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Thread: Time for a new capacitor - Compak K3?

  1. #1
    Senior Member CafeLotta's Avatar
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    Time for a new capacitor? (Compak K3)

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Does this sound like a capacitor on the way out?

    A few times recently, my 10 y.o. Compak K3 has just buzzed/hummed when turning on the grind switch (no grinding). On 2 separate days I switched it on and off a couple of times and it then started grinding.

    Today I had to remove the hopper, tip out the remaining beans in the grind chamber and manually turn the bottom burr back and forward to clear the remaining whole and partly ground beans. Nothing foreign or odd inside that I could see and it wasn't jammed. Same grind setting and beans which were used over the last few days without issue. Switched on and it began grinding no problem.

    It's happened 3 or 4 times so far. Never missed a beat before this.

    Haven't looked inside yet but it appears the K3 uses a 6.3 f 450v 50/60hz capacitor similar to / like the one below. (Compak Part# K.409)

    Compak K3 Capacitor Ducati energia.jpg

    DUCATI Energia Series 4.16.10.10 (or equiv. ?)

    If it needs replacing, what brands do I look for to avoid the "duds"?
    Last edited by CafeLotta; 1 Week Ago at 08:05 PM. Reason: replaced image (No company watermark)

  2. #2
    Mal Dimal's Avatar
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    Have you tried contacting any of our Site Sponsors who sell Compak grinders?
    Coffee Parts have equivalent items in stock...
    https://www.coffeeparts.com.au/parts...tor-6-3mf-450v
    Failing that, they would be easily obtained from any of the major electronics suppliers as e14, RS or even Wiltronics for example.

    Mal.
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  3. #3
    Senior Member CafeLotta's Avatar
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    Have had a quick look earlier at E14 & RS but can't find the DUCATI Energia Series 6.3 f 450v (4.16.10.10). Can find a 6 f in the same series but don't know enough about them as to whether this would suit? I read the replacement should be exactly the same rating as the original?

    Not sure which of the other brands are worth looking at or which to avoid.

    Am aware I need to check and discharge the old one before removal.
    Last edited by CafeLotta; 1 Week Ago at 11:48 PM.

  4. #4
    Senior Member Lyrebird's Avatar
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    The run capacitor is there to supply a second phase that runs "across" the main supply (90 degrees out of phase). If you draw the two phase waves you'll see that this angle "fills in" the valley in the waveform*.

    The phase shift is given by SQRT (LC) where C is the capacitance and L is the inductance of the motor winding. From this, if the 6.3 uF gives exactly 90 degrees (not necessarily the case) 6 uF will give 88 degrees.

    I used to design tiny electronic motor drives with variable phase angle, a 2 degree phase shift was detectable but not problematic.

    *The motor responds to the square of the current because energy in the winding is I^2L. If the two phases are equal in magnitude, the torques sum to a constant because sin^2(x) + sin^2 (x + 90) = 1. The 2 degree phase shift makes the torque function sin^2(x) + sin^2 (x + 88) which varies from 0.97 to 1.03, so there is a 6% variation of torque at 100 Hz, which creates noise.
    Last edited by Lyrebird; 1 Week Ago at 10:11 AM.
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  5. #5
    Senior Member CafeLotta's Avatar
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    Thank you for the detailed reply Lyrebird. Exactly the info I was after.

    Are there any brands of capacitors to avoid?

    Might just go with the 6.3 f capacitor Mal referenced from Site sponsor Coffee Parts. They appear to be a Chinese brand called "Last One"?

    Thinking about the grinder's recent behavior, I also wondered if the installation of new burrs a few weeks ago might have contributed. I did notice I was getting more fines than previously. I'll need to take the top burr off this weekend and see if these fines are collecting anywhere and loading things up a bit, making life harder for an older grinder.
    Last edited by CafeLotta; 1 Week Ago at 04:39 PM. Reason: Added Coffee Parts reference. Added "Last One" brand name.

  6. #6
    Mal Dimal's Avatar
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    For the most part, "brand" is inconsequential...
    You don't need to find a Pirelli capacitor, the one I linked to is perfectly fine.

    Mal.
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  7. #7
    Senior Member Lyrebird's Avatar
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    I agree with Mal re brand, at least for metallised polypropylene capacitors (which is what these are). Electrolytics are a whole different ball game.
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  8. #8
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    I need a capacitor myself...

    I'm slow to start in the morning and just whine...
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  9. #9
    Senior Member Lyrebird's Avatar
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    As do we all.

  10. #10
    Senior Member CafeLotta's Avatar
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    After a dismantle and full clean today I checked the original capacitor specs. Turns out it's an "Inco Sintex" 6f with the date (07/09) matching near enough the grinder build date. I'd imagine there's been a couple of changes in the newer model like motor and matching 6.3 f capacitor.

  11. #11
    Senior Member robusto's Avatar
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    As Mal said, capacitor brand is immaterial. The three things that matter are the same microfarads, at least the same voltage....and phyical size so it slots into the space.

    Capacitors are cheap. Buy and try.

    Be very careful handling it though. Even though it has been removed from power it can be loaded with dangerous elecrical power. So with a plastic handled screwdriver short the contacts before touching them with your hands.

    There are reliable unreliable ways to test with a multi-meter... but just get a new one and see if that fixes the problem.
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  12. #12
    Mal Dimal's Avatar
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    Need to be game though, to short out a (possibly) charged capacitor with a screwdriver....
    Not without eye protection at least.

    Mal.
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  13. #13
    Senior Member level3ninja's Avatar
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    Quote Originally Posted by robusto View Post
    As Mal said, capacitor brand is immaterial. The three things that matter are the same microfarads, at least the same voltage....and phyical size so it slots into the space.

    Capacitors are cheap. Buy and try.

    Be very careful handling it though. Even though it has been removed from power it can be loaded with dangerous elecrical power. So with a plastic handled screwdriver short the contacts before touching them with your hands.

    There are reliable unreliable ways to test with a multi-meter... but just get a new one and see if that fixes the problem.
    The type of load the cap is designed for is relevant too. Buying one made from the same material should ensure you're all good.

    In this type of installation (with a motor) the likelihood the cap is still charged is nil as long as both leads are still connected. In old CRT screens yes they'll hold a potentially deadly charge for 6 months or so, but this one will have been discharged within a couple of seconds of the grinder being turned off. And don't go shorting capacitors if you don't know what you're doing, they can get very nasty and explode and/or produce a nice arc-flash.
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  14. #14
    Senior Member CafeLotta's Avatar
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    Thanks for all the info guys.
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  15. #15
    Senior Member Jackster's Avatar
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    Get a Rubicon cap if you can.

    Also there is a difference between domestic caps and automotive. It might be just the temperature rating, but they are more hardy
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  16. #16
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by Jackster View Post
    Get a Rubicon cap if you can.

    Also there is a difference between domestic caps and automotive. It might be just the temperature rating, but they are more hardy
    Rubicon doesn't have an equiv. one that I could see. Went with an ICAR Ecofill 6uF MLR25PRL from Wiltronics. Dimens are 30D x 71L instead of original dimens of 35D x 57L. Had another look inside the grinder and it appears it should fit OK. Optional removable mounting stud is M8 matching the original.
    Also has dual terminals instead of single.

    Wiltronics6uF.jpg

    Otherwise performance Specs match the original Inco Sintex 6uF.
    Last edited by CafeLotta; 1 Week Ago at 12:30 PM. Reason: Added dimensions
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  17. #17
    Mal Dimal's Avatar
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    Wiltronics are a highly reputable company and don't stock dodgy components, so you can relax any concerns you may have re: quality...

    Have used Wiltronics myself, on and off over several decades.

    Mal.
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  18. #18
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by CafeLotta View Post
    Went with an ICAR Ecofill 6uF MLR25PRL from Wiltronics.

    Wiltronics6uF.jpg
    Received the Capacitor today but unfortunately not the ICAR 6uF with + or - 5% Tolerance as advertised. The received Item had the same model no. (?) with + or - 10% Tolerance printed on it (made in Romania, not Italy). Wiltronics said they would refund payment which is good.

    Fortunately the grinder has been OK the last few days after the big clean-out. Maybe there were trapped xtra fines from the new burrs loading up the grinder while they were settling in over the last few weeks? Does sound like its running a little more freely too.

  19. #19
    Senior Member robusto's Avatar
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    So 5.4mf to 6.6mf instead of 5.7mf to 6.3mf. I'm not expert enough to say whether that would make a material difference.

    Irrespective, you should be able to turn the spindle by hand. If you can't then the grinder appears jammed.

  20. #20
    Mal Dimal's Avatar
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    Small value differences like those will make no material difference to the function of the grinder.
    Using it would have been fine...

    Mal.
    P.S.
    Qualified knowledge is but a PM away...
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  21. #21
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by robusto View Post
    Irrespective, you should be able to turn the spindle by hand. If you can't then the grinder appears jammed.
    Grinder was never jammed. As I said previously, after installing new burrs I noticed there were more "xtra fines" which after a few weeks use seem to have reduced. There was more than usual residue collected around the bottom burr which was cleaned out.

    Quote Originally Posted by Dimal View Post
    Small value differences like those will make no material difference to the function of the grinder.
    I was taking as fact the recommendations that were on various capacitor manufacturer and suppliers websites saying to stick with the same run capacitor ratings including tolerances. The main issue I had was that full specs were published in the ad and what was advertised was not what was provided. When I spoke to Wiltronics they seemed concerned that this had occurred and said they were investigating.

  22. #22
    Mal Dimal's Avatar
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    Well, I guess that's where professional qualification, kowledge and experience come in...
    Like I mentioned, only a PM away.

    Mal.
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  23. #23
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by Dimal View Post
    Well, I guess that's where professional qualification, kowledge and experience come in...
    Like I mentioned, only a PM away.

    Mal.
    Cancelled the item return and will fit the one supplied. Had a false start with humming again today. Had to switch on/off to get going.

    Next job is to finally fit PID brew temp control to the Vibiemme. May need to take you up on your PM offer.

    https://coffeesnobs.com.au/brewing-e...t-howd-go.html Post #46
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