That MHS-5200A function generator

[Alex Eisenhut]

Got one a few months ago. Seemed to work, so I stored it for future use.

This morning, the display lights up but no characters appear.

Voltages seem to be present inside next to the regulators. The STM processor has power, but scoping the oscillator I didn't see anything, it's a 16MHz crystal. I'd expect to see something there, no?

Is there a known defect here? I've looked and not found anybody mention that it just stops working.

[SaabFAN]

Usually there should be something resembling a square wave at th crystal, but I found out that some processors that are advertised as low power do not show any activity at the crystal when probed with a passive scope probe.
More telling is if there's something happening at the other pins.
Also check the power-pins. If there's basically no noise, then the chip isn't working properly (no switching noise from the processor).

What are the lights and buttons do? Is there a signal present at the outputs or at the input of the relays?

[Alex Eisenhut]

Thanks, for now it's back in the box. I'm starting to re-think my "cheap Chinese test gear" philosophy.

I might have to go back to "crusty long-obsolete 1960s stuff full of tubes and weird ICs".