Boyer Black Box Capacitors

It has been suggested that Boyer Electronic Ignitions that have not run for a while can have capacitors that go bad, leading to a flat spot in the advance curb. I took a look at Dave Comeau's site where he depotted a Boyer black box and from the schematic see that it contains 5 capacitors.
I find capacitors in the black box that go bad interesting because the story is that the black box works or it doesn't. Maybe there is an in between state where it works badly. Thoughts??

Hi Stephen - Some background:

The first one was with my dad's '74 850, which had sat unused for about 5 years with a Boyer Mk 3 that was about 18 years old. It had misfires at 2500 and 3500 RPM. It was impossible to accelerate through these two ranges in the higher gears (3rd & 4th).

After much trouble shooting, and ruling out carburation issues, black box was switched out, and the problem went away.

I have had at least 3 in my experience that displayed this behavior. I had one of my electrical engineer colleagues (I am a mechanical engineer) examine Dave's de-potted look inside and the conclusion that he reached was that is was most likely one of the capacitors. He stated that this has been his experience with similar capacitors in other applications - with long periods of non-use, the oil inside the capacitor hardens and the capacitor fails shortly there after once exercised.

I am open to other explanations, but the common thread in all of these cases has been with a bike that has sat without running for an extended period. The age of the Boyer could also have something to do with it.

As Mk 3 and earlier Boyers have displayed a propensity for kick-back under low voltage conditions, I worry that a bad capacitor could have a similar affect. I typically switch out an older box on a customer's bike rather when recommissioning it rather than risk injury. To me, it is $125 well spent.

Plus, the Mk 4 does not have the low voltage sensitivity that the earlier models do. This also makes them e-start friendly.

Personally, after about 35 years of experience with Boyers, I have been won over by the TriSpark.

FWIW

As an EE with 45+ years of field experience, I've seen aluminum electrolytic capacitors dry out and get "leaky" with heat and age. Tantalum and ceramic caps don't suffer from this. It's not from non-use, but from exposure to heat and time that takes a toll.

That said, I have had Boyer MKIII boxes get intermittent and misfire at certain RPM ranges, and it's always been from bad connections at the pickup plate.

YMMV

The capacitor in the Boyer powerbox is known to fail, never had one in a Boyer EI go.

I have read that the advance curves on Boyers are all over the map. I wonder if this is from the various capacitors failing as they age.

Stephen Hill said:

I have read that the advance curves on Boyers are all over the map. I wonder if this is from the various capacitors failing as they age.

Click to expand...

Boyer is 50 year old technology. Whilst fairly robust and people have had good use out of them, they weren't even the best technology available 40 years ago!

Don't over analyse, move on.

maylar said:

As an EE with 45+ years of field experience, I've seen aluminum electrolytic capacitors dry out and get "leaky" with heat and age. Tantalum and ceramic caps don't suffer from this. It's not from non-use, but from exposure to heat and time that takes a toll.

That said, I have had Boyer MKIII boxes get intermittent and misfire at certain RPM ranges, and it's always been from bad connections at the pickup plate.

YMMV

Click to expand...

In my military days, electrolytic capacitors were stocked by various departments as spares. The procedures issued to stockholders required you to 'reform' certain types after a defined shelf life by applying power. Tantalum capacitors were fun, liable to explode and fire the core across the room if handled badly.

There are countless threads on here discussing Boyer problems. Bad pick up plate connections on a Boyer is a fairly well documented and the source of more problems than people realise. And still people use them!

Buy a better box and pick up plate. Take care with connections.

SteveA said:

In my military days, electrolytic capacitors were stocked by various departments as spares. The procedures issued to stockholders required you to 'reform' certain types after a defined shelf life by applying power. Tantalum capacitors were fun, liable to explode and fire the core across the room if handled badly.

There are countless threads on here discussing Boyer problems. Bad pick up plate connections on a Boyer is a fairly well documented and the source of more problems than people realise. And still people use them!

Buy a better box and pick up plate. Take care with connections.

Click to expand...

US MIL-HDBK-1131B gives 15 years storage shelf life and this is under controlled climate conditions .

Does anybody know if the capacitors in a Boyer black box are the electrolytic type??

Stephen Hill said:

Does anybody know if the capacitors in a Boyer black box are the electrolytic type??

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Are you referring to the EI black box? Back in the mid eighties I repaired a couple of these.The main power transistor was the part that would blow ,all other components OK . There was nothing special about the quality/grade of the components , not high temp components . It's a long time ago and the circuit diagram and copper foil trace I made and later loaned to a fellow in the Sydney NOC, he did not return my stuff so going from memory the cap/s were tag tantalum .Those Black boxes were rubbish to repair as the potting material was very inert and hard to remove ,maybe I just did not have the correct solvent.Back then I worked at a Comms repair lab and had lots of different solvents . If you run one of these make sure you have it out in the breeze as per DD suggested in his articles ,heat is the main enemy . Possibly DD has the info ,is he still about?