Amergraph V28-VMS troubleshooting

[NoSuchNick]

Hi, I got my hands on an Amergraph V28-VMS a few months ago for my at-home photogravure set up. The vacuum pump, integrator display, housing, etc. all seem in working order. I've added a new bulb and calibrated the unit according to the manual. Since installing it though, I'm beginning to suspect that the relationship between the light units it's outputting and the numbers on the integrator display aren't in consistent alignment. At first I thought, my inability to dial in an exposure was the result of photogravure's myriad variables, but after auditing my entire workflow 20-ish times I began to suspect my exposure unit is the issue. To check, I tried shooting silkscreen emulsion (due to it's ease relative to gravure's gelatin) and came up with similar issues of being unable to dial in a consistent exposure (one run it was 5 units of light and another it was 15); however, I'm still uneasy diagnosing my unit as broken, given that they're not manufactured anymore and very difficult to come by. Would anyone know a way for sure to check, for certain, if my unit is broken? If there is an even simpler way of checking the the integrator for errors? And if it is broken, if there were a way to fix the issue?

It should be noted, that I am by no means an expert on exposure units. If I could also provide any info that could point someone toward diagnosing this problem as "user error" I would be happy to do so.

 

[Nicholas Lindan]

The mercury arc lamp in these units change both their spectrum and their light output as they warm up. The light sensor in the unit will have (should have) a filter that matches the spectral sensitivity (er, makes a half-arsed approximation thereto) of the material being exposed. The need for integration is because the light output varies so much as the lamp heats up to operating conditions.

Two possible problems may be

• The filter on the integrator is for exposing some other material or is missing;
• The integrator is broke - however, if it's rate is tracking the light output it is probably mostly OK.

 

[NoSuchNick]

The mercury arc lamp in these units change both their spectrum and their light output as they warm up. The light sensor in the unit will have (should have) a filter that matches the spectral sensitivity (er, makes a half-arsed approximation thereto) of the material being exposed. The need for integration is because the light output varies so much as the lamp heats up to operating conditions.

Two possible problems may be

• The filter on the integrator is for exposing some other material or is missing;
• The integrator is broke - however, if it's rate is tracking the light output it is probably mostly OK.

That’s so helpful! I’m doubting that replacement filters to my desired specs still exist (or are at least easy to find). Can I alter the pre-existing filter somehow? If not, would you know if the v28-1200 (as opposed to my v28-vms) has the same filter-based operation? Could I use a 1200 and rely only on its light output rather than light output relative to the filter?

 

[NoSuchNick]

Bumping my own thread