Replacement for TD125 Mrk 2 Neon strobe

Discussion in 'Turntables' started by wapfunz, Jan 17, 2011.

  1. wapfunz

    wapfunz WapfuNZ

    What is a viable alternative for the replacement of the neon/strobe bulb as once used on Thorens TD125 mrk 2 turntables. Is there a relatively simple replacement without going to major lengths of circuits etc. I currently use a strobe disc from the vinyl engine but have always wondered if there was a way to make a replacement cheaply and simply.
  2. Karma16

    Karma16 Super Member

    I have seen the complete strobe assembly on ebay. Might check it out. Search on Thorens TD125.

  3. Grainger49

    Grainger49 Old Fart Subscriber

    Neon bulbs are available from a number of sources. I'm not familiar with the size of the bulb you need to replace but the voltage checker neon bulb is easy to find at a hardware store. That is much more expensive than buying the bulb itself but fast and available.
  4. wapfunz

    wapfunz WapfuNZ

    I can purchase what is called here, a 6 volt mini lamp 0.1Amp with insulated pigtails from jaycar electronics. Would this work? Also could a 6Volt LED with 220 ohm resistor in series also be used without doing any damage to the TT electronics?
  5. saea501

    saea501 Well-Known Member

    LED will not work. The neon bulb works with the 60 cycle line frequency which is why the lines appear to move faster or slower as the platter speed varies.
  6. wapfunz

    wapfunz WapfuNZ

    Thanks. LED out. So my best option then is the 6 volt mini lamp 0.1Amp. Will this affect the electronics in any way. As the original was 20mA and I am thinking of using 100mA?
    I suppose the question is will it draw to much current more than what the original circuit was designed for.
  7. Pio1980

    Pio1980 AK Member Subscriber

    Probably an NE-2, 'cockroach'-standard soldered-in pigtail neon. I've a row of them in an old varactor TV tuner in my junk box.
    Just a suggestion; It's really helpful for folks to put their location in their stats so someone nearby may volunteer to help out.
    Last edited: Jan 22, 2011
  8. wapfunz

    wapfunz WapfuNZ

    Sorry Pio1980. Updated profile. Dang went out and bought 3 mini lamps too. Pigtail neons - wonder if any down under?
  9. wapfunz

    wapfunz WapfuNZ

    The closest NE-2 pigtail neon I can see in NZ is from jaycar electronics but its 120volt. $1.50 each. mmmmmmmmmmm feel this is not going to be easy.

    Blue NE-2 120-Volt Neon with Pigtail leads

    Would you believe it? After about 100 years of orangey-red neons we now can get blue and green ones! You'll buy one out of curiosity!
    - Strike Voltage: 82V
    - Needs 270k resistor in series for 240V operation.
  10. Pio1980

    Pio1980 AK Member Subscriber

    Any necessary current limiting resistor is likely already in place. Check the value of uch resistor with the power disconnected against stated value. If it's drifted up the bulb may not 'strike' and light properly.
  11. wapfunz

    wapfunz WapfuNZ


    They also do a 90V NE2 Neon

    90V pigtail neon.- Needs 270kohm resistor in series for 240V operation.
    Picture attached.
    Given that the resistor, from the photo, is not attached.
    Resistor will drop voltage.
    Neon says 90 volt I need 6?
    Geez I wish my electrical knowledge were better for this.

    Attached Files:

  12. goldear

    goldear Certifiable Audio Junkie

    The LED would flash at 60 Hz if fed AC, whereas the neon bulb flashes at 120Hz. While I have not tried this myself, it seems like flashing at half the frequency would still provide an accurate strobe.
  13. Tucker99

    Tucker99 AK Subscriber Subscriber


    suggest contact bear-kola, an ebay vendor, and ask him if he has what you need. I have purchased from him and he is quite reliable. He has lots of 125 stuff, maybe some not listed. find an auction of his and you can contact him that way.
  14. Enochrome

    Enochrome New Member

    I have the same issue. Did you ever find a suitable replacement?
  15. Enochrome

    Enochrome New Member


    Wapfunz and I just messaged each other and I wanted to share with this thread. Also,
    wanted to thank everyone for the help, especially Pio1980. Pio1980 you were right that type bulb is the perfect replacement!!!! I was about to pay mucho cash for a whole new strobe unit on Ebay because I had lost hope.

    Here's a copy of the message that I sent Wapfunz (so I don't have to write it all over again :) :

    Last edited: Jan 31, 2011
  16. Enochrome

    Enochrome New Member

    Nevermind about getting those bulbs from Australia: the bulb's were $3.60, the shipping was $90.00.

    Anyone know of a place here in the states? Pio1980?
  17. wapfunz

    wapfunz WapfuNZ

    And thanks to you enochrome I have found an answer. A 90 volt neon needs a 270K 1/4 watt resistor in series to run from 240 volts. 600microAmps is the current draw. As NZ uses 240 volt the original thorens circuit shows the strobe across the 240 volt taps of the transformer. The circuit shows a 47k ohm resistor in series with the old strobe. Thus 47k + 220K should suffice. Neon $1.50 and 28 cents for 4 off 220K resisitors.
    So a neon 90 volts or 110 volts from an electronics shop will work with 270k or 220k resistors in series as replacemnt for the original thorens strobe - allot cheaper than the electronic version in the TD 126 Mrk III service manual.
  18. Karma16

    Karma16 Super Member

    HI Enochrome,
    You guy's are interesting. Nice effort. But I question the value of the work involved when the stock Thorens strobe assemblies are available. I guess you are challenged by the effort. Not me. I have worked in electronics for so long that work like this is just drugery. I'm not saying that I don't respect what you have done. I do. But the time and work required is just not worth the result to me. I would have used the stock Thorens parts. But, good for you.

    Here is one:

    I noticed in your pics that the strobe pattern in the window is not evenly illuminated. The right side is dim. On my TD125 Mk 1 the pattern is evenly illuminated and looks better. Functionally, it doesn't make any difference. Both will work fine.

    What do you think the cause is? Is it the light pattern from the bulb or where and how it is mounted?

  19. wapfunz

    wapfunz WapfuNZ

    Hi karma16,
    True, TD125 Mrk 2 assy are out there, nearly 10 pounds, the neon and resistor less than $2 - go figure which is the cheaper option. And yes that assy is on ebay. I know of two TT's with out strobes - mainly mine. So the neon and resistor option is easier and may I say really cheap. The original strobe was cylindrical and about 22mm long It was coated on the inside to leave a thin window along its length. The TD 125 Mrk 1 used a totally different strobe - which you can easy get replacements for - the TD 125 Mrk 2 strobes are somewhat rarer to come by.
  20. Karma16

    Karma16 Super Member

    HI wap,
    Yes, the cost for parts is definitely on your side. Neon bulbs are cheap and resistors cost almost nothing. You'll get no argument from me on those points. But, where I come into conflict is the value of the labor you had to put into the project. If you count your labor as worth nothing then your solution makes perfect sense. But if you count labor as I would have in my repair shop at about $60 an hour, then the situation is reversed. In that case, buying the stock Thorens part is far cheaper.

    However, I understand that this is a hobby for you and the labor expense is not a big factor. It's the challenge and its the ultimate victory that's important. That being the case, you certainly should be proud for a solid victory.

    I noticed that the strobe assembly listed in the ebay link states that it is for both the Mark 1 and the Mark 2. Is this incorrect?

    I also noticed in my TD125 Mk 1 Service manual that the neon bulb is not a simple assembly but combined with some sort of plastic holder and must be replaced as a pair. The Thorens part number is not given. This must have been what you ran into when trying to find a replacement. And why you went with a bare neon bulb. You had no choice.


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