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Thread: Trying to save a train

  1. #21
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    Default Re: Trying to save a train

    OK, here you go! [Updated based on new information: SCR & 150V DC]

    From what I can tell, the circuit: (note: try #2 on circuit diagram)
    Circuit_2nd_try.jpg

    Please consider this tentative - others will need verify or amend.

    BOM: These values are plainly evident in the photos.
    D1-D4: 1N4004
    R1: 100K 1/4 W
    VR1: 1M (variable resistor; 'trim pot')
    C1: 33uF 40V Catalytic
    C2: Probably 0.1uF 100v ceramic cap [value not visible]
    Q1-Q4: PCR406 SCR [updated; was incorrectly suspected to be K1851D MOSFET Power Transistor due to marking on PCB]
    Custom IC: Entirely unknown. Pins numbers LET to RIGHT from top side, with two power wires oriented at top of view.

    Notes:
    1. Q1 is not installed. Corresponding connection point JP2:1 is also not installed.
    2. Q3 installed but no wire is connected at JP2:3

    Operation: Again, tentative - open to revision.
    1. JP1 is power in (from 110-120 A/C) mains plug.
    2. Full-wave bridge provides (unfiltered) DC (about 150 V) for lights; DC switched on/off by SCR's.
    3. 100K resistor from 150 V DC provides power to Custom ASIC (application-specific integrated circuit). Low power ~ 150 V / 10,000 ohm = 1.5 mA. Should be sufficient for IC to drive SCRs (that only require 0.2mA base current)
    4. VR1 with C2 appears to control the blink rate of (one?) string of lights.
    5. It is unknown what Q1/JP2:1 and Q3/JP2:3 would control. Likely other (ie. additional) light strings OR the current strings but sub-divided. Experimentation is in order!
    6. JP2:5 pin is the COMMON wire. All strings must connect one end here, the other end to one of the other 4 connection points.

    Once this is verified, then you can start moving wires and possibly adding lights. This circuit is fairly simple and could be easily build in a perf board. The Custom IC could be adapted for use, or a new PIC (8 pin would work) could be programmed. This would give you a back-up 'controller' for your train.

    NOTE: Attached image is the OLD try #1 circuit.

    Jimboha
    Attached Images Attached Images
    Last edited by jimboha; 01-13-2019 at 05:10 PM. Reason: Rev 2: MOSFET to SCR, Vdc
    Springville, Utah

  2. #22
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    Dec 2015
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    Crofton MD
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    Default Re: Trying to save a train

    The clean up is all my dadís doing. It his prop and has had it for 10+ years. Thanks for all the help when I get over there we will cut the wires and reattach. Then we can see if whatís going on from there. Thanks again... this is an amazing community!!


    Sent from my iPhone using Tapatalk

  3. #23
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    Default Re: Trying to save a train

    I would not be surprised if under the blob was a HL2202LF, they just use an RC for timing and support 1,2,3 or 4 strings:
    asian site -
    https://pdf.datasheetbank.com/datash...2202LF?lang=zh

  4. #24
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    Default Re: Trying to save a train

    Quote Originally Posted by davros View Post
    I would not be surprised if under the blob was a HL2202LF, they just use an RC for timing and support 1,2,3 or 4 strings:
    asian site -
    https://pdf.datasheetbank.com/datash...2202LF?lang=zh
    Yes, it certainly has the same set of pinouts, if not in the same position. But that would imply that it flashes ALL of the attached strings sequentially. Is this the normal behavior?

    Jimboha
    Springville, Utah

  5. #25
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    Default Re: Trying to save a train

    The OP said some lights were on constantly ( please correct me)?but
    We only have 3 wires total on the output side that I observed?
    I now wonder if the flasher wasn't indeed set up for the 2 strings alternating but driving a Y with 1/3 bulbs in each leg, leaving one 1/3rd string in the return path always.

  6. #26
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    Malden MA
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    Default Re: Trying to save a train

    1. JP1 is power in (from 110-120 A/C) mains plug.
    2. Full-wave bridge provides (unfiltered) DC (about 110 V) for lights.
    For a full-wave bridge, the output is 1.414*Vrms, so it is about 155Vdc for 110Vrms in
    /mike

  7. #27
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    Default Re: Trying to save a train

    If I find the controller (I think I know where it is...
    I can send you the board from my train, for cost of postage, if youíd like. I converted mine to pixels. It was working, when I hacked the wires off.
    Seems about the same age. Yours seems to have aged nicely. With mine, the artwork faded and the overlay plastic began falling off.


    Sent from my iPhone using Tapatalk

  8. Likes TazChaLet, davros liked this post
  9. #28
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    Dec 2015
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    Default Re: Trying to save a train

    Thanks Iíll talk to the owner about getting the controller... here are a few pics that might finish off the BOM



    Thanks again for all the help


    Sent from my iPhone using Tapatalk

  10. #29
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    Default Re: Trying to save a train

    OK, PCR 406J - SCR not MOSET. I'l update diagram and re-post above soon.

    Jimboha
    Springville, Utah

  11. #30
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    Default Re: Trying to save a train

    Quote Originally Posted by Rjlangley View Post
    If I find the controller (I think I know where it is...
    I can send you the board from my train, for cost of postage, if you’d like. I converted mine to pixels. It was working, when I hacked the wires off.
    Seems about the same age. Yours seems to have aged nicely. With mine, the artwork faded and the overlay plastic began falling off.
    Wow, this seems to be the best option yet! Why make another one when you can find a replacement of the same thing.

    Jimboha
    Springville, Utah

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