The International Cessna^® 170 Association

I tried re-polarizing my generator today and have a quick question. Is it supposed to spark when you connect the jumper between the battery and armature terminals? Mine didn't spark when I briefly connected the jumper. When I fired up the engine and ran it above 1700rpm it still showed a discharge.

Should you disconnect the leads that go to the regulator and then connect the jumper? Not sure what I am doing wrong....

You connect a jumper between the ARM and the BAT terminals momentarily with the master on but the engine not running. I seem to remember a spark.

That's exactly what I did......no spark

check your generator brushes

Had the generator bench tested and it checked out fine.

Okay then check all the grounds from engine to the firewall and anywhere else. check with a continuity tester.

Thanks, I'll look into that tomorrow and report back. Grounding the voltage regulator should just mean having good contact between the voltage regulator and the firewall. When I installed it I used some rubber shock mounts that were supplied with the unit. There was also a metal bushing that I thought would allow for a good ground but I guess I was probably wrong. We'll see.

Check for voltage at the BATT terminal of your regulator with Master ON but engine not running. (Should see battery voltage.)

The normal path of the ground from the voltage regulator to the engine is from a strap around the vibration damper between the fire wall and the VR. Then through a strap that jumps the dampers at the motor mount and fire wall. And last a strap that jumps the motor mounts and the motor mount frame. If any are missing or dirty which is likely, you will not have a good ground.

A friend once found the only ground path to the engine was the throttle cable. He wondered why the starter wouldn't spin very well.

I like to run a ground wire directly from the generator to the VR chassis.

Bruce Fenstermacher wrote:The normal path of the ground from the voltage regulator to the engine is from a strap around the vibration damper between the fire wall and the VR. Then through a strap that jumps the dampers at the motor mount and fire wall. And last a strap that jumps the motor mounts and the motor mount frame. If any are missing or dirty which is likely, you will not have a good ground.

A friend once found the only ground path to the engine was the throttle cable. He wondered why the starter wouldn't spin very well.

I like to run a ground wire directly from the generator to the VR chassis.

Exactly, and sorry I was not more specific. Thanks Bruce. D

Got sidetracked today fitting the new carpet and didn't get around to the troubleshooting the voltage regulator. I will look into all your great inputs and let you know what I find sometime next week. Heading up to Seattle til next Wen to do my float rating with Kenmore:)

Mike

Ok, still no luck after troubleshooting today. I grounded the VR with a wire from the VR chassis to the firewall. Looked for power at the bat terminal of the VR... there was none. I found two of the grounding straps that bypass the engine mount bushing are broken. I'm going to have to do some more troubleshooting tomorrow.

If you have the cockpit master ON...with the engine not running...and no voltage at the VR BATT terminal......then there's your problem.

After much investigation I found my problem. The previous owner had the wiring all messed up....and I didn't look at it closely enough to verify everything was going where it should be. Now all I have to do is make a few more wires and get it all back together. The original wires actually have printed on them the same numbers that are found in the parts manual. This made the process of figuring out what went where fairly easy. The hard part was the master switch. The posts are not labeled so you have to use a few brain cells to figure out what goes where.