Gauges not working when headlights are on

[Lugnut]

I woke up to snow again this morning in north Georgia, so I drove my '79 K20 to work. I noticed this morning that when I turned on my headlights that I had no dash lights, the dash blinker lights came on, my gas gauge went to empty, oil pressure went to 0, and heat gauge went beyond hot. If I turned my lights off everthing goes back to normal. I haven't had time to look into it yet, but hoped someone might have an idea where to start looking.
Thanks

 

[bucket]

My '77 did that once, it turned out to be a bad spot in the cluster's printed circuit. It was repaired by soldering in a bypass wire to go around the bad spot.

 

[Lugnut]

Thanks, I checked fuses and grounds, but I haven't pulled the cluster out yet. Will do that this weekend once all this snow is out of here and it warms up a little.

 

[bucket]

Oh, and IIRC, the bad spot was in the ground trace around the perimeter of the cluster. I think it was near an edge and moisture probably got in between the layers over time. It's been a few years though, so I could be talking out of my ass at this point

 

[Lugnut]

Thanks bucket for the heads up. I pulled out my cluster yesterday to find that the printed circuit had started coming apart, and some of the copper had broken. I had another printed circuit laying around and changed it out and everything is working again.

Tried to post it up last night but couldn't find it everything got moved around.