A Philips GM4144 R-C Bridge, part 1: Observations
Friday, June 19, 2026 at 09:15:46
This piece of equipment was purchased in the same lot at the EICO 150 Signal Tracer that was posted earlier. This is the other piece that caught my attention and one of the reasons I bid on the lot. This one, as with the tracer, had some issues but they are more related to age instead of customer modification.
This is a relatively unusual piece of equipment for the USA, and is built to a different design language. Here’s the front panel of the unit:
The unit has the standard eye tube as it’s indicator, much like other bridges. This one uses a European variant (of course,) the EM34. This is a relatively unusual tube that’s roughly equivalent to the 6E5. It can be replaced with, but requires some changes. It also has a strange rim-connected socket type. It also uses an EZ40 and an EF40 as the business end of the device. That’s the rectifier and a pentode amplifier. There are rough equivalents to those, but they seem to be easily available which is good because they were not in the device.
It also had this monstrosity attached as the power cord:
While that apparently is a real piece made by Leviton, it looks so janky and is so improperly used that I originally questioned if it was real.
Under a back plate is a voltage selector dial that has a number of different voltages on it:
The original serial numbers are still attached:
The unit features a set of jacks on the side that allow you access to all of the internal voltages.
Inside, the device is built like a brick s**thouse.
It does have an immediate issue, however, the dial cord that drives the dial is broken. I hate dial cords.
I’m planning on at least giving this thing a go at living again, we’ll see what happens.
Next part of this series: Coming soon.
References
Device manual: https://wereboar.com … 0RC%20Bridge.pdf.zip