Ign. Pick-up

General Chat About Electrics, And Ignition Systems.

Moderator: phpBB2 - Administrators

Post Reply
mike-b
Gold Member
Gold Member
Posts: 208
Joined: Thu Mar 25, 2010 8:49 pm
Location: Markfield, Leicestershire.

Ign. Pick-up

Post by mike-b » Sat Oct 13, 2018 7:18 pm

Have I missed something here ......

Today I was going to fit a new Dizzy pick-up and base plate unit ( Rimmer part No. RTC 5090P1 ) this is OEM unit NOT the "Britpart" cheapest or the Original very expensive unit either, a middle range job? At £80+ it should be a decent replacement.
Before I begun to fit this unit I checked the pick-up for a resistance test using a very good multimeter, the one in the car reads 3K2 Ohms (3200 Ohms) and it will help produce a spark though it is playing up. I have tested my amp and that is perfect. My amp is a £25 - £30 job from a motor factor and has worked well for at least 5 years with the 35DML8 dizzy.
The resistance test on this new unit produced a Zero reading so I tried a continuity test and that also produced a Zero reading.
The pick-up itself is just a coil surrounded by a magnet, therefore the coil sits in the middle of a permanent magnetic field. Disturb that magnetic field with metal very close to - or touching the coil with it - and a very small AC voltage is produced. A very, very basic principle .... but it works
Would you the reader think as I do the pick-up coil is useless? No continuity and no resistance either through the winding.
What, if anything have I missed?
Many thanks ....Mike


Mike B Drives a 1984 Mk2 Granada ghia V8.

GDCobra
Helpful or Confused
Helpful or Confused
Posts: 58
Joined: Sat Feb 04, 2017 9:21 am
Location: North West

Re: Ign. Pick-up

Post by GDCobra » Sat Oct 13, 2018 8:24 pm

How can it have neither continuity or resistance? That's like saying it's a perfect conductor and a perfect insulator.

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3986
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Re: Ign. Pick-up

Post by DaveEFI » Sun Oct 14, 2018 8:44 am

According to my SD1 BL manual, the correct resistance for the VR sensor in a DLM dizzy is 950-1150 ohms.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

mike-b
Gold Member
Gold Member
Posts: 208
Joined: Thu Mar 25, 2010 8:49 pm
Location: Markfield, Leicestershire.

Re: Ign. Pick-up

Post by mike-b » Sun Oct 14, 2018 12:15 pm

Thank you Gentlemen for your replies.

GDCobra ... I am talking about a coil of wire - the pick-uo - if it hasn`t got continuity the resistance must be infinity, i.e. open circuit.

Dave, Thanks for those readings a useful point to remember. I checked my multimeter on the Ohms reading with a 4700 4K7 Ohm resistor ( yellow, violet, red ) and it read true as I didn`t believe the 3K2 reading.
The reading I get from my fitted Pick-up ( disconnected from the amp ) of 3K2 Ohms explains why my pick-up coil is playing up. The amplifier is easily tested and produces a very good output at the coil - I have seen the king lead spark 40mm and felt the bugger as well.
The pick-up coil without continuity is obviously US - I just wanted to know I hadn`t missed something.= it can now be returned as faulty.
Thank you both, Mike
Mike B Drives a 1984 Mk2 Granada ghia V8.

DaveEFI
Forum Contributor
Forum Contributor
Posts: 3986
Joined: Fri Feb 26, 2010 4:27 pm
Location: SW London, UK

Re: Ign. Pick-up

Post by DaveEFI » Sun Oct 14, 2018 1:51 pm

The connectors on the end of the sensor leads are crimped on spade types - 1/8"? I'd check they aren't corroded where crimped. Trying to guess why the unit would go high resistance.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y

mike-b
Gold Member
Gold Member
Posts: 208
Joined: Thu Mar 25, 2010 8:49 pm
Location: Markfield, Leicestershire.

Re: Ign. Pick-up

Post by mike-b » Sun Oct 14, 2018 7:00 pm

Hi Dave,
Good point but not here. When I dumped the original amp from the side of the dizzy I joined a thin 2-core cable to the wiring of the pick-up.
This was done by soldering the two joints and covering them ( insulating ) with heat shrink sleeving. This cable then goes direct to the amp that is positioned well away from engine heat.
however, I have checked my work of 5 years ago and it is still good, nevertheless a good point.
A resistance of 3200 Ohm - still helping produce a spark is beyond me.
Mike B Drives a 1984 Mk2 Granada ghia V8.

Post Reply

Return to “Electrical & Ignition Area”