg/Krohn-Hite_1600_Sheet_1.JPG

Mysterious Symbol


Thank you for these replies. I see that the component I highlighted is a switch now.

Attached is a picture of the burnt component.

Anyone know what component this might be on the schematic? I understand more photos might be necessary to answer this question.

enter image description here

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    \$\begingroup\$ That is a switch ....not a diode. The arrow marks the moving end of the wiper. \$\endgroup\$ – Jack Creasey Apr 7 '17 at 23:15
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    \$\begingroup\$ It's a rotary switch, I suspect. \$\endgroup\$ – jonk Apr 7 '17 at 23:17
  • \$\begingroup\$ The schematic shows no "high impedance output", only the 50-ohm "main output". More likely, the burnt component is R636 (51 ohm), or some component in the final power amplifier that feeds it. \$\endgroup\$ – glen_geek Apr 7 '17 at 23:49
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    \$\begingroup\$ How can you be certain that component is burnt out when you don't even know what it is?! \$\endgroup\$ – duskwuff Apr 7 '17 at 23:50
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    \$\begingroup\$ @WhatRoughBeast Right, but I'm not sure how they'd be sure that the charred mess matched up with that schematic symbol. (Especially seeing as they've identified part of a symbol as the "component".) \$\endgroup\$ – duskwuff Apr 8 '17 at 0:26
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Looks to me like a rotary switch.

They are switches that you rotate to select the connection. (Do not confuse with a potentiometer, which dials a particular resistance.)

The arrow represents the "wiper". I imagine that the numbers next to the nodes represent the rotation angle, or perhaps a setting that the user would select.

Rotary switches are commonly used as a mux/demux.

Rotary switch symbol

rotary switch photo

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If you have more clues that caused the burnup, we can get more insight into your repair issue.

1) Do a physical inspection inside for bulged caps smoke parts, cracks, and any epoxy smells

2) examine attenuator contacts for burnt contacts or loose contacts or oxidized.

3) If DMM ohms indicates contacts are ok then trace back to Supply voltage +/-135Vdc then output stage ought to be 0V

enter image description here

If switch is damaged beyond repair then you may have dumped DC into a big cap.

These contacts are rated <2A and are usually gold plated. (broke it)

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  • \$\begingroup\$ This Gen must have pretty good linearity for +/-135V supply with only +/-20V into 50 Ohms with +/-10Vdc offset ( but poor efficiency) \$\endgroup\$ – Sunnyskyguy EE75 Apr 8 '17 at 6:15
  • \$\begingroup\$ I think you'll find a decimal point between the 13 and the 5 if you zoom in close (+13.5V). It's unlikely that the offset lets the output go much further than +/- 10V. \$\endgroup\$ – W5VO Apr 8 '17 at 8:56

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