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Tomasz Sokołowski edited this page Feb 11, 2026 · 7 revisions

Preface

Due to the rising cost and worsening availability of original light bulbs for old slide projectors (especially: BA15S bayonet-mounted 220VAC 150W and 250W bulbs) an idea was raised to develop a simple retrofit solution to use modern halogen light bulbs in these projectors. The modifications described below were developed using Pentacon Filius 4 projector and then adapted to other projectors. To this moment following projectors were converted:

  • Pentacon Filius 4 (including version with additional active cooling)
  • Leitz Prado 150
  • Leitz Prado 250 (in multiple versions: with and without additional active cooling, with extended base)
  • K.W. Belplascus V
  • ŁZK Diaprex Prexer B11 with Rotokolor attachment

The intention of this manual is to present already made modifications as a guideline and a starting point for all enthusiasts who want to replicate developed upgrade.

Important safety notice!

The operations described in this manual require working with 230VAC voltage as well as DC currents up to 15A. DO NOT PROCEED with any works without understanding the basic principles of electrics physics, electrical installations, safety precautions and limitations.

ERRORS DURING ELECTRICAL WORKS CAN CAUSE ELECTRIC SHOCK, WHICH CAN RESULTS IN HARM AND DEATH. IMPROPER ELECTRICAL INSTALLATION CAN CAUSE DEVICE FAILURE, DAMAGE AND FIRE.

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