Moderators: eastlmark, BIG_MVS, phildini, Test Moderator, Alpineandy
Non Member
7
Fri Feb 14, 2014 8:50 pm
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
7
Fri Feb 14, 2014 8:50 pm
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
7
Fri Feb 14, 2014 8:50 pm
MFaulks wrote:.
Hi,
Just had a quick look. Right, well you are likely biasing the back-emf flyback protection diode for the injector feed, as there is a pn junction between 19 and 20 / 21, so not passive resistance as such. If you are seeing circuit resistance which ever way you connect your meter leads ie reverse them and get the same result, then the protection diode may be fobar. I've just quickly powered up a board, and I see 3.5V on 20/21 on my scope, so within range of what you are measuring, and thinking about it makes sense, as the electronics on the board is doing a check for open circuit injectors, and the 3.5V supply is used to drive a loop current to make that connectivity test / measurement.
So from the above, what you are seeing all looks fine, except possibly the protection diode if you are seeing a low value in both bias directions.
Hope that helps.
Martin
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Non Member
1407
Fri Apr 16, 2004 4:50 pm
Kent
Non Member
1499
Thu Apr 29, 2004 1:03 pm
Horley - Nr Gatwick
Non Member
1552
Sun Sep 28, 2008 4:25 pm
Club Member
5097
Wed Jun 30, 2004 9:12 am
Sandbach
Users browsing this forum: Bing [Bot], Google [Bot] and 182 guests