[visionlist] Photo Research PR-655 and Macs?

Andrea Grant gran0260 at umn.edu
Mon Jun 27 17:20:39 -04 2022

TL;DR: PR-655 freezes when connected to any Mac but works fine with Windows

I have a Photo Research PR-655 that was purchased in 2012. For about 8
years I ran it mostly from a Mac to measure luminance curves of projectors
and displays. A few years ago it stopped working with any of my Macs--the
behavior I observe is that w*hen I plug the USB cable from the PR-655 to
the Mac, the PR-655 freezes up* (sometimes instantly, sometimes after a
minute or two). Both the PR-655 display and the ability to put it into
remote mode and take remote readings stops working. I sent the unit back to
PR for repair and calibration and they said the unit is working normally.
It works fine when I connect it to Windows computers, and PR said they test
them only with Windows and couldn't help me debug this issue with the Mac.

The most maddening thing is that I have a Mac laptop that I have set up to
dual boot into Windows--the PR-655 works fine when the laptop is booted to
Windows but has this freezing behavior when booted to Mac--identical USB
hardware! I've tried numerous Macs (both old and new, USB-A and USB-C, OS
from 10.10 up through the latest). I also tried using a USB current meter
in between the PR-655 and the laptop in both OSes but couldn't see any

I'm wondering if anyone else has encountered this and if you have figured
out what the problem is.


Dr. Andrea Grant, Ultra High Field MRI Manager
Center for Magnetic Resonance Research, University of Minnesota
gran0260 at umn.edu
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