Hello all. I've got isssues with a Sundown SAZ500D preamp board. It is not outputting any audio to the driver card. I recently solved this problem by swapping out IC102 (JRC074D) and it worked. However,the driver card failed and since then ths preamp board is no longer producing any audio. I replaced this IC again but now, I've got 6.2V of DC on pin 14 of this IC and no audio. (According to the datasheet, pin 14 should be output 4). When i crank the gain, bass and sub knobs all the way to the max, there is a small half of a sine wave riding along the 6.2V of DC but that only appears when i turn the gain, sub and bass boost pots all the wat too the max. I have swapped out this IC 6 times for brand new TL074 ICs and everytime i drop it in, the DC reappears in pin 14 and no audio. However, with the IC removed, I've got -0.6V on pad 14, -0.7V on pin 13(input 4). On all the other pads which are supposed to have audio (according to the 074 datasheet), there are sine waves present, but there are no waves present on 13 input. Can anyone advise me here on what else to check? I have got two of these preamp boards with the exact same problem. Will attach a schematic and some videos for reference if i can.
