need help identifying this circuit.

Discussion in 'The Projects Forum' started by KMK, Oct 31, 2010.

  1. KMK

    Thread Starter Active Member

    Feb 11, 2010
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  2. themindflayer

    Member

    Oct 29, 2010
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    that black dot you see on the vertically mounted pcb add on is an ic ... a complex chip on pcb kind of thing ... what the circuit does is mostly in that black dot .... the transistors are most probably for amplification of the signals the black dot produces ... the diodes are most probably rectifiers for 220V ac .... the big cap i would assume to be the ac - dc converter cap .... but its voltage levels are too low only 50 volts which would imply that it had a transformer too?? a step down transformer is probably used in conjunction with this circuit to be able to run of 220V .....

    the question now is ... do you want to replicate this thing .... if you do it wouldnt be this small .... it would be big and fancy .... and reprogramable

    ;)
     
  3. KMK

    Thread Starter Active Member

    Feb 11, 2010
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    thanks for this info the mindflayer..
    it seems like one of the components is not working.. mostlikely the dot..so thats
    is the dot a programable IC.. would like to know that as well..there is a small button which changes the way the kights flash..& dosent sem to be any transformer with the circuit.. it suns a series of miniature bulbs..
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    The button most likely signals the IC to change direction, and most of the "work" is done there.

    The dot can be any kind of IC. They are used from calculators to cheap stereo equipment.

    Do you have a decent multimeter to identify inputs and outputs, and see if one of the transistors failed? (without power, just use diode check on them)

    Would need better photos of board, from top down, and the bottom side, full on views so layout and components can be guessed at.

    --ETA: It would likely be cheaper to replace than repair.
     
  5. KMK

    Thread Starter Active Member

    Feb 11, 2010
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    does the D-803 signify anything ?
    also i will try to get photos from all sides to help get better picture of the circuit..
    also i had another question..
    i have 2 types of relays..

    1] solid state type.. which can be soldered on to PCB...ratingas follows: part NO SC5-S-DC6V
    7A 300VAC |10A/125VAC
    50Hz cos1|10A 28VDC
    coil:6VDC|

    2] proper solenoid relay in transparent casing, where on the coil its written 6V DC.. nothing else..

    so can these relays be used to control 240 VAC
     
    Last edited: Oct 31, 2010
  6. themindflayer

    Member

    Oct 29, 2010
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    the D-803 is the ID number of the vertical pcb .... it means nothing ... no indication of what the circuit does / supposed to do .... it is used by the manufacturer to identify one pcb from another and relate the pcb to its corresponding schematic which he has .....

    thatoneguy is right on all counts ... pics, transistors, and cheaper to buy one then repair one ...

    also if the black dot has problems ... then its ir-repairable (unless ofcourse you can find another D-803 working pcb .....

    you need to apply 6 v to the coil to turn on/off both these relays .... the switch side can be used to 240V with a max load of 7A .... which is a shitload of current .... care needs to be taken when working with relays when switching them on/off ... because the contacts bounce a lot (make/break and then re-make many times during one on or off time .... before they make good and permanent contact ) ..... so it is suggested that there should be zero current through them when turning on and off .... additional circuitry is needed to accomplish that ....

    this bouncing causes noise and shortens relay life ...... at low currents it should'nt matter ....
     
  7. KMK

    Thread Starter Active Member

    Feb 11, 2010
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    i plan to use the replay with a 555 timer to induce blinking in a 240V lighting garland... will it work? .. any precautions i should take care of ?
     
  8. iONic

    AAC Fanatic!

    Nov 16, 2007
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    I don't think there's any way to identify the chip. Even if you could file down the "black dot" you may not find a IC part number on it, either that or you may file it away with the dot!

    My suggestion would be to start fresh. Describe to us exactly what you are attempting to do and the functionality of the device you want.

    iONik
     
  9. KMK

    Thread Starter Active Member

    Feb 11, 2010
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    Last edited: Nov 1, 2010
  10. iONic

    AAC Fanatic!

    Nov 16, 2007
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    It doesn't help us any.
     
  11. n1ist

    Active Member

    Mar 8, 2009
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    This looks like the controller for a Christmas light string. The three TO92 packages are SCRs. Be careful playing with this as it is NOT isolated from the incoming AC line.

    The input to the board is 220V AC; the outputs to the LED strings are 110V or 220V DC. If the controller IC is dead, there's no way to fix it. You may be able to jumper across the SCRs (anode to cathode) to turn on the LEDs.

    As for the circuitry, you have a full-wave bridge made out of the 4 diodes, with the electrolytic cap as the filter. One of the resistors is likely a current limiter used along with an on-chip zener to generate the power for the IC under the blob. The blob directly drives the SCRs to turn on the three strings of lights.

    /mike
     
  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    How much is a replacement string of lights w/controller?

    Working with 220VAC, even isolated, let alone non-isolated like this board, is not encouraged by people unfamiliar with circuits, functions, and safety.

    As attaching it to the line to test function is required, I'd suggest replacing it, or converting the entire string to LEDs running at a low DC voltage, powered by a "Wall Wart" AC -DC converter, this could be safely built by somebody new to electronics, but would be a large project to undertake.

    The last case would likely cost a good deal more in parts, let alone time, than simply replacing the broken controller.

    Most inexpensive Christmas light displays are built with an intended useful life of around 6 months of use, or 2-3 years worth of holidays.
     
  13. KMK

    Thread Starter Active Member

    Feb 11, 2010
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    thanks for the information guys...
    i'd like to replace it.. but the problem is its not available..
    thats why was wondering if it can be repaired..
     
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