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SCR Rectifier Need cross Reference help

Discussion in 'Troubleshooting and Repair' started by TheButcher69, Feb 21, 2015.

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  1. TheButcher69

    TheButcher69

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    Feb 21, 2015
    I have a Dayton 5amp Speed Control that the Rectifier shorted between the cathode & anode. The part # is: 66497 RCA Date code C-7613. I've called & searched everywhere & no one has any info. I've tried to replace it with: "S8040R-ND" & "S4010LS2-ND" but on variable speed the motor just hums. Any help would be appreciate! Here are some pictures.
     

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  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    It strikes me that it's more likely to be a Triac than an SCR.
     
    hevans1944 likes this.
  3. TheButcher69

    TheButcher69

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    Feb 21, 2015
    Thanks for the reply Steve! Dayton said no to that but I'm open for suggestions. Any ideas how to go about finding the correct part?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I'd just try some random triac with a voltage rating at least double your mains voltage and a current rating at least double what the motor will draw and see how it goes.

    It looks to me like the triac is mounted on the metal case without any insulation, so I would also look for a triac with an "isolated tab" or one in a fully plastic case

    I'm making the assumption that the motor runs from your mains (110/220/240 V 50/60Hz depending on where you are in the world)
     
    TheButcher69 likes this.
  5. TheButcher69

    TheButcher69

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    Feb 21, 2015
    Ok thanks I will try that. It's mounted to insulation tape with thermal paste. It's 110v USA. I'm not sure the amps but I'm thinking anything at or above 240v & atleast 10amps. Would I be correct on that?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    Yeah, I'd go with that. 400V devices are relatively common, and reflect a value closer to double the peak voltage of 110VAC (the peak is closer to 160V).

    Assuming that the device is insulated, preserve all the mounting materials and re-use them. Unless the insulating material is a soft rubber looking material, you should place some heatsink compound on the various surfaces before bolting it all back together. You may be able to get away without this for a brief test.

    Be aware that the pinouts may be different between the old and new device, and that there may be some other problem in the circuit.
     
  7. TheButcher69

    TheButcher69

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    Feb 21, 2015
    I actual ripped the whole thing apart & test each piece including the pot. All checked good. The only bad piece was the SCR. It showed .002 on "K" & "A" cathode & anode. And when the unit was switched from off to "Full" or "Variable" the pot did not adjust motor speed & ran at full speed either way. When I changed the SCR out with the (400v 10amp which I test each pin it showed an open between the cathode & anode) "Variable" no longer ran at full speed but would only make the motor hum at "3". Here is a picture of the outside.
     

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  8. TheButcher69

    TheButcher69

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    Feb 21, 2015
    So I put a Triac NTE5637 in today 600v 10 amp & the motor does start to hum until it gets to 5 & still will not turn. Before with the SCR 400v 10 amp to motor stared to hum at 3.
     
  9. shrtrnd

    shrtrnd

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    Jan 15, 2010
    It may be that your controller is not operating correctly, but the motor itself has a problem.
     
    duke37 likes this.
  10. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    It is possibly a simple phase angle controller. Can you draw the schematic?
    Try it controlling a bulb.
     
  11. TheButcher69

    TheButcher69

    6
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    Feb 21, 2015
    I tried the unit on a bench grinder, Fan & drop light. Here is the schematic.
     

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