Overvoltage light

[Mooneymite]

I have a '74 C model with a factory alternator.  Out of the last few starts, half the time the OVERVOLTAGE annunciation comes on as the alternator comes on line.

Each time, cycling the master switch has brought the alternator on line.  Once the alternator is on line, it doesn't happen again....it only happens after start....some of the time.

I have ordered a Zephtronics replacement Voltage regulator for the original Oeco 20082, but I'm wondering if there's anything else I neecd to do.

I have checked the connections on the altenator itself, but I'm wondering if an overvoltage can be caused by something other than the VR.  Since the alternator output is good once the master switch is cycled, I'm guessing the problem is NOT in the alternator itself.....is this correct?

I realize that there are a lot of generator equipped C models out there, but mine is a "from the factory" alternator set-up.

Any wisdom/experience out there with the OVERVOLTAGE light?  Has anyone installed the R1530B Zephtronics VR on a C model?

Thanks!

Gus

'74 M-20C

 

[N33GG]

I had the same problem with my C. Replaced the regulator ... I think it was a Zephtronic unit... completely fixed the problem.  

If I remember correctly, the over voltage sense is in the regulator, and like you I still had the original.  Over time, the kicking on of the over voltage light progressed beyond just after start.  It has been about a year since it was replaced, and absolutely no problems.  I bet you will be fine.

Good luck!

[Mooneymite]

Quote: N6719N

I had the same problem with my C. Replaced the regulator ... I think it was a Zephtronic unit... completely fixed the problem.  

If I remember correctly, the over voltage sense is in the regulator, and like you I still had the original.  Over time, the kicking on of the over voltage light progressed beyond just after start.  It has been about a year since it was replaced, and absolutely no problems.  I bet you will be fine.

Good luck!

[N33GG]

Don Maxwell did mine.  I think it was plug and play as far as the connection went, but I do remember they had to drill a new hole to move the mounting location over a bit due to interference with something.  

[jamesm]

If you go to Zefttonics web site http://www.zeftronics.com/ and have the right web browser and virtual machine combination. They have an excellent troubleshooting guide and give specification for resistance(s). Make sure the resistance  falls with the Specification that Zeftronics calls out for the generator control unit (GCU), if you are going go with Zeftronics . I had to send back a rebuilt generator because the generator resistance were out of tolerance for the GCU  to work correctly. The GCU does have a terminal bus bar for the connection no cannon type plug between the GCU and your generator.

You might want to consider plane power alternator conversion you save about 8 to 9 pounds on the front of  your engine and your batterey will charge at a lower RPM. http://www.plane-power.com. I went the expensive route prior to Plane Power's conversion kit. I had to replace the starter support assembly (aka Ring gear) since the alternator belt is narrower and the belt pulley diameter are different. I put in the Plane power alternator with Zeftronics voltage regulator since  Plane Power's Voltage regulator wasn't available at the time I did my switch to alternator. So far no trouble.

Hope this helps.

James

'67M20C

[Mooneymite]

Quote: N6719N

Don Maxwell did mine.  I think it was plug and play as far as the connection went, but I do remember they had to drill a new hole to move the mounting location over a bit due to interference with something.  

[Mooneymite]

Quote: jamesm

If you go to Zefttonics web site http://www.zeftronics.com/ and have the right web browser and virtual machine combination. They have an excellent troubleshooting guide and give specification for resistance(s). Make sure the resistance  falls with the Specification that Zeftronics calls out for the generator control unit (GCU), if you are going go with Zeftronics . I had to send back a rebuilt generator because the generator resistance were out of tolerance for the GCU  to work correctly. The GCU does have a terminal bus bar for the connection no cannon type plug between the GCU and your generator.

You might want to consider plane power alternator conversion you save about 8 to 9 pounds on the front of  your engine and your batterey will charge at a lower RPM. http://www.plane-power.com. I went the expensive route prior to Plane Power's conversion kit. I had to replace the starter support assembly (aka Ring gear) since the alternator belt is narrower and the belt pulley diameter are different. I put in the Plane power alternator with Zeftronics voltage regulator since  Plane Power's Voltage regulator wasn't available at the time I did my switch to alternator. So far no trouble.

Hope this helps.

James

'67M20C

[laytonl]

Given the age of the VR,I suspect it is your problem.  However, a high resistance connection at the master switch or circuit breaker can also cause this.  If you do this yourself - it is easy - make sure the VR is solidly grounded to the airframe.  Don't just put the ground under another screw with other grounds.  The VR ground is important enough to deserve its own connection to the AF.  

 

Lee

[Mooneymite]

Given the age of the VR,I suspect it is your problem.  However, a high resistance connection at the master switch or circuit breaker can also cause this.  If you do this yourself - it is easy - make sure the VR is solidly grounded to the airframe.  Don't just put the ground under another screw with other grounds.  The VR ground is important enough to deserve its own connection to the AF.  

Lee

 

 

 

Well, the overvoltage light only comes on once in a blue, blue moon, so it is very hard to track down.  I bought the Zeftronic regulator from Spruce, but it is sitting in its box in my baggage compartment since the problem seemed to have "gone away".

 

Yesterday, right over top of ATL at 4500', the darn overvoltage light came on again.

 

I thought I'd just cycle the CB for the alternator and be able to keep my avionics on for the controller, but I see that the CB is one of those that can be re-set if it pops, but can't be pulled and re-set.  I had to wait until I was clear of the Class-B, then cycle the master switch.  The over-voltage light went out and the alternator has continued to work just fine.  I know I should just install the new VR.....but.

 

Question:  if the over-voltage light comes on, does the alternator stop charging until re-set?  I thought this was the case, but the ammeter did not show any discharge even though I was running the normal load.

 

Strange.

[N601RX]

Usually there is an overvoltage relay in the circuit.  Sometimes its external, other have it built in to the regulator.  If it is activated, the the field circuit is opened and the alternator will not produce any output.

[carusoam]

Does the existing regulator have the big springs inside?

I've never seen springs inside an electrical device until I took the cover off the voltage controler of my 65C.

Get on to the Zefftronics device. It is centuries newer in design compared to the original! Works better, less noise.

There is no digital logic in the old design.

Best regards,

-a-

[N601RX]

Plane power also has a nice solid state regulator that is cheaper than the Zeftronics.  Read the STC and AML closely, it is not approved for all models. It is approved for models that had the previously installed interav alternator STC that was popular in the 80's and 90's. It also gives you a path to move toward a plane power alternator when the interav one needs replacing.