Fluke 8520A Err23 HDWR Time error, incorrect response from A/D Converter

[mario_nks]

Hello,

Unfortunately I have a non-functioning Fluke 8520A.

I have already found an error:
Err17 HDWR_ | Sync failure between the microprocessor and the A/D converter

Here it was IM6402-1IPL defective.

BUT:
But now I still have the following errors:
Err23 HDWR Time error, incorrect response from A/D Converter

I just can't get any further here.

Can someone help me here?

Kind regards

Markus

[mario_nks]

Can someone explan me where the " guard crossing cable" is located ?