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Author Topic: Rigol MSO 2202A input circuits damaged  (Read 1237 times)

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Offline Dieter

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Rigol MSO 2202A input circuits damaged
« on: March 19, 2017, 12:59:06 AM »
Rigol MSO 2202A input circuits damaged

By accident, the input impedance was switched to 50 Ohm and a Voltage of about 60 Vpp applied at the same time to both channels . The fist resistors after the BNC sockets are damaged such that the value can no longer be identified. Batronix (I bought the rig from them) could only offer to change the whole motherboard at cost of € 1.300.--. They even cannot help me with a schematic diagram and even worse are unable to give me the value of the resistors in question.
Can anyone help and me with an information to this problem?

 

Offline ElektronikLabor

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Re: Rigol MSO 2202A input circuits damaged
« Reply #1 on: March 19, 2017, 01:30:42 AM »
You can find tear down photos of the DS2000 on Daves Flikr account: https://www.flickr.com/photos/eevblog/sets/72157631618295437
I believe that the mso2000 could be roughly the same.
« Last Edit: March 19, 2017, 01:32:16 AM by medvedev »
 

Offline Dieter

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Re: Rigol MSO 2202A input circuits damaged
« Reply #2 on: March 19, 2017, 03:34:10 AM »
Hi,
thank you again. Meanwhile I found the right picture showing a similar design. However the resistor I was looking for is marked "51X" which obviously is a number and not a resistor value. Any Idea how I can translate this number ?
Thank in advance.
Dieter
alternative my mail: [email protected]
 

Offline Carrington

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« Last Edit: March 19, 2017, 03:47:59 AM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Online Monkeh

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Re: Rigol MSO 2202A input circuits damaged
« Reply #4 on: March 19, 2017, 03:48:36 AM »
Easy 51 \$\Omega\$
http://venkel.com/docs/default-source/technical/0603-marking-code-venkel.pdf?sfvrsn=2

Err, 33.2.

I'd be willing to bet the rest of the termination is a little unhappy, and possibly the relay, too.
« Last Edit: March 19, 2017, 03:52:30 AM by Monkeh »
 

Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #5 on: March 19, 2017, 03:59:29 AM »
Yes, check my previous post.  :)
I noticed it two seconds later.
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #6 on: March 21, 2017, 02:57:41 AM »
Hello Dieter!

I received your PM, I will try to help you, as far as I can.

First I recommend you to review this post:
http://www.eevblog.com/forum/projects/project-yaigol-fixing-rigol-scope-design-problems/msg890966/#msg890966
I'm pretty sure it's going to be very useful to you.
Also, I think that you should post here some pictures from your MSO2000A (front-end) here, as well. Just to compare.

Cheers.
My English can be pretty bad, so suggestions are welcome. ;)
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Offline mikeselectricstuff

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Re: Rigol MSO 2202A input circuits damaged
« Reply #7 on: March 21, 2017, 03:00:34 AM »
Do the inputs still work in non-50R mode ?
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Offline Dieter

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Re: Rigol MSO 2202A input circuits damaged
« Reply #8 on: March 21, 2017, 06:48:52 AM »
thanks to everybody for trying to help me. I am sure together I will get my scope back to work. Tomorrow I will post several pictures from the front end lay out.
Only channel 1, and only 1MOhm setting, detects signals but the amplitudes are too low. I will change the resistors and if necessary the relays as the next steps.
 

Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #9 on: March 21, 2017, 07:47:19 AM »
Only channel 1, and only 1MOhm setting, detects signals but the amplitudes are too low.
Too low on AC & DC mode?
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Dieter

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Re: Rigol MSO 2202A input circuits damaged
« Reply #10 on: March 22, 2017, 04:44:27 AM »
made some experimental measurements today before taking the scope apart in order to make some images that i will post later.
Signal applied to scope from a waveform generator:
wave form: sine
U = 2Vpp, f= 7, 14, 30, 100 Mhz........scope displays:   20mVpp on all "f"
      5Vpp                                                                  45mVpp
     10Vpp                                                                  90mVpp
amplitude unchanged 7 to 100 Mhz
same amplitude coupled A or D
channel1: however the displayed sine wave is not stable, it moves up and down slightly at appr. 10Hz.
Surprisingly also channel 2 works today giving very similar results. Maybe fiddling around on the rig has changed something.

up to this test channel 2 was dead.



 

Offline Twoflower

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Re: Rigol MSO 2202A input circuits damaged
« Reply #11 on: March 22, 2017, 06:59:13 AM »
Your values seem to indicate that you haven't setup your scope correct. It seems you are using 10x probes with a 1x setting in the scope. It does nothing but tell the scope to multiply the measured voltages and voltage/div by 10.

And that makes me wonder what happened. You seem to use a 10x probe, that means on the termination resistor is 'only' 6V. The input is rated in 50Ohm mode to be 5V RMS, so a 6V wouldn't kill the front end immediately. Or did you connect the signal direct to the BNC connector?

EDIT: I'm still jet-lagged :palm: . So it is not 10x but more in the 100x region. Which would be rather odd for a wrong setting (even since the scope allow a 100x setting too). So probably you should just ignore my post.
« Last Edit: March 22, 2017, 04:20:39 PM by Twoflower »
 

Online technogeeky

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Re: Rigol MSO 2202A input circuits damaged
« Reply #12 on: March 22, 2017, 03:19:11 PM »
I have more pictures (and non-macro pictures, if somehow they would be helpful) from repairing my scope front-end also. Granted, it's only a 1054z but it's the same manufacturer, and assuming "CH2" is essentially oscilloscope input (and not the RF input) it should be similar enough damage.

See the attached pictures.

Note:
  • In damage-01, the traces (from input to a 75R, to square pad, to relay) appear in-tact but they are not.
  • In damage-02, you can see the debris from the 75R resistor "fanning out" between a input ground pad and the square grounding pad.
  • In repair-01: For the repair, I simply bypassed the curved ground-shielded trace there; it was ripped halfway out. The pads for the resistors were also heated off. I used some 30 AWG silicon multistranded wire I had laying around. I glued the wire and the resistor down in place (with glue stick glue... ugh!).
  • In possible-remaining-damage-01: I noticed that, at some angles, this trace from signal pad to relay looks damaged too. However, since I have tested the scope's input as pictured and have found no errors, flaws, or extra noise (up to about 10 MHz for fast signals, 300 MHz for sinusoidal ones)... I am just going to leave that as-is.

I suspect I did what was suggested here (and what you may have done): I think I may have mistakenly put a powerful source (in this case, a handheld radio with outputs 60Vpp or RMS, I forget... but a lot) straight into the scope input with a BNC.

Also note: this is clearly not a good enough fix in general. The original trace was embedded in a ground plane, and this is not. I suppose you could have used some very small coax cable (like what's used with SMA) and grounded the outside.
 

Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #13 on: March 22, 2017, 11:18:28 PM »
made some experimental measurements today before taking the scope apart in order to make some images that i will post later.
Signal applied to scope from a waveform generator:
wave form: sine
U = 2Vpp, f= 7, 14, 30, 100 Mhz........scope displays:   20mVpp on all "f"
      5Vpp                                                                  45mVpp
     10Vpp                                                                  90mVpp
amplitude unchanged 7 to 100 Mhz
same amplitude coupled A or D
channel1: however the displayed sine wave is not stable, it moves up and down slightly at appr. 10Hz.
Surprisingly also channel 2 works today giving very similar results. Maybe fiddling around on the rig has changed something.

up to this test channel 2 was dead.

Was the signal applied a sinewave? Do you get the same relations for a DC signal?



The 60V you applied by error were DC or AC? If AC, high frequency?

Find the affected parts should be easy, just follow the path. But avoid links/images/schematics from the non-A versions, because it's input stage is slightly different to A versions. However, I don't know if there are different variants for the A versions, that's why we need images/pictures from your oscilloscope PCB (front-end).

http://www.eevblog.com/forum/projects/project-yaigol-fixing-rigol-scope-design-problems/msg890966/#msg890966
The information contained in the link above should be enough to find/replace the faulty parts, assuming that both are the same variant.
However, the capacitors are a different history, and maybe a big problem, because we don't have any reference, so fingers crossed.

Do you have problems to found the relationship between the electrical scheme and the components in the pcb? SMD marking codes, etc...
For semiconductors this link may help: http://www.ecadata.de/mysuchneu/ecadata.php?F_SPRACHE=1

What components have you checked?

Also, are the vertical position knobs responsive?


Edit 1: Wrong link.
« Last Edit: March 22, 2017, 11:23:40 PM by Carrington »
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #14 on: March 22, 2017, 11:20:08 PM »
@ technogeeky

Wow, almost volatilized!
My English can be pretty bad, so suggestions are welcome. ;)
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Offline Carrington

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Re: Rigol MSO 2202A input circuits damaged
« Reply #15 on: March 22, 2017, 11:53:07 PM »
Non-A version, avoid it. I post it just as a curiosity.
Note: The yellow and black values correspond to different Non-A revisions.
My English can be pretty bad, so suggestions are welcome. ;)
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Online Bud

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Re: Rigol MSO 2202A input circuits damaged
« Reply #16 on: March 23, 2017, 12:20:32 AM »
Use the schematic in the link Carrington provided. Should be a no brainer to isolate the fault.
 


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