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Discussion Starter #1
Speaking of electric bikes, my Aprilia Enjoy racing bike appears to have
had a controller failure. Turn the key, controller pulls power, but
nothing happens.

Since the controller doesn't exist anywhere on the earth it looks like
I'm going to have to fix it. However all the components are of course
potted to the heat sink base plate.

So the question: What's the best way to remove the potting compound
without damaging the components? I have SMT rework tools and a
pre-heater for PCB boards; should I try heating it up? How hot can I
take it without risking damage to any of the components? How about if I
sacrifice non-silicon components (like the capacitors)?

Once I get the stuff off I can probably fix the thing. No schematics of
course, but how many ways can you build a 24 volt controller? :)

Chris

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70 Posts
Discussion Starter #2
Most electronic components are rated for at least 70C and quite a few in the
industrial field are rated at 85C, including most bus caps (automotive is
usually 125C).
If you heat the control up to 70C, most potting compounds can be picked out
quite easily with a screwdriver or similar tool (just

be real careful not to dislodge any of the electronic components, I would assume
most are surface mount).
You can start out by taking out large chunks of the thermal compound and then
re-heating the control and using a finer tool
to clear away the more intricate details. I've done this many times to analyze
controls that failed in the field (not mine of course :)
I think you're familiar enough with electronics after fixing those USelectricar
controls to figure out what the problem is.
Whatever you end up fixing, I would definitely replace the bus caps regardless,
hopefully with ones that have a higher temp rating, lower ESR and
higher ripple current rating.
Good luck!
Rod


----- Original Message ----
From: Christopher Zach <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Sun, November 21, 2010 5:41:58 PM
Subject: [EVDL] Removing potting compound on an Aprilia Enjoy controller

Speaking of electric bikes, my Aprilia Enjoy racing bike appears to have
had a controller failure. Turn the key, controller pulls power, but
nothing happens.

Since the controller doesn't exist anywhere on the earth it looks like
I'm going to have to fix it. However all the components are of course
potted to the heat sink base plate.

So the question: What's the best way to remove the potting compound
without damaging the components? I have SMT rework tools and a
pre-heater for PCB boards; should I try heating it up? How hot can I
take it without risking damage to any of the components? How about if I
sacrifice non-silicon components (like the capacitors)?

Once I get the stuff off I can probably fix the thing. No schematics of
course, but how many ways can you build a 24 volt controller? :)

Chris

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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| OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
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