1610D Volt Reg Wells VR728 no joy

evofxdwg · Jan 1, 2005

Help!
Yanmar 1610D: Charge light came on the other day. Batt voltage is about 12.6VDC, running or not running (obviously not charging). All four fuses OK. Checked the alternator – it puts out close to 26V AC at 2000 RPM, 15.6V AC at 800RPM. So I assumed it must be the regulator. I seached the TBN Yanmar forum and found that a Wells regulator from a 70-73 Datsun should work.

Went to Autozone – they said that store does not have a regulator tester. They looked up the Datsun part and I got a Wells VR728 and put it in. No change (i.e. NOT charging) except the charge light NEVER comes on (even with ign. on – motor not running). I hooked up old reg back up – charge light on all the time.

The Wells VR728 plugs right in but are the pin assignment different than on the Yanmar? Did I goof and assume this regulator has the rectifiers in it but it doesn’t? Did I simply get a bad new part? Has anybody actually used this part successfully in a 1610? Does anybody have a Datsun wiring diagram with signal name/pin assignment data?

I did some more research and found Hoye has one (model 7522) that seems to replace both the volt reg and the other little box next to it. Also - my parts manual lists two PN's - 121450-77710, and -77711. It also says "(A=E02997)" after the -77711 and the PN for the other little box. Was this an "Engineering Order" change? What is that about? I have a schematic but cant figure out which item the little box is - maybe the relay shown next to the regulator? But there is no label on the switch or sensor connected to one wire of this relay???? The schematic shows a lamp in series with one of the relay wires, the to ground. What lamp is that on my tractor?

Any help appreciated.

kayssupply · Jan 1, 2005

The little black box is the holding relay that keeps the light off if the current limiter is working. If you get a Yanmar limiter it will come with a wiring adapter to make it work without the box. Most Yanmar parts dealers can supply the correct limiter.
With what you say it is a 99% chance a new limiter will fix it. 3 out of ten Yanmars need a limiter when they hit the dock, or soon after.

evofxdwg · Jan 2, 2005

Sounds like they need a redesign with beefier componets. Do the replacement units have a high failure rate also?

It seems after reading an old long string of posts on this subject that the Wells VR728 is NOT a direct replacement. I jumped the gun on that one. Curious that the above poster calls it a "current limiter". My schematic labels it "Regulator." I suppose it doesnt matter and current limiting is a fundamental method to regulate voltage - is this a clue to the type of circuit inside the Yanmar units?

Im an electronics engineer but without info on what's inside the little "black boxes" and an accurate wiring diagram, im more clueless than the "remove and replace" mechanic, who at least has the experience of what works and what doesnt. Except for the guy that said the Wells unit will work!.

Has anybody ever removed the potting on one of the yanmar units? Are there any mfr ID and part numbers on the components in there? My curiosity drives me to understand the circuit in there.

My wiring diagram (in the Murray translated operators manual) shows the holding relay wired up - i guess the diagram is wrong since my tractor had it disconnected and the charge light was working properly until this failure. However, the old regulator/current limiter has no connector adapter on it (unless it is still on the harness and i didnt notice it - will check today). The old "regulator/current limiter" does have 6 wires and a rectangular plastic connector on a pigtail.

Im still confused about the adapter for (using?/not using?) the holding relay, partly because my schematic has an unlabeld switch or sensor connected between the relay and Main Switch. But also because my schematic shows 6 wires to the "regulator" (current limiter) AND shows the relay wired in. My inital thought was that the holding relay was built into the newer units, but woudnt this require the newer units to have more wires than the old? So why does my (presumably old) schematic show 6 wires on the "regulator" (current limiter)? I will try and ohm out the wiring and ID components to get a true schematic.

blackd · Jan 2, 2005

I pulled my solid state regulator/limiter from my FX24D. It has 4 IN-4004 rectifier diodes, a resistor which I can not read the # from, a brass/copper plate with 2 of the diodes attached & 2 other leads which I think went to the connector, the resistor is screwed to the case and has 1 diode attached to it and then a wire goes from the same diode to the metal plate, the resistor looks like it has 3 leads 2 of which were destroyed in removing the insides, there is another lead screwed to the case (ground?) and a 5 prong connector. Components to fix this cost @ $4/5 at radio shack. Anyone know how to wire components?

Don

California · Jan 2, 2005

( Except for the guy that said the Wells unit will work!. -evofxdwg )

Hey! I resemble that remark! /forums/images/graemlins/smile.gif

I'm sorry if I led you astray. In my experience Wells VR728 (Datsun '70-73) is an exact replacement for the Hitachi regulator used throughout the 1970's on several Yanmars including YM2000.

Datsun kept the same alternator but went to a different regulator after 1973, so that regulator was apparently considered obsolete several years later when Yanmar designed the 1610.

It sounds like the Wells unit isn't going to help for your 1610.

reb · Jan 2, 2005

I am a retired electronics engineer. I have looked at the schematic for my 1500D and followed several posts about the "voltage regulators" on these machines. I think it would be fairly easy to build a circuit that would do the job, but putting it in a package as rugged as the OEM parts would not be very easy. Considering the cost it is probably better to go with the Yanmar part.

Soundguy · Jan 2, 2005

( Curious that the above poster calls it a "current limiter". My schematic labels it "Regulator." I suppose it doesnt matter and current limiting is a fundamental method to regulate voltage - is this a clue to the type of circuit inside the Yanmar units )

Does the yanmar unit use field current variation?

My unit has a hitatchi alternator and a regulator from a chrysler on it.. so I don't know anything about the oem yanmar parts.

Soundguy

California · Jan 2, 2005

( I may still try to use the Wells unit, but obviously i have to find out if it has rectifiers in it, and if not, add an outboard rectifier. And i need to find out what its pin/signal assingments are.
Anybody got a wiring diagram for a 72 datsun that uses a Wells VR728 regulator? )

Better yet: here's a Yanmar application for Wells VR728, from the YM240 (YM2000) operators manual.

The original and AutoZone replacement alternators used with this regulator have an internal diode pack.

But I think we are learning that this regulator and alternator don't match the ones used on 1610D.

evofxdwg · Jan 2, 2005

here's an update:

Today i verified the 1610D "Dynamo" (alternator) output using an oscilloscope. (yeah - im a high tech red neck!). It puts out a clean sine wave 40 volts peak to peak (no load)at idle (e.g AC). There are no rectifiers on the Dyanmo/alternator unit. I also started to reverse engineer the wiring around the regulator and found that the wiring diagram in the Murray Publishing manual is wrong in at least a couple of areas. I ended up pulling the instrument cluster out to check wiring to the charge lamp.

By the time i get this problem fixed, i should fully understand the tractor wiring.

If i can figure out how to dissolve the potting compound (looks like hard epoxy), im going to expose the circuit in my old Yanmar regulator part.

CALIFORNIA: Sorry i didnt mean to flame. I now realize Yanmar has several different charging system designs on different tractors. It was my fault in rushing to assume the VR728 would work without checking my tractor thoroughly. I got excited when i saw the VR728 has the same connector - which means exactly nothing!

BLAKD (and everybody): thats some good info on the rectifier/regulator on the FX24D. Except where you describe the "resistor" with three leads, it sounds almost like a simple bridge rectifier (4 diodes) and a current-limiting resistor, which is exactly what fgo65 (over on the Yahoo Yanmar forum) did with an external circuit, using a lamp as a low resistance current limiter. Are you sure the 3-leaded component isnt a transistor or other semiconductor? Is the "resistor" cylindrical with color bands around it?

REB: I consider it a challenge (Im a working electronics engineer but i dont get to do much analog circuit design). Besides, it sounds like the yanmar voltage regulator is kinda unreliable. I should be able to do better by selecting more robust parts. And I can pot it with silicone or epoxy (of course the vibration could be a cause of failure). See above post - if it is a simple bridge rectifier and limiting resistor I feel like $80 is gouging - especially if the replacement is also unreliable.

SOUNDGUY: Since there are only two wires hanging out of the "Dynamo", there is no externally controlled field current. The oscilloscope sine wave was very "clean", leading me to belive there is not a brush-type armature. I have not removed or disassembled it, but suspect it is a simple permanent magnet, single-phase alternator, with a rotating magnet and a single stator coil. This is a reliable design since there are no moving electrical contacts. The Murray schematic calls it a "Dynamo". Its interesting that a Google search has some links that say a Dynamo is an AC generator and others that call it a DC generator. At least one google link said the magnets can be electromagnets or permaent magnets. I got out my old "Intro to Electrical Machines" course text (copyright 1969)and I cant find the word "dynamo" in it anywhere. I have a partial collection of Audels New Electric Library (copyright 1929) - They define a Dynamo as a DC commutator/brush-type DC generator. I guess it is one of those words that lost its original meaning over time. Like "motor" can be a gasoline engine or an electric motor.

Unless I can find a very small alternator, it will not fit as there is a coolant hose right behind the "dynamo". And the dynamo body itself is (estimating) less than three inches long. SOUNDGUY: What are the approximate dimensions of the Hitachi alternator?

evofxdwg · Jan 2, 2005

CALIFORNIA:
Thanks for info on the Autozone alternators having a diode pack. That, along with what i learned today in measuring my "dynamo" output, confirms the VR728 is unusable on my 1610D without adding an external rectifier.

stay tuned to this string - i hope to have a "cheap fix" soon.