Saturday, 12 September 2009


Since I couldn't see one of the pads under the edge electrolytic capacitor (C10), I wasn't able to check continuity across the pads to see if the capacitor had made decent contact with the board. I tried checking from the wide terminal of IC3 5V regulator to one side of the capacitor (continuity found with R set to 2000 k ohm on multimeter), but could get nothing from IC3 to the other side of the capacitor.
I decided to see how firmly it was attached, and when it wobbled slightly under pressure, I peeled it away from the board. I shall remove the solder that's there and re-solder by hand.

As for the other electrolytic capacitor (C11), I can't get any readings at all, owing to the proximity of the chip on one side and the molten black plastic in the way on the other.

I checked the LEDs with the diode setting on the multimeter, and was pleased that all A B C and D LEDs lit up, and that using the probe terminals the wrong way round lit up the neighbouring LED instead! That shows that there is continuity of those circuit portions.

Unfortunately, I couldn't get the power LED to light at all, even using the component casing (either way round), so I guess that's a dud, then. That means I can't check the power circuit, with those electrolytic capacitors, as a whole. More hand-soldering coming up, but again, I don't have any spares.


  1. It's may be absolutely fine that the Power LED couldn't be lit by your probe.

    Other stuff on the board might have taken the power from your probe, say they are used to power up the ICs, and so nothing go through the Power LED.

    Sometimes you need to believe yourself, be bold and put the power in :).

    Just make sure all your cap and ICs are correctly oriented, no shorts from the solder remains and such, and it shouldn't end up in smoke :)

  2. yep, once you've soldered a circuit, things can have a knock-on effect - like the battery in the multimeter trying to power-up the entire circuit!

  3. Yep, I think you're both right. I shall have Faith!