Iwasaki TR-3101 Synchroscope

So I was cleaning up, and I noticed a leather case holding some kind of oscilloscope. It looks unused, and from the 60s, based just on look. If anyone has details let me know!

I plugged it in, but I couldn’t get any scanning on the screen (though I didn’t take it down to the function generator). The central light indicator was acting a bit funny as well, it may need repair.

I opened up the side covers, and the inside looks SO nice, “cordwood” style is what somebody said

So I couldn’t get it working on my first go, I didn’t see any blown caps, but it probably needs a full recap, and maybe a calibration after that. If anyone can find ANY details, please post here. I would love to see this pretty little box running again.


Thanks. I donated that scope. It was given to me by one of my co-workers years ago, who found it next to the dumpster in the garbage room of their apartment building.

It sat on the shelf in my office for years – I never got around to doing anything with it, but I couldn’t bear to get rid of it with its beautiful cordwood construction on the inside.


That’s wild, thanks for sharing the pics

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If it works, you’ll likely need two signal generators for testing, as synchroscopes were intended to enable the coupling of generators to one another, or a power grid (damaging currents can occur if large AC generators are coupled out of phase). The role of the synchroscope was to show the difference in phase and frequencies between the two generator systems. Then, speed of the generator being added, could be tweaked to bring it into phase alignment with the initial generator or grid.

I agree that’s what synchroscopes as we know them now do, but I think this doesn’t do that. The controls on the front are very much oscilloscope controls.

Unlike the old electro mechanical types, this type of synchroscope is an oscilloscope of sorts (though very low frequency), and will probably show both generator waveforms superimposed on the same screen to allow for more precise alignment. The controls will likely be for time/div and levels just like in a regular oscilloscope.

My father-in-law loves fixing old electronics and would be delighted to bring that beauty back to life. He’s just finished fixing an old Motorola RF generator from the 70s and has an assortment of old electronics on shelves in his workspace. Would you be open to trading it for a donation to the makerspace/assortment of beer/cash?

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Personally (since I brought to VHS originally), I don’t have a problem with that idea, but I’ll defer to @Rob_MacKenzie in case has plans for it already.

I picked up the synchroscope from John yesterday - thanks guys! I’ll follow up with any updates on getting it working!