The EICO 150 Solid State Signal Tracer: Wrapup and final thoughts.

Friday, May 8, 2026 at 06:04:59

The EICO 150 is finished…for now

This was an interesting device to repair, but it’s a good example of why you have to expect the unexpected when working with older equipment. Never assume that what you’re going to find is the same as what you’d find in a new device.

For the most part, the device was functional but needed all the small capacitors replaced. I went one step further and replaced all of the capacitors, because why not? You’re in there, just do it. Capacitors are cheap and will extend the life of the device. Resistors were checked, most are within or close-enough to tolerance that I didn’t worry about it. The biggest issue was the speaker.

Small value parts probably could have been left in place, but I’ve seen some of the styles in there short out. Again, they’re cheap, replace them.

Diagnosing the EICO 150

Initially, I looked at the output transformer because the color-codes on the wires were wrong. While the original kit builder installed it correctly, it still took a hot minute to figure out what was going on. I took the opportunity to extend the wires on the transformer to reduce stresses on components, and re-installed it according to impedances.

The transformer was fine, so checking the speaker was next. DC resistance was really low, and impedance was also low enough that it was mostly zero. Speaker was shorted. Why? Not sure, perhaps age did something, or maybe as Mr. Eric HABETS from my LinkedIn crowd suggested - someone used it as an external speaker and blew it out. The world will never know.

What I do know here is that there’s still some issues within the output side of the unit. Vc should be zero, or close to it - but it’s not. There’s also the noise in the unit. Either a resistor is bad, or a transistor is breaking down under load. I have new transistors for the unit, so I will probably open a new project with this device and replace the remaining passives and clean up some of the messy wiring on the bottom.

This was a fun, interesting repair. I’m hoping perhaps I can find some transistor output transformers, or a complete unit at Dayton for comparison checks. Stay tuned, there will be more with this device later.