Initially I just power up default an hook probe to the probe compensation signal. Ch1 selected, 1V trig lev 320mV DC. 500us.
Changing time base up or down does not matter no signal. Changing input level from mv to Volts same. In with CH2 /3 or 4 relay click and we have signal
After leaving it on for more than half an hour it sometimes work ok, but then just a yellow line above zero that does not react on my finger on the probe. In with channel4 and bang i triggers ok, out an its gone.