How to set operating voltage for Macbeth TD-504A Desnsitometer

Discussion in 'Darkroom Developing and Printing' started by Phil Glaser, Feb 9, 2004.

  1. Phil Glaser

    Phil Glaser Guest


    I have recently acquired a Macbeth TD-504A densitometer on ebay and I
    have a bunch of questions.

    First, it is currently set up for for operation at 220V, and I need to
    get to work on US voltage. The manual Gives instructions for setting
    the the voltage by using two switches on the power supply, but when I
    opened the back cover and looked where the switches are supposed to
    be, according to the instructions, they are not there. Instead, there
    are a set of screws numbered 1 through 9 and two jumper cables that
    connect screws 1 and 3 and 7 and 9. The instructions for setting the
    operating voltage say to refer to "Addendum # 1", which I gather
    explains what to do with these jumpers. Without the instructions, I am
    at a loss as to know how to reconfigure those jumpers to make the unit
    operate at 110 V?

    Second, my solution to dealing with the power cable and UK-style plug
    was to purchase a plug converter that converts a 3-pronged UK plug to
    a 3-pronged US plug. (This is _not_ a power converter; it merely
    converts the prongs of one plug to the prongs of the other). Based on
    a previous post to the newsgroup (which I did not see before I bought
    the the adapter:$%[email protected])
    I am now wondering whether this cable configuration will work at all:
    do I need to just remove the UK plug and re-wire it it with a USA
    plug making the necessary modifications?

    Third, I am not sure how to use this densitometer for measuring the
    density of black and white negatives. It has has a four different
    filter positions, one for "visual" and three additional postions for
    blue, green, and red "Kodak Status A" filters. Will setting it to the
    "visual" give the correct "filter" for measuring black and white

    Fourth, the instructions discuss a step tablet with a "calibration"
    step. It does not specify the density of this calibration step. So,
    question four is: What is the density of the step at which this
    densitometer should be calibrated.


    Phil Glaser, Feb 9, 2004
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  2. Phil Glaser

    MFHult Guest

    I upgraded my TD-504 seven or eight years ago, so I can't look inside .... You
    didn't say what terminals the 220 supply was connected to so it can't be
    determined with the info you present. But an electrician with a voltmeter
    could figger it out right quick. Or if you post a complete diagram or put a
    picture at a web site, we can prolly figger it out remotely.

    One quick and dirt solution would be to use a 220-> 110 step-down transformer.

    Such a transformer can be purchased surplus relatively inexpensively, or made
    from four identical transformers (secondary rating unimportant as long as it
    is not high voltage).
    Forget the adapter. Get a three-prong replacement cord. They sell them at Home
    Depot. Or cut it off an appliance you are going to throw away.
    Status A is for color transparencies/E6. You won't be needing that for black
    and white negative film.

    "Visual" puts a filter in the light path that corrects the response of the
    sensor to the visual spectrum which is what panchromatic (normal) film
    records. That's the setting you will use for B&W.
    Buy a calibrated 21-step transmission wedge # T2115C from Stouffer for about $15. You don't need
    "certified" which is four times as expensive and unneeded if you always use
    the same wedge.

    IIRC, the TD-504 auto-zero's itself when you turn it on. Don't have a
    negative or wedge in when you turn the instrument on. There *may* be a zero
    button (I don't recall one).

    Calibrate the slope by putting the ~2.0 density of your wedge in the measuring
    window and adjusting a screw in the back so that the reported density is the
    same as the indicated density of the wedge. Dmax for this particular wedge is
    about 3.0 You don't need to go that high.

    (I *hope* I'm not remembering a different densitometer ... Some one will
    correct me if I am. At any rate, the instrument is 'zeroed', and then the
    value reported by the densitometer is set to the value of the wedge.)

    HTH ... Marc
    MFHult, Feb 9, 2004
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  3. Phil Glaser

    Nick Zentena Guest

    I have one. At least I think it's the same model. I don't know to what
    extent they drift over time but I haven't gone to the trouble of
    calibrating mine since getting it last fall. I did compare it to the
    densitomer function of my colour analyzer and the results are close enough
    that I've put off getting a step tablet. I will when I remember but it seems
    accurate enough for now.

    If I understand how the calbration works you stick your reference under
    the probe. You then fiddle with the knob on the back until the numbers
    match. You should do this twice. Once for a low value and once for a higher
    one. Hopefully that is all you need to get the thing within tolerances. I've
    got the manual some place and could check.

    For use you turn it on. I'm not sure you really need to let it warm up
    but I've seen references to older models needing a warm up period. You then
    zero the channels. Basically lower the probe. Hit the zero button. Rotate
    the dial to the next colour. Do all four and then go back and check them.
    They should be reading zero. If not redo it.

    Mine is a 504AM. Whatever that means.

    Nick Zentena, Feb 9, 2004
  4. Phil Glaser

    MFHult Guest

    Status M is for color negatives (assuming that's what the M suffix on your
    model number refers to). For black and white, you don't need or use the three
    colored Status M filters so there is no point in calibrating them. The filter
    colors don't stay true indefinitely and with these ~30-year-old instruments,
    the filters would require/warrant replacement if you did want to do
    quantitative color work .

    Many/some Status-M models don't have a "visual" channel for panchromatic film
    but instead have a filter for ortho (i.e, reproduction with reduced
    sensitivity to red light) film. For most purposes with panchromatic black and
    white film -- unless you are using negatives that are heavily stained like
    pyro -- any of the channels will work more or less OK. For pyro, preferably
    use a blue filter.

    You can easily determine whether your instrument requires a significant warm
    up period to stabilize, or *much* worse, that it drifts, simply by watching
    its behavior. I've been pleasantly surprised by the stability of the
    densitometers that I've used.

    .... Marc
    MFHult, Feb 9, 2004
  5. Phil Glaser

    Phil Glaser Guest

    wrote in message
    Ah, there's the rub. The power cable on this thing has 9 pins. It's a
    rather involved affair. I think I can describe the situation
    adequately without resorting to uploading an image.

    Picture the female power plug on the back of the machine as
    three rows of sockets. Based on a previous description
    ($%[email protected])
    my plug is _sideways_ with respect to the half-moon and round
    pin sockets (that post discussed the possibility of the
    arrangement being upside down; mine is sideways). Having made that
    adjustment, we have this arrangement of sockets, where 2, 7, and 9 are
    the "half-moon" sockets:

    1 2 3
    4 5 6
    7 8 9

    As I look on the machine's female plug, I see that female sockets
    have no contacts in them. Looking on the back of the male connector
    that plugs into the back, I see that:

    a) there are two white jumper cables, one that connects pin 5 and 2
    together and another that connects pins 4 and 5 togeher. Since 4 has
    no contact, this second jumper would appear to be meaningless.

    b) Socket 7 is connected to yellow/green, 1 to blue, and 9 to brown.
    At the other end of the cable, on the UK power plug, yellow maps to
    ground, and blue maps to the left prong (as you face thew all), and
    brown to the right. This plug has a built-in 3A fuse between the blue
    wire and the right power prong.

    According to the afforementioneed post, the pins have these meanings
    for the 120 V setup: "The AC hot is pins number 2 & 3, AC neutral is
    pin number 9 and ground is number 7." For my unit this interpretation
    does not hold becuase number three
    is an empty contact. Again, in terms of that posting, my plug is
    sideways but
    I have numbered in accordance with the position of the half-moon
    So I'm quite perplexed.

    But we have not gotten to the power switches yet. In the back of the
    where the power switches should be, I have this straight bank of 9
    screw-posts, numbbered 1 through 9. There are two
    jumpers cocnfigured as follows:

    1 2 3 4 5 6 7 8 9
    | | | |
    |_____| |_____|

    In other words, 1 is jumpered to 3 and 7 is jumpered to 9.

    So much for the electrical aspect.

    As for the step tablet: I have a 21 step tablet from stouffers, but
    it's not
    calibrated. Is it necessary for it to be calibrated? The specs for it
    that it begins (if memory serves) at 0.15 and increases in density
    increments of
    .. . . I can't remember but I have it written down somewhere. Can't I
    rely on what they say are its specifications rather than having it
    officially calibrated?

    Thanks for your help!!!

    Phil Glaser, Feb 9, 2004
  6. Phil Glaser

    MFHult Guest

    You might consider contacting the "Donald" who has the manual who responded
    back in November.

    Alternatively, make the reasonable assumption (or scout out the circuitry
    to verify) that everything that matters is powered by the secondary/ies of
    the power transformer that almost surely will have a pair of primary leads
    that are connected in series for 230VAC supply and in parallel for 115VAC.

    Work backward from there, bypassing unneeded jumpers, switches, and
    multiconnector plugs -- ending up, if needed, with a three-prong
    replacement cord connected to the transformer through a fuse and a
    single-pole single throw switch on the 115VAC hot.

    You have the $5 uncalibrated version. The $15 calibrated version I
    recommended is preferable. The ~$60(?) certified version is unnecessary.

    The 21-step Stouffer wedges in common use have 21 steps of 0.15 (Dmax

    Yes, the assumptions you suggest will get you close and may be entirely
    adequate for your purposes -- especially if you don't share data/results
    with others and don't lose or damage the uncalibrated wedge. (Many folks
    live successfully in their own realms, unconnected quantitatively to others

    I dunno what you intend to do, but 'calibration' of B&W film and paper can
    involve contact printing with the step wedge, so its use goes beyond
    calibrating the densitometer (for which you really only need one known-good
    value somewhere around 2.0).

    For the amount of effort you will/may be going through, I'd at least spring
    for the additional $15 once I knew everything else was working as needed
    and before I began using it for exposing film/paper.

    Mis dos centavos... Marc
    MFHult, Feb 9, 2004
  7. Phil Glaser

    Nick Zentena Guest

    Okay I found my manual. Don't you have the addendum? It's in the back of
    my manual.

    I'm assuming you're currently setup for 220V high. If so you should be
    seeing the following from top to bottom

    Wht connected to the top screw
    This should be connected but it doesn't give a colour

    Assuming you've got that. Then for 115 high it should be

    connected but no colour

    Caveat my manual might be different then you're unit. I may have misread

    Nick Zentena, Feb 10, 2004
  8. Phil Glaser

    Phil Glaser Guest

    Wow, thanks for looking that up! No, mine definitely does not have the

    But this is still confusing. I don't have anything that I would
    describe as top-to-bottom. On the female blug into the rear of the
    machine, I have the three rows of three for a total of 9 socket pins.
    Inside the machine, I have a row of screws from 1 through 9, numbered
    from left-to-right. Moreover, that row does not have colored wires
    connected to it. Just two jumpers as I've described.

    Are you describing a row of screws inside the machine or the plug on
    the back?

    Phil Glaser, Feb 11, 2004
  9. Phil Glaser

    Nick Zentena Guest

    I'm just describing the diagram . It's two diagrams. One for 115/220V
    high and a second one for 115/220V low.

    Nick Zentena, Feb 11, 2004
  10. Phil Glaser

    Nick Zentena Guest

    My message is related to this I think. The problem is this seems a cross
    between the 115 and the 230 setup. For 115 you should have 6 not 7 connected.
    OTOH for 230 you should have 8 not 9. But you said your wires aren't coloured.
    The diagram is labelled TB402. Terminal block?

    Nick Zentena, Feb 11, 2004
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