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Stamford C20B Alternator Looking to identify VCU Components

Discussion in 'Troubleshooting and Repair' started by MGN, Jun 19, 2013.

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  1. MGN


    Jun 19, 2013

    I have a 1972 vintage Stamford C20B Alternator (Generator) that recently failed. I found the problem to be with the VCU (voltage control unit). This is an epoxy encapsulated module with an external SCR (Thyrister) and Diode.

    Both the SCR and Diode are bad (both shorted) and its possible that the entire encapsulated VCU may indeed be bad. I need to see if I can find replacements for the SCR and the Diode. Once replaced I can determine if the encapsulate unit will function.

    My internet searching suggests that the SCR markings (CS915-600) show it to be a 15A, 600V, T0-48 package. I think I can find a replacement for this but I'm having trouble finding information on the Diode.

    The Diode markings are as follows: SBAR6/N 7213

    It is a T0-48 package as well.

    I would greatly appreciate any suggestions or help identifying these components as well as any thoughts on the health of the encapsulated VCU.

    Many Thanks,

    Mike Nash
  2. duke37


    Jan 9, 2011
    I do not know what the diode is but would suggest that you use a 15A 600V diode to match the SCR. Without the circuit it is difficult to give more advice

    The VCU is encapsulated so can only be tried in situ.
  3. MGN


    Jun 19, 2013
    Hello Duke37,

    I agree a diode with characteristics that match the SCR makes sense and that will likely be my approach. I felt that it was best to make an attempt to find out what the original part was or its exact replacement. Unfortunately I have had no success finding a schematic for the encapsulated circuit.

    Thank you for your input.

    Mike Nash
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