Question on PMD / FSD

[crazpony]

Has anyone torn an PMD / FSD apart? I am contamplating this, just wondering what makes it tick and which component gives up first.

[john8662]

They're glued together really really well.

As sponge bob would say "well, good luck with that".

J

[Robyn]

There are two large power transistors inside the PMD.
I dont really think ripping into one is going to provide any real personal satisfaction.
AS John posted they are glued together well.
There well may be some other circuitry but I doubt with the way these are made that it will be of any value once extracted from its hiding place,
If you do get one apart please share with us.
Robyn

[moondoggie]

Good Day!

Do some searching, this was pretty well documented a few years ago. It is possible, however, that some or all of the topics where this was discussed have been lost over the years.

Basically, the potting material is a thermoset, meaning once they pot this thing, there's virtually nothing that will dissolve it. And, it doesn't melt, it burns. That in fact is (if memory serves) how some have re-soldered the drive transistor leads - burn through the potting with a Pace or similar desoldering machine to get down to the pads.

I've got two of these laying around myself (if I can find them); sure wish I had time to pursue attempting a repair.

Blessings!

[rjwest]

I have attempted post mortem on quite a few PMD's.
Only 1 had a bad power transister,

Doing any further investigation would be quite difficult
without having a non destructive method of removing
potting material...

My guess on primary failure mode, POOR Quality,
'cold solder'

[stingthieves]

I have been anguishing the last few weeks with a stepper motor fault. Blew a head gasket last week so as long as the thing was almost loose - I finished the job and sent my IP to the Standine guy in Green bay this noon. BUT I forgot to send the remote PMD. He hooks the thing into his test bench - now lets set the stage - He installed the IP in this truck three years ago with the remote PMD - HE hooks it into his test bench and blew the test bench because the mounted PMD is bad,
Wonder who is going to pay for that?
Makes me wonder about this dealer!
Rick