Golf 4/A3 8L Speedometer, Voltage Regulator

Hello,

"Does anyone have a picture of the circuit board from a Golf 4 or Audi A3 speedometer (instrument cluster)? A customer is experiencing intermittent contact issues; the speedometer sometimes works, and sometimes it doesn't."
The speedometer part number is 8L0920900N.

Best regards, Rainer.

Hi,

I guess the Ibiza 6K (GP99) might be getting a bit old for you?

"On my board, one leg of an electrolytic capacitor went through the connection between the two layers of the circuit board, but it probably damaged the board mechanically. The end result was a cold solder joint on one side, which meant that the intended "power transfer" from the other side no longer worked. It was difficult to measure because the protruding leg of the capacitor was making contact, but the solder joint around it wasn't always making a good connection."

Best regards,

Jan.

Thanks for the tip! The "B1184" is definitely not a voltage regulator. My suggestion to the person who asked the question would be to trace the +12V wire from the connector.

Meanwhile, there are better pictures available.

Hi,

I would do it that way too. In the Ibiza's dashboard, the voltage converter was a five-pin device (I'd have to look up the exact designation at home), and it was easy to find information about it. When the total failure occurred, it was easy to determine that the 12V, which should have been present at a particular pin, was not actually there.

For preventative maintenance (i.e., when failures are infrequent), I would check which electrolytic capacitors are used for power supply and carefully inspect anything that looks suspicious.

However, I have to add that this wasn't the solution for my Ibiza. While it did fix the complete failure, I still experienced sporadic issues (resets, all gauges going to zero, then everything working again) with the instrument cluster, occurring roughly every 100 to 1000 km, depending on the temperature. This started happening before 100,000 km and didn't improve by the time I sold the car with 218,000 km (though it also didn't get worse). After repairing the complete failure, I also removed the instrument cluster a second time and checked and re-soldered all the power supply connections, but this had no effect. My (unconfirmed) suspicion was that one of the BGA solder joints on one of the chips might have been poorly done. This is something that happens relatively often with graphics cards and similar devices...

I left it as it was and didn't modify it further. For attempts to improve the soldering of the BGA components, the cost of using AI was too high, and the level of frustration was not significant enough to justify it.

Best regards,

Jan.