Charging system trouble (Regulator/rectifier 1988 Vmax)

[Waylander]

When the voltage of the charging circuit is above the battery voltage
- the current splits and
- part flows normaly thru the bike to power stuff like ignition, lights etc
- the other part flows (backwards) thru the battery to charge it

Ah makes sense now. So something is wrong between the Rectifier and the batter.

[Waylander]

rooted rectifier / regulator! time to go visit a wreckers

edit: where do u live?

Tauranga-area

[paturoa]

Ah makes sense now. So something is wrong between the Rectifier and the batter.

nope, between the rectifier input and output.

With the motor off you saw 12v, which can only come from the battery so that is connected, but we don't know how well.

With the motor running the input to the recitfier was correct as you measured earlier. But the output dropped slightly to 11.8 volts. This again came from the battery and shows the drop in voltage caused by the ignition current draw thru the battery.

If there was a short between the batteryand the rectifier the voltage would have dropped well below 12v and if it was open and the rectifier was putting out properly the voltage would have risen to 14/15 v

[paturoa]

Tauranga-area

I'm dorkland based - do you want me to have a ring around the wreckers tomorrow?

[Waylander]

I'm dorkland based - do you want me to have a ring around the wreckers tomorrow?

That would be great man thanks, I owe you a case for this.

STupid thing is for the last few weeks there was a Vmax being parted out on trademe, now it's not there!! I can't even remember what shop it was at.

[paturoa]

Year and model number?

If it is cheap I'll just go buy it, otherwise I'll PM you with the price.

What is your definition of cheap?

[Waylander]

Year and model number?

If it is cheap I'll just go buy it, otherwise I'll PM you with the price.

What is your definition of cheap?

Year doesn't really matter lol as the Vmax' are esentially unchanged in 22 years production. ut it's an 88 make sure they know it's the motorcycle as they use the same engine but different wireing for yamaha snowmobiles. Bike model number is VMX12U and reg/rec number is (or rather all the number printed on it)
42X-A1
SH569A-12
T3.4
272

I think the first two are what's relevent.

Yamaha part number is

42X-81960-A1-00

RECTIFIER & REGULATOR ASSEMBLY

$50 is cheap for me at the moment.

[paturoa]

cool, I'll PM you tomorrow.

[Waylander]

I'll check and see how much it is from the shop aswell as call around.

[paturoa]

did u get my PM??

only one from AK wreckers $80 bucks...

[Waylander]

did u get my PM??

only one from AK wreckers $80 bucks...

Got it and replied mate.

[vmx1200nz]

fit a switch to turn off the head-light, and use a battery trenderiser.

[vmx1200nz]

the 93 onwards models get a gruntier alternator, if you are going to do a swap.
also the ground strap, if soldered, not bolted, improves the current.

[Waylander]

Got it sussed now mate thanks. When we gonna meet up to compare years man?

[davereid]

To test that rectifier without dismantling it...
1.. put your multimeter om DIODE TEST ( looks like ---<|--- )

2..Test D1 - put meter across TERMINALS 1 & 4
You will get NO READING in one direction, and 0.4-0.8 in the other.

3.. Test D2 - put meter across TERMINALS 2 & 4 same result as above

4.. Test D3 - put meter across TERMINALS 3 & 4

5.. Test D4 - put meter across TERMINALS 5 & 1

6.. Test D5 - you guessed it Terminals 5 & 2

7.. Test D6 - Terminals 5 & 3

OK. If you get NO READING in BOTH Directions across a diode it has failed and gone open circuit. You need a new rectifier. If you get a LOW READING in both directions same thing, but the diode has gone short circuit.