Optical Attenuator teardown Repair

Pete sets out to fix a recently acquired Photodyne 1975XQ optical attenuator to add to his lab. But it is not to be, an unobtanium missing EPROM makes life difficult. But the video still shows the teardown and quite a lot of details about the circuit as Pete checks which parts are, and are not working. He deides to use the optical assembly as the basis of a future project.
Contents:
00:00 - Introduction and Ominous label
00:53 - Take it apart
01:06 - Optical Attenuator implementation
07:50 - Power Supply Recap and testing
11:38 - First Power On - Oh Dear!
12:04 - Internal board Overview
14:40 - Processor Board in Detail
16:06 - Why is there a DAC and OPAMPS?
18:17 - Is the missing EPROM an option or essential?
20:17 - Motor Driver Board
21:18 - Display Board Diagnostics
24:38 - Keypad logic
26:18 - Reviewing the faults
26:41 - A Plan is hatched A MOD
27:55 - How does a linear graduate make logrithmic attenuator
28:18 - Final throughts and wrap-up
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I looked at keeping processor board and writing a new program including new display driver, but couldn't face the assembly programming.