Checking LED on soft start - two won't light

[Paully]

I put a good bit of solder on my LEDs so I thought I would check them to make sure I didn't burn any out.  Two won't light.  But oddly it is the same two on each board.  With the boards oriented as instructed it is D1 on the left hand side of both boards.  Any reason they shouldn't light up?  If not, I will replace them with some extras I have.  Thanks!

 

[Paul Joppa]

Have you adjusted the trimmer for the correct plate voltage?

 

[Paully]

I haven't even installed the boards.  I was just using my voltemeter.

 

[Brillo]

Not ruling out that there may be an issue Pauly, but these two LEDs take a little while to 'warm up' at first.  I thought I had an issue when starting in on the voltage checks described in the manual, but after about a minute these two LEDs were glowing brightly. 

 

[Paully]

Cool, thank you!

 

[Paul Joppa]

Oh - OK. It's the soft start delay, which takes 20 seconds if you apply 300 volts ... got to charge up that 10000uF cap before the LEDs can glow.

 

[Paully]

Heh, heh, I feel kind of silly now!  It was probably going to take my voltmeter a while to charge that capacitor...

 

[Grainger49]

I don't know the schematic, is the capacitor in parallel with the LEDs that are not lighting?

 

[Paul Joppa]

I don't know the schematic, is the capacitor in parallel with the LEDs that are not lighting?

Yes it is. It charges slowly, from the LED bias current, preventing the LEDs and transistors from turning on until it is charged.