Manual for Macbeth TD-904 Densitometer

[skahde]

Threads on this topic are several and they are all quite dated so I dare to start a new one.

I'm looking for a manual for a TD-904 densitometer. They have been offered on this forum but many years back when this was still apug.org.
If anyone could help with a download or attachment via mail I would be grateful.

Thanks in advance!

Stefan

 

[skahde]

I'm asking because I bougth one at that auction site and the fan blows, the incandescent lamp fires up, the buttons on the right react when pushed but all I get shown by the display is:
"+1 . 1" and this doesn't change a bit when pushing any buttons. Am falling victim to my own stupidity or is it broken?

 

[skahde]

I found the manual online, but I still have no clue what is going on here.

For the record: https://www.johnesimmons.com/Graflex/MacBethDensitometer/MacbethDensitometers.pdf

 

[Mr Bill]

Hi, the usual way to calibrate a unit like this starts like so: hold the probe head down, and while holding it down, momentarily press the zero button. (You do this with nothing in the aperture; no film.) The display should then read 0.00, or similar. Then you let the probe head back up; the reading should remain on the display.

What happens if you do this (with any color selected)?

If this was successful then the second part of the calibration requires a "check plaque" or whatever they call it. (This is essentially a piece of film with a known density value, perhaps somewhere around 1.50 or 2.00 or whatever.) You would act as though you are reading this, holding the probe head down. If the reading is correct (matches the check plaque value) then it's OK. If the reading is too high or too low then you adjust it with a small knob on the back of the instrument (while holding the probe down).

If things seem to be working, here are the fine points... you need to zero each color individually. But only adjust the back knob, essentially a "slope" adjustment, for one of the colors.