Yashica GT "Long Exposure" Not Working

[Iskra 2]

Everything back together and checking out OK except, whenever the shutter speed should begin to slow down with the "slow" light on it seems to go into "B".

In other words the shutter stays open for as long as I keep my finger on the shutter release. It will close if I point the light meter to a brighter light.

The "pad" looks good (solid and tight) and all the meter/shutter functions seem OK(ASA dial/aperature etc).

I wonder if the shock messed something else up?............. or is the pad not working/adjusted?

 

[Iskra 2]

Works OK in "B" mode. "Slow" lite comes on and stays on while shutter is open, shutter closes when released.

Am I correct in assuming the shutter should stay open longer and longer as the subject lighting is decreased, to at least 20 seconds?

 

[Kin Lau]

Indoors (typical office, not near a window), f8 iso100 should give you a 1 sec shutter speed.

 

[Iskra 2]

Has to be something in the shutter circuit, as I look more closely at the shutter during normal lighting, it looks as if it is staying close to 1/500. I wonder what's going on inside this evidentally brain damaged GT?

 

[davidbivins]

I don't know if this helps, but I've found that my GSN shutters go far beyond 30 seconds in low light. It might be that it wasn't done. On all those that I've used for long exposures, I've heard an escalating whine near the end of the exposure, before the shutter closes. You might just not be waiting long enough.

 

[Iskra 2]

They looked clean, so I cleaned them again. Still goes into "B" mode. Looking at the electro magnets, they never move, like maybe they aren't getting any voltage?

Don't have a schematic, but shouldn't there be some volts running around on the shutter leads coming from the body?

 

[Iskra 2]

I'm sure the resistor values are getting back to the circuit in the body because the "slow" and "over" lights are switching based on changing the aperture settings in the lens. There is no significant voltage to the shutter, only a few millivolts.

I need the schematic.

 

[Iskra 2]

Thanks greyhoundman!

I wasn't expecting brain surgery to get this GT running. :bang:

 

[jon_flanders]

One other question, possibly irrelevant if your shutter is bad. Did you check to see if the linkage from your asa dial to the opening for the meter was working?

 

[Iskra 2]

One other question, possibly irrelevant if your shutter is bad. Did you check to see if the linkage from your asa dial to the opening for the meter was working?

What an amazing linkage! Amazing piece of machinery!

Before I took the top cover off I was sure the meter opening was loose or something like that.

I'm hoping there is a loose connection to the brain (circuit board). If it's the brain this one becomes a parts donor for the other one I have. :bang:

 

[nervousfede]

Hello,

I'm having the same problem with my 35 GS!
May be a typical "bug" of electro 35 series.

P.S. sorry for my English!

Thaks

Federico

 

[john neal]

Works OK in "B" mode. "Slow" lite comes on and stays on while shutter is open, shutter closes when released.

Am I correct in assuming the shutter should stay open longer and longer as the subject lighting is decreased, to at least 20 seconds?

Make sure your pad is in good condition and 2mm thick. The yellow light should go out BEFORE the shutter opens if everything is working correctly, regardless of mode. I would suggest you also check that the sliding contacts are clean, making correct contact with the tracks and moving correctly. I had one on a GTN that looked OK but was not actually making contact.

Second, ensure that the small switch above the pad is opening correctly as the shaft moves down - if this does not open the control circuit will not charge.

If these do not sort the problem, try substituting the timing capacitor with a new tantalum bead type of about 2.2uF.

As to your second point, yes, the shutter should stay open longer in lower light - roughly doubling as aperture is moved to next smaller size (f11 to f16, etc). Incidentally, does your problem happen at all apertures, or only f16? I have seen this on a GT and GSN, but do not have a reliable fix - it was not the aperture resistor.

Let us know how you get on.

 

[Iskra 2]

Make sure your pad is in good condition and 2mm thick. The yellow light should go out BEFORE the shutter opens if everything is working correctly, regardless of mode. I would suggest you also check that the sliding contacts are clean, making correct contact with the tracks and moving correctly. I had one on a GTN that looked OK but was not actually making contact.

Second, ensure that the small switch above the pad is opening correctly as the shaft moves down - if this does not open the control circuit will not charge.

If these do not sort the problem, try substituting the timing capacitor with a new tantalum bead type of about 2.2uF.

As to your second point, yes, the shutter should stay open longer in lower light - roughly doubling as aperture is moved to next smaller size (f11 to f16, etc). Incidentally, does your problem happen at all apertures, or only f16? I have seen this on a GT and GSN, but do not have a reliable fix - it was not the aperture resistor.


Let us know how you get on.

Thanks for the info on the yellow light, lens sliding contacts and pad. Something that is not obvious is amiss with GT#1. Now I'm going to put it aside for later surgery and work on GT #2. :bang:

Thanks everyone for the help, I'll let you know what happens to GT #1. 🙂

 

[nervousfede]

Hi,
in my GS with the same problem I checked contacts on lens rings and CDS
resistance and all is OK.

I tried to measure the voltage on capacitor pins (with a digital multimeter)
and it is always zero.

I suppose the problem could be in the release switch. Where are the contacts?
I can't find them by myself.

Thaks

Federico

 

[john neal]

Federico,

Have a look at this page on the Yashica-Guy site:

http://www.yashica-guy.com/document/repair.html#nine

If you follow the release shaft up from the pad you will see a black lump with a white wire soldered to the right hand side. This is the contact base and the contacts are to the left in the picture with an orange wire soldered to the upper contact. These should be shaped in a gentle curve and open as the shaft is pushed down by the release button.

Check that they are clean and that they open, also that one of he wires has not become detached.

Incidentally, did you check the CDs resistance in or out of circuit? Also, I'm not convinced that you would be able to measure a voltage across the capacitor even if it is charged due to other elements in the circuit (bicbw).

 

[nervousfede]

Pad?

Pad?

I've already checked the contacts.
Surfing on the net I read this is a common problem.
I'm thinking about the pad because is one of the parts
wich suffer life time. I will check the pad and let you know.

Suggestion about pad replacing rubber?

Thanks

Federico

 

[john neal]

I guess you should always check the pad first.

I use rubber hose connection washers 2mm thick - I have also used the orange rubber washer off a Grolsch bottle. You should get 5 or 6 pads from one washer.

 

[nervousfede]

pad!

pad!

Hi,
I checked the pad and it is very corroded!
I'll try to replace it.
I don't want to dismantle all the camera. I will
try only removing the top. Anyone have tried?

Thanks

Fede

 

[nervousfede]

Pad!

Pad!

Hi,
I'ts the pad!
I tried inserting a thik (tape)
Now I'll install the new rubber.

Thanks to everyone.

Federico