Rebuild a power pack

[redjmp]

So with winter here and my boats all out of the water I want a project to entertain myself for a few months.

I have always been miffed at mercury for building these unreliable and unserviceable power packs and charging me a fortune to replace the entire unit when in fact only 1 channel has gone bad.

I have had to replace too many so I want to try to take 1 apart to see exactly what is in there.

I have several old ones to use parts from and I want to see if there is a way to make it so that it is modular and easy to replace just a blown component/circuit rather than replace the whole unit.

Maybe even develop an aftermarket line of serviceable ones...

It has been over 30 years since I got my diploma in electronics (which I have never used lol) but I think I remember enough to understand the basic idea of what's going on.

Has anyone ever tried to take one apart?

I wonder what type of solvent if any that could be used to break down the epoxy?

 

[mercury713]

Re: Rebuild a power pack

Might be just a burnt diode.

Is it all siliconed in or its easy to unweld on board?

EDIT: you said at end it was... anyways good luck

 

[daveswaves]

Re: Rebuild a power pack

The resin is a urethane so hard to dissolve per se, you can heat it and dry it out then pick it out. Not really worth it though since the heat can damage other components. Usually what goes wrong is the tantalum capacitor at the end on the switchbox, it is possible to dig that out and replace it. The other thing that goes is the bias circuit, usually bad connection inside, corrosion due to urethane drying out. If the scr inside is gone usually its from reverse polarity being applied to the engine. Good luck........

 

[redjmp]

Re: Rebuild a power pack

The resin is a urethane so hard to dissolve per se, you can heat it and dry it out then pick it out. Not really worth it though since the heat can damage other components. Usually what goes wrong is the tantalum capacitor at the end on the switchbox, it is possible to dig that out and replace it. The other thing that goes is the bias circuit, usually bad connection inside, corrosion due to urethane drying out. If the scr inside is gone usually its from reverse polarity being applied to the engine. Good luck........

Thank you!
I'm not so interested in rebuilding mine per se, but I would be interested in making one from scratch as I'm sure most if not all the components are mere pennies each.

Even the active stuff like scr's and triacs are only a few bucks if that much so I have no doubt the total bill would be a tiny fraction of what mercury gouges us for one.

And then it would be serviceable if a component fails...

Do you have a schematic showing this circuit?

Thanks again!

 

[Faztbullet]

Re: Rebuild a power pack

Here ya go... most pack failures are due to failed maintenance not workmanship. Frayed wires, bad/loose grounds, defective coils & stators,failed/miswired keyswitches, misdiagnosed repairs These failures damage or destroy the blocking diodes, SCR's, internal rectifier or bia's capacitor.(see if you can tell where bia circuit gets its voltage )

 

[redjmp]

Re: Rebuild a power pack

Thanks for that diagram Fazt.

Now I just need to know what are the values of the caps and the part # of the scr's (or are they transistors?)

 

[daveswaves]

Re: Rebuild a power pack

Thanks for that diagram Fazt.

Now I just need to know what are the values of the caps and the part # of the scr's (or are they transistors?)

Well, I told you they were scr,s and that you would have to bake out a power pack to dig out the components. Just cause I live in ONTARIO does not mean I can,t help a BC'er. I fish for salmon too ya know

 

[daveswaves]

Re: Rebuild a power pack

Bias voltage?
OOOH, a puzzle, may your yin provide a source of energy and your yan balance the effects
Good info FB.

 

[redjmp]

Re: Rebuild a power pack

Bias voltage?
OOOH, a puzzle, may your yin provide a source of energy and your yan balance the effects
Good info FB.

You totally lost me on this?

Are you referring to something on FaceBook or? FB?

Yes I have boiled one of mine and It does soften up the urethane (thanks!)
I am in the process of digging it apart and as I suspected there is more going on than Fazt's diagram shows.

Seems like 2 resistors, 2 caps, a diode. and a mini isolation transformer are being used to switch a small transistor which then triggers the scr's.

Still digging!

 

[daveswaves]

Re: Rebuild a power pack

You totally lost me on this?

Are you referring to something on FaceBook or? FB?

Yes I have boiled one of mine and It does soften up the urethane (thanks!)
I am in the process of digging it apart and as I suspected there is more going on than Fazt's diagram shows.

Seems like 2 resistors, 2 caps, a diode. and a mini isolation transformer are being used to switch a small transistor which then triggers the scr's.

Still digging!

OOPs sorry, FB is Faztbullet, and he left you a quiz " see if you can find where the bias voltage comes from. I was havin some fun and left you a clue to where the voltage comes from, yin yan, positive negative, just like the one that comes out of your trigger hint hint. The positive cycle fires the trigger, the negative cycle charges the bias cap. The diagram that Faztbullet provided is from Mercury training which conceptually describes how the switchbox works so that the techs can understand enough of the theory of operation to troubleshoot a switchbox problem. It was never Mercs intent to disclose the full schematic.
Sometimes my humor is lost on those that don,t know Im twisted:redface:

 

[Faztbullet]

Re: Rebuild a power pack

HE HE HE we are both twisted alittle Dave
As for the bia's voltage, school teachs it comes off high speed stator...

 

[daveswaves]

Re: Rebuild a power pack

HE HE HE we are both twisted alittle Dave
As for the bia's voltage, school teachs it comes off high speed stator...

Well....the high voltage for the discharge cap comes from the stator, via the internal rectifier...but the bias cap voltage comes from the trigger signals negative swing.