Vp 2002 alarms - yenka simulation

[Plevier]

If you haven't got a rev counter then there shouldn't be anything on W. If the wire that was supposed to be connected to 61 was connected to W, it might explain your observations. W will be AC, with a voltage that varies with RPM.

Andy

I do have a rev counter - and it works.

Overnight I've reached same conclusion about the brown wire. Should be safe to move it.

I also repaired the old module - bridged the broken tracks - and put it back yesterday. The charge light (and the water light as explained before) never go out at all!

Next weekend I will ring the circuits through. End up removing alternator to examine I expect.

 

[philip_stevens]

No problem but you appear to have blown up the oil light first!

That was easy to fix

Now back to the circuit!

 

[misterg]

With the old circuit as published, no...

OK, I'll get my coat

Found a schematic for the Volvo box, and I agree that your circuit matches. The one I was thinking of was a Yanmar one which was just diodes from the sounder to oil pressure, O/temp & alternator excitation - v. sorry.

If there's no connection to 61, I think you need to trace the wiring to your alternator to see what the charge warning light is connected to (pin 1 of the module).


Andy

 

[Doug_Fenna]

Thank you

Thank you Willow3 for your detective work and for posting this circuit. I thought my alarms weren't working because the buzzer never sounded except for the test button, but now I see why - it doesn't work unless the alternator is running, so it's no use testing it with the engine stopped. There doesn't seem to be any safe way of testing the full alarm circuit right back to the sensor terminal.

I've copied the circuit and redrafted it as a gif file so it's easier to print and I've posted it on Flickr so you can all use it. I hope that's ok. It's at
http://www.flickr.com/photos/16214923@N05/3927255262/

The mysterious diagram in the engine manual is no longer a source of head-scratching!

Doug

 

[Plevier]

Doug

Strictly speaking you're right. The only way of testing the full function would be to short the oil pressure or temp switch with the engine running.

Overall the whole system is pretty cr*p really! A test button that doesn't really test, a water temp light that comes on with the low voltage alarm, and no buzzer alarm if you have no charge...!

Do note that this module is long obsolete and the replacement is quite different and better - but at a horrific price.

I note that later engines with the revised module as original fit have a 74 ohm resistor feeding from the switch (or key) "on " terminal to 61 on the alternator. I don't know whether it's advisable to add this when you change to the new module. Presumably the warning lights no longer supply the excitation current - but my alternator does charge. Maybe it has enough residual magnetism.

 

[johnnyx]

Willow3, et. al.,

I found this thread extremely useful. The old part schematic was sent to me in another forum. It was very helpful and explained perfectly how the thing worked. It helped me figure out the problem I was having on our boat tonight.

We had some engine water leaks a month ago which took out our alternator and killed the start panel. I replaced the alternator. Although we could start the engine, the alternator wouldn't charge and the panel was still dead including the gauges.

I removed the electronic unit from the panel and put a bulb between the panel's switched power and the alternator D+/61 line. At first the bulb wouldn't extinguish. I revved the engine and the lamp went out and the battery voltage jumped to 14+ volts.

The operation of the old electronic unit had its shortcomings, but it worked well for years. I'd like to replace, but some of the strange operation and interface issues of the new unit described here has me concerned. The replacement part isn't cheap. My unit is potted, so I can't repair.

Can I make the new unit (873737) work? Would you recommend purchasing it? (short of making my only replacement, I'm not sure I have a choice). I don't mind paying the money if it will work right.

Thanks.

 

[johnnyx]

Willow, I just re-read the entire thread. It seems that the new unit should work fine if I hook it up right.

I'll admit that the old unit had it's compromises, but I thought it had some clever features. For one, by having ALT and TEMP warning lamps tied to alternator's field terminal (D+/61), you would still get excitation current if the ALT bulb failed. Second, the use of the alt field voltage to power the buzzer via the zener to limit the voltage across the buzzer was original. In some ways, the simplicity of the circuit has merit. Less parts to fail.

I'd be real interested to get a schematic of the new unit. Could the resistor in the new panels be used as backup for excitation if the ALT bulb fails? A 74 ohm resistor would only allow a draw of 170mA initially. (~2W). I'm not sure this is enough to excite the field. Doesn't excitation need to be in the amp range?

Again, I appreciate your comments in this thread. They were very helpful in diagnosing a big problem we were having. I'd also appreciate any tips you may have in installing the new unit.