Problem with VAGCOM Adapter 2.4

Hi!

I soldered the adapter together today.
LED 4 lights up when power is on.
LED 3 is blinking at longer intervals, regardless of the potentiometer setting.
LEDs 1+2 are not blinking at all during the LED test (VagCom 2082DE).

VAGCOM also reports 'ComPort status:OK, Adapter status: 3 - not found or not ready'.

Unfortunately, I only have enough electronics knowledge to read a schematic and solder something based on it, and I vaguely remember what resistors and capacitors do; after that, things get hazy.

Since LEDs 3+4 are lit, I think I'm smart enough to build it myself.
Since 1+2 doesn't do anything, I suspect I've made a serious mistake...

Where/How should I start looking?

Sure, here's the translation:

'Thanks and greetings,'
Chaoz.

Hello,

First, apply 12V to terminal C1. Then, short pins 3 and 4 on connectors OK 1 and OK 2. At the very least, the LEDs should light up then. If they don't, the LEDs are probably installed incorrectly. If yes, we will proceed.

Hello!

LED 2 is lit, while LED 1 is not.
I checked the polarity of the two LEDs again, and in both cases, the same terminal connects to pin 3 of the respective OK connector.

Hello,

The error with LED1 should be easy to find. The circuit is grounded through R2 and T1 (base-emitter).

Chaoz wrote:

Unfortunately, I only have enough electronics knowledge to read a schematic and solder things based on it, and I vaguely remember what resistors and capacitors do, but that's about it.

Hi.

. . . then it should actually be sufficient to, with the help of downloading the adapter test software along with the instructions (in the adapter product article), check and determine the internal reactions of the circuit with the various input signals and to find out where the bugs are hidden .

Well... you're right, but unfortunately, when a test fails, it doesn't usually tell you where you might need to look for the problem.
Troubleshooting instructions are not published here, because even a single incorrect, defective, or improperly installed component can render the adapter useless, meaning there are potentially 'infinite' possible error scenarios. In addition, it should be mentioned here that solder bridges can occur.

That's why I thought I might find my mistake here... it would be really great if you could help me out here! I don't have anyone in my circle of acquaintances who knows enough about it...

@Andy:
LED1 is working now, it was a cold solder joint...
LED2 is still failing the LED test. What should I check now?

Hello,

You can test LED 2 as follows:
a) Apply 12V to terminal C1.
b) Provide an additional 12V connection on the Buch connector, connecting the positive wire to pin 3 (TXD, the RS232 connector) and the negative wire to pin 2 of the OK2.

By applying 12V to the OK2 input, you activate it. LED2 should then light up. Okay, hier ist die Übersetzung:

'Otherwise, look for errors.'

Take a closer look at these corners; they can be easily overlooked. Depending on the situation, etching the circuit board in these areas could lead to interruptions or short circuits. Simply check them with a multimeter or visually inspect them.


http://www.golf-vw.de/fehler.jpg

@Andy:
ominous... I took the test, and only LED1 is lit, not LED2!
Okay, I have 5 more minutes. Comparing the circuit diagram with what I built, I couldn't find anything wrong...

@golf-vw:
I didn't have a circuit board etched; instead, I connected everything in the back with cables in a rather unprofessional way...
I'm starting to have the silly suspicion that somewhere, your fault lies.

Chaoz wrote:

ominous... I ran the test, and only LED1 is lit, not LED2!!

You probably reached checkpoint 1.

Does R6 have the correct value (and not, for example, 22 kOhms)?

Is transistor T2 installed correctly, is it undamaged, and is the correct type (NPN) being used?

Endless, unproductive speculations like these were the reason I wrote that (actually) no help is provided for troubleshooting!

Then you probably reached the OK 1.

LED1 is lit, regardless of whether I connect the negative terminal to OK1 or OK2.

Does R6 have the correct value (and not, for example, 22 kOhms or something)?

That's right...red-red-red-gold.

Is the T2 transistor installed correctly, is it intact, and is the type correct (NPN)?

The BC547C transistor is installed correctly, as recommended and according to the circuit board layout from HP. How can I check if something is intact?

Chaoz wrote:

The BC547C transistor is installed correctly, as recommended and according to the circuit board layout from HP. How can I check if something is intact?

Connect pin 3 and 4 of OK 2 and LED 2, and apply 12 volts to C 1.
Then, approximately 0.6 volts should be measurable between the base and emitter of transistor T2.
And the K-line should measure approximately 0 volts relative to ground.

Then, approximately 0.6 volts should be measurable between the base and emitter of transistor T2.
No measurable voltage.
And the K-line should measure nearly 0 volts relative to ground.
I then have 12 volts available!

Chaoz wrote:

Quote: Then, approximately 0.6 volts should be measurable between the base and emitter of transistor T2. No measurable voltage. Quote: And the K-line should measure nearly 0 volts relative to ground. I then have 12 volts available!!

That looks like a B-E short circuit from transistor T2. Either within the transistor itself or through a solder bridge.

Or perhaps something else is completely structured incorrectly - does R6 really have a connection to T2?

It's probably not a short circuit; the resistance is around 1 kOhm (through resistor R7), which is what it should be.

R6 and R7 connect to the B terminal... nothing more.