For Sweep interference from the SM-220 back into either a TS-520 or TS-180S, install an additional shield in the RF compartment in the SM-220.

1. Disconnect the power cord from the back of the scope.
2. Remove the scope top cover.
3. Loosen the function and RF ATT shaft couplers using a 1,5 mm allen key. Withdraw the shafts away from the RF compartment.
4. Remove RF compartment screws from the rear panel.
5. Remove 4 screws to open the RF comp.
6. Remove one screw to remove internal shield.
7. C6, a .01uF. runs from the Function Switch to a ground point under the RF ATT switch. Cut the ground lead and shorten so the cap is grounded to the ground point under the Function Switch.
8. R2, a 10 Kohm, is attached to the terminal strip directly under the Function Switch. Reposition this resistor from the top of the terminal strip the bottom of the strip.
9. Install the additional shield to the ground point under the Function Switch.
10. Reverse disassembly procedure to reassemble.

We have found a few cases of feedback when the pan display option was installed in the SM-220 Station Monitor. This is due to the isolated ground of the BS-5 or BS-8 pan display option.
It may be remedied by grounding the case of the input transformator in the BS-5 or BS-8 to the case. (See drawing below.) This change will be incorporated in all future delivered of the BS-5 and BS-8.