[Musaeum]

If you are still using a UPS, it may, in fact not isolate you from the AC line. Only true "On Line" UPS units where the power is rectified, batteries are in line, and then inverted back to AC will isolate.

Actually I use (or used) the UPS from battery only, no connection to mains. So I could be quite sure there was no galvanic connection to anywhere.

But since I had rather strong hum all over the scale I ran it from mains which improved things a lot. Leaving the dreaded tuning-hum I'm currently fighting with.

Perhaps I'll leave it like that. My friend will certainly be happy using it as a couple of stations come in nicely and the "dangerous" parts have been changed. With todays line voltage I get 326 volts on B+ instead of 315. That is less than 5% above nominal, should be OK.

cheers
Martin