HP82160A HP-IL troubleshooting

[MeindertKuipers]

Thanks JF,

Then its is probably the zeners in the input circuit. When I test them with a DMM in-circuit I get a beep in both directions for both zeners, but in this case I am also measuring through the transformer which has a very low DC resistance. Next is to remove the zeners and test them off circuit.

Is it safe to test the IL loop without the zeners? I am a bit uncomfortable with this analog stuff ...