- 2025
- Jun
- 18
The Heathkit AG-7 Audio Generator part 4: Repairs
In the last post, something went bad in the oscillator portion of the Heathkit AG-7.
There were other things wrong as well, if they were caused by or were pre-existing to this failure, I don’t know. But one of those was easy to fix, that of the 10kΩ resistor in the power supply. This resistor decided it was going to be about ~300Ω or so, and had to go. Fortunately, I had some spare 2W units from a previous rebuild project, and put one in.
That, unfortunately, didn’t fix the issue. Since everything else seems to be mostly ok, I have to assume that I damaged the tube(s) during my testing of the device, or the incorrect power supply voltages damaged the tubes and it was just coincidence that it failed when it did.
Therefore, this unit gets set aside until I can replace the two oscillator tubes, verify it works, and rebuild the unit.
In the meantime, here’s the 10kΩ that was removed.
It looks pretty crusty at this point. Not sure what cause it to short.
But short (relatively) it did:
This one goes in my bin of oddball parts for later fun.
Next part of this series: Coming soon.
Previous part of this series: https://wereboar.com … or-part-3-diagnosis/