Long story short, I am in the middle of repairing an AWG2020 arb generator I got very cheap on ebay. I have restored a lot of things (all SMD electrolytics leaking all over the boards, PCB traces, pads, and the dead ADC chip) but I now have error 630 which according to TeK support guy means "5 X mag DA offset adjust fail". I know for sure (tested multiple times) that the big wideband CFA op-amp CLC561AI is dead. I am planning to replace it with a THS3001 or THS3091. I will install it on a small adapter board and connect the pins by wires and change the feedback resistors to have the same 20dB gain and 50 ohm I/O impedance like the original amp.
But that amplifier is only switched into the signal path (ahead of the attenuators) for amplitudes larger than 500mVpp. Below this amplitude that op-amp is completely cut off from the signal path by two relays. So I dont know if that is related to the error 630 or not.
However, I have two more suspects one of which I cannot even identify what it is. One is an 8 pin SOIC marked 842 (there are two of them. I suspect the lower one which has -15V supply) By the looks of it and the circuitry around it, I am pretty sure it is a UPC842 dual op-amp. It definitely looks like a chip by NEC. It is not in the signal path and certainly it does something else (perhaps used in auto calibration of amplitude or offset).
The other suspect is another 8 pin SOIC marked as CL404A. There are 2 of them on the analog board. I cannot find out what it is. I have looked everywhere and there is no information about this IC. I don't think it's custom made. It has no tektronix number on it and seems to be from a third party. Anybody has any idea what this IC is?
thanks