Volvo Penta Alarm too quiet

[superheat6k]

The alarm buzzer on my VP TAMD60Cs seem to emit varying volumes at the differing helm positions and engines. It should sound on both Low Oil Pressure and Over temperature coolant, with the buzzer sounding on start up.

There is a complex network of diodes and a zener on the PCB along with a transistor on I think the alarm test, which does work.

Any tips on how to approach the fault finding. I have already checked the connections. Could it be a blown diode or Zenner on the PCB.

Tried to copy the diagram but can't do it on this ipad.

 

[nigelmercier]

Two recent threads that might be handy:
http://www.ybw.com/forums/showthread.php?406071-DIY-volvo-penta-instrument-panel
http://www.ybw.com/forums/showthread.php?406305-Home-Made-Volvo-Penta-2003-Instrument-Panel

However, if you have two control panels, there is also a diode matrix in the lead joining them.

 

[superheat6k]

Two recent threads that might be handy:
http://www.ybw.com/forums/showthread.php?406071-DIY-volvo-penta-instrument-panel
http://www.ybw.com/forums/showthread.php?406305-Home-Made-Volvo-Penta-2003-Instrument-Panel

However, if you have two control panels, there is also a diode matrix in the lead joining them.

Thanks Nigel - it would appear the circuitry is virtually identical for the 2003.

I will study the connection to the remote panel to see if I can suss these extra diodes out. Looks like some testing directly on the feeder leads to each panel to simulate the senders operating will be my first step, as I am sure not all four PCB blocks will be U/S.

Thanks also to ComradeRed for his efforts.