12V Power supply troubles....

Discussion in 'The Projects Forum' started by mrflamboynt, May 22, 2011.

  1. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    i have a Pyramid Ps-46Kx (40A 16VDC) ..... i accidentally bumped the outlet while it was doing about 30A and toasted the 8A 32V glass fuse.... replaced it but still no output.... the lights for the guages do not come on (when they usually do), but it does turn on the red light in the power switch, which comes on usually when unit is powered on.... removed the cover and inspected by eye and didnt see anything burned or damaged. but i know NOTHING about circuits, including most components in a circuit.....

    http://www.pyramidcaraudio.com/manuals/PS46KX.pdf

    here is a link to the manual, which shows circuit diagram.... any input as to how i can track down the problem and replace it would be greatly appreciated... hope i came to the right place.

    thanks in advance....
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Welcome to AAC Mrflam_etc.

    Yes, you have certainly posted the information well.

    Except I can't find the 'red light' on the circuit diagram. Pity as this would reveal useful information.

    To service you power supply it will be necessary to identify various circuit points from your diagram on the actual circuit board and measure voltages at these points.

    Are you able to do this.

    It is possible the surge protection diode has also blown, along with the fuse.

    This is the component marked CR6 - P6KE39A.

    Are you capable of removing it and soldering in a replacement?
     
  3. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    studiot thanks for the reply! im sure trouble shooting this will be "something simple" ha ha.... looks like im gonna have to get off my lazy bum and actually learn something (more than i had anticipated) ...... actually i think the best advice i need right now, is pointed in the direction of where i can learn the basic symbols on the diagram. would probably make things easier on everyone.

    however at this point i am capable of taking measurements with a multimeter.... i will do my best to locate its (switch light) position in the circuit.... and i will also try to locate the CR6 components physical location based on the diagram......

    this could take a few minutes ;)

    thanks again
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
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    I am sorry I didn't read your post properly.

    You said the red light is in the power switch (itself?). This simply means that mains power is reaching the unit.

    I am concerned with the personal safety of a beginner opening a mains unit and poking around inside.

    Can you post any photos?
     
  5. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    lol, i appreciate the concern for my safety.... i was thinking about that myself last night as i was typing the previous post.... but i figure as long as i treat everything as being hot im sure i will be careful enough to take a measurement or 3.... but if we can figure this out without too much danger would be best...

    here are a couple photos, yes the power light is located within the power switch.... let me know if you need something more specific.... i took a bunch, and lost track of which ones i wanted to post.... on a few pics, the flash washed out some of the print on the circuit board, wires in the way of others, so a bunch of different angles, and moved wires.... again let me know if you need a better look at something specific...

    thank you

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    org/forum/members/mrflamboynt/albums/my-stuff/4943-pyramidguts.jpg[/IMG]
     
  6. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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  7. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    oh i did locate the diode you specified, i will try to find a replacement for it.....
     
  8. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Yes these look useful pictures.

    If you want to try some trouble shooting with a multimeter here is a safe (if slow) way.

    First we should work from the known good mains supply towards the known not working output.

    Be aware that one of your photos shows typical american practice with the transformer terminals (at mains) exposed to any slip of the hand.

    So for general safety adopt the old service engineers technique.
    Keep one hand in your pocket!
    Clip one lead onto the zero or earth and use only the free had to manipulate the second prod of the multimeter, watching what you are doing all the time.

    But before this test the AC part of the unit ( the transformer)

    First disconnect the unit from the mains.
    Set the multimeter to AC volts at a range greater than 120 volts.
    Clip the leads to the transformer terminals. Keep both hand clear.
    Switch on the unit and record the voltage.

    Disconnect the mains.
    Move the leads to another pair of terminals
    Switch on the mains and record the voltage
    Disconnect the mains and repeat until all the transformer voltages are measured.

    I would expect the transformer to be intact.

    So move on to DC testing.
    Disconnect the mains.
    Set the multimeter to 30 volts range and connect the black lead to the negative terminal.
    Switch on the unit.
    Using my hand-in-the-pocket technique measure the voltage at C1 positive.

    If you get this far post the results.
     
  9. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    ok i am ready to work, and i am clear on the procedures for taking slow but safe measurements.

    however i just need a little more verification on the rest of your instructions....

    which wires are the 'mains'?

    i am assuming the transformer is the big coil component directly behind the cooling fan. if so, to disconnect it for measuring, would that require removing the soldered wires from it? if it were disconnected from the mains, then how would it get any power when i switch the unit on?

    lastly, in the beginning of your last post you mention clipping the the black wire from the multimeter to the "zero or earth" i am assuming this is a ground location inside of the power supply? or should i clip it to a ground outside of the unit? i was under the impression that i would have to connect both pos. and neg. prods to the component i am measuring....

    again i apologize for my ignorance of these most basic definitions. but im a fast learner, and you will only have to explain it once.

    your patience is greatly appreciated.
     
  10. studiot

    AAC Fanatic!

    Nov 9, 2007
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    No you do not need to unsolder anyhting at this stage.

    The transformer appears in many of your pics, but first in the third pic above the pyramid front panel. In another pic it is labelled PS 46KX

    The secondary (low voltage) leads appear out of the body of the transformer as dark wires ending in eyelets that have thick red leads soldered in them.
    Clip the alligator clips (if you do not have any - get some, do not poke about with prods they can easily slip) to these exposed connections. Label them with paper/sellotape for future reference.

    The high voltage mains leads from the transformer will be connected to the fuse holder and mains switch. You do not need to measure these as the mains light is working.

    The multimeter socket for the black lead is marked 'common'. This means that it is the same for many things. Similarly the zero voltage terminal on your power supply is 'common' to the power supply circuitry. It does not matter wher you attach it to this and the terminal itself should be convenient. Once the black - common lead is attached you move the other (red) one about thus always connecting two leads to the component of interest. Pretty well every component, except the transformer, sees the zero as common. The transformer is an example of the odd case where you will need to attach the leads differently ( and don't forget AC volts setting for the transformer DC volts for everything else)
     
  11. CDRIVE

    Senior Member

    Jul 1, 2008
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    Uh, yeah B-17's and B-24's were typical American practice too. At the time the UK didn't complain about our shoddy workmanship... go figure?

    Sorry, but I think you hit a nerve.
     
  12. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Nice to hear from you too.

    Read more carefully what I actually wrote and you will see that it is a statement of bald fact, not a complaint.

    It was stated as a warning to someone preparing to poke inside equipment having exposed live terminals.

    Are you suggesting the american way is to keep silent and not issue a warning?

    This is not the first such picture we have seen on AAC showing exposed mains terminals inside equipment.

    Incidentally not so many years ago this would have been standard practice in the UK as well, but times and hopefully standards move on.

    go well
     
  13. CDRIVE

    Senior Member

    Jul 1, 2008
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    These facts could have been conveyed to the OP without a negative reference to American practices. If I had made a statement like that about the UK I would fully expect a negative response, .... and I would have deserved it!
     
  14. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    ugghhhh.... Gordon Bennett!! do i have to say it?
     
  15. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    ........ please stand by...... experiencing problems with multimeter....

    also, not sure if it helps, but the voltage meter measures voltage when outputs are connected to the 12V car battery, but amperage meter does not read anything..... also when connected to battery, the lights inside both meters are lit.

    i should have measurements by morning PST...
     
  16. studiot

    AAC Fanatic!

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    please don't tell me you have connected the ammeter section of your multimeter directly across the battery.

    You only need to measure volts to do the troubleshooting.
     
  17. CDRIVE

    Senior Member

    Jul 1, 2008
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    This is very odd. You state that the meter lamps are lit when you connect the output to a 12V auto battery. Does this mean that they're not lit when not connected to the battery? If so, they're being lit by the battery, not your supply. Secondly, I've searched east, west, north and south on your schematic and can't find ANY indicators, lamps or LEDs anywhere.

    Unrelated, but you have two analog meters measuring the output of the supply. One is a Voltmeter that reads output voltage. The other is an Ammeter that measures output current. Just for the record, the Ammeter is actually a Voltmeter that's reading the voltage drop across one of the emitter resistors (R102) in the pass transistor bank.

    By the way, your power supply employs an over voltage 'Crowbar' circuit that's connected directly to your output terminals. If the crowbar ever fired while you are connected across an automobile battery you will pee in your pants!!! What I'm telling you is.. I doubt that this supply was intended to be connected across another voltage source, especially something as potent as an auto battery. I would recommend not doing so without a fuse in the output line.
     
  18. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    studiot, i have not done any measuring yet, and there will be nothing connected to outputs of power supply when i take measurements. no, the main problem i had, was finding insulated alligator clips to use with my multimeter for safe measuring. i am located in farm town, northeast-oregon. where there are approx. 3 times as many cows as humans. the nearest radio shack is 40 miles away. we have a walmart though, who ran radioshack out of town about 3 years ago. (limited local resources)
    so, to make a short story longer, i ended up cutting off the sharp prods, then spliced, soldered and taped alligators to the m.m. test leads.... anyway, then the display stopped working on the multimeter when one of my kids knocked it off the table. anyway we are ready to take measurements now....



    CDRIVE, thank you for the helpful post! you are correct, that the lighted meters when the power supply is switched off is from the battery. i was simply mentioning this fact, because it was pointed out, like you said, lights are not indicated on the circuit diagram. i thought it might be helpful to point this out.
    you are probably also correct, stating that this power supply was not intended to be operated the way i am.... infact i was skeptical too, when i set this up at the car audio shop i used to work for. we used them for our high-wattage sound demo board (beginning early 2002). surprisingly, the issue i am having now, is the only one i have encountered with this type of setup and 10 years of doing it this way. i have only 1 battery, and have intentionally been keeping current output below 60A when operating at home. but at the stereo shop, we would use 2 group 31 batteries connected to this same model power supply, to power high wattage displays.... the subwoofer amplifier setups connected to it would pull greater than 150A for up to 5-10 minute periods (and various other power/time scenarios), and never had a single failure with the power supply or batteries. the problem i am experiencing now is caused by user error. the only thing i have seen fail regularly from this type of setup is the Ampere gauge. it doesnt like getting slammed beyond its limits by 100A+ surges, but the power supply seems to handle it just fine. the only thing we had to make sure the batteries werent getting too much juice when the store was slow.... but when we were busy, this type of setup was producing good power all day long, without complaint.... the cost was FAR less than a display designed specifically for this purpose....

    i will post measurements very shortly, thanks again.
     
  19. mrflamboynt

    Thread Starter New Member

    May 22, 2011
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    i was wrong!

    so i went to measure voltage at the transformer and got nothing. didnt make sense at first because if the transformer was damaged im sure there would have been more action at time of failure (smoke/sparks)..... so on a whim i check the fuse and it appears ok by eye. but tested it (ohms) and it also read nothing.... i screwed the cap back on the fuse holder, empty, and the red light on the switch still comes on. so we thought that because the red light was on there must be power (going to next item in circuit), but evidently the light is wired before the fuse. so i put in a different fuse, and voila! she's singing like new again. wiped out some dust, wrapped it up and we are back in business. I told you it would be "something simple" ;)

    studiot, i appreciate u taking the time to help out. especially on the safety thing, someone else could have assumed i knew better, and it could have gone wrong pretty fast. so thumbs up on that.
    thanks to CDRIVE too, for the help, and for keeping things exciting.
     
  20. studiot

    AAC Fanatic!

    Nov 9, 2007
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    Glad it worked out so well.
     
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