Pertronix gets 12v, output only ~.5v...what's wrong?

deathpunk dan · 06-11-2008, 07:01 PM

Finally figured out why there was no switched power at engine bay fuse #3 - it was the ignition switch wiring bulkhead connection that was slightly loose. So, now I'm getting 12v to the distributor, but the pertronix unit is only putting out approx .5 volts and there is no spark. I have checked all connections and nothing appears amiss. Surely .5v cannot be enough to tell the permatune CDI what to do?

Is it possible the new pertronix unit is no good right away?

Still refusing to admit defeat and take it to a professional.

john70t · 06-11-2008, 08:03 PM

I can't remember if the pertronix is a hall-effects or a pickup coil type sender, but I think these only require the output of a small signal voltage.
Sorry I couldn't give more info, try here: http://pertronix.com/support/default.aspx

deathpunk dan · 06-12-2008, 06:24 AM

The permatune CDI and stock harness are not original to the car. I purchased both from forum members. I know I should be hearing a distinct 'whine' from the cdi with the key in the run position, but I don't and there is no spark, either.

Wondering now if 1 or both of these items are bad (bad wire in the harness?)

Are there instructions for bench testing a permatune unit?

MikeBogue · 06-12-2008, 06:49 AM

The Pertronix unit that I had for an old Volvo was a hall effect type and you can check it fairly easily. Disconnect the You should see the resistance change as a function of the engine rotation. If the resistance does not change then the hall cell was damaged. Otherwise it is probably fine. I do not know how the CDI can be checked.

RoninLB · 06-12-2008, 09:46 AM

Pertronix

deathpunk dan · 06-12-2008, 10:19 AM

Ronin
This confirms my suspicion that the hall cell is dead...which means it was junk right out box new.

With the voltmeter on it and rotating (turning over), it was constant .5v, not the alternating 12v/0v reading you should get with points or any electronic points replacement.

Oh well...just more downtime.

RoninLB · 06-12-2008, 11:26 AM

Quote:

Originally Posted by deathpunk dan

Ronin
This confirms my suspicion that the hall cell is dead...which means it was junk right out box new.

progress

MikeBogue · 06-13-2008, 03:06 AM

FWIW I ran some testing with the pertronix unit on my Volvo and I had a simelar problem due to a poor ground between the plate the hall cell was mounted on and the gap adjustment plate that mounted on the eccentric screw for the points. After I had that fixed there was a problem with the idle. It turned out that, with two seperate magnet rings, I had a timing variation of over 10 degrees that I verified by rotating the magnet ring to different lobes. Since that time I have been working at an electric motor design company for 6 years and I am not surprised with the variation due to magnetic field variation from manufacturing tolerances. I would recomend exchanging the pertronix unit for an optical system which should work much better.

john70t · 06-13-2008, 03:13 AM

Quote:

Originally Posted by john70t

I can't remember if the pertronix is a hall-effects or a pickup coil type sender, but I think these only require the output of a small signal voltage.
Sorry I couldn't give more info, try here: http://pertronix.com/support/default.aspx

[edit-this post was incorrect and apoligize. Thank's Ron]

RoninLB · 06-13-2008, 06:01 AM

Quote:

Originally Posted by MikeBogue

After I had that fixed there was a problem with the idle. It turned out that, with two seperate magnet rings, I had a timing variation of over 10 degrees that I verified by rotating the magnet ring to different lobes.

appreciate posting your findings.

all I know is that anytime the spacing between ring and module is adjusted the timimg changes.