K model voltage regulator

[DonMuncy]

Can anyone tell me where to find the alternator voltage regulator on a 231.

[Bob - S50]

Is that 14V or 28V?  If it is a 14V, try this:

 

http://www.chiefaircraft.com/zef-r15300.html

 

Bob

[DonMuncy]

Jim,

Maybe I'm a little dense. Are you saying the flush screws go in from the outside of the fuselage, with the regulator up about mid panel level.

I want to be able to go to the A&P and tell him to put his screwdriver in that hole and twist until the JPI reads 13.75 to 14 v with the engine running at about 1500 RPM.

[KSMooniac]

Crawl underneath the copilot side panel with a flashlight and you should be able to find it.  If you don't know what it looks like, find a pic here http://www.aircraftspruce.com/catalog/eppages/zeftronicsreg.php and cross-reference a part number with your parts catalog.  I believe mine was screwed into a piece of sheet metal that was attached to one of the angled steel tubes behind the panel, but it has been a few years since I changed it.

[DonMuncy]

Thanks Scott. I was looking on the firewall under the cowl. Obviously, I have never seen one in real life, but it must look like the one you referenced me to or the one chief sells that Bob sent.

[KSMooniac]

Good luck!  Working under there is one of the least fun parts of owning a Mooney.    If you need a new one, get the Zef replacement...good stuff and made in Texas!

[laytonl]

Jim,Maybe I'm a little dense. Are you saying the flush screws go in from the outside of the fuselage, with the regulator up about mid panel level.I want to be able to go to the A&P and tell him to put his screwdriver in that hole and twist until the JPI reads 13.75 to 14 v with the engine running at about 1500 RPM.

Don, please don't have the mechanic adjust the Vreg until you are sure you don't have a high resistance connection somewhere between the battery and the Vreg (master solenoid, master switch, field CB.). If the voltage is close to batt voltage at the output of the filed circuit breaker, then have your mechanic adjust the Vreg. Lee

[larryb]

What is the problem we are fixing?

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[DonMuncy]

Good point Lee. Yes I will confirm the battery voltage and the voltage at the regulator match within a couple of tenths of a volt before moving forward. If it is not, I will have to check backwards toward the battery.

I know I can trouble shoot it up to the regulator and then have him adjust if necessary.

My only fear is that I will confirm the cables are good, and then find the adjustment won't fix it. Then I will be in the position of having to remove the alternator and regulator to have them bench tested. If that is what the situation turns out to be, I don't know of any other test to figure out which one it is.

Larry, the problem is a voltage reading of 12.8 at cruise RPMs. I suppose I also have to consider the possibility the JPI could be erroneous. Something else to check.

[DonMuncy]

Lee, I'm sitting here re-reading your article I previously copied from the MAPA log, and you don't specifically address my particular problem. Extrapolating from the article, it seems my steps are:

1. Check voltage (alternator output to ground) at speed, to verify JPI reading.

2. Verify battery voltage and voltage at Vreg match fairly closely.

3. Verify Vreg is well grounded.

4. Check for good connections from Vreg (B terminal?) to Field terminal on alternator.

5. See if Vreg adjustment will bring cruise speed voltage to 13.7 to 14 v.

6. If not, pull alternator and Vreg for testing.

Did I miss anything?

[larryb]

My master also went bad. One of the terminals was physically loose, causing a high resistance, which caused the famous oscillating ammeter. But the voltage reported by the jpi was steady. I think the jpi averages the voltage.

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[carusoam]

Could be loose or oxidized connectors...

What's the price on a proper new Zeftronics Vreg?

Other than the hidden nature of the K....

A modern Zeftronics device may make swaptronics a viable option...

The Zeftronics device made my '65 Generator work like magic...

My mechanic spent a few hours chasing the situation. Then I ended up with a rebuilt generator and Zeftronics device.

The worn/ mis adjusted controller ruined the generator... Melted internally...

The upside of the Zeftronics is it has additional LEDs or outputs for the many types of impending failures.

I'm hoping this may be helpful.

Best regards,

-a-

[FBCK]

I replaced the VR in my 1981 231 a couple of years ago with a Zeftronics one, the best $200 I ever spent.  The LED used to blink before that and the amps would jump around from 14 to 23, now everthing is nice and steady, showing 14,1 volts as well.

[KSMooniac]

Lee, I'm sitting here re-reading your article I previously copied from the MAPA log, and you don't specifically address my particular problem. Extrapolating from the article, it seems my steps are:

1. Check voltage (alternator output to ground) at speed, to verify JPI reading.

2. Verify battery voltage and voltage at Vreg match fairly closely.

3. Verify Vreg is well grounded.

4. Check for good connections from Vreg (B terminal?) to Field terminal on alternator.

5. See if Vreg adjustment will bring cruise speed voltage to 13.7 to 14 v.

6. If not, pull alternator and Vreg for testing.

Did I miss anything?

I can't remember...does the K use a belt driven alternator, or that magic clutch with direct drive from the engine?  If is is direct drive, you should consider that the clutch might be slipping and you'll need to change it soon.  Sit down before you get the price for that one...

[DonMuncy]

It uses the direct drive, and yes, I recognize that possibility. Hope not!

[CoachTom]

Don,

Start at the connections on the Master. Make sure clean and tight... Radio Shack sells some stuff call "De-Oxit" and it cleans at the molecular level.  Take the connections off and use a Dremel wire wheel and spray it with the DeOxit.  If it was working normal and you had a slow degradation, probably resistance "somewhere" on the connection path...

 

Not 100% sure on the elastomeric connection of the alternator, but it either works or it snaps... You can check by looking in the aft portion of the Alternator and rotating the prop to see if there is any slop in the movement.

 

One other thing to check is if the voltage changes with the load.  Turn everything on in cruise and watch your amp meter when you key the mike, you should see a dimming and or good discharge, but volts stay the same as you are pushing the charging system to the max...

 

Let us know how you make out.  Also, if the regulator was ever changed, it might be installed where your Loran or ADF used to be????

 

Take care,

TMcD

1980 M20K

[laytonl]

I really doubt it is a bad Vreg. I don't understand the direct drive type alternator, but on a J model, a slipping belt could cause this. Most often it is a poor connection somewhere. Let us know what you find. I assume the voltage doesn't drop with load which would indicate a bad diode in the alternator. Good luck. Lee

[DonMuncy]

I'll keep everyone posted.

[carusoam]

We're going to need a poll for all the arm chair mechanics!

I hope for a quick, low cost solution,

-a-

[manu damaschin]

Don, I wish I could give you my opinion as you helped me not long time ago, unfortunately I don't know much about electronics...so the only thing I can do is to keep my fingers crossed...good luck!!

Manu

[DonMuncy]

To all of you keeping up with my problem, and offering help. It turned out to be the best kind of problem to have. That is, no problem at all. My first step was to verify the JPI reading. I ran a jumper wire from the output side of the alternator into the cabin and hooked it to a good VOM. Sure enough, as soon as I fired it up, the voltage showed over 13.5 v.

It appears that the avionics guy who installed the JPI hooked the sensor of the JPI to a source that reads the battery voltage rather than the alternator output voltage. I'm not sure where/what that is. My avionics guy will be back in town Monday. I will check and see what he says.

There is always the possibility the JPI reads wrong, but I doubt this is the case.

Thanks again to all.

[ArtVandelay]

Is the battery in the engine department?

 

The alternator voltage should be close to voltage at the battery, otherwise the battery may not be properly charge. Sometimes there is sensor wires if alternator is some distance from battery to prevent this.

 

The JPI probably giving the voltage it sees from it's own 12V power supply, in that case, smaller wires, longer runs, dirty switches/circuit breakers, there could be a voltage drop.

[DonMuncy]

Lee,

Can you chime in here. What do you think about a situation where the JPI says 12.8v, but the alternator is clearly putting out 13.5+. Could the JPI be tied in somewhere it would "see" less than the 13.5, without a bad connection somewhere.

[DonMuncy]

To Teejay, no, the battery in in the tailcone, but if they should read the same, it would seem to me that there would have to be a serious continuity problem to go from 13.5 down to 12.8.

[laytonl]

It shouldn't be that much difference. It still sounds like a dirty connection. You might try pulling the CB to the JPI and spraying a little CRC contact cleaner in the CB. Just pulling the CB in/out a few times may be sufficient. I believe the JPI is using its internal reference for voltage, so it may be slightly less than the alternator. Lee

Ps. You can get CRC contact cleaner at radio shack and some auto parts stores. Good stuff for electronics.