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Diode ID Help

Discussion in 'Datasheets, Manuals and Component Identification' started by carpboy, Oct 13, 2012.

  1. carpboy

    carpboy

    4
    0
    Oct 13, 2012
    Anyone recognize these?

    This is from a CNC spindle drive board. The anode goes off board to a connector somewhere else, the cathode is on a couple of those 1/4 W resistors. It also goes to the power transistor (40W).

    Thanks!
     

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,206
    2,695
    Jan 21, 2010
    Here's what may be useful:

    1) slightly wider view of the board (preferably the whole board)
    2) view of the other side of the board
    3) part numbers of nearby parts
    4) voltages and currents that are used.
    5) identification of connections to the board if not obvious

    We almost certainly can't tell you the part number of these diodes, but we may be able to deduce suitable ratings for them and suggest a replacement.

    (I presume one has expired...?)
     
  3. carpboy

    carpboy

    4
    0
    Oct 13, 2012
    LOL, expired is an understatement. Actually, an NMOS went and took out everything around it.

    Here's the deal with the board. Attached are two pictures but I am afraid they aren't going to be of any help. This is out of a CNC, Yaskawa I believe. I think this board drives a bunch of spindles. Sounds like a high load, no? Its part # is JPAC-C343 or YPCT21043-1. I believe the former is how it is referenced.

    There are 8 identical "channels", the rightmost one is the one that went. Also attached is a sketch I made of the components of interest. I apologize for my chicken scratches. All resistors are 1/4 W except for the one noted.

    If one takes 1/4 W as the max power through each resistor, the 100 ohm one is 50 mA and the 2k one is 11 mA. The 100 ohm into the MOS gate is zero, of course. That means the max current through the unknown diode is about 60 mA.

    I have no idea of the voltages involved nor what is on the other end of the wires plugged onto the connector.

    Thanks for the interest.
     

    Attached Files:

  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    I would personally just try swapping out for a generic 1N400x diode and give a a whirl... The 1N4007 is good to 1000 volts and $ for $ is worth the extra penny or two just to be safe with an overkill voltage rating, that is assuming the lead will pass the hole in the board, and IMO the hole looks plenty big in the pictures...

    I do understand that you can see the more traditional 1N400x series diodes on the board as well and thus these are likely something else but it's probably not crucial to have an identical replacement in a simple controller board...
     
    Last edited: Oct 14, 2012
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,206
    2,695
    Jan 21, 2010
    Well, gate current into a mosfet can be very high during switching, and you haven't really specified the voltages, currents to the spindles, or what connects to what.

    Taking a few guesses, it sounds like a voltage rail of about 5V, but I expect that is for the logic.

    The mosfet itself is rated at 600V 15A, so I think the voltage it is switching is somewhat higher than 5V.

    It seems like the device is protected from the inductive kick generated by the motor being switched off by some series diodes. If these have failed, it is not inconceivable that the mosfet may have failed short circuit between the gate and drain and this has lead to excessive currents through the diode, however I would have imagined that this would take out the 100R resistor before the diode.

    Your images do not have sufficient resolution for me to verify your circuit as correct.

    Perhaps you could be more explicit about what voltages are used, and what the connections on the left actually go to.
     
  6. Jamie7

    Jamie7

    29
    0
    Sep 28, 2012
    Carpboy,

    On the first jpeg you sent I noticed that Q22 the left upper FET looks to be in backwards at least when comparing it to the other channels to the right Q23 & Q24.
    Would that be a fact or is the picture not clear?

    The diodes in your circuit are for protection and recirculating current in the spindle coil. As "CocaCola" said about the diode in question, is good. The larger black diode carries more current obviously and the other one in question is surely 1-3A
    and most likely 1A. The 1000 PIV is a good idea and best solution if you do not know the HV supply voltage,etc.


    I work at a CNC company called Servosource (servosource.com) and I am familiar with the design an operation of these circuits should you desire extended information on them. We design a product called Servo II and Impact. Retrofit 3 phase variable reluctance motor design and mini-mills. We have a similar drive circuit in ours and they are 3 phase with added current feedback switching and commutation. Your spindle motor is probably single phase PWM.

    If you cannot resolve your issue or you would like more input or help getting the diode you are looking for, I will take the time to look it up for you.

    Let me know, Good luck Jamie7
     
    Last edited: Oct 14, 2012
  7. carpboy

    carpboy

    4
    0
    Oct 13, 2012
    Hi all,

    Sorry for the delay, been swamped in work junk.

    Thanks for taking the time to respond.

    CocaCola: I have a few scavenged 4007's here and I was surprised at how small they are. Any ideas as to the reason for the shape of the damaged one? It appears that the pn junction is maximized but then total volume minimized.

    (*steve*): Adding in gate current limited by the 100 ohm resistor, that is another 50 mA so now total current through the diode is 110 mA. I was wondering what the reverse bias voltage might be with the A1010 bjt there?

    Jamie7: All transistors are oriented correctly. I will try to obtain some more info as to the sources/loads connected this board.

    Thanks again.
     
  8. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    It's some kind of 'nonstandard' diode the body shape might play a roll in something or it just might be how said manufacture does their diodes... Unless you track down the manufacture and part number I doubt you will have any solid answers even then you might not...
     
  9. carpboy

    carpboy

    4
    0
    Oct 13, 2012
    Revisiting this as I finally have time to work on it...

    In addition to the unknown diode there also are those labeled as '3108' but I can't find any reference to them.

    Turns out this board is part of a VFD. The motor is 208 3 phase. I am not certain if there are higher voltages present or not. The owner believes the service is 208/120 though.

    The 4007 has 1 A max forward current, that feeds three 1/4 W resistors, making the total current possible a little more than 100 mA well w/in specs for the diode.

    The '3108's are in the same boat as the unknown diode, maybe. I don't know what is on terminal 'E' or 'B', whether the MOSFET current is flowing into some load there.

    Since the K1573 has a max DS current of 15 A, worse case scenario is 7.5 A per 3108 diode.

    So I guess a reasonable equivalent to the 3108 would be something like 600V and 7.5 A?

    Thanks.
     
    Last edited: Dec 27, 2012
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