The attached excel file is a list of broken cards that have been looked at. With most of these cards at least one bad component or connection had been identified. Bad components have also been marked with tape. The cards are in a box labled “PREAMPS TO BE FIXED”

broken_preamp_cards.xls

The following is a schematic of a SINGLE CHANNEL on a preamp card. Each preamp has two channels. The LS221 and SN75183 chips are each dual packaged so there is only one of each per card.