OMC Esoterics Web Site

[realboats]

Hi. I remember reading somewhere on this forum that there is a web site with tips and tricks for OMC stuff, especially the electronics with schematics.<br /><br />Would anyone know of a site that discusses the inner workings of things like power packs and such? I'm really curious on what's inside the CDI power packs and would like to find more information on them. Thanks!

 

[G DANE]

Re: OMC Esoterics Web Site

Some electronic engineer once made a schematic on a twin power pack. I have it in PDF, and can mail it if I get your mail adress.

 

[realboats]

Re: OMC Esoterics Web Site

That would be great G! Email is DenisNH@yahoo.com <br /><br />Thanks!

 

[McGR]

Re: OMC Esoterics Web Site

Some of the service manuals, at least on the older models, had diagrams of the internal components within the power pack. When my power pack failed on my '76 85hp I de-potted it and compared it to the diagram in the manual. It was almost totally correct, I believe there was one resistor on the powerpack that wasn't present on the diagram. Basically the circuitry on the 70's vintage packs consists of a rectifier bridge that rectifies the energy from the charge coils to DC. This DC charges the (CD) capacitor. Then there are discrete SCRs, one for each cylinder that are gated by the sensor coils. When these SCRs are triggered the charge in the cap is discharged through the ignition coils producing a spark. It's really an elegantly simple but effective circuit.

 

[OBJ]

Re: OMC Esoterics Web Site

Question McGR....how do ya' depot the darn things?? I like tearin' apart to put don't know how to depot them.

 

[McGR]

Re: OMC Esoterics Web Site

A couple of modules I have "de-potted" have been OMC originals that used the green urethane type encapsulent. I just slowly chiseled away at them with a small tweaker screwdriver. It takes time, but if you're patient and careful it can be accomplished with minimal damage to the circuit within. At least this is true in the case of the green stuff. However, some packs are potted with a much more rigid epoxy compound. I've been inside these also, but it usually resulted in irreversible destruction of the module. So... there's no real art to my method of de-potting. It's just a matter of slowly hacking away at the potting compound until it's all gone.

 

[OBJ]

Re: OMC Esoterics Web Site

Dang Mc.....I thought I was doing it the hard way.... There gotta be a way to do it without the knife and chisel. I know about that black epoxy stuff......darn it's some tuff stuff.

 

[Paul Moir]

Re: OMC Esoterics Web Site

If you can identify what you're working on, there's commercially available de-potting compounds.<br /> This stuff for example.

 

[OBJ]

Re: OMC Esoterics Web Site

Thanks Paul....may be a "tinkers" dream!

 

[Paul Moir]

Re: OMC Esoterics Web Site

If I ever end up with a dead-un, I'm not letting it stop me.

 

[McGR]

Re: OMC Esoterics Web Site

I've used some of the Dynaloy products in the past. These are some nasty powerful chemicals. A good whiff of this stuff will practically knock you on your behind. They work fairly well. But they sometimes destroy things in the chemical decapsulating process that you need to stay intact. The stuff is wonderful for removing resistor color codes. I've never tried this stuff on ignition modules. Who knows, maybe it would work well. But, the cost of a container is not cheap, probably approching the cost of the module. One note, if you ever try the chizeling technique, some heat from a heat gun can often be beneficial in softening up the compound.