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Component Identification Assistance

vettedac

New Member
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
 

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Nigel Goodwin

Super Moderator
Most Helpful Member
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

Active Member
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

Well-Known Member
Most Helpful Member
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

Active Member
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.
 
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dr pepper

Well-Known Member
Most Helpful Member
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.
 

dr pepper

Well-Known Member
Most Helpful Member
Quite, the repair was necessitated by finance not practice.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Quite, the repair was necessitated by finance not practice.
I think we've all been there :D

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! :D)
 

vettedac

New Member
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.
 

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