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Thread: Crown K1-K2 Sleep Mode Mod

  1. #1
    Senior Member 1audiohack's Avatar
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    Crown K1-K2 Sleep Mode Mod

    Hi All;

    For those who may have issues caused by the sleep mode or low signal standby feature of the K series amps here are some options.

    First, the first two production years had a low or no signal sleep time of only about six seconds, after that it was increased to about 56 seconds. The duration is determined by the value of a ¼ Watt resistor on the input board designated R-15. 6 sec=82KΩ. This can be increased up to about 56 seconds with the use of an 820KΩ. Above this value it won't sleep.

    Also should you want it never to sleep, next to the R-15 space is an open space marked Z-1, a jumper installed here defeats the standby mode entirely.

    Many thanks to Kevin at Crown and Subwoof for the help.

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    If we knew what the hell we were doing, we wouldn't call it research would we.

  2. #2
    Senior Member BMWCCA's Avatar
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    Great information. I'm filing that away for when I have a K1/K2.

    A bit off-topic but I'm still looking for some help on a PS400. I may have posted this before but here's the update. I'm still trying to identify the suspect C4 cap on the board controlling the turn-on delay. Not well marked but maybe someone here has the experience to know.

    I posted this on the Crown board:
    One of my PS-200s has developed a problem with the clear-plastic cube "relay" on the circuit board above the power switch, visible with the top cover of the amp removed.
    The box is marked "Japan" with a four-digit number printed on it and has four contacts to the circuit board.
    On turn-on it will sometimes buzz for several seconds as if the relay contacts are dirty or aren't getting enough voltage to close. Eventually, usually, it will "lock" in the closed-circuit mode and all is well. When it buzzes, all the four red LEDs on the faceplate light up and flicker. I can see the "relay" fork attempting to close the contacts but they won't stay closed.

    What is this part? I'm guessing part of the turn-on delay?
    Is this a replaceable part that's still available from Crown? (Couldn't find a part listed on the circuit diagram.)
    Symptomatic of some other ailment?

    Thanks for any help. First problem I've ever had with a PS-series amp out my five!
    To which I received this reply:

    There is a good chance that C4 on the little board with the relay you speak of is bad. There was an update for that cap many moons ago, and your amp may not have gotten it. Or, due to age and use (I think more due to age) it doesn't work as it should. Replace it with an electrolytic cap, 10uf at 100V. I think the original designed cap was less than 100V and that was why the update happened. The Crown part number for the replacement cap is C 8889-5, if they still have it. If you have to search for an alternate part, do not go lower on the voltage rating! No problem to go higher. Also, PAY ATTENTION to the polarity of the old cap BEFORE you take it out. Put the new one in backwards, be prepared to buy another one, clean up a mess in your unit, and a loud BANG!

    Hope this helps.
    So, I dug in with my schematic and got stumped at this point and asked:
    Thanks! What I think is C4 (indicated by red arrow at lower left in photo below) is marked 6.8uf at 50v. The schematic in the PS200 manual shows C4 as 10uf at 50V. I can't see the mark on the board for the component number but maybe it's underneath the cap? The part listing on-line at Crown for the PS400 shows C4 as part number C3728-0 that supersedes C5050-7. It gives no indication of value for C5050-7. Could my 6.8uf have been superseded by a 10uf? Am I looking at the right cap?? (see red arrow at bottom left of photo)? Is the part for the PS400 the same as the PS200? What difference will 6.8 versus 10.0uf make??

    Thanks for helping someone who can barely tell a resistor from a capacitor! (But I have replaced caps in a DVD player with success.)
    No reply so far, so here's the photo:
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  3. #3
    Senior Member Baron030's Avatar
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    As an owner of both a Crown K1 and a K2, I say thanks to iAudiohack, Subwoof and Kevin at Crown. I have known about the sleep mode mod for some time now. But, sometimes a picture is worth a lot more than words. Now, I know what to look for and that’s a lot better than just trying to make heads or tails out of the schematic.

    The only work around that I have had for that sleep mode issue is just to play it louder.

    Baron030

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