Precision Electronic Levels - Taylvel
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    Default Precision Electronic Levels - Taylvel

    In the now closed (why? the title is perfectly clear to me) recent Taylvel thread, I mentioned that the legacy electronic circuitry was simple to implement using present-day electronics, and mentioned that I had dug into the building of such a level.

    These kinds of levels can detect the slight changes in local earth surface slope due to imperceptible passing seismic waves and the like. They were originally built for exploration of large surface plates to find low and high spots. These days, optical means are typically used for this.

    Anyway, for those who are interested, the original thread was on the <rec.crafts.metalworking> usenet newsgroup circa April 2009. Many references are given. Search for "taylvel" and "gwinn" to recover the traffic. Here is one hit in that thread, as a starting point.

    Precision Electronic Levels - The Germans Arrive
    Last edited by Joe Gwinn; 06-20-2021 at 03:26 PM. Reason: typo

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    Quote Originally Posted by Joe Gwinn View Post
    In the now closed (why? the title is perfectly clear to me) recent Taylvel thread, I mentioned that the legacy electronic circuitry was simple to implement using present-day electronics, and mentioned that I had dug into the building of such a level.

    These kinds of levels can detect the slight changes in local earth surface slope due to imperceptible passing seismic waves and the like. Thew were originally built for exploration of large surface plates to find low and high spots. These days, optical means are typically used for this.

    Anyway, for those who are interested, the original thread was on the <rec.crafts.metalworking> usenet newsgroup circa April 2009. Many references are given. Search for "taylvel" and "gwinn" to recover the traffic. Here is one hit in that thread, as a starting point.

    Precision Electronic Levels - The Germans Arrive
    The title wasn't very clear, and the gibberish inside was completely without direction.

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    Thought talyvel was rank hilger watts ie j Arthur rank hilger watts proprietary kit, there were levels and also centre line average surface texture gauges, very good it their time to be honest, we used the roughness comparators but not so much the inclinometers, though I have 2 mechanical ones and the box of an autocolimator, I’m guessing the boards fried?
    Mark

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    Quote Originally Posted by digger doug View Post
    The title wasn't very clear, and the gibberish inside was completely without direction.
    Digger, it is not gibberish if you know the language it is written in.

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    Quote Originally Posted by boslab View Post
    Thought talyvel was rank hilger watts, ie j Arthur rank hilger watts proprietary kit; there were levels and also centre line average surface texture gauges, very good it their time. to be honest, we used the roughness comparators but not so much the inclinometers, though I have 2 mechanical ones and the box of an autocolimator.
    Yeah, that's my recollection as well.

    I was more interested in the inclinometers for detecting passing seismic waves. But I got over it.

    I’m guessing the boards fried?
    That's my guess. Or it could be pretty simple to fix if one knows electronics. Given the era, I bet there is a bad electrolytic capacitor.


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    Yeah, I thought it was pretty clear to the folks that knew what it was and what I was talking about, although I did misspell , should be Talyvel, but made by TAYlor-Hobson..cheeky British, oh well. I replaced the electrolytic capacitors, and unfortunately did not fix the problem. My electronic knowledgable friend thought that a new board with new up to date components was the way to go, but I am not him, and this would be a large project for me. But it may end up as something I will have to do. Since all there is left is a few transistors and resistors, I will replace the transistors and see what that does. I did possibility find a "smoking gun" as I was examining the transistors in situ, one fell apart as I was positioning it to find the numbers. Thanks for the replies.

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    Quote Originally Posted by daryl bane View Post
    Yeah, I thought it was pretty clear to the folks that knew what it was and what I was talking about, although I did misspell , should be Talyvel, but made by TAYlor-Hobson..cheeky British, oh well. I replaced the electrolytic capacitors, and unfortunately did not fix the problem. My electronic knowledgeable friend thought that a new board with new up to date components was the way to go, but I am not him, and this would be a large project for me. But it may end up as something I will have to do. Since all there is left is a few transistors and resistors, I will replace the transistors and see what that does. I did possibility find a "smoking gun" as I was examining the transistors in situ, one fell apart as I was positioning it to find the numbers. Thanks for the replies.
    Hmm. Falling apart is not normal behavior for a signal transistor, even then. What happened?

    You may not be able to get the exact transistor types used then, but these are jellybeans today, so a cross match should be possible. Although I think they were jellybeans in their day as well. What numbers have you found?

    I don't recall if I have any circuit diagrams. They may well have held that close.

    Even if you replace every component on the old board, it could be less work than developing a new design.

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    Why didn't both of you post your threads in the ......wait for it...."Meteorology Section" ?

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    I did, no hits and a much smaller audience.

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    I found a evilbay listing with photos, one of which shows a partial schematic. Perhaps the seller would be willing to provide a copy.

    It's a steal at $3K USD. Title is "Taylor Hobson Dual Head TalyVel Leveling System w/ bases & case - NS51".

    It did show one transistor, a 2N1307, which is a Germanium PNP type.

    Taylor Hobson Dual Head TalyVel Leveling System w/ bases & case - NS51 | eBay

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    Turns out there are Practical Machinist threads as well. The wonders of Google.

    Taylor-Hobson Talyvel 4

    And also:

    Building differential electronic levels?
    Last edited by Joe Gwinn; 06-20-2021 at 06:21 PM. Reason: add url

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    Quote Originally Posted by digger doug View Post
    Why didn't both of you post your threads in the ......wait for it...."Meteorology Section" ?
    In hopes of a tornado of replies ?

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    Joe, many thanks. I just bought a couple of the original NOS OC75 transistors off of Ebay, as I know the one I have is bad. I figure I'll start to check the other ones with a tester and see how it goes. The transistor list is fortunately small:
    1) BCZ11-3ea.
    2) OC42- 2ea.
    3) OAZ204- 1ea. This is a Zener diode?
    4) OC75-1ea. This is the one I just bought NOS

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    Replacing all the transistors is wasteful and not necessary. You need the schematic, and you need to analyze it and understand it. Then start measuring steady state voltages at important nodes. This will probably lead you to the problem. You can debug 90% of problems without even using an oscilloscope.

    Disclaimer: I have no idea what’s inside a Talyvel. (Because you didn’t post pics.)

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    What a fascinating bit of advice. I can assure you had a schematic been available this thread would never have been posted. It seems Taylor-Hobson is very secretive about these things, even long obsolete units, and do not give out this information. I had hoped some member on this board might have attempted a repair in the past and might have more info, this has yet to happen. I might be the first one, even though I am totally electronic deficient.thumbnail.jpg

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    Quote Originally Posted by Joe Gwinn View Post
    In the now closed (why? the title is perfectly clear to me)
    Of course it's clear to YOU.... the point is to give some hint of what the topic is actually about so that others can determine whether to spend time opening your topic or not.

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    [QUOTE=Joe Gwinn;3773474]I found a evilbay listing with photos, one of which shows a partial schematic. Perhaps the seller would be willing to provide a copy.

    I sent them a note with offer to pay for a scan or photo, but they responded "Nope, cannot help you". It was a long shot.

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    Quote Originally Posted by daryl bane View Post
    What a fascinating bit of advice. I can assure you had a schematic been available this thread would never have been posted.
    So just draw it up. You have the board right in front of you and it doesn't look too complicated. This is not unusual for vintage electronics.

    Your easy fix (electrolytics) didn't work, but that doesn't mean you have to replace the rare transistors, and it definitely doesn't mean "IT IS WORTHLESS!!!". You have some debugging to do first.

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    Quote Originally Posted by Admin5 View Post
    Of course it's clear to YOU.... the point is to give some hint of what the topic is actually about so that others can determine whether to spend time opening your topic or not.
    You mean the 1-2 seconds required to open a topic, and then the 30 seconds required to determine whether the topic is of interest or not.

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    The tricky thing is trying to repair it whilst being either "totally electronic deficient" or too modern/young.

    The board looks to be fairly simple in the grand scheme of things, It's certainly not a three band superhet wireless!

    The circuit boart looks as if it may be two layer (Unless HW just liked putting the components on the wrong side, but it should be simple to trace out the circuit diagram from the board tracks. Simple, but mind numbing...

    Armoured with that and the assumption that Talyvel reader heads are LVDTs/Linear Variable Differential Transformers, it should be possible to calculate what DC voltages to expect and have a guess at what AC voltages are likely. At this point, the meter and/or scope lead to the source of the problem.

    It's not rocket surgery, but it isn't machining or computers. If one could find a local chap who had analogue electronics knowledge and nothing to do for two or three days, it would be simple. Simpler still if one could trace out the circuit and lay it out neatly beforehand.

    All the transistors are Mullard PNP types and are still available from some suppliers and the zenner diode is a 6.8V one that was Mullard but could be replaced by any other 6.8V zenner.

    The most common causes of death with ciscuits of that vintage were dry joints on the soldering (easily fixable) and putting the batteries in back to front (rebuild time).

    Hopefully you can find an enthusiast to help.

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