Dueling Heathkits

[Jon A.]

No glow, filament seems fine, no reading when checking filament voltage. My meter has been having problems, but I hooked it to a power supply and it checked fine on the same range.

[jr_tech]

Does your answer pertain to the CRT heater or the 3A3 filament?

jr

[zeno]

You usually wont see a HV rect light up. After running a while
it will get quite warm. Odds are the tube is bad. Many early
SS sets ( Moto, RCA, Sony ) used a tube & they went often.
Sony was an exception probably cause they used a 25KV tube
in a 12" set.

73 Zeno
LFOD !

[Jon A.]

Originally Posted by jr_tech

Does your answer pertain to the CRT heater or the 3A3 filament?

jr

Oh, the 3A3 filament. The CRT heaters are lighting. I did notice some purple arcing in the 3A3 though.

Originally Posted by zeno

You usually wont see a HV rect light up. After running a while
it will get quite warm. Odds are the tube is bad. Many early
SS sets ( Moto, RCA, Sony ) used a tube & they went often.
Sony was an exception probably cause they used a 25KV tube
in a 12" set.

73 Zeno
LFOD !

Actually I did notice the HV cage get warm after a little bit when I first started the set.

[N2IXK]

You may have difficulty directly measuring the 3A3 filament voltage, because it is a high frequency (15.7 kHz) and pulsed waveform.

Most AC voltmeters won't read correctly on non-sinusoidal signals. And of course, if the 3A3 plate cap is connected, the filament is floating at HV to ground.

[Jon A.]

Originally Posted by N2IXK

You may have difficulty directly measuring the 3A3 filament voltage, because it is a high frequency (15.7 kHz) and pulsed waveform.

Most AC voltmeters won't read correctly on non-sinusoidal signals. And of course, if the 3A3 plate cap is connected, the filament is floating at HV to ground.

Thanks for the info, I'll keep that in mind for future reference.

Problem solved. There was a VERY loose transistor on the horizontal output board. One leg wasn't being gripped at all. I re-seated the board just for good measure, stuck a piece of wire beside the loose pin, powered on and presto, the HV was back. The picture is awful and barely holds sync in either direction, but hey, she's a runner. The piece of wire can barely be seen in the photo.

Edit: Later on it lost vertical sweep. The fellow I got it from did say it has a vertical problem.