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Thread: Source for LT99 opto? (Vox Pathfinder)

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    Source for LT99 opto? (Vox Pathfinder)

    Hey all, I have a small Vox Pathfinder that had low/distorted output. After some debugging I found the resistive side of the tremolo opto is open and not responsive. I can't find a replacement for this badboy anywhere.. does anyone have any suggestions? Is LT99 the actual part number (only writing on the package).

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    Senior Member Enzo's Avatar
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    Actually LT9912 or LT9914, I believe.

    Do a search for those numbers on this forum, we have discussed it in the past. I know some have subbed a different opto. But you can search for the part at Vox part suppliers. Don't just look on their web sites, CONTACT them and ask if they have the part.
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  3. #3
    g1
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    Quote Originally Posted by Enzo View Post
    Actually LT9912 or LT9914, I believe.

    Do a search for those numbers on this forum, we have discussed it in the past. I know some have subbed a different opto.
    This one? (VTL5C3)
    Vox Cambridge 30 Reverb Twin keeps blowing TDA2050
    Last edited by g1; 08-13-2017 at 05:51 PM. Reason: add part #
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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by waspclothes View Post
    Hey all, I have a small Vox Pathfinder that had low/distorted output. After some debugging I found the resistive side of the tremolo opto is open and not responsive. I can't find a replacement for this badboy anywhere.. does anyone have any suggestions? Is LT99 the actual part number (only writing on the package).
    Maybe the opto is open and unresponsive but thatīs unrelated to "low/distorted output", worst case Tremolo would not work, period.
    Juan Manuel Fahey

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    Senior Member Enzo's Avatar
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    Sorry Juan, the opto resistive element is in series with the signal path, at least on the Cambridge 30. Those fail and the symptom is exactly what he reports. I replaced many of them under warranty. One batch the store got in required every one of them to be replaced.
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    Old Timer J M Fahey's Avatar
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    Ok, I stand corrected.
    I was based on Classic "shunting signal to ground" Tremolo used by all others since forever, but hey, I should never ignore designer capacity to turn a fail safe circuit into something that nukes your amp if damaged

    I remember reading tons of complaints about poor quality optos used by Korg/"VOX" , in that case I guess a regular Vactrol type will be way more expensive (say a couple bucks instead of 99 cents) but also way more reliable ... and easier to find.

    From what I read it is best NOT to replace it with original one.

    Of course, I just "read it on the Net" so due disclaimers apply.
    Juan Manuel Fahey

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    Anyone have an actual part # and place I could order something that will work in this amp as a replacement. I don't need it to be exact, just something that -works-.

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    g1
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    I put the part number in post #3. (see also the link from that post)
    Where to get it will depend on your location. Google search of part # should give you many options.
    "there's another kind of party lights that I can't stand to see,
    when there's a man in that patrol car and he don't wanna party with me"

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    Stray Cap DrGonz78's Avatar
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    I was looking for this part pre-emptively while working on a Vox a few months back. I still have the link for it saved to my watch list on eBay.
    Xvive Audio VTL5C3 Opto-Coupler | eBay

    Now can anyone source this part for cheaper? You may find something similar for cheaper on Mouser, Digikey, etc... Perhaps soldering on wired connections to convert a Dip4 package to fit in place of this original part package? It seems to me that all that I could find on the big parts stores sites was smd or dip type packages for a replacement part. Hence I had to start looking at sites like eBay.
    When the going gets weird... The weird turn pro!

  10. #10
    g1
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    Small Bear has them for about the same price:
    Photocoupler XVive VTL5C3 Work-alike - Small Bear Electronics
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