Need Help with Corvette electronics...

Discussion in 'General Electronics Chat' started by Mattias, Mar 27, 2008.

  1. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0
    Hi. I'm back again! :rolleyes:

    This time with a problem I have identify a component and some generall thoughts that might help me. I'm currently trying to fix a Digital Cluster to a mid 80's Corevette. As far as I know it still works exept for the back lighting. And all the lamps are ok and the circuitboard seems ok exept for the discoloration from the 10watt bulbs. I suspect that the component (K513) has stopped working. But I can find a replacement for it, so I ask the pros on the subject. ;) I belive that the component is a High current - low drop- voltage regulator??! Please correct me if I am wrong. :confused:
    It reads: K 513 1301 and what I belive is the logo for Motorola and in the circle it says KOREA.

    Here is Pic of the component.

    [​IMG]

    Direct link: http://img181.imageshack.us/img181/310/1copyih6.jpg

    Thanks alot.
    Sicerely
    -Ma$cH
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That device could be several things. A designator starting with "k" normally designates a relay, but the TO-220 package seems to be more for a transistor or voltage regulator. Do you have a meter, and do you know how to check a transistor?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    That's definitely the Motorola logo.
    I suspect the "K513" is a "house" marking which may or may not have a similar or equivalent on the open market.

    It looks like the large pad that the tab of the TO220 package is connected to might be the + supply to the dash lamps, due to the other side of the lamps being connected to the - pad of the electrolytic capacitor below. An LM317 adjustable regulator has it's output on both the center terminal and the tab. However, it also needs support components, like a resistor from the output to the adjust terminals, and a resistor to ground to vary the voltage, along with an output cap for stability.

    There is just not enough of the board showing to be absolutely certain about what the part might be.

    The large yellow and dark brown or black thing is an electrolytic capacitor. The arrows on the side indicate the pad on the left is more negative than the pad on the right. You should consider replacing it, as they have a limited lifespan, and an auto's dashboard is a brutal environment due to the heat. The electrolytes eventually either dry out, or the foil layers corrode away. They can short out and wreak havoc with other components.
     
  4. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    Seems like every dash problem I ever saw on a corvette was a bad ground. Are you testing this in the car? Have you checked for a good ground? Several 10 w bulbs are going to draw a few amps and a marginal ground will ruin your day..
     
  5. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,


    As we all know (?) rule #1 when you have a transistor-like device with a single letter and some digits is that they most likely left out the prefix "2S", so I find it likely that you should be looking for a 2SK513 or an equivalent.

    The numbers for 2SK513 looks like this:
    N-Channel Enhancement MOSFET
    V(BR)DSS (V)=800
    V(BR)GSS (V)=20
    I(D) Abs. Drain Current (A)=3.0
    Absolute Max. Power Diss. (W)=60
    @(VDS) (V) (Test Condition)=20
    I(DSS) Min. (A)=1.0m
    I(GSS) Max. (A)=1.0u
    r(DS)on Max. (Ohms)=5.0
    g(fs) Min. (S) Trans. conduct.=0.4
    g(fs) Max, (S) Trans. conduct,=0.7
    @V(DS) (V) (Test Condition)=20
    @I(D) (A) (Test Condition)=2.0
    C(iss) Max. (F)=470p
    t(r) Max. (s) Rise time=35n
    t(f) Max. (s) Fall time.=35n
    Package=TO-220AB

    You should be able to first verify if it's likely and then to find a substitute.
     
  6. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0


    Thanks for the reply. Yes I have a meter and it does measures like a regular PNP tranststor with hfe=305.
    And it seems like it is working properly, but stranger things have happened.
    :confused::cool:

    But I appreciated the help.
    Thanks.

    -Mattias
     
  7. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0


    Hi.

    Yes. the large pad that the tab of the TO220 package is connected to the + to the lamps. it seems to work. But I suspect another component ( i think it is a transistor aswell ) it's a BC518 and it controlls the base of the K513. but I'm not sure. I will definitely get you guys a better picture.


    Thanks alot for your reply.

    -Mattias S
     
  8. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0

    Hi. Yes I talked to some hardcore Corvette fans, and they also told me to check the ground. I did that and it seems ok. And if there was a bad ground shouldn't I see that or the ground be burned off or something?? :confused: there are 4pcs 12V 10W bulbs for backlight and 3pcs 12V 1.2W for turning signals and something else.:D so it's needs some juice to run.

    Thanks for your input though, even the smallest of piece of advice could be The One that cracks this problem.;)

    -Mattias.
     
  9. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0

    Hi. Hehe I guess I would be filed in the category " (?) ". I don't know the rules at all. :p:confused: But I learn every day, it seems. :cool:

    But as I researched your advice, I came to understand that the prefix "2S" is for japanese spec. only. please correct me if I'm way off.:confused: The motorola is american but their components are probably made in Asia somewhere. so maybe the prefix applys to it anyway.

    Thanks alot for sharing your wisedom and taking the time to reply to my thread.

    Thx
    -Mattias
     
  10. Mattias

    Thread Starter New Member

    Mar 27, 2008
    6
    0
    I had another question regarding the K513, and you might have the answer to it.

    the panel has a photoresistor.
    So if it is daylight outside, the lamps will run on 4*10W for the tachometer and other things... to be visable.
    And at dawn it should then dim the light so it won't blind you while driving in the dark. So in that case it might only need 25% of the light. 25% of 40W is 10W, which means that the transistor needs to get rid of 30W of pure Heat, right?! And that is alot of heat considering the small pad that the K513 is mounted on.:confused:

    I would love everyones input on this, and please feel free to correct me if I'm wrong, which I am quite often.:eek::D

    Thanks in advance.
    -Mattias
     
  11. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Your reasoning is good, but there is no way for the transistor to dissipate all that heat with just the little pad.

    Can you get power to the board? If so, does the BE junction have about .7 volts? That would indicate there is current through the junction and that the transistor should be turned on. Checking continuity to the bulbs is important, too. I had a Dodge with a printed circuit dash that lost the backlighting. It turned out that the bulb sockets had lost their electrical contacts. I had to remove them and solder bulbs in with stiff wire (I used 1815's because they were rated for 14 volts and wouldn't burn out ever).

    Anyway, one contact to all four bulbs should be in common to a voltage terminal, and the other should lead to the pass transistor. It's also important to check the connectors to make sure none of the contact pins has a crack around it so it's lost electrical continuity. That's a simple solder job, but use lead solder or you're asking for trouble.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It depends on how the device is being used.

    If it were strictly linear, then yes - it would have to dissipate a lot of power.
    40W @13.8v ~=2.9A, which is right at the limits of the specs that Soeren posted.

    If the K513 device is indeed a power MOSFET, it would be more likely that it was being used with a PWM driver circuit, the ratio of ON to OFF times being adjusted by the photoresistor. Normally, photoresistors/phototransistors decrease their resistance as the light intensity increases.

    What would be most helpful is if you traced out the circuit, and drew up a schematic of your findings, then posted it on here. This may take a few iterations, as it's easy to make a mistake. It will help us help you, and we may all learn some things in the process.
     
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