Component Identification Assistance

[vettedac]

Hello Everyone, looking for assistance in identifying the two components in the image attached. The circuit board is Motorola used in the mid 90 Chrysler JTEC power control modules. These two components appear to be related to the ignition coil driver circuit. The identification codes appear to R100 and F100.

Thanks,

Dave

 

[Nigel Goodwin]

I would imagine they might be 0.1 ohm resistors, in parallel, to give 0.05 ohms - for current measurement?.

I also imagine that they are both R100, with the R on the second slightly damaged?.

 

[narkeleptk]

Nigel is correct.
It looks to be the current sense for the IGBT.
95% of the time when they go bad you will visually see it.

 

[dr pepper]

You'll have to remove the conformal coating before you try to solder it.
An electronics repair company I deal with just returns anything conformally coated and says they will not do it.

 

[narkeleptk]

This conformal coatings not bad at all. scratches away with ease. the newer JTECS and original NGC's ECU's from Chrysler are what Nightmares are made of in rework. They are completely filled with this rubbery almost transparent orange potting material. Pretty difficult to work with.

 

[dr pepper]

I've had to unpot stuff twice, your right its a pain, last time I used a heat gun to soften the gunk.
Ironically the fault was caused by potting compound leaking into a relay.

 

[Nigel Goodwin]

I've had to unpot stuff twice, your right its a pain, last time I used a heat gun to soften the gunk.
Ironically the fault was caused by potting compound leaking into a relay.

We pot using some kind of epoxy resin, with no expectations of repairs or even battery replacement.

 

[dr pepper]

Quite, the repair was necessitated by finance not practice.

 

[Nigel Goodwin]

Quite, the repair was necessitated by finance not practice.

I think we've all been there

Not necessarily for financial reasons, often because a new unit isn't available - but we make stuff for water company use, so they MUST be waterproof (and we sell them a new one when the battery finally runs out! )

 

[vettedac]

Thank you everyone for confirming. I am glad this is not one of the later JTEC's that is fully potted. I was able to unsolder the burned resistors from my other pcm and will replace. Do you think the ignition coil driver transistor should be replaced also? I attached and image of the burned resistors from the "bad" pcm. I also replaced the ignition coil with one of higher primary resistance (closer to factory specs). I believe the low resistance aftermarket coil was at fault here.

 

[narkeleptk]

You can test the driver with a DMM in circuit and have a fair bit of confidence if it is okay or not.