DSO4102c waveform generator broken?

[jjedele]

Hey all,

First post in this forum, despite having watched the Youtube channel for a while now! I'm an informatics person with a hobby interest in electronics and just got a used KKMOON (Hantek relabelled?) DSO4102S for cheap as my first oscilloscope to play around with.

The measuring seems to work nicely, but the waveform generator seems to be broken somehow. (Or I really don't understand how to set it up, but I think I tried everything, including auto-calibration). It seems to always have an output of ~+2.2V, even when it's turned off. The waveforms themselves seem to be OK, but I don't get the amplitude to exceed  ~200mV.

I uploaded a video of the whole thing here: https://share.mailbox.org/ajax/share/066c778800548d44614c9350548d438bbf13a65ea1f8b589/1/8/MzQ/MzQvMTM1.

I learned in another post in this forum that the AWG consists of two stages:

• Generation stage based on a DAC902E
• Amplification stage based on a EL5166ISZ op-amp

I have the suspicion that the AWG might have been used in a way that overloaded the op-amp and it blew, now shorting this constant offset onto the output and not amplifying the signal. I would hope the DAC is OK, since the general waveforms look good.

But before I try to find a replacement for it, I was wondering if people with more experience think this is a likely scenario or if it could be something completely different

All hints appreciated - thanks!
- Jeff

[jjedele]

Seems the diagnosis was correct. I replaced the opamp and it works like a charm again