Incredible poor workmanship and how I spent $1000 to fix a loose wire connection

[TTaylor]

It all started as random low voltage reading showing no charging from the alternator a few weeks ago. Cycling the system the normal 13.5 volts returned and I didn’t think too much about it. This last weekend it showed up again so I scheduled an appointment with my mechanic to look at the charging system. On Monday we ran a few tests and found the alternator was fine so by default it was likely the regulator. I needed to fly to California today so we ordered a replacement regulator and paid the hefty overnight mailing charges having missed the shipping deadline even on the west coast. I was hoping to drop the new regulator in today and depart for CA but it was not to be. The regulator was delayed in transit and arrived at noon rather than the promised 10:30. We put the new regulator in and the system was still the same. Next step was to start chasing wires and voltages through the entire system. It was something like a needle in a haystack trying to eliminate one thing at a time. All afternoon we continued to get voltages that would go up and down on testing. We finally started disassembling an adapter cable that likely was installed with the last regulator in 1993. It was a short foot long cable that had a hefty Cannon plug on one end to match the original Mooney wiring and an Amphenol plug on the other to match the regulator. On the Cannon plug end I found a cold solder joint on the Field wire that was loose and thought that was the problem. No luck, still no charging. We disassembled the Amphenol end and pulled on the wires that were attached to the pins in the plug. Several pulled out! Fortunately my mechanic had the tool to remove the pins from the plug and we both stood there in disbelief. All four pins had never been crimped or soldered. The wires had been slipped in and somehow had stayed there and worked for 20 years just loose in the pins. I would not have believed it if did not see it. The plane is ready to go again in the morning with only the damage of about $1000 in parts and labor to track unbelievable workmanship from 20 years ago. My mechanic was great and stayed late to find the problem and get the plane flying knowing I wanted to fly home for my father’s 80th birthday tomorrow.

[Bill_Carter]

So, If I followed you correctly, this was an aftermarket cable/regulator that was installed 20 years ago? Glad you figured it out, I guess you have a spare regulator now

[bumper]

Being a former Navy Eletronics tech, I know how truly frustrating chasing down intermittent electrical problems can be. Good on you both for finding that sucker and glad you get to be home for your dad.

 

bumper

 

"sent from my free Obama phone"

[TTaylor]

Bill, yes I have a spare VR415-F on the shelf now

[BigTex]

I had something similar in that my low voltage light came on when I ran my Nav and/or landing light... After much work, it turned out to be the alternator switch.

[MooneyMitch]

Seems like human nature when troubleshooting, we tend to overlook the most simple aspects first.  Being a former communications engineer and technician, I'm guilty of this as well.   Wires and terminals, leading to/from end equipment are more often than not, the culprit.  I'm glad you're on your way to CA now.  Have a wonderful celebration with your dad

[Bill_Carter]

For you fellow IT folks: It is always layer 1.

[thinwing]

Every electrical problem I have had to trouble shoot was always a failure at a switch terminal,crimped splice,multiplug(amphenol/rst)and rarely the component it self...it is just the way we lateral think a problem..being its easier to pull the regulator/alternator and forget trouble shooting the wiring in between...because tracking a chaffed wire bundle rubbing on an engine mount covered with oil and grime..

[Marauder]

For you fellow IT folks: It is always layer 1.

I always thought layer 1 was me, the user of the application!

[Bill_Carter]

I always thought layer 1 was me, the user of the application!

Too funny. No, you are not Layer 1, you are in the OHT group. That group is below Layer 1. OHT is Operator Headspace and Timing. LOL

[wishboneash]

I had similar issue but with a frayed wire. Mine wasn't as expensive, but I do have a spare alternator now and was looking for an excuse to replace the Kelly.

Vibration appears to be the biggest issue in avionics/electrics from auto-pilots to GPSs and other equipment. Looking at the connections to ground and other power/signal connections should be the first step.

 

http://mooneyspace.com/topic/8788-intermittent-charging-failure-m20j/

[Marauder]

Too funny. No, you are not Layer 1, you are in the OHT group. That group is below Layer 1. OHT is Operator Headspace and Timing. LOL

 

Well, OHT sounds much better than being called a USER...

[Bill_Carter]

After I posted that I reread it and was hoping you wouldn't be offended by that. It was all in fun I assure you. I have plenty of OHT moments believe me!

[Marauder]

After I posted that I reread it and was hoping you wouldn't be offended by that. It was all in fun I assure you. I have plenty of OHT moments believe me!

 

Not offended. My wife is a DBE for a large bank and gets to deal with users on a regular basis. She has much more choice words for them! Most that would make a sailor proud.

[Marauder]

Tim -- being that we own similiar F models, I share your pain. When I got my F I spent 6 months chasing an intermittent gear breaker popping. I had the gear breaker replaced, the gear position switches replaced, the gear lever replaced, the gear tore apart looking for wear and the wiring traced. Once all that was eliminated, the voltage regulator replaced and the alternator checked (it was fine). It was only after we remounted the alternator did we conclude that the belt was slipping.

 

22 years later, it still is working fine... knock on wood...