Tonight I was working on the IF alignment of my Silvertone/ctc-15 chassis. It is on the bench, as it has been quite a while now. I have the horizontal output tube and the horizontal oscillator tube removed, and a resistor loading the power supply down to simulate the current draw of the horizontal section and the CRT.

Last night I thought I heard a little snap. Not normal crackling, either. The high voltage isn't running. I couldn't find a source, so I just went on. Tonight there was another little snap. This time I saw a little spark from voltage doubler area of the low voltage power supply. I started beating on power supply parts with my alignment stick. I hit one of the power supply diodes and KA-SNAPPPPPPPPPP!!!!!!!!!!!! :yikes:. Sparks flew from the connection at one end of the diode and the circuit breaker tripped. Oops :rolleyes:. On closer inspection the wire running to the floating 160mfd cap was not soldered. I don't think it had ever been soldered. It wasnt even tinned.

I soldered the wire on and tried to bring it up on the variac, but no dice. I pulled the diode out. Sure enough, It's shorted. I pulled the other one, and it was ok.

I had already redone a lot of soldering in this set. The wave soldering on the boards was typically bad. I redid a lot of it. I also cleaned up several old ugly repairs under the chassis, but I missed this. It had apparently been laying there unsoldered for the last 42 years or so, and working fine.

John

I started beating on power supply parts with my alignment stick. I hit one of the power supply diodes and KA-SNAPPPPPPPPPP!!!!!!!!!!!!

heh. Sounds as though your TV doesn't like abuse:D

Seriously that really sucks. I've run into a few sets that had been worked on by the previous owner, who didn't really re-attach a few things causing arcing and other problems. Now every new set I aquire goes through rigorous inspection. I hate that HV snap. Makes me jump every time...

So what would be the effect of that cap not being connected if otherwise the set was working?

It had to be making connection... barely. If it was disconnected half of the 405v B+ would be missing. Theres a thread somewhere here about a Zenith doing exactly that. It was dim, didnt have much deflection and had a bunch of what looked like 120 cycle ripple in the picture.

John