Author Topic: Need a scope, Is vertical sensitivity important?  (Read 5041 times)

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Offline deezdramaTopic starter

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Re: Need a scope, Is vertical sensitivity important?
« Reply #25 on: December 12, 2022, 04:01:40 pm »
So I cleaned up my bench a little bit and made a home for the scope, got the probes color coded, set to 10x and compensated.
:-+
Quote
Im wondering if the little green "ready" indicator is supposed to be flickering between ready and auto like this?
Normal in Auto triggering mode.
Remove probe from Comp output then switch to Single trigger mode and then reconnect to see what is does in Single mode. It's just to tell you the trigger state, Armed/Ready or Triggered. Single will STOP the acquisition. Try Normal too.

Thank you!


I ordered a cheap 1Hz -1MHz signal generator to play around with different waveforms and to play with triggering etc....
Once Im comfortable with the scope and move on to testing the chassis board in a monitor im having problems with.... Im wondering how I will probe the legs of surface mounted IC packages with the scopes included hook probe?
Are there normal probe tips I can buy, or should I be soldering on jumper leads/wires to my test points on situations like that?
 

Offline tautech

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Re: Need a scope, Is vertical sensitivity important?
« Reply #26 on: December 12, 2022, 06:48:15 pm »
So I cleaned up my bench a little bit and made a home for the scope, got the probes color coded, set to 10x and compensated.
:-+
Quote
Im wondering if the little green "ready" indicator is supposed to be flickering between ready and auto like this?
Normal in Auto triggering mode.
Remove probe from Comp output then switch to Single trigger mode and then reconnect to see what is does in Single mode. It's just to tell you the trigger state, Armed/Ready or Triggered. Single will STOP the acquisition. Try Normal too.

Thank you!


I ordered a cheap 1Hz -1MHz signal generator to play around with different waveforms and to play with triggering etc....
Once Im comfortable with the scope and move on to testing the chassis board in a monitor im having problems with.... Im wondering how I will probe the legs of surface mounted IC packages with the scopes included hook probe?
Are there normal probe tips I can buy, or should I be soldering on jumper leads/wires to my test points on situations like that?

The probe hook/top hat pulls off and then you have a pointed tip for fine work however removing the top hat also exposes the Gnd ring which adds a second hazard to probing live circuitry.

They expressly are the risk of shorting 2 points in the PCB for which in the probe accessories pack there are 2 yellow probe condoms to cover part of the tip and all of the Gnd ring of which remove the 2nd hazard namely shorting part of the circuitry to the Gnd ring on the scope.

One of the condoms is shaped to perfectly fit over DIP IC leads to prevent slippage and shorts between adjacent pins.
Siglent NA have these probe accessory packs should you ever lose them:
https://siglentna.com/product/probe-accessory-kit-pak1/
Avid Rabid Hobbyist.
Some stuff seen @ Siglent HQ cannot be shared.
 

Offline deezdramaTopic starter

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Re: Need a scope, Is vertical sensitivity important?
« Reply #27 on: December 12, 2022, 09:11:33 pm »
So I cleaned up my bench a little bit and made a home for the scope, got the probes color coded, set to 10x and compensated.
:-+
Quote
Im wondering if the little green "ready" indicator is supposed to be flickering between ready and auto like this?
Normal in Auto triggering mode.
Remove probe from Comp output then switch to Single trigger mode and then reconnect to see what is does in Single mode. It's just to tell you the trigger state, Armed/Ready or Triggered. Single will STOP the acquisition. Try Normal too.

Thank you!


I ordered a cheap 1Hz -1MHz signal generator to play around with different waveforms and to play with triggering etc....
Once Im comfortable with the scope and move on to testing the chassis board in a monitor im having problems with.... Im wondering how I will probe the legs of surface mounted IC packages with the scopes included hook probe?
Are there normal probe tips I can buy, or should I be soldering on jumper leads/wires to my test points on situations like that?

The probe hook/top hat pulls off and then you have a pointed tip for fine work however removing the top hat also exposes the Gnd ring which adds a second hazard to probing live circuitry.

They expressly are the risk of shorting 2 points in the PCB for which in the probe accessories pack there are 2 yellow probe condoms to cover part of the tip and all of the Gnd ring of which remove the 2nd hazard namely shorting part of the circuitry to the Gnd ring on the scope.

One of the condoms is shaped to perfectly fit over DIP IC leads to prevent slippage and shorts between adjacent pins.
Siglent NA have these probe accessory packs should you ever lose them:
https://siglentna.com/product/probe-accessory-kit-pak1/

Thank you!!!

I tried to give the hook end of probe a tug the other day to see if it came off and felt like it wouldnt and didnt want to break it. Ill check it out again when I get home.

I wondered what those little yellow caps were for, makes sense now 🤣
 

Online Martin72

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Re: Need a scope, Is vertical sensitivity important?
« Reply #28 on: December 12, 2022, 11:00:18 pm »
Ive watched daves video and alot on the same topic, and read alot of articles and its left me confused. Seems like back in the day everyone suggested isolating the device being scoped and now they dont.
Going to research it some more as ill ultimately end up using the scope to test crt monitor circuits and IC's.
The monitors have seperate power boards but not sure if the chassis board is connected to earth ground. Ill have to test for continuity between earth ground and the chassis board and how to safely probe these circuits.
Alot to learn

The "idea" or better the warning in most of the service manuals from CRT TVs are based on the fact that the chassis are not grounded to earth.
(2 pole mains plug).
And there are "hot", will mean the chassis gnd could have high potential, depending on how the mains plug is connected.
It´s a 50:50 chance to have neutral or phase on the chassis.
The scope´s input gnd is the same as it´s Earth potential.
So when the TV chassis it´s gnd have phase potential and you connect the gnd clip of your probe to chassis gnd for measuring....BAMM.
A 100:1 probe won´t protect you for this as it´s gnd is also the gnd of the scope/earth.
(When measuring with a DMM you don´t have this problem, ,but as mentioned before, with a DMM you won´t "see" everything.*)
To avoid this risk, the recommendation came up to use a galvanic transformer for the DUT.
(As I´ve started to work in the testfield here, the guys who were already there use the transformer to isolate the SCOPE... :scared: )
Differential probes are more convenient to use, are not really isolating potentials from each other, got the advantage of switchable input dividers, got the possible disadvantage of noise when looking at lower signals, limited bandwith (for your purposes not remarkable).
There a cheap but good ones avaible from micsig.

Martin

*) https://www.eevblog.com/forum/repair/hioki-3532-50-lcr-schematic-service-manual-wanted/msg4575439/#msg4575439

Actual example why a DMM is often not enough..
« Last Edit: December 12, 2022, 11:02:27 pm by Martin72 »
 

Offline james_s

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Re: Need a scope, Is vertical sensitivity important?
« Reply #29 on: December 13, 2022, 02:05:02 am »
I tried to give the hook end of probe a tug the other day to see if it came off and felt like it wouldnt and didnt want to break it. Ill check it out again when I get home.

I wondered what those little yellow caps were for, makes sense now 🤣

The hats always come off, just pull harder. They have to fit snugly enough that they don't come off from the weight of the probe tugging on it when you've got it clipped onto something.
 

Offline Brumby

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Re: Need a scope, Is vertical sensitivity important?
« Reply #30 on: December 13, 2022, 11:33:06 am »
I will always recommend differential probes over an isolation transformer.

Why?

Using differential probes is very straightforward and uses an unaltered circuit topology, where the risks are easy enough to understand.  An isolation transformer changes that topology which can introduce risks that are not easily identifiable and can cause catastrophic failure and/or potentially lethal situations.
 

Offline bdunham7

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Re: Need a scope, Is vertical sensitivity important?
« Reply #31 on: December 13, 2022, 04:31:28 pm »
I will always recommend differential probes over an isolation transformer.

Using an isolation transformer to remove the ground-reference of mains power, disconnecting or breaking the PE circuit, using a differential probe and using an isolated probe or scope are in fact four different things that each need to be considered individually--they are not interchangeable options. 
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Brumby

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Re: Need a scope, Is vertical sensitivity important?
« Reply #32 on: December 14, 2022, 12:22:06 am »
The best option will depend on use case - but my comment was directed at the simple either/or choice so often discussed - especially in regard to safety.

In short, you are far less likely to damage equipment or cause injury with differential probes than with an isolation transformer.
 

Online Martin72

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Re: Need a scope, Is vertical sensitivity important?
« Reply #33 on: December 14, 2022, 11:39:30 pm »
You shouldn´t use an isolating transformer on devices which got a protective earth connection( 3pole mains connection).
This is electronics basic knowledge, if someone don´t know this, he should keep his fingers away from mains powered devices in general.



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