How to check the components of the soldered kit?

[Jens]

I just finalize my second TV-B-Gone kit. When I pressed the button (or insert the battery) the green LED is only blinking few times (not flashing like a code signal).
I checked the processor (with the first kit) - it works.
First the infrared-LED slowly blinked (check with digicam) - but now nothing just the green.
The ceramic oscillator may be faulty?
How can I check all electronic components with my e.g. multimeter?

Thanks.

[adafruit_support_bill]

Most problems come down to soldering. If you post clear photos of the front & back of the board we will take a look.

[Jens]

Dear Support,

Most problems come down to soldering. If you post clear photos of the front & back of the board we will take a look.

Hopefully clear enough:

[adafruit_support_bill]

A couple suspicious joints on the ICSP header, but that shouldn't affect normal operation.
Are you using a fresh battery? That symptom is consistent with a weak battery.

[Jens]

Yes, the batteries are fresh. I checked it with an other TV-B-Gone.
And, I re-soldered (melded) all pins.
So, back to my first question. How can I check the single elements?
A link forward to a wiki or - old school - a book will be fine.

[adafruit_support_bill]

It is difficult to test individual components once they are soldered into a circuit. What test equipment do you have access to? You can verify the operation of the oscillator with an oscilloscope or a frequency counter. With a multimeter, you can check that the battery voltage stays relatively constant. If the voltage sags significantly during operation, that would indicate a short or damaged component somewhere. Those can often be located by feeling for what is getting hot.

[adafruit_support_rick]

I suggest double checking that you installed the right transistor at Q5. The 5 transistors all look alike, but Q5 is a very different part. Q1, Q2, Q3, and Q4 are NPN transistors and should all have the same markings, while Q5 is a PNP, and will have different marking.

[Jens]

Thanks to driverblock,
Yes of cause I double checked before I posted. Every component is at there right place.
4 equal transistor "PN2222A" close to the LED and the single transistor "PN2907" at the single place.

Thanks to adafuit_support,
Yes I have only a multimeter. I checked the lack of voltage, it fall only from 5V (4 x 1.2V AAA accu) to 4,8V while I pressed the reset button.
So, my next steps are to re-solder single components and solder it in an existing (working) TV-B-Gone or give google a try.