I am currently reworking my ATS2. Since I haven't found an official calibration procedure I'm starting this thread, maybe someone is interested in exchanging ideas.
The first thing I did was to replace some faulty AD797 opamps (got incredibly hot and caused very high THD values). I have also replaced some caps. Now all values are okay. Nevertheless, generator B produces much higher THD values than generator A when the system gets warm, but they remain just below the specs.
I was able to identify the effect of most of the trim pots by trial and error, I will try to summarize the results here later. Does anyone have any idea what the pots circled in red in the picture are tuning
I hope someone is interested as well.
Best regards
The first thing I did was to replace some faulty AD797 opamps (got incredibly hot and caused very high THD values). I have also replaced some caps. Now all values are okay. Nevertheless, generator B produces much higher THD values than generator A when the system gets warm, but they remain just below the specs.
I was able to identify the effect of most of the trim pots by trial and error, I will try to summarize the results here later. Does anyone have any idea what the pots circled in red in the picture are tuning
I hope someone is interested as well.
Best regards
Attachments
If those opamps became so hot you had to replace them, I wonder what else is defect.
Maybe fix that first before attempting calibration.
The go-to guy at this forum for AP stuff is @Audio1Man .
Jan
Maybe fix that first before attempting calibration.
The go-to guy at this forum for AP stuff is @Audio1Man .
Jan
Sorry for the delay in this thread. I am currently working abroad with my main job.
Nothing else seems to be defective. The operating conditions fit, the search for bad solder joints and defective chips etc with icespray brought no further results. Only when one DAC was treated with icespray did the THD values drop further. After I replaced it, I got top values for both generators. The cross-check with my system one confirmed this.
However, I have often heard that AD797s change their values as they get older! I mean they are high end BJT based opamps with great noise figures, maybe that's why they are a bit sensitive
As I bought the ATS2 second-hand, I also don't know whether it was always handled properly.
@Audio1Man : Is it possible to get official documents for the calibration?
When I am back home I will provide further results.
Thanks all for participating in the discussion!
Raik
Nothing else seems to be defective. The operating conditions fit, the search for bad solder joints and defective chips etc with icespray brought no further results. Only when one DAC was treated with icespray did the THD values drop further. After I replaced it, I got top values for both generators. The cross-check with my system one confirmed this.
However, I have often heard that AD797s change their values as they get older! I mean they are high end BJT based opamps with great noise figures, maybe that's why they are a bit sensitive
As I bought the ATS2 second-hand, I also don't know whether it was always handled properly.
@Audio1Man : Is it possible to get official documents for the calibration?
When I am back home I will provide further results.
Thanks all for participating in the discussion!
Raik