Electroplating Machine in Talking Book Production

Print, Photographic

Accession Number: 2019.11.8-10

Description: Three (3) prints, electroplating transformers in Talking Book Production at the American Printing House for the Blind. In (.8) David McGee looks at the camera.

Print Size: 3.5" (h) x 5" (w)

Date: ca. 1986

History/Provenance: From Dave McGee, then an electronics technician at APH: "These are the plating rectifiers used to make the nickel stamping masters for record production. One photo shows the condition that the equipment came to APH. It is the one that shows bank of fins (Selenium Rectifiers) used to convert the AC to DC. At the bottom are 3-phase transformers (Saturable Reactors). These converted the 240Vac to 28Vdc. This type of transformer uses a separate "small" transformer that takes low voltage from the mother transformer, feeds it back to the "mother" wound in such a way that it can totally shut the "mother" down. Output essentially going from 0v/0amps to 28v/200amps. I rebuilt using solid state diodes; 6 mounted into copper plates above the transformers. Above that in the black plywood box is a bank of 12 capacitors. There was a fan that blew through the cabinets to keep everything cool. The timer was simple to allow the operators to set the amount of plating time. The reconfiguration of equipment allowed for almost pure DC to be sent to the plating tanks. We reduced plating time from about 6 hours down to a couple. We also had about a 50% reject rate on stampers; this went to zero."

Credit Line: APH Collection, 2019.11.

Subjects: Machinery