142 gtl blowing fuse at turn on

[nomadradio]

Boy, did I screw that up. Interpreted "not showing any ohms" as low ohms, or a short.

What you meant was there was no continuity at all, as if you had not connected the meter's leads.

Oops.

And that's what you should see. No response from the meter at all.

It's time to check each of the four diodes in the rectifier bridge. At least you don't need to unsolder it for that test.

Let's hope it isn't shorted in a way that could feed AC voltage into the DC-only filter cap. Not good for it.

73

 

[kaos513]

I hear the transformer humming power switch turns off the humm I'm assuming the rectifier is gone

 

[Shadetree Mechanic]

Check for voltage out of the rectifier

 

[kaos513]

Think voltage regulator went South.

 

[nomadradio]

There are four rectifiers in the full-wave bridge circuit. If only one of them goes bad, the AC current through the transformer winding becomes out of balance. More current flow in one direction than in the other.

That will cause a perfectly-good transformer to hum. Usually louder as you load it more.

Only takes one of the four diodes in that bridge to fail and cause this. The "diode" test on your multimeter is your friend for this test.

73

 

[kaos513]

fixed the issue d60 was shorted.

 

[nomadradio]

Rock on! Glad to hear you found it.

Congratulations for sticking with it.

73