Black box

[chrisx1]

Is there anyway to check if my black box is working correctly. Boyer Bransden MKIV

[rhyatt]

I believe you can measure the AC output of the trigger coils with a multimeter on AC volts.
And of course the + and - support TO the box.
The ht coils will also require a +ve supply to the ht coils and the box will provide a triggering ethical pulse to the coil.
Exactly the same as cb points do but electronic.
So if the box has its ac feed a pos and good earth but is not switching the coils , then potentially it is defective.

However BB are very helpful

[chrisx1]

Probably a stupid question but does the engine have to be running to get the reading from the coils?

[Allan G]

No. You just need a multimeter with the ability to measure ohms

[rhyatt]

You need ohms to look at each pick up coil for continuity and you need AC volts scale to measure the output of each coil when kicking over.
It is the tiny pulse of AC as the magnet whizzes past the coil, that triggers the box and tells it to switch the ht coil on and off

[Mike Farmer]

 

May I suggest you go to the Boyer web site and have a read of their trouble shooting blurb. If it warrants it then send it to them for a test, They have always been obliging and fairly quick. I have no idea of the cost. I sent in one that tested 'duff' and they sold me one ex factory 'exchange' at a reduced price. Not recently I must confess.

Just a thought.

Mike

[chrisx1]

I put the Ohm meter on the coils set at the 200 mark both coils showed between 3.3 and 3.5 ohms with the ignition both on and off kicking over and not. Didn't change at all. then I twiddled the wires as I was removing them and the ohm reading shot up and down all over the place. Minus readings and plus 40 readings. So Im no clearer whatsoever.

[rhyatt]

The earlier instructions I mentioned were,

Ohms scale across the pair of wires for each coil will show each coil has continuity, hopefully the same number of ohms for each coil.

Then change the scale on the meter to AC volts and connect the meter leads to each individual pair of wires for each coil, then kick over and the rotating magnet will induce a tiny voltage that you can measure coming out of each coil.

If you are getting these voltages coming out of each coil and the box is supplied with + and - then it should switch the coils and give a spark.

[chrisx1]

OK thanks. I will try that tomorrow.
it looks like my head gasket is leaking again, so may well be the main problem with running badly.
After repairing and travelling 100miles or so I know your supposed to torque the head bolts again. Does this mean taking the rocker arms to pieces again to get at inner head bolts or are they just referring to the outer four bolts?. I assume it all of them.

[LightningAndStarfire]

I get the impression that you are not distinguishing between the pickup coils and the high tension coils.

If you are, I apologize.

[rhyatt]

Every single bolt holding the head down to the cylinder barrel needs checking

[chrisx1]

In responce to L&SF I am refering to the HT coils that the plug leads come out of.