Re: Bulbdial Kit – Issue with Multiple Blue LEDs

Home Evil Mad Scientist Forums Clock Kits Bulbdial Kit – Issue with Multiple Blue LEDs Re: Bulbdial Kit – Issue with Multiple Blue LEDs


Hey Windell,
Thank you for your response.

Before beginning the project, I installed a brand-new, out of box soldering tip, also from Radio Shack, a part number designed specifically for my soldering iron. I tinned it according to the instructions and standard practice, and it was kept clean during assembly using a moistened folded-up paper towel. Not high tech, but it does the job.

Since updating this forum post I have been back to my kit. In manual blue ring testing mode (or whatever it’s called) I was able to signal each of the problem LEDs on with the +/- push buttons and each time I was able to read between 4.5 – 4.9 volts DC at each of the problematic LED leads, polarized in the correct direction. If that’s not enough, I also measured voltage at the resistors that power each LED combination, and found 4.5 – 4.9 volts DC at the resistors as well. Finally, with power removed, I was able to check continuity between the resistors and the leads to the LEDs. In all cases, the solder joints and components supplying power to the LEDs appear to be working properly according to my multimeter.

D25 reads voltage between positive at R2 and negative at R5
D16 reads voltage between positive at R1 and negative at R6
D61 reads voltage between positive at R6 and negative at R1
D13 reads voltage between positive at R1 and negative at R3
D23 reads voltage between positive at R2 and negative at R3

Sorry to differ with your previous experience with other customers, but if I can read 4+ volts at the base leads of the LEDs in the correct polarity, and they do not light, I would have to believe the LEDs are at fault. I suppose there could still be a current delivery issue even if I can read voltage with a voltmeter whereas under the 100-some-odd milliamp load there is an issue, but alas, I digress.

I wish now that I had tested them ahead of time, but I didn’t expect to be left with 5 dead LEDs so early in the assembly process.

I read here and else where the you do not recommend reheating or reflowing a joint – I’m very curious how you propose to repair a cold joint, if not with heat? Not an excessive amount of heat, mind you, but enough to fix the joint? I guess I don’t understand this recommendation. The solder tip is applied for a few mere seconds – again a 30 watt. How do you replace parts if not be reheating and removing them? This advice sounds absolutely bizarre to me.

This second bulbdial kit was a gift. I suppose this isn’t the right forum to address that however with the return/exchange issues and whatnot, I will take it up with customer service if there’s no other avenues to pursue here.

Any chance the exact specifications of the blue LEDS are available? What voltage, forward current and brightness characteristics do they have? I guess I’d like to see if it’s possible to source the replacements elsewhere in case customer service isn’t willing to replace since, this was a gift, it’s been halfway assembled already, and the assumption that the customer has overheated any LEDs that fail to light – becomes an obstacle for me.