Volvo Penta Engine Control Panel Alarm Unit

[nigelmercier]

The more I look at the diagram below the more I think it's weird.
Why the diode across the transistor, the 3 round the horn (is it 9V or something) and between the Water & Charge lamps? Even the horn test is not valid, as the current takes an entirely different path.

This is my (revised) version of my MD22P-B alarm unit in situ, taken from various sources:

I'm thinking of building a box that takes inputs from the alarm panel, processes them with a microcontroller, and sounds different alarms for the different faults. I plan to use a 100dB+ alarm unit, as I can't always hear the existing one at around 85dB (SC 235 BF made by Sonitron: http://view.ceros.com/sonitron/catalogue/p/12)

My diagram above shows the 5 wires that go from the encapsulated alarm unit to an "Extra Display" via an AMP Universal MATE-N-LOK 350810-1 connector, this mates with an AMP 350809-1.

Does anyone know where these 5 wires are connected internally to the alarm unit?

 

[superheat6k]

These are common to many VP engines so might be worth looking at wiring diagrams for the TAMD or KAD ranges.

www.motoren.ath.cx has many manuals listed

The wiring details explaining the circuit is available here ...

https://www.dropbox.com/s/s483ek6t42rqhmq/INSTRUMENT PANEL12V.doc?dl=0

 

[nigelmercier]

Thanks for the links, that's a better diagram. Still no hint where the 5 wires go.

 

[superheat6k]

Thanks for the links, that's a better diagram. Still no hint where the 5 wires go.

Most boats don't seem to use these extra connections. I know the later modules have slightly differing functonality, and I think the alarm pulses. The circuit is certainly complicated by the transistor network and zener which only serve the buzzer and test circuits.

I find it bizarre that the temp lamp provides secondary excitation source for the alternator should the field bulb fail. I do have another diagram showing use of the glow lamp as an extra alarm which I used for exhaust warning, and with LED lamps with ballast resistors.

I can now recover the old casing and lamp mount with the new circuit on a piece of veroboard that sits in the slots the original PCB sat in. You have to double check the orientation of the lamps as it is difficult to change this around if you get it wrong - don't ask me how I know this !

 

[nigelmercier]

I've just realised something. As shown, the diagram of the alarm unit will cause an alarm as soon as the ignition is turned on, and continue until the oil pressure builds up. If I turn my ignition on and do nothing, there is a 20 second delay. What am I missing?

Better diagram (but I've made it low-res) from document linked by superheat6k above:

 

[Len Ingalls]

I've just realised something. As shown, the diagram of the alarm unit will cause an alarm as soon as the ignition is turned on, and continue until the oil pressure builds up. If I turn my ignition on and do nothing, there is a 20 second delay. What am I missing?

Normal to get alarm until oil press. builds up.

Could it be that you just shut the eng. down,then turned key back on & there is residual pressure til it bleeds off?

 

[nigelmercier]

Normal to get alarm until oil press. builds up.
Could it be that you just shut the eng. down,then turned key back on & there is residual pressure til it bleeds off?

No, my panel has a fixed and repeatable delay of 20 seconds before the alarm sounds after the key is turned. Even after a month.

 

[Len Ingalls]

No, my panel has a fixed and repeatable delay of 20 seconds before the alarm sounds after the key is turned. Even after a month.

Re diagrams post 1 & 5
I don't see a capacitor,which would be reqd for a timer ckt.
Best guess is sticky oil pressure sender. Eliminate possibility by removing & grounding it's connector,during 20 sec delay-or-conn an ohmmeter to the sender,with wire removed,& check if sender has delayed grounding.

The diode across transistor is not reqd,but it provides some protection to xsistor in event of rev polarity?

 

[nigelmercier]

I don't see any timing components, so I assume they have updated the unit. It has done this for 10 years, I'm sure it is deliberate.

 

[rogerthebodger]

No, my panel has a fixed and repeatable delay of 20 seconds before the alarm sounds after the key is turned. Even after a month.

Nigel

It sounds like your panel has a delay on timer that disconnects the alarm sound for 20 seconds after the ignition is switched on.

IMHO that is unusual as the alarm sounding as soon as the ignition is switched on confirms that the alarm sound is working every time the ignition is turned on. With the 20 second delay the sounder could fail and would not necessary know that an alarm condition existed unless you happened to look at the lights.

 

[Len Ingalls]

I don't see any timing components, so I assume they have updated the unit. It has done this for 10 years, I'm sure it is deliberate.

OK-10yrs. Yes it sounds deliberate,but I can't envision a purpose for a 20sec,or any delay.
My VP2003 1984 uses same ckt as first post,& your revised ckt looks identical.
I got thinking about a failed diode across the spkr/horn coil. It is there to quickly discharge the coil-good practice.
When power is removed from ckt (key off), the bottom of coil becomes +,&,if it can't dischg thru it's parallel diode,it will try to dischg thru the far left diode & up toward transistor (alm tst key open).
What will that cause,if anything...? When you say alarm continues for 20sec.-is that the horn? lights?both-& is that after key off or key on?

 

[Len Ingalls]

http://www.bluemoment.com/manuals/volvo_penta_2002_worksh.pdf

page 28 alarm panel

 

[Len Ingalls]

http://www.bluemoment.com/manuals/volvo_penta_2002_owner.pdf

 

[Plevier]

I've just realised something. As shown, the diagram of the alarm unit will cause an alarm as soon as the ignition is turned on, and continue until the oil pressure builds up. If I turn my ignition on and do nothing, there is a 20 second delay. What am I missing?

Isn't it the case that until you press the alarm test button the driver transistor is turned off?
That's how it works in a simulation of it in Yenka (free program. I cans end you the simulation file if you like.)


If you're saying the alarm starts after 20 sec, i can't explain that.

Are you actually using this alarm module - 828605 - or do you have the later 873737 which is much more clever?

 

[nigelmercier]

Are you actually using this alarm module - 828605 - or do you have the later 873737 which is much more clever?

I have no idea. Do you have a diagram of the "clever" one?

 

[Plevier]

I have no idea. Do you have a diagram of the "clever" one?

No I have not managed to get one.
The part number should be marked on it if its encapsulated (if it's a bare board it's a very old one)

 

[nigelmercier]

No I have not managed to get one.
The part number should be marked on it if its encapsulated (if it's a bare board it's a very old one)

Thanks, but it's on the boat in Tenerife. I can still build my louder alarm, but I've decided to keep it simple and just have a couple of spare diode OR inputs and a driver transistor for the sounder, driven from the existing sounder input. I can then create different sound signals in any devices I build, such as my fuel gauge.

 

[Gypsy]

Nigel, my Volvo D2-55 CP circa 2002 has an 8 second delay before the buzzer sounds after switching on the ignition. I have always considered it is done to stop the 'annoying' buzzer sounding pending the engine developing sufficient oil pressure. I acknowledge that having it sound is a good test of the buzzer, but I have a separate 'Test' switch on my panel if there is ever a doubt.

An extract from the D2-55 Users Manual for the Start procedure is attached. Note it says that when the ignition is turned on that the 3 lights will glow, no mention of the buzzer. Then it says to test the buzzer use the Test switch.



I take this as confirmation that the buzzer delay is intended. Actually, the way I use it is to turn on the ignition, then immediately hold the Glow switch on until the buzzer sounds, then I hit the start button. Good timer for the Glow period and I hear that the buzzer works. Suits me.

 

[nigelmercier]

Nigel, my Volvo D2-55 CP circa 2002 has an 8 second delay before the buzzer sounds after switching on the ignition...

Thanks for the confirmation.

 

[Plevier]

I think you must be using the later module not the one for which you have the circuit. Here's a bit from the instructions for an MD2020 with this unit:

5. Alarm test/acknowledgment switch.To test alarm: Press the switch. All warning lightslight and the acoustic alarm sounds.Alarm acknowledgment: Press the switch if thereis an alarm. The acoustic alarm stops but therelevant warning lamp continues to flash until themalfunction is corrected.

Conspicuous differences from the old one:
1 The 3 alarms operate uniquely, none of the business of 2 coming on together for one fault (I forget which it is but it's in one of the links above)
2 The alarm lights flash after acknowledgement of an alarm

It is a much better unit functionally but I have not found them very reliable, had 2 fail on different engines.

I took one apart, very thoroughly potted in very tough compound, it is full of SMDs, no resemblance to the old circuit.