Problems with CH 4 in Lecroy LC574AM Error CL_match_gains_or_offsets: 4,8.

[hafrse]

Hello,

I have newly acquired a used LC574AM, but it seems there is a problem in channel 4. When I connect to the cal signal and press Auto Setup, a message appears in red  CL_match_gains_or_offsets: 4,8.

The displayed trace shows noise only when Volts/Div is lower  or equal  0.2V.

Any clue where to look? the instrument had manual Reset a number of times but still the problem shown. The other 3 channels are ok.

Please see the attached images, last image is when zoomed
Thanks in advance!

George

[nctnico]

With a bit of luck you can swap the EXT input module with the module of channel 4. But likely this is a contact issue to re-seating the input module itself might do the trick.

[hafrse]

With a bit of luck you can swap the EXT input module with the module of channel 4. But likely this is a contact issue to re-seating the input module itself might do the trick.

Thanks, do I need to open the instrument or just release the 2 screws and slide back?

[nctnico]

With a bit of luck you can swap the EXT input module with the module of channel 4. But likely this is a contact issue to re-seating the input module itself might do the trick.

Thanks, do I need to open the instrument or just release the 2 screws and slide back?

You'll need to open & disassemble the oscilloscope quite a bit. On my Lecroy Wavepro 7200A it was a difficult job especially due to Lecroy using threaded standoffs which may unthread at the wrong end. As in turning the entire threaded standoff instead of releasing the screw. You'll see once you open it up. Be really carefull not to bump / scrape the casing onto the boards. If you can flip burgers at McDonalds, you can also have a career as a senior mechanical engineer at Lecroy 

The screws at the front just hold a bit of plastic in place to make the connectors stick out nicely.