Rigol 1022U fried output

[oleksiy]

hi Guys,
recently fried my Rigol 1022 by mistakenly applying high voltage on one of its inputs. close board inspection showed one component with sign of smoke and damage. unfortunately it has label sanded off, giving me hard time to find replacement.. can someone help me identify it ? 

on photo I have I component (choke) unsoldered which was shortened

[Kleinstein]

From the circuit around the 8 pin chip, this is a single OP in SO8 case. It's driving a 50 Ohms output, so it might need to be a slightly more powerful OP. 

[oleksiy]

thank you, Kleinstein

on other post here I just found same issue people reported:
https://www.eevblog.com/forum/repair/rigol-dg1022-attempted-repair-(and-reverse-engineering)/msg950961/#msg950961

it's seems like this is THS3095.. I will go ahead and order it..
also if someone knows where/how I may get replacement for unsoldered component , which might be faulty choke. does anyone have any experience with it ?

[Kleinstein]

The de-soldered ouput filter looks like a current compensated common mode choke, or a kind of 1:1 transformer. AT least this would make sense from the circuit. As the inductance can be rather low (e.g. 1 µH range) this might very much look like two shorts. Its only a problem it all 4 contacts a connected somehow.

For a test one could use two wires through one ferrite bead.

[oleksiy]

Kleinstein, you absolutely right..

I just made picture of cracked unit and counted number of loops.. (12 loops in one row)
based on original dimensions  it might be ACM4532
http://www1.futureelectronics.com/doc/TDK/ACM3225-271-2P-T001.pdf

if I go with ACM4532 (800 Ohm OR 600 Ohm impedance) will it make big difference ?
(same data found on http://www.mikrocontroller.net/topic/203503)

[oleksiy]

hi guys,
just in case it's interesting to anyone.. I ordered THS3095D and installed it..

after I power-up signal generator and set it to any other amplitude above 2v on channel 1 it says "protection overload" and disable channel..
however, if amplitude is 1v on low frequency (300mHz)--> if i measure output on channel 1 it swings from 0.57 to -0.61 volts..

channel 2 has also little difference between shown amplitude and actual voltage..

it seems like THS3095D is not the right opamp for 1022U ?

[ManateeMafia]

Is that a burnt trace to the right of the removed choke?

Also, the TL082C looks like it might be damaged but it could also be fallout from nearby burnt parts.

Look at the part next to J801, it appears that it could have issues based on the solder joints.