Author Topic: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!  (Read 9258 times)

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Offline SAUL BRITTO

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Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« on: November 13, 2016, 10:47:48 pm »
http://i63.tinypic.com/2h81ws3.jpg
I don't know if it's value is 2031 or 2021. Can anyone help me?
IT is of a keysight 2000 series, DSO-X 2012A.


« Last Edit: January 21, 2017, 10:48:16 pm by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of a keysight PS,doubt!
« Reply #1 on: November 13, 2016, 10:54:37 pm »
More images:

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Offline SAUL BRITTO

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Re: Resistor of a keysight oscilloscope DSO-X 2012A PS,doubt!
« Reply #2 on: November 13, 2016, 11:01:01 pm »
 
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Offline HackedFridgeMagnet

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Re: Resistor of a keysight oscilloscope DSO-X 2012A PS,doubt!
« Reply #3 on: November 14, 2016, 12:14:34 am »
If the resistor was in the series E96 or E192 then it could only be 200, 203, 205, 208. With the trailing 1 as the multiplier.

As it seems to be part of the rectifier its value may not matter too much.

Do you have any closeups of the other blue resistors? Once that will show the font of the 3s, 5s etc.
 
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Offline SAUL BRITTO

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Re: Resistor of a keysight oscilloscope DSO-X 2012A PS,doubt!
« Reply #4 on: November 14, 2016, 12:21:19 am »
If the resistor was in the series E96 or E192 then it could only be 200, 203, 205, 208. With the trailing 1 as the multiplier.

As it seems to be part of the rectifier its value may not matter too much.

Do you have any closeups of the other blue resistors? Once that will show the font of the 3s, 5s etc.
Yes,I made a closeup and nothing looks like that number,please say me,what is E96 or E196.
It is linked to the pin 1 of Q1 that is a mosfet P12nm50
« Last Edit: November 14, 2016, 12:49:10 am by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of a keysight oscilloscope DSO-X 2012A PS,doubt!
« Reply #5 on: November 14, 2016, 12:26:32 am »
I am not sure but,sometimes I see a number 2 on that resistor.
« Last Edit: November 14, 2016, 12:33:35 am by SAUL BRITTO »
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Offline HackedFridgeMagnet

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #6 on: November 14, 2016, 03:11:03 am »
https://en.wikipedia.org/wiki/Preferred_number

thats for the series.

Resistors normally come in a series of exponentially increasing numbers. what series they belong to is often dictated by their tolerance.

 

Offline HackedFridgeMagnet

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #7 on: November 14, 2016, 03:34:47 am »
Yes,I made a closeup and nothing looks like that number,please say me,what is E96 or E196.
It is linked to the pin 1 of Q1 that is a mosfet P12nm50

So its attached to the gate of an N channel Mosfet.

2k does seem an unusual value to me. Not sure if it in series or a shunt from the gate to the source. 

Have a look what resistor is in a similar position in regards to Q3.

It may be in parallel with Q3 Q2 in which case they should have similar gate topologies, including resistor values. (as part of PFC?)

Also look for shorts on all the semiconductors nearby.

edit: meant q2 but third semi from left on heatsink.
« Last Edit: November 14, 2016, 05:50:52 am by HackedFridgeMagnet »
 

Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #8 on: November 14, 2016, 03:52:26 am »
Yes,I made a closeup and nothing looks like that number,please say me,what is E96 or E196.
It is linked to the pin 1 of Q1 that is a mosfet P12nm50

So its attached to the gate of an N channel Mosfet.

2k does seem an unusual value to me. Not sure if it in series or a shunt from the gate to the source. 

Have a look what resistor is in a similar position in regards to Q3.

It may be in parallel with Q3 in which case they should have similar gate topologies, including resistor values. (as part of PFC?)

Also look for shorts on all the semiconductors nearby.

This resistor on the gate of Q1 ( In short) as you can see, there is smoke on the foto of PCB.This resistor on the image is measuring 246 Ohms it is linked to another resistor of 5.1 Ohms on the gate of Q3 ( there is one 5.1 Ohms resistor on the gate of Q1 too) I will try to make another image for you.
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #9 on: November 14, 2016, 04:02:07 am »


Here are the images I hope you can understand.
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #10 on: November 14, 2016, 04:10:38 am »
So its attached to the gate of an N channel Mosfet.

2k does seem an unusual value to me. Not sure if it in series or a shunt from the gate to the source. 




Yes you are right, it is attached gate/source of Q1.

That other semiconductors are  one diode  and two IRF840.
« Last Edit: November 14, 2016, 04:39:32 am by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #11 on: November 14, 2016, 04:27:58 am »
Yes,I made a closeup and nothing looks like that number,please say me,what is E96 or E196.
It is linked to the pin 1 of Q1 that is a mosfet P12nm50

So its attached to the gate of an N channel Mosfet.

2k does seem an unusual value to me. Not sure if it in series or a shunt from the gate to the source. 

Have a look what resistor is in a similar position in regards to Q3.

It may be in parallel with Q3 in which case they should have similar gate topologies, including resistor values. (as part of PFC?)

Also look for shorts on all the semiconductors nearby.

I think 2k is a strange value because it is measuring 246 Ohms "on board"
Just if it changed for less  than your original value. But,as it is in parallel with the shorted mosfet...Maybe this is the effect caused by the short.
« Last Edit: November 14, 2016, 04:44:48 am by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #12 on: November 14, 2016, 05:12:17 am »
Removed that "smoked" Tr and measured the resistor again, it measures 1.15 mega Ohms.
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Offline HackedFridgeMagnet

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #13 on: November 14, 2016, 09:18:19 am »
Because it such an expensive bit of equipment It might be reverse engineering a schematic of the section. Including all known values and chip types.
I dont think I can help anymore without this info.

Apparently in parallel mosfet circuits it is very important to match the gate drive circuits but if there is only 1 of that type of mosfet on the board then I dont think the exact value can matter very much.

Just for the record, is there any sign of previous work done on the board? This is always something to watch out for.

EEVBlog does a teardown
http://www.eevblog.com/2011/02/15/eevblog-144-agilent-2000-x-series-infiniivision-oscilloscope-teardown/

at 2:00 can see the board but it has 4 semiconductors mounted on that heatsink?




« Last Edit: November 14, 2016, 09:40:31 am by HackedFridgeMagnet »
 

Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #14 on: November 14, 2016, 01:56:43 pm »
Because it such an expensive bit of equipment It might be reverse engineering a schematic of the section. Including all known values and chip types.
I dont think I can help anymore without this info.

Apparently in parallel mosfet circuits it is very important to match the gate drive circuits but if there is only 1 of that type of mosfet on the board then I dont think the exact value can matter very much.

Just for the record, is there any sign of previous work done on the board? This is always something to watch out for.

EEVBlog does a teardown
http://www.eevblog.com/2011/02/15/eevblog-144-agilent-2000-x-series-infiniivision-oscilloscope-teardown/

at 2:00 can see the board but it has 4 semiconductors mounted on that heatsink?

HI. Yes it has 4 semiconductors on that heatsink and there are 4 more on the other side of the board and no, no sign of previous work,it looks original.

I have a "service manual" for this unit but it doesn't help as you can hope,we just  can find things like trubleshootings,no electric schematics.
« Last Edit: November 14, 2016, 02:15:26 pm by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #15 on: November 14, 2016, 03:00:25 pm »
It would help a lot if someone had a photo or a layout or any information about this card, I think it would solve this problem quickly.
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #16 on: November 14, 2016, 09:00:29 pm »
I've found a diode and was thinking it was a Tr but,no!


Looks like JV3 isn't a transistor but a diode in SOT-23 BAT54 http://www.s-manuals.com/ru/smd/jv
http://www.s-manuals.com/pdf/datasheet/b/a/bat54_series_taitron.pdf

If I am right,no more than a  Schottky diode in three terminals, one is NC.
« Last Edit: November 14, 2016, 09:36:06 pm by SAUL BRITTO »
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Offline Vinchi

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #17 on: January 20, 2017, 05:44:55 pm »
Hi!

I also have a broken DSO-X 2012A.

I have attached the power supply image with resistor.

Was you able fix your oscilloscope?
 
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #18 on: January 21, 2017, 10:46:14 pm »
Hi!

I also have a broken DSO-X 2012A.

I have attached the power supply image with resistor.

Was you able fix your oscilloscope?

Wow ! Thank you so mutch Vinchi, this will helps me so mutch! I will try to fix the scope and tell you the result. What's the problem with your scope?
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #19 on: January 21, 2017, 11:03:02 pm »
Hi!

I also have a broken DSO-X 2012A.

I have attached the power supply image with resistor.

Was you able fix your oscilloscope?

Can you say me what's the refference of Q1?
« Last Edit: January 21, 2017, 11:51:54 pm by SAUL BRITTO »
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Offline Vinchi

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #20 on: January 22, 2017, 09:15:27 pm »
My scope has same symptoms as this one:


The power supply for my scope shows 13 VDC so it is ok, i think the problem could be with Windows CE boot. Who had the idea to put windows on the oscilloscope :D

I think you can fix your scope easy by installing open frame 13vdc 200-250W power supply from Mean Well :)

Which value you need to know?
 

Offline Vinchi

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #21 on: January 22, 2017, 09:26:29 pm »
Another image.

Does the scope provide power to USB host device when it starts to boot?
In my case i think there could be  some problem with some voltage regulator or step-down converter chip. May be power problem for graphics chip.
 

Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #22 on: January 27, 2017, 05:49:00 am »
My scope has same symptoms as this one:


The power supply for my scope shows 13 VDC so it is ok, i think the problem could be with Windows CE boot. Who had the idea to put windows on the oscilloscope :D

I think you can fix your scope easy by installing open frame 13vdc 200-250W power supply from Mean Well :)

Which value you need to know?

Hey guy, did you look the screen voltage? maybe a LCD problem...
« Last Edit: January 27, 2017, 05:44:03 pm by SAUL BRITTO »
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #23 on: January 27, 2017, 05:57:04 am »
Another image.

Does the scope provide power to USB host device when it starts to boot?
In my case i think there could be  some problem with some voltage regulator or step-down converter chip. May be power problem for graphics chip.

My scope is completely dead! I need to fix the P.S at first to know how it will reacts
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Offline SAUL BRITTO

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Re: Resistor of an agilent oscilloscope DSO-X 2012A PS,doubt!
« Reply #24 on: January 27, 2017, 06:02:19 am »
Another image.

Does the scope provide power to USB host device when it starts to boot?
In my case i think there could be  some problem with some voltage regulator or step-down converter chip. May be power problem for graphics chip.
Yes, see the the PWM if it does not have a smoked component.

Lets think as if it was a notebook mobo, maybe this is a good way to solve the problem.

I don't know what kind of technology is used in this screen, common LCD or LED.
« Last Edit: January 27, 2017, 06:05:37 pm by SAUL BRITTO »
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