Topic: ADI 8-DS converters partly out of specs
first of all: Happy new year.
I've got a used ADI 8-DS MKII here, bought it via eBay. It was built in November 2010. I was fiddling around with it for a bit and it turned out that the converter for channel pair 3 and 4 runs out of specs.
I was measuring SNR (unweighted) at loGain position, these are the results:
Channel 1 + 2 : 115 dBfs
Channel 3 + 4 : 103 dBfs
Channel 5 + 6: 114 dBfs
Channel 7 + 8: 113 dBfs
I consider the readout of channels 1,2,5,6,7 and 8 as normal. Channels 3 + 4 with their 12 dB difference compared to channels 1 +2 are apparently not behaving as they are supposed to.
My first thought was that there might be a problem with the power supply, since the SNR drops about a dB from converter to converter - but since channel pair 3 + 4 are about 12 dB up in noise I'm not so sure about this. The power supply looks fine, no bulging caps. I was contemplating replacing it anyways, because I read here and elsewhere that aged power supplies could lead to overvoltage in this unit.
Any thoughts what the cause for this all could be ?