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-   -   Why do some of the RV-12 VRs die young? (https://vansairforce.net/community/showthread.php?t=145841)

DaleB 01-29-2017 08:28 AM

Make that eight.

John-G 01-29-2017 09:41 AM

Install Silent Hektik with heat sink compound
 
For those of you RV-12 owners that are about to switch over to the Silent Hektik regulator I have a couple of suggestions.

Heat is the killer of electronics so to help mitigate the affects of heat you will want to do yourself and the regulator a favor and slather a thin film of heat sink compound onto the entire bottom of the regulator prior to bolting it down. A glad bag over the finger will work well for spreading a smooth thin coating onto the regulator bottom. The heat transfer paste that is used on the Rotax's spark plugs will work well for this application if you have it ... else, get some thermal paste from Radio Shack or any electronics supply house. Artic Silver ( a high quality microprocessor heat transfer compound ) would probably also be a great choice for this application as long as it was spread thinly.

If mounting the regulator on the inside of the cockpit, be sure to remove all paint and/or primer from the bottom of the instrument panel base where the regulator will mate.

If you are keeping the regulator on the firewall shelf, consider moving it more to the left side of the firewall shelf to keep it away from the outflow from the coolant radiator and then run a scat tube to the lower cowling to get plentiful cool air from the air duct ahead of the radiator.

My two Lincolns

alexe 01-29-2017 06:20 PM

Joeri,
Please add me to the list. Let me know how you would like payment. My email is alex at fpcounsel dot com.
Thanks,
Alex

jweir43 02-09-2017 07:18 PM

Quote:

Originally Posted by E. D. Eliot (Post 1143082)
I know that this has been hashed out a lot - but - I can't help but wonder what it about the RV-12 electrical system that is causing some VRs to die quite young?

Really? Something is wrong - what is it?

One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim

Mich48041 02-09-2017 07:57 PM

Jim Weir,
Welcome to VansAirforce ! !

Mich48041 02-09-2017 08:34 PM

People to talk with:
Gilles Theseus (France ?)
Mike Miller
Link to Contrails Rotax Ducati
There are two opinions about the failures: vibration and heat.
Ducati Schematic The schematic may have changed over time.
The generator is permanent magnet, single phase (dynamo).
The Ducati rectifier/regulator changes the AC to DC and regulates the output voltage. Terminal "C" both enables the regulator and senses aircraft electrical system voltage.

DaleB 02-09-2017 09:06 PM

Quote:

Originally Posted by jweir43 (Post 1148897)
One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim

Jim, there's a schematic posted (as noted above) and there are similar devices in widespread use, mostly in motorcycles it seems. It's a rectifier-regulator, Google is your friend once you use that search term. I'm no EE, just a hack with a soldering iron... but if I were describing the circuit I think I'd say it's an odd hybrid of bridge rectifier and sort-of-switching regulator.

The older designs use SCRs in the rectifier, triggered when the voltage exceeds a set value to short the incoming AC voltage to ground. Talk about your brute force regulation, right? The newer ones use MOSFETs.

The Ducati failure modes are pretty well documented. My "replacement" went poof because of really poor physical design, a defective part (surprise, surprise) or both. I'm guessing thermal runaway caused by a lack of heat sink and a mass of rubber thermal insulation around the critical parts. The power components are surface mounted on a PCB, inside a nice massive heat sink casting... but the PCB is glued to the heat sink, not the components, slo they've got good thermal insulation from the heat sink. ::rolls eyes:: For $30 I'm not inclined to spend too much time analyzing it, but you're welcome to the corpse if you want it.

I was tempted to build something new in the case of my deceased Chinese John Deere "replacement" regulator, but my appetite for stress testing in my airplane is not too great - and my desire to set up a meaningful test rig is even less. This is a rare case where I'm willing to spend a few bucks to avoid screwing with it. I'll be installing one of the German made Silent Hektik regulators, hopefully before my Ducati gives up the ghost. It's running less than 13.5 or so in flight lately, I think its days are numbered. I plan to un-pot it and have a look once I have a stable replacement in service.

73 de N0XAS...

rv9builder 02-09-2017 09:25 PM

Hi Jim,

Welcome to VAF! Thank you for offering to take a look at the problem.

BillL 02-10-2017 06:42 AM

FYI
 
Quote:

Originally Posted by jweir43 (Post 1148897)
One of the Kitplanes editors asked me to address the problem, so here goes. I need somebody on this forum with direct experience and a bit of technical knowledge to describe for me exactly what this "regulator" does. Seems to me that it is taking a raw AC waveform from a generator, rectifying it into DC, and then providing that for your DC power source.

The SUPPOSITION is that heat is the problem. I'd like some data on why you all think this, rather than some sort of spike that kills the regulator from the output, but that's just me trying to see if it is the belt or the suspenders that are letting the jeans fall off.

If I can solve the problem, I think I can do it for less than a hundred bucks ($100) in parts, but y'all have to spoon feed me as to what size I can have, what the maximum temperature I can expect where this sucker is mounted, and all that good stuff .... MEASURED and not SEWAGed.

Anybody up for this?

Jim

Jim, this link was buried and you may not have seen it or it may be of no help. It may provide a contact for you to discuss with a peer.

http://contrails.free.fr/elec_ducati_en.php

EDIT: Another EE experimenter on the VR - Very good - you will have to join the forum to see the results. HERE

Piper J3 02-10-2017 07:41 AM

jweir43

Perhaps you can also compare the Ducati to the John Deere AM101406 regulator that many of us RV-12 guys have substituted.


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