[ARC5] Scope Question

[J Mcvey]

 It's so true about the "new stuff" having less chance of being repaired due to "unobtnaium" parts.The problem is not limited to scopes either. Radios, Tvs , surround sounds, you name it and it has custom ICs that are not or soon will not be available.Some of the BGA components fail not because of the silicon, but because the solder connections crack. Reflowing them will sometimes restore operation, but is not always reliable. They actually need to be removed, cleaned and re-balled- but who wants to do that?
Modern LED TVs have a high panel fail rates because they overdrive the LEDs which guarantees their early demise 
The mfrs do not make the LED strips available , besides it's a bear to disassemble an LED panel anyway, so the 3 year old TV goes on the curb. .
Sadly much of this present day "high tech" is not going to survive the test of time like the old discreet technology has.Not only is it planned obsolescence , but with a built-in self destruct mechanism too!  
    On Tuesday, March 20, 2018, 6:19:11 PM EDT, Jim Wiley <jwiley at gci.net> wrote:  
 
  
Wayne - 
 
 

 
 
The switch setting "ground"  means "disconnect the incoming signal going into the scope and ground the scope signal path, so the input INSIDE THE SCOPE is connected to ground". 
 
 
Or to put it another way,  internally inside the scope the "ground" setting opens the circuit connecting the signal from the  external probe  (or input cable) and the oscilloscope internal amplifier so there is no connection  from the outside world, and instead shorts the vertical amplifier input to ground.  
 
 
The other two settings are  used to set the vertical amplifier as a DC coupled or AC coupled amplifier, to display  signals.   The "ground" setting is  used so the operator can make sure there is no  external signal coming in, and can thus get  the trace "on screen" somewhere so  he or she can see it (giving a place to  start).  
 
 
I hope this makes sense.  
 
 

 
 
- Jim, KL7CC
 

 
 

 
 
 On 3/20/2018 7:32 AM, Robert Eleazer wrote:
  
 
I am troubleshooting a Tektronix 2236 scope.  Tektronix says to use another scope to do that.  Now, the general settings they say to use for the test scope says for the coupling switch, which offers the options of AC, Ground, and DC, is to use "Ground."  I set the coupling to Ground and I don't get any reading.   Does this make sense to y'all?  I get readings with either DC or AC coupling selected.  The signals being measured are all pulsating DC voltages of various kinds, such as square waves, triangle waves, etc..   Thanks,   Wayne WB5WSV        
 
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