512-D Robin Diesel not charging - how do I test?

[Jon_Tallis 0]

My 512-D (Robin DY41D engine) is not charging. Can someone help me narrow down if it is the generator or the reg/rectifier at fault.

When I got the tractor all the wires from the R/R had fatigued off. Fortunately there was enough wire left to solder on new tails and enough insulation to work out what went where. I've refitted the R/R to the engine and wired up as per the Robin engine manual but I have no charge (battery volts stay at around 12V engine off, running fast or idle). I don't want to shell out for a new R/R unless I know that's definitely the problem.

Connections are

Regulator / rectifier

Red - Ignition 12V (which is showing a good 12V)

Blue - Earth (good earth on engine)

Brown - to brown on generator

White - to white on generator

Generator

Brown - as above

White - as above

2 yellow wires - not connected to anything (they're not even shown in the Robin manual)

Can anyone tell me how I test the generator and the regulator individually and what the two yellow wires are for???

Thanks in advance guys..............

[Sparky-(Admin) 21,350]

Hopefully one of our Euro members has a 512D and can get you set straight. Over here in the US we weren't so lucky to have the Robin Diesel offered up at the dealer.

Mik......

[Save Old Iron 1,566]

Jon, here is my best educated guesstimate based on the knowledge all we are trying to do is charge a battery - be it in the USA or in Europe.

Brown to white resistance - engine off - brown and white wired disconnected from the rectifier diodes - less than 10 ohms - infinite resistance = bad generator

Brown to white AC voltage while running full throttle - probably in the 28 to 30 AC volt range. The rectifier diode will cut the 28 - 30 VAC in half - giving a maximum DC output of 14 to 15 volts to charge the battery.

The diode rectifier can be checked with an ohmmeter - each diode in the "bridge" can be checked independently.

For example - start with the ohmmeter leads across the Red to Brown leads. Place the red ohmmeter test probe on the red rectifier wire and the black ohmmeter test probe on the Brown rectifier wire. Note the resistance (should be very high ohms or infinite reading).

Swap the red and black ohmmeter test probes across the same Red and Brown rectifier wires. The meter reading should indicate much lower ohms - probably less than 200 ohms.

Repeat this same test across the rectifier's other leads - reverse the meter leads across each pair and note the readings.

Test across Red / Brown

then across Red / White

then White / Blue

then Blue / Brown

with meter leads in one orientation, a high ohms reading should be seen, when the ohmmeter leads are reversed across the same connection, the ohms should be much lower.

This process will test the rectifier. Any readings which remain the same across any individual diode when the leads are reversed will indicate a defective diode and the need to replace the rectifier assembly. Substitutions are readily available at a local electronics store.

AS indicated by the schematic, your system rectifies the AC from the generator BUT DOES NOT HAVE THE CAPABILITY TO REGULATE THE CHARGE VOLTAGE.

Over-voltage regulation is provided by the "designed in" maximum output voltage from the generator.

I have no clue to the purpose of the yellow wires - maybe a call to a Robins dealer will get you an authoritative answer.

[Jon_Tallis 0]

SOI.

Awesome - precisely what I was after. Will report back on what I find.

Thanks

Jon

[Save Old Iron 1,566]

any news Jon?

[Jon_Tallis 0]

SOI,

Yes - sorry for not responding earlier.

Tested as you suggested. It appears I have one dead diode in the rectifier (low resistance in both directions) and also a generator problem. Geno tested out at approx 2 ohms resistance but only generating approx 5V at full revs. Possibly an internal short between windings?? Haven't gone any further at the mo as the machine is running OK with the odd re-charge to the battery. Seems I'll need to get the flywheel off and have a look at the Geno windings.

Incidentally, I still don't know what the 2 yelow wires do but they produce around 12V AC at full revs - I guess they could rectifier feeds for a 6V charging system but whould they need to be different colours to connect into the rectifier??

[Save Old Iron 1,566]

Jon, sounds like you are on the right track. Could the yellow wires be the AC power to run headlights on the tractor?

A temporary battery charger could be created by putting a single diode in line with the yellow wires and wiring the output to the B+ circuit of the tractor. You will have the equivalent of a trickle charger to keep your battery charge from total depletion.

[Jon_Tallis 0]

SOI,

You obvious know your stuff electrically!

The headlights are run from an ignition controlled live from the battery so that's not the purpose of the yellow wires.

For now I'l leave as is (I'll probably make things worse - being more familiar with spanners) but thanks for the suggestion.

Thanks again