problem with m15mk1

  • Hi, I've a problem with my m15mk1: I have to do the test for the power_supply board and I've checked attentively all schemes and part (and all should be correct) but when I turn on the amp, smoke comes from the resistor r23 between capacitors c22 (100uF) and c18 (47uF) and it become burning... I don't know if there was an error in the resistor (I don't have check 3,9k with my multimeter, I've just read the value that was written in the little card of the resistors) but now my multimeter shows 2,6k and 2,3k in r16 and r23 (that are the same) resistors (I've tried both resistors, so they could be damaged (should I have to replace other parts? How can I understand if a part is damaged?)... What can I do? I'm despear, help me please...
    THANK YOU matteo

  • Hi,

    everything "behind" C18 (and C18 itself) could be the cause... That means, that there is a connection to ground that should not be... Are C10 and C18 connected correctly (plus and minus, you know)?

    And yes, you should renew these suspicious resistors.

    Bernd

    Jaichweiß (Andy Pipkin)

  • Zitat von eBernd;256340

    Hi,

    everything "behind" C18 (and C18 itself) could be the cause... That means, that there is a connection to ground that should not be... Are C10 and C18 connected correctly (plus and minus, you know)?

    And yes, you should renew these suspicious resistors.

    Bernd

    (C10? do you mean C22?) I have checked the connections and I think all is connect to ground and plus and minus is ok...
    I've also tried to replace all 3 capacitors of the power supply but no result...

  • Zitat von eBernd;256340

    Hi,

    everything "behind" C18 (and C18 itself) could be the cause... That means, that there is a connection to ground that should not be... Are C10 and C18 connected correctly (plus and minus, you know)?

    And yes, you should renew these suspicious resistors.

    Bernd


    (I have also (obviously) replace the resistors and I've also tried to put a bigger one, but no results)

  • Hi,

    the replacement is for safety, but by this you won't have eliminated the fault.

    The smoking resistor(s) are results of the error but not the cause...

    Find the connection (probably to ground) which shouldn't be or a wrong connected electrolytic cap...or...

    Bernd

    edit: What do you mean by "bigger one" - other values?:eek:

    Jaichweiß (Andy Pipkin)


  • I know I know, I've just think that the resistor could be small (I've tried to put a 4,7k... oops I made a big error?) because I think all is connect to ground and I've follow the scheme and plus and minus are OK... I don't know, tomorrow I'll try to connect the minus of the caps to the chassis directly (now the wiring is made under the power supply and maybe there is a little error)...
    Tomorrow I'll communicate again every result...
    THANK YOU
    matteo


  • I've checked all capacitors and I also made the connections directly from the minus of the caps to the chassis but the problem remains... if you want I send you some photos...


  • hey!? Someone can help me? I pray you, i'm beginning to be despressed...

  • Zitat von Kramusha;256608

    Disconnect the PSU Board from the remaining circuit. Is the resistor still getting hot?

    Stefan :)

    Ich hasse Englisch soooo sehr :( Icth hab für diesen Saz ich glaub 1 Minute gebraucht. Brauch Übung..


    ok, I wish you'll can have more time (I don't have perfectly understood the German sentence:))...

    However I have disconnect the power supply board from the remaining circuit (what do you mean exactly? I have disconnect (view the image) the white and red wires, the 2 blue wires,and the black... it should be correct...) and now the resistor is OK
    (THANK YOU)
    matteo

  • Zitat von Kramusha;256616

    Very good. Now you can connect the remaining parts step by step. So you can encircle the defect.

    Stefan :)

    OK fantastic... I have step by step connect the wires: the resistor burns when I connect the plus of C18 to the Mainboard!!!
    (thank you)
    matteo

  • Zitat von Kramusha;256616

    Very good. Now you can connect the remaining parts step by step. So you can encircle the defect.

    Stefan :)


    (ehm... and now?????:))

  • Zitat von Kramusha;256628

    Cool down.. ;D

    We know now, that the poweramp is OK. Disconnect every anoderesistor from the Ub rail. Try to find the part of the amp, that makes us crazy. Part by part...


    (The "Ub rail" is the course of the circuit? or the main board? or...) What do you mean exactly? must I try to disconnect every resistor and capacitors (can I disconnect every part I want without to risk to damage something?)
    (obviously thank You:))
    matteo

  • Zitat von Kramusha;256628

    Cool down.. ;D

    We know now, that the poweramp is OK. Disconnect every anoderesistor from the Ub rail. Try to find the part of the amp, that makes us crazy. Part by part...


    as soon as I've removed R18 (I don't know if you know the scheme of m15mk1, if you want I post photos or image of the scheme...) the resistor wans OK...
    mh... what I have to do? Do you have some ideas?
    I have to do other test (remove some other resistor or...)
    I've no ideas...
    (thank you)
    matteo

  • Zitat von Kramusha;256628

    Cool down.. ;D

    We know now, that the poweramp is OK. Disconnect every anoderesistor from the Ub rail. Try to find the part of the amp, that makes us crazy. Part by part...

    The resistor is OK disconnecting R25 too (obviously with R18 and R19 connected)

  • Zitat von Kramusha;256690

    R18 or C18?

    Ok, solder everything you disconnected together and unsolder one leg of R16. Now the preamp is disconnectet and we know if the phase inverter is ok.

    Stefan :)

    Wenn jemand Bock hat mich zu korrigieren kann er es gern tun.


    I've tried to disconnect Resistor18 and then R25...
    Now I've unsoldered one leg of R16 and the the problem of the resistor there isn't

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