A Heathkit IT-12 Signal Tracer, part 2: Missing the obvious.
Monday, May 25, 2026 at 18:58:58
And miss it I did.
I did some troubleshooting on this device, checked tubes, voltages, transformers, there’s even a video about it that will show up soon and will be linked as soon as it posts. But I overlooked the obvious thing.
You see that switch in the middle of the device marked “Speaker On/Off” Good. You were probably screaming at the screen going “CHECK THE SWITCH!” I finally checked the switch. It was dirty and open. Some Deoxit later, and the tracer now works just fine.
That time was not wasted, however. I did confirm that the filters are good and that the coupling capacitors aren’t leaking, so I feel confident that I can use this device without worrying that it’s going to red-plate a tube - even though that 12CA5 output gets smoking hot.
What’s the takeaway here? Always check the little things because they tend to bite just as hard. That’s all for this device, it goes on the bench as an amp. Plenty more on the EICO 950A to come!
Previous part of this series: https://wereboar.com … -part-1-examination/
Youtube videos on this device: Coming soon.