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    Replacement of selenium rectifier in ST-70

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    rossini

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    Join date : 2017-11-04

    Replacement of selenium rectifier in ST-70 Empty Replacement of selenium rectifier in ST-70

    Post by rossini on Sun Nov 05, 2017 5:50 am

    Hello,

    I know there has been already a number of discussions before about this topic, however, as I would like to replace the selenium rectifier by germanium diode, can anyone advise me the specifications of the diode which will fit for this replacement, thank

    regards,

    Rossini
    Peter W.
    Peter W.

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    Location : Melrose Park, PA

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    Post by Peter W. on Sun Nov 05, 2017 8:20 am

    Germanium would not be your first choice. Finding such a diode that would be rugged enough is one thing - and the basic characteristics of such a diode in that use would be another.

    I use a 1N4007 silicon diode in those applications. Fast enough, rugged enough and cheap enough that going to anything more exotic than that would be without merit.
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    rossini

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    Post by rossini on Sun Nov 05, 2017 10:21 am

    Peter W. wrote:Germanium would not be your first choice. Finding such a diode that would be rugged enough is one thing - and the basic characteristics of such a diode in that use would be another.

    I use a 1N4007 silicon diode in those applications. Fast enough, rugged enough and cheap enough that going to anything more exotic than that would be without merit.

    I have already tried 1N4007 silicon diode and find that the sound is a bit forward and not so soft as the previous selenium rectifier. This is why I would like to look for the germanium diode.
    Peter W.
    Peter W.

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    Post by Peter W. on Sun Nov 05, 2017 11:29 am

    OK - but, consider that musicians use germanium diodes to add distortion.

    Other issues: Germanium has 'soft knees' - that is, they start to conduct on a continuum. They are not as fast as selenium or silicon.

    They do not like heat - at all.

    High current germanium diodes also decay more quickly than even selenium. Low-current, no problem.

    Mouser.com has a pretty large selection of power-diodes in Germanium - all under US$10.
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    rossini

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    Post by rossini on Sun Nov 05, 2017 6:28 pm

    Peter W. wrote:OK - but, consider that musicians use germanium diodes to add distortion.

    Other issues: Germanium has 'soft knees' - that is, they start to conduct on a continuum. They are not as fast as selenium or silicon.

    They do not like heat - at all.

    High current germanium diodes also decay more quickly than even selenium. Low-current, no problem.

    Mouser.com has a pretty large selection of power-diodes in Germanium - all under US$10.

    So, can you advise the voltage and current specifications of the germanium diode for this replacement, thanks.
    Peter W.
    Peter W.

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    Post by Peter W. on Mon Nov 06, 2017 8:16 am

    http://www.mouser.com/ds/2/427/vs-25frseries-71595.pdf

    This is a range of germanium rectifier diodes.
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    DougWHolt

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    Location : Mooresboro, NC

    Replacement of selenium rectifier in ST-70 Empty Re: Replacement of selenium rectifier in ST-70

    Post by DougWHolt on Fri Mar 01, 2019 12:59 am

    I got this package for only $5 off eBay The member is out of California (not HK or China) and only took only a few days to get.  I wont put the eBay link here (not sure if its allowed) But I'll tell ya, when on eBay do a search for: 14 Values 200pcs Switching Schottky Rectifier Diode Assorted Kit Assortment US

    On the picture below you see the part numbers, voltages and amps.  Instead of using the 1 amp 4007 I chose the 2A RL207.  Replaced the selenium with the RL207 as well as add two 207s to protect the rectifier.

    Replacement of selenium rectifier in ST-70 Pbn91
    Replacement of selenium rectifier in ST-70 Dq2bmw

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