SEI Photometer help needed

[almostpilot]

Hi
I recently acquired from ebay a SEI Photometer (the english spotmeter used by A Adams) that had all the mnuals, spare bulbs etc and was listed as fully working. Unfortunately covid restrictions got in the way and I was only able to get to the package recently, past the Ebay "help" window.
The bulb that you need to use and calibrate every time you use this very complicated piece of equipment will not turn on when you press the button on the rheostat control at the bottom cover.
I have tested the bulb and the spares and they work. The battery also obviously is brand new and works.
So I can only think that the issue is in that bottom cover which houses the rheostat and the ON button.
I have contacted the seller who reiterated the meter worked when he sent it to me. Well it sure does not work now.
Can anyone help me? Is there any tech who could look at that bottom cover for me and see if it needs servicing? I even managed to find a doc online with repair instructions for this meter. But I am no electrical engineer and would never know how to even take that bottom cover apart.
I am based in the uk.
Hope some kind soul can point me in the right direction. this thing cost me a lot of cash and i hate having something that does not work in my collection. i bought it to use in the field with my Gandolfi Half plate.
thank you

[Alan9940]

I am sorry to say that there's probably no one who can work on it for you. Over the years, I bought 3 of them and had to return because they either didn't work or wouldn't calibrate properly. As you say, it's a very complicated piece of equipment. Long shot...have you checked the battery compartment for corrosion?

Good luck!

[grat]

I assume you've seen http://www.jollinger.com/photo/cam-coll/manuals/meters/SEI_Photometer.pdf which also comments the battery should go in base first.

[Greg]

See my post at:
https://www.largeformatphotography.info/forum/showthread.php?158723-Tale-of-the-elusive-SEI-Photometer&highlight=SEI+Photometer
Unfortunately 99% of sellers of SEIs on Ebay have no idea of how SEIs work. Over the years have corresponded with dozens of sellers on Ebay and never found one who knew how to operate the meter.
Best of luck with yours. If you need a spare part, just contact me and I'll see if I can help you out.
Greg

[Jerry Bodine]

My SEI is still working just fine, but I’m certainly no expert on this meter, nor am I really qualified as an electrical engineer. But I can offer some suggestions. First, it seems that since you say both the battery and the bulb/spares are working, but the bulb does not work when installed in the meter, then I’d guess either the bulb is not grounded or the microswitch (button on the rheostat) is faulty. First check that the battery is inserted correctly – the negative end of the battery should be inserted first per page 3 of this illustration:
http://www.cameramanuals.org/flashes_meters/SEI_Photometer.pdf
If that doesn’t solve the issue, then you may have to figure out how to partially disassemble the rheostat region to insure that the lamp switch (button) is grounded and is closing the circuit. The best person I know of who has done work with the rheostat is Bill Burk on the Photrio forum. Here’s one of his threads about repair work he’s done on the rheostat part:
https://www.photrio.com/forum/threads/sei-photometer-selenium-cell-replacement.136097/
Incidentally, when I bought my SEI new, there was a phenolic liner in the battery compartment, wrapped around the D-size battery. It was simply a tube - slit over its full length - and could be slid into the chamber before inserting the battery. Its purpose is to prevent the brass bulb holder from falling out when the chamber is empty. However, I found that D-cell batteries do not have tight standards between brands on their diameters, because the batteries I use would not slide out easily because the thickness of the phenolic liner was a hair too thick, creating enough friction to hold the battery in place. So I made my own liner with a clear piece of plastic material .002” maximum thickness, and the battery now slides out OK.
If you ever need to replace the bulb, you must remove this liner and allow the brass bulb holder to come out, then after screwing a new bulb into the holder, reinstall the holder. Note that the holder has a notch at one point on its circumference; this notch MUST align with a peg on the innards of the meter. It’ll be obvious by just looking at it. Then replace the liner, insert the battery, and screw on the rheostat housing.

[almostpilot]

Thank you.
The bulbs are ok, I tested them. The issue must be in the bottom cover where the rheostat and the switch are, but I have no idea how to fix that part. I will look at the link you provided. Thank you.
Yes I know about the battery orientation, the bulb change procedure, etc etc.
I managed to get the meter to work with a piece of kitchen foil placed so that it touches the tube of the battery compartment and the metal spring of the bottom cap. This way the light turns on but of course it stays on constantly. proves, I think, that the issue is in the bottom cap. Either the switch as you say is not grounding or something else. Unfortunately I am totally ignorant of electrical things (can go no further than wiring a plug I am sorry to say) so even something I guess quite simple like that is beyond me.



My SEI is still working just fine, but I’m certainly no expert on this meter, nor am I really qualified as an electrical engineer. But I can offer some suggestions. First, it seems that since you say both the battery and the bulb/spares are working, but the bulb does not work when installed in the meter, then I’d guess either the bulb is not grounded or the microswitch (button on the rheostat) is faulty. First check that the battery is inserted correctly – the negative end of the battery should be inserted first per page 3 of this illustration:
http://www.cameramanuals.org/flashes_meters/SEI_Photometer.pdf
If that doesn’t solve the issue, then you may have to figure out how to partially disassemble the rheostat region to insure that the lamp switch (button) is grounded and is closing the circuit. The best person I know of who has done work with the rheostat is Bill Burk on the Photrio forum. Here’s one of his threads about repair work he’s done on the rheostat part:
https://www.photrio.com/forum/threads/sei-photometer-selenium-cell-replacement.136097/
Incidentally, when I bought my SEI new, there was a phenolic liner in the battery compartment, wrapped around the D-size battery. It was simply a tube - slit over its full length - and could be slid into the chamber before inserting the battery. Its purpose is to prevent the brass bulb holder from falling out when the chamber is empty. However, I found that D-cell batteries do not have tight standards between brands on their diameters, because the batteries I use would not slide out easily because the thickness of the phenolic liner was a hair too thick, creating enough friction to hold the battery in place. So I made my own liner with a clear piece of plastic material .002” maximum thickness, and the battery now slides out OK.
If you ever need to replace the bulb, you must remove this liner and allow the brass bulb holder to come out, then after screwing a new bulb into the holder, reinstall the holder. Note that the holder has a notch at one point on its circumference; this notch MUST align with a peg on the innards of the meter. It’ll be obvious by just looking at it. Then replace the liner, insert the battery, and screw on the rheostat housing.

[Jerry Bodine]

Thank you.
The bulbs are ok, I tested them. The issue must be in the bottom cover where the rheostat and the switch are, but I have no idea how to fix that part. I will look at the link you provided. Thank you.
Yes I know about the battery orientation, the bulb change procedure, etc etc.
I managed to get the meter to work with a piece of kitchen foil placed so that it touches the tube of the battery compartment and the metal spring of the bottom cap. This way the light turns on but of course it stays on constantly. proves, I think, that the issue is in the bottom cap. Either the switch as you say is not grounding or something else. Unfortunately I am totally ignorant of electrical things (can go no further than wiring a plug I am sorry to say) so even something I guess quite simple like that is beyond me.

I'd suggest you get in touch with Bill Burk via PM; I'm sure he can help. In the Photrio thread link I gave you, click on his name & then click "Start a Conversation" (in Photrio a PM is called a Conversation) > must have a title > compose your message > click Start a Conversation. His post #7 in the thread link will be a good starting place in your discussion with him.

You'll notice in that thread a number of "disconnects" where he refers to comments from silveror0 (that's me). My comments were deleted, due to a very aggresive "spam cleaner" in the forum at that time, causing hundreds of my posts to be purged from the forum. The forum moderator (Sean) was very busy with the upgrade from the old forum name (APUG) to Photrio and never did reinstate my lost posts. Bill is familiar with that issue.

[almostpilot]

I'd suggest you get in touch with Bill Burk via PM; I'm sure he can help. In the Photrio thread link I gave you, click on his name & then click "Start a Conversation" (in Photrio a PM is called a Conversation) > must have a title > compose your message > click Start a Conversation. His post #7 in the thread link will be a good starting place in your discussion with him.

You'll notice in that thread a number of "disconnects" where he refers to comments from silveror0 (that's me). My comments were deleted, due to a very aggresive "spam cleaner" in the forum at that time, causing hundreds of my posts to be purged from the forum. The forum moderator (Sean) was very busy with the upgrade from the old forum name (APUG) to Photrio and never did reinstate my lost posts. Bill is familiar with that issue.

Thank you very much. Yes I will get in touch with him.
In the end I went and bought another SEI meter, luckily for a fraction of what I paid for the first one. It came and it does not work either. In fact it is pretty unusable as the 3 ND filter used for the "patch" are shot.
However, I put the base with switch and rheostat of this newly bought SEI on the previous one and... it works.
It is clear therefore that the issue is with the base of the first SEI.
I will get in touch with Bill and see if he can tutor me in taking apart the non working base and get it back into service. Would be nice to keep as a spare.

[Jerry Bodine]

Well, you certainly lucked out with your resolution of this issue. Good thinking on your part. When you contact Bill be sure to mention what color your microswitch button is. When I bought my SEI in 1970 at one of several Ansel's workshops, it had a silver-colored button; one of my friends who did likewise at about the same time found that his SEI had a black button. So, there may have been some other design changes to the rheostat housing that Bill may be aware of.

[almostpilot]

Well, you certainly lucked out with your resolution of this issue. Good thinking on your part. When you contact Bill be sure to mention what color your microswitch button is. When I bought my SEI in 1970 at one of several Ansel's workshops, it had a silver-colored button; one of my friends who did likewise at about the same time found that his SEI had a black button. So, there may have been some other design changes to the rheostat housing that Bill may be aware of.

Hello again.
Well, curiouser and curiouser...
Now both bases are working! I cannot for the life of me understand how, but yes, the base that has not worked for about 2 weeks suddenly started to work yesterday afternoon. And I also found that the cheap SEI can indeed be used, albeit with only two of the ND filters (the ones used for dark and medium brightness), as the ND filter for the brightest conditions does not slot in properly.
I have not done anything special, other than keep pressing the microswitch button. All I can think of is that by trying it again and again some gunge inside freed up. I did spray some Servisol S10 switch cleaning lubricant in there 2 weeks ago, when I first tried to get the SEI to work, but as I said it looked like it had not done the trick. Oh well, now I have 2 SEI meters, (and 3 spare bulbs!).
PS
As a test I switched bases again from one unit to the other, and yes they now both work, on both units.

Go figure!
I also wonder if storage has something to do with it. The first unit had been stored horizontally for months (maybe years) but in the last 2 weeks I kept it upright. Whon knows...

[Jerry Bodine]

Quite the mystery. It's a shame that one of the meters does not provide the high brightness range, since that's the range most daylight luminances fall. But at least you have the white medium range that would provide readings for indoor subjects. But since you do have a meter with all three ranges working, and if you're feeling brave enough to attempt to find out why the high range filter setting is malfunctioning, you might try carefully loosening the two tiny screws - at 180 degrees apart - just above the housing separation near the setting thumbwheels. If it comes apart, probably holding the meter vertically, you may be able to see what's wrong (I'd suspect a mechanical issue rather than electrical). If there are three separate filters involved to produce the three ranges, the high range filter would be equivalent to ND 2.0. Why? Look at p. 22 of the link provided by my first post in this thread. Notice how the bright range covers from 32 candles/sq. ft. all the way to 3200 candles/sq. ft. (6-2/3 stops). However, from the Figure 1 illustration of the filter drive mechanism in that link, it's implied (to me) that graduated filters are used rather than separate filters. But Figure 1 may just be a concept sketch, so who knows what you'll actually find in there.

[Michael Whyte-Venables]

Have you a multi meter? You need to check that a variable resistance exists between the battery contact button. I have two of these and am converting one to use a AA lithium ion battery. In the process my son and I have thought a lot. One important thing is that save for through the variable resistor, the negative end must NOT contact the brass tube which holds the bulb.

[Jerry Bodine]

Hello again.
Well, curiouser and curiouser...
Now both bases are working! I cannot for the life of me understand how, but yes, the base that has not worked for about 2 weeks suddenly started to work yesterday afternoon. And I also found that the cheap SEI can indeed be used, albeit with only two of the ND filters (the ones used for dark and medium brightness), as the ND filter for the brightest conditions does not slot in properly.
I have not done anything special, other than keep pressing the microswitch button. All I can think of is that by trying it again and again some gunge inside freed up. I did spray some Servisol S10 switch cleaning lubricant in there 2 weeks ago, when I first tried to get the SEI to work, but as I said it looked like it had not done the trick. Oh well, now I have 2 SEI meters, (and 3 spare bulbs!).
PS
As a test I switched bases again from one unit to the other, and yes they now both work, on both units.

Go figure!
I also wonder if storage has something to do with it. The first unit had been stored horizontally for months (maybe years) but in the last 2 weeks I kept it upright. Whon knows...

I discovered something worth knowing this week. The fact that the bulb lights up does not mean that all is well. My SEI developed a very “jittery” rheostat and very difficult to get the ammeter to hold still on the red calibration mark. The bulb was still lighting up. I re-read the instructions at the very end of the manual (http://www.cameramanuals.org/flashes_meters/SEI_Photometer.pdf) that pertained to installing a new bulb and calibrating it, and it all came clear to me. I sprayed some Radio Shack “Precision Electronics Cleaner” that I’ve had for years into the rheostat base, then worked the rheostat control vigorously back and forth and let it dry. That solved the jitters, but the ammeter was not reaching the red mark. I still had a spare bulb that came with the meter when bought new, so I installed it and found that it went right to the red mark without further work needed. So now I understand more about how this system works:
The bulb degrades and puts out less light gradually over time. The function of the rheostat is to counter this degradation by adjusting the supply voltage from the battery sufficiently to enable the bulb output to return to its original output (thereby calibrating it). But eventually the bulb output diminishes to the point where the rheostat can’t cope sufficiently and the red mark can’t be reached. That’s when the bulb MUST be replaced.

The rest of the story:
I recently had my Gossen meter (not a spotmeter) recalibrated by George Milton at Quality Light Metrics in Hollywood, so I was confident it was usable as a standard for comparing other meters to. Then I was fortunate in finding a NEW Pentax Digital Spotmeter from a dealer in California. To check all three meters for accuracy, I set up a whiteboard outdoors in full sunlight on a day with clear blue sky at my home in the Seattle area (a miracle in itself), I made readings over a range of about 6 stops – EV 16.33 to 11 - using ND filters. All three meters agreed within 1/3-stop over this luminance range, with the largest difference being that the Pentax read ½-stop high only at the very lowest luminance (EV 11). I can live with that.

[Bill Burk]

Glad to hear this all worked out for you!
You could always put a ND filter in front of the telescope to replace the missing one if you don’t want to take the top off. It can be tricky to get the whole thing back together again if you open it up.

[almostpilot]

Glad to hear this all worked out for you!
You could always put a ND filter in front of the telescope to replace the missing one if you don’t want to take the top off. It can be tricky to get the whole thing back together again if you open it up.

Thanks to all for the useful comments. I will not open it up, also because the darker filter does move into position, not fully (about 90% of the aera is covered) but the calibration spot is well covered by the filter, I have done a few tests and it looks like it is reading ok.

I do not have my Pentax spotmeter (which I know is correct, ar to put it differently, gives readings that make my negs look the way I want them to... which is the name of the game IMHO) with me but in a few days time I will be able to compare the two SEI with it and see where I am.
I will report later then.
thanks

[Bill Burk]

I would calibrate the SEI to a trusted meter when you have it. For example set both SEI and your Pentax meter to agree... then put some Scotch tape on the SEI ammeter glass and draw a new “calibration” line where it happens to be. The selenium cell is probably weaker than original, so with both meters in agreement the ammeter needle should be close to where it “needs to be”.

[almostpilot]

I would calibrate the SEI to a trusted meter when you have it. For example set both SEI and your Pentax meter to agree... then put some Scotch tape on the SEI ammeter glass and draw a new “calibration” line where it happens to be. The selenium cell is probably weaker than original, so with both meters in agreement the ammeter needle should be close to where it “needs to be”.
Yes, thank you
that is what I am planning to do.
thanks for all the advice, I will let you know how it goes.