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Jagstang
Tinkerer
Username: Jagstang
Post Number: 1
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 25, 2013 - 04:31 pm: | 
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Hi there all. I've read this forum a lot and hope to add to it, but right now I have an issue with an Autoreflex T3N I just bought. I bought it online which I hate doing, but the price was right and I've been looking to upgrade from my TC for awhile, plus my local store is getting away from niche film stuff. Shutter works fine, but the meter is not functioning properly.
The needle didn't seem to want to move, and it has a quirk where at the low end shutter speeds the red flag that indicates max aperture moves downward (starting at about 1/15th). I took the top off; I know I am getting voltage at the meter. The problem is the needle is not moving free. It doesn't move when I shake the camera or poke it. Left it over night and no change. I can move it by gently touching it with a screw driver or moving the max aperture scale down but it's not moving on it's own at all.
I've gone as far as getting the prism out. I see two brass screws on top of the meter but I'm very hesitant to remove them as it looks like it would involve lifting out the mechanism that indicates the aperture. I also don't want to put any type of fluid down where the needle is without knowing what exactly is there, and based on a TC I parted out I'm guessing it's just a coil that moves the needle. I'd be surprised if the meter is dead as there were one or two times with batteries in it where it seemed like the needle wanted to move.
I'd hate to give up on this one as I've been looking for one for awhile, and by total luck this one has the split image focusing screen (my eyes aren't good enough for me to use the typical fresnel/ground glass screen) and it other wise seems to work. I do know someone tried to fix the camera before me; no technician tracks on the outside, but the screw that holds the strap lug in tight is missing, the brass screws on the meter are buggered up, and the leather on the right side is peeled back. The depth of field preview isn't working either but I'm not concerned about that if the meter is dead... anyone have any tips? Also, where are the trim pots to adjust the meter for higher voltage batteries? If I can get it working I might as well do that while I have it apart. I've searched around and it seems like 95% of the meter issues on these are from a dead meter due to lack of power, couldn't find anything for this model's needle actually being stuck. |
Fidji
Tinkerer
Username: Fidji
Post Number: 28
Registered: 12-2011
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 25, 2013 - 05:42 pm: |
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Try http://mattsclassiccameras.com/konica_auto_t3.html
Usually its wires from battery box that look OK ,but are just dust inside the plastic insulation.
Another thing to check is that there are no tiny bits of metal stuck in the coil spring,and that the needle is not stuck on a decomposing,sticky pad that it rests on when the meter is off. |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 2
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 25, 2013 - 06:46 pm: |
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Thanks for the response. Matt's site actually was helpful in me getting it apart; I don't think I would have pulled the prism had I known it was fairly easy. I tested the voltage up at the meter and the black wire that comes into the board. I think tiny bits of metal is really possible... I noticed a few tiny specs around the meter from the brass screws, so if I can figure out how to access the thing that could well be it. |
Arfd
Tinkerer
Username: Arfd
Post Number: 4
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 26, 2013 - 04:58 am: |
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The most obvious cause of a stuck meter is a disengaged auto-ring. Look into the mirror box, you should see a black ring held by 2 chrome pivots. If the ring is not attached to 1 or both of these pivots you will have to gently coax them to slide into the 'forks'. It is possible the galvanometer in the meter assembly is defective, or one of the thin wires connected to the spring needs resoldering. If the previous "repairer" has taken out the coil and replaced it he may have tightened the suspension screw too tightly and the coil is stuck. Easy to spot if there are tooling marks near the varnish seal to that screw. Another explanation is the needle locking mechanism is jammed and is partly engaged with the meter needle. You should be able to spot this problem when the prism is off, but before removing the prism you will need to place a small screw in the vacant screw hole to hold the spring-loaded viewfinder display of shutter speeds in place. If you don't, it's not a big deal unless you like spending a Saturday afternoon getting the display realigned! |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 3
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 26, 2013 - 06:28 pm: |
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Thanks for the info. The auto-ring is connected and working fine. The needle locking mechanism is also working free, as I can see it move down when I depress the shutter button. What is weird is that now the needle seems to want to stick around f11/16 and f2/2.8. If I try to move it from these positions it springs back to them, but no motion with the batteries in it or by shining light onto the meter cells. I'm leaning towards the suspension screw being too tight or the galvanometer having some issue.
Which screw is the adjustment screw? I see two green varnish sealed brass screws on the top of the brown board on the meter (these are the ones that are scratched up), along with another brass screw that is sealed with a brown varnish and seems to act as a stop for the arm and two hard to reach flat heads on the back black plastic that I assume houses the meter that are also varnish sealed. When looking at it head on there is also a screw that holds a brass plate to the meter, but the head is mostly gone on this one. Thanks for the info so far. |
Arfd
Tinkerer
Username: Arfd
Post Number: 5
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 27, 2013 - 11:14 am: |
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Referring to my notes of a few years back, the galvanometer suspension screw is actually under the brown plastic board that holds the lens-speed sensing lever and the metering vane lever. So it is best to leave them in place for the time being.
All Konica T models use a positive earth voltage system. Check the resistance of the coil by setting your multimeter to about 2k ohms, apply the red lead to the body and the other (black) to where the black wire terminates on the circuit board that normally sits on the prism. The coil should have a resistance of about 1.5k ohms, and the needle should move. If the needle doesn't move try switching to 1k or 500 ohms range. Don't switch to a more sensitive range as there is a possibility of overloading the coil! |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 4
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 27, 2013 - 02:37 pm: |
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Alright, thanks. Tried it and got nothing; just my multimeter reading Open. No needle movement on the camera either. The only other thing I notice is the power wire on the circuit board on top of the prism looks to have been resoldered, and the solder is also making connection to one of the terminals for the photo cell. Is this correct? Otherwise, I guess I'll just have to write this one off. |
Arfd
Tinkerer
Username: Arfd
Post Number: 9
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 28, 2013 - 12:57 pm: |
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IIRC the 2 solder points are connected just as you have observed. It is not a complete loss as the T3 and T3N share the same meter. Find a parts body and swap over the whole CdS / circuit board / meter housing and AE mechanism as one unit.
It is worth examining the coil for any break in the fine wire attached to the spiral suspension spring. The brown plastic board must be removed also the strong coil spring at the base of black plastic body. There is also a critical brass washer under the brown board, the meter housing won't move properly without it. |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 6
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 30, 2013 - 06:58 pm: |
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Might as well go and take it down to the coil to check that out... not working now anyway. I figure if I can't get it to work I'll use it as a manual camera. I'm bummed but it came with a 50 1.7 AR (I have a 1.4) so I figure I can get about $20-30 of my $40 investment back with that. I'll let you guys know what I find or if by some chance I get it working. |
Robau
Tinkerer
Username: Robau
Post Number: 2
Registered: 06-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 28, 2013 - 03:50 pm: |
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Hello, Iīm new here!
After one year with Sony Nex and Hexanon glass I want to get back to shooting film.
Iīd like to do a screen conversion with a Minolta X screen to either T2, T3 or T4 (all of them very dark), as described here:
http://photo.net/classic-cameras-forum/00YVvd
In one of the older entries here there was a very good starting point in calibrating the meter adjusting the tensioning string and the potentiometers:
https://kyp.hauslendale.com/classics/forum/messages/6899/7731.html?1162569589
Unfortunately that thread died just before it became really interesting.
Itīs clear whitch screws to adjust, but how?
Can someone give advice how to set the high brightness readings against the low brightness ones, and against what reference? Adjusting for silver oxide cells in the same time would be good also.
Thanks, Roland |
Arfd
Tinkerer
Username: Arfd
Post Number: 27
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, July 29, 2013 - 03:01 am: |
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You will need a standard light source. It is not difficult to make, Tomosy in Book 1 gives details, and there is also a description in the instruments / tools section of this forum. The secret is to calibrate the light against a camera known to be giving correct meter readings.
The adjusting screw for low light levels is mainly to compensate for slackness in the coupling cord and can often be left alone.
It is surprising that those members of the forum who are gifted in the electronic arts haven't published details about making a circuit to deliver a stabilized voltage from an unstable battery voltage. A simple diode isn't any good. Come on guys, it's not rocket science. |
Robau
Tinkerer
Username: Robau
Post Number: 3
Registered: 06-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 30, 2013 - 11:56 am: |
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I donīt have the Thomosy book and actually I donīt plan to get into it as much. On the other hand, I have no experience at all with camera-tinkering.
Just some common sense and the internet.
The Konica-guy here in Germany refuses to do the screen-conversion. I have abot 3 T3s, some T4s and some T2s, most of them not working in some way.
So there`s enough stuff to experiment with.
Back to calibration: Iīd use a Gossen Digipro as a reference. Can someone give me step by step advice in calibrating? How do low light, highlight and batterycheck settings influence each other? At what light values should be calibrated? One light and one dark I guess?
Does the batterycheck-poti overrun the sensors in the camera and how does its setting influence the others?
Electricity is something very strange to me, so just imagine I was a complete fool (with some common sense).
I donīt need to understand what I do, results are all that counts. Thanks in advance! |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 26
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 07, 2013 - 06:51 pm: |
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Memory serves from being this one (I junked it awhile ago)that what you're adjusting is resistance. The more resistance, the less voltage is going through the circuit. The meter measures light when light hits a light sensitive resistor or diode (resistor in this case I think), changing the resistance in the circuit and moving the meter needle. By adjusting the trim pots, it changes how the meter responds to light by altering resistance in the circuit.
I obviously never got to experiment as I could never get it to work, but I do have another broken down T3 I should play with. You'll also need to do this AFTER you put the screen in, as screens that let in significantly more light will affect meter readings. The other trade off is your depth of field will be less apparent, both wide open and stopped down. If you just want a split image screen, I'd actually advise against; my current T3 has the microprism and find it more usable because in my TC, the split image blacks out too soon. |
Robau
Tinkerer
Username: Robau
Post Number: 4
Registered: 06-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 08, 2013 - 02:54 pm: |
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donīt know why i bother with those bitchy Konicas...maybe because theyīre bitchy. An SRT oder K 1000 would be to simple I guess.
I donīt care for the split imagae, have a T3n
with one and itīs just as dark. Just need some more light! What I donīt understand is how the screen brightness should affect depht of field?
The rest is clear, even I know that potis adjust resistance. Just want to know how the brightness poti and the batterycheck poti work together if at all.
What kind of soldering iron do I need for that fine stuff? Got one with 30 watts I guess, for soldering thermoplasts (car repair stuff).
Anyway, gonna dive into it tomorrow. I plan to use ambient light (evenly illuminated white wall in a dark corner of my home plus the hopefully overcast sky as a highlight) as references for calibration.
Tell you whether it worked or not. I plan to use Silveroxide cells 1,55 V too, so perhaps the potis donīt cover up for that much light at the cells? |
Jagstang
Tinkerer
Username: Jagstang
Post Number: 27
Registered: 01-2013
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 09, 2013 - 05:15 pm: |
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Coincidentally, my run of broken Konicas ended when I found one that worked... next 4 I've bought all worked fine (even an FS1, how rare is that?!).
As for focusing screens, basically as they make them brighter it decreases contrast so the difference between in and out of focus becomes less apparent. I believe it has to do with how the glass is ground; it's worst in modern DSLRs, but that's another story.
As for how they work together, I am not sure. A GUESS would say the battery check is totally independent of the others, as all it does is indicate life; you turn it into the needle points in the designated zone with fresh batteries. No clue about the others, sorry.
I would also say the 30w is fine. For something like this I don't see a huge difference if you use good technique. I use something in that range for PCBs. Just make sure you have a good, fine tip on it and a steady hand with a magnifier.
For calibration, just have a known good meter handy; for instance, when I'm checking accuracy I have a Sekonic Digilite that I know is can't miss. For something more demanding like calibration other members might have a more refined technique. |
Robau
Tinkerer
Username: Robau
Post Number: 5
Registered: 06-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 14, 2013 - 03:43 pm: |
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dove into it today and got everything apart...
the Minolta screen seems to be thinner than the old Konica one, so the condensor and the new sreen rattle somewhat inside their assembly. Any idea how to solve this, some glue or tape? Also I lost one of the screws that hold that assembly to the body of the camera, now it is buried deep somewhere inside the shutterrelease side of the body and doesnīt come out...luckily i tinkled with the worst of my T3s just to get a feeling.
Had to magnetisize my screwdrivers, now Iīm going to pull the mirrorbox to find that damn lost screw...I couldnīt do that job all day long.
Somehow I prefer chainsaws as tools! Iīm taking lots of pictures of everthing. When I will have discovered how it really should work Iīll compose a nice pdf for all of you masochistic Konicanians! regards Roland |
