Author Topic: Lecroy 9350 ch. 2 amplitude issues  (Read 1983 times)

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Offline highrollerTopic starter

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Lecroy 9350 ch. 2 amplitude issues
« on: June 07, 2017, 03:07:19 am »
Hi,

My Lecroy  9350 oscilloscope developped some noise spikes or amplitude jitter on channel 2.

It happen on all input coupling type (DC, AC etc...)  and at any volt/div setting but does not seem to affect the time.

Not sure if it can be related to an input amplifier, a relay or part of the digital acquisition circuit.

Any clues ? 



Thanks
 

Offline highrollerTopic starter

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Re: Lecroy 9350 ch. 2 amplitude issues
« Reply #1 on: June 07, 2017, 03:24:03 am »
More  screen shot of the issue.
 

Offline TAMHAN

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Re: Lecroy 9350 ch. 2 amplitude issues
« Reply #2 on: June 08, 2017, 02:35:06 am »
Sorry to be stupid. One thing - did you already try moving the probes?

I have one probe which, um, seems to be a little "smelly".
Feel like some additional tamile wisdom? Visit my YouTube channel -> https://www.youtube.com/user/MrTamhan for 10min tid-bits!
 

Offline highrollerTopic starter

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Re: Lecroy 9350 ch. 2 amplitude issues
« Reply #3 on: June 08, 2017, 03:51:37 am »
No probe attached, these pics are taken with the cal output connected with a 50ohm cable.

The issue also appear without any connection to channel 2 input, I can see the noise spikes on an idle trace.

 
 

Offline DaJMasta

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Re: Lecroy 9350 ch. 2 amplitude issues
« Reply #4 on: June 08, 2017, 05:37:09 am »
Does the noise look sort of 'digital' in nature?  In the second shot it almost looks like a bit of the ADC (that isn't the first bit) is just twitching a bit on its own, maybe there's a connection issue on the output of the data bus or on the receiver end.


I think the chance it's that is sort of a longshot, but that sort of glitch does look somewhat distinctive and that could tell you something.
 

Offline highrollerTopic starter

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Re: Lecroy 9350 ch. 2 amplitude issues
« Reply #5 on: June 08, 2017, 12:58:47 pm »
Good point DajMasta.


I start to think its digital in nature too, I may reflow some chips in the a/d part first.
 


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