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Restoring a Lowrey TLO

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  • Restoring a Lowrey TLO

    I recently got hold of a Lowrey TLO that someon ewas giving away. It is not in great condition, and I would like to restore it. There are a lot of issues, e.g. there is a constant hum (just below a G#, which makes me think it's something shorting rather than a faulty key) which gets louder when I switch on any reed stops. The only stop that works on the upper manual is the twelfth 2 2/3. There are a few keys that don't sound, or don't sound correctly, and most of the effects (vibrato, repeat, etc) don't work, or don't work consistently. It also looks like someone has tinkered about with it before; there are some solder joints that look rather messier than the original and some wires that have clearly been replaced (the originals were cut instead of being unsoldered).

    I found a manual online for a TLO-1, but I'm not sure it's the same. The circuitry seems generally to match, but some of the components look different (e.g. a 1.5k resistor vs a 27k resistor in the service manual), and I don't know if that's because the TLO-1 was made differently or because someone rewired things at some point in the past.

    It's been about 20 years since I last dug into the internals of an organ, and it seems I've forgotten most of the little bit I ever knew. It also turns out I need a bit of a refresher in basic electronics. So while I am really looking forward to the project, I do feel a lilttle out of my depth.

    First question is, does anyone know how different the TLO and TLO-1 are? Can I use the TLO-1 manual even if some of the components are slightly different, or will that just send me on the wrong track? And secondly, any suggestions as to how I go about finding the source of the hum? Using an oscilloscope I can trace it easily to the tabswitches, but I'm not sure where to go from there.

  • #2
    I can't comment on the TLO/TLO-1 differences, but I have a TBO, and the TBO and TBO-1 are not very different.

    As for hum, is it 60Hz or 120Hz? If 120Hz, it's probably power supply noise. If 60Hz, it may be a grounding problem.

    These Lowrey organs are not easy repairs even for experienced combo organ techs. The effects that make them cool are also what make them tricky to repair. Sustain functions require them to use keying diodes and timing capacitors for each key. Other effects rely on neon/LDR units that may be bad. Switch contacts can be broken.

    This sounds like a pretty challenging project, and you're going to have to refresh your memory on the electronics part.
    I'm David. 'Dave' is someone else's name.

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    • #3
      Thanks, I haven't measured the exact frequency of the hum, but based on pitch it's more like around 100Hz than either 120Hz or 60Hz.

      I'm not expecting it to be easy, or quick, but since this is just a hobby project it also doesn't matter too much if it takes a long time to get all the effects working.

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      • David Anderson
        David Anderson commented
        Editing a comment
        Sorry, forgot that South Africa is a 50Hz country, so a badly filtered power supply will result in 100Hz noise, not 120Hz.

      • David Townshend
        David Townshend commented
        Editing a comment
        Ah! Strange, but I honestly didn't know that, I thought it was 60Hz. Thanks. That helps a lot!

    • #4
      I had a TLO-1R for a short time before I found a TBO-1. I have some service manuals for the TLO-1R. I think the -1 means the addition of the Wow-Wow function - does yours have a green switch on the lower right hand switch panel? The R related to the rhythm section.
      B3, XB3, XB5, M102 Factory Split x2, TTR-100, L162
      145 x3, 251, 760 x2, Farfisa Compact Duo, Compact Deluxe, Lowrey Berkshire, Heritage
      drawbardave.co.uk

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