Philips PM3305 Oscilloscpe

[Refugee]

Be careful even with X10 probes.
An engineer I once worked with tried to measure ripple on a high voltage power supply with one and it went bang and smoke came out of the matching adjuster hole.
The power supply exceeded the maximum DC voltage of the probe and it let him know in no uncertain terms what he had done wrong.

[Murphyv310]

The scope is 400v max.
The amp in question HT Is less than 300v
The issue IMO is an earth loop.

[Refugee]

The unit that blew the probe up was significantly highrr than 400V.