Yashica Electro GTN -- Intermittent Shutter

[monopix]

Having a bit more time, I thought I'd respond to your thoughts...

Here's what I've figured out from reading the diagram:

1. If the Capacitor Shorting Switch S3 never closes, then the capacitor is always charged and the circuit never holds the blades open. Everything would look fine in the "red" and "yellow" positions of the shutter release switch. Check voltage across the cap.

Possible but the capacitor would self discharge so you might expect the shutter to fire correctly (more or less) once if the camera was left for some time. More likely is the capacitor is u/s so there is no time constant and the shutter closes immediately.

2. If the electromagnet is dead or the circuit to it is open, then it never holds the blades open. Check continuity from T4 thru Electromagnet and on to the + side of battery.

Yes. Might also be a mechanical problem or a contaminated magnet face maybe.

3. If TR4 is working well enough to light the yellow ("under") lamp, but not to provide the current for the electromagnet. How to check?

I think you can assume if the TR operates the lamp then it'll do the same for the magnet. The lamps take around 60mA, if I remember correctly, and I wouldn't have thought the magnet would take any more.


As I said before, the switches have to be a starting point. The switch which selects the capacitor would be the first thing I'd check.

 

[ColSebastianMoran]

Monopix, thanks again. Yes, I see that... If the capacitor is open-circuit or the switch S4 doesn't put the capacitor in the circuit, then as the shutter opens there is immediately a voltage on TR1 and therefore the shutter will go at 1/500th instead of staying open. That suggests looking closely at C1 and the last position on switch S4, in the lower left corner in the diagram above.

Many thanks. It will be a while before I can dig into this, but I'll post the result.

 

[farlymac]

No knocks on Russ, I've heard nothing but good things about his refurbs. And he is being honest with you about what he can and cannot do when it comes to repairs. There are many things I still am learning about the Yashicas, and it would take a few years of experience working on them to be able to pinpoint a problem such as yours.

My problem is I like too many cameras, so I have plenty to repair, as they don't always come as advertised. So instead of concentrating on one brand, I have to learn many variations of mechanisms to be able to keep my gear running. I'm hoping that you can find the right fix for your camera, so that the rest of us can share in your future happiness.

PF

 

[b1bmsgt]

Thanks for all the kudos, guys. I really appreciate it. 😀

I'm sure that the camera can indeed be fixed, but it was beyond the point that I am able to go, as I told Richard. I basically offer a service that covers probably 90 percent of the cameras that I receive, which is the repair of simple problems such as dirty contacts, corroded battery wires, etc. that the average camera owner either can't do or doesn't want to do themselves, plus a complete cleanup of the camera to the point that a lot of people tell me that the camera looks like new. The Electro's are such a very robust design that it is actually pretty rare for me to have to send one back unfixed.

I'll be watching this thread closely to see what the problem turns out to be. It might help me out as well!

Sincerely,

Russ

 

[jrbrubaker]

I can confirm that adjustments to the well-named adjustment rod can fix this issue. There's a sweet spot that may take a couple tries to find, but it has ended my frustrations with random intermittent exposures.

I found it. In the Repair Forum.

Update: I just did a POD on a 2nd electro, had the same problem (lag/miss). I think this is probably related to the new pad being slightly too thick. There's a related thread on flickr about this. Here's how I solved it, on one of the electros (haven't tested other one yet):

1. Remove bottom cover
2. On the left side, there are 2 brass adjustment screws, one larger and one smaller. The smaller one is to the left of the larger one and further in. Turn this counterclockwise. I believe this adjusts the shutter button stroke somehow and compensates for a slightly thicker pad.

**Update** This has solved the above problem on both cameras. Note, if you turn the rod too far in the opposite direction, it can also cause problems.

Try that, and see if it clears things up.

PF

 

[monopix]

I recently wrote up my method of adjusting the rods. You can find it at http://www.monopix.co.uk/yashicarods.shtml

 

[dogbunny]

Thanks for your post monopix, it gave me hope. I can hear the three clicks and they are off, but I can't see what part is the latch? I see the wheel turning to the left, but the clicks don't seem to coincide. Hmm I need to look more.

 

[monopix]

The latch is the part that engages with the end of the larger (right hand) rod when it is fully pressed. Maybe yours isn't engaging? Try turning the right hand rod counter-clockwise until the latch just drops in behind the end of the rod when it is pressed. Sorry I'm not in a position to post a picture but I'll add something to my Web site when I can to show the latch.

 

[monopix]

I've added a video to my page. http://www.monopix.co.uk/yashicarods.shtml

 

[jasperquaint]

So, I had the exact same problem, and decided to find the cause last night. The metering worked every now and then, the flash sync setting fired at 1/500 and in bulb the shutter didn't close until I started to wind.

The culprit in my case were some dirty contacts. You know when you open up the lens, there's this small circuit board protected with a plastic sheet, with loads of resistors on it? Yeah, underneath that one was some really dirty contacts. Once those were clean again (some rubbing with the eraser tip of a pencil), the metering worked. The flash sync setting and the bulb then returned to normal once I adjusted the shutter (thanks monopix for the wonderful instructions).

 

[ColSebastianMoran]

jasperquaint, when it was mal-functioning, did the yellow and red light work to indicate over- and under-exposure?

 

[ColSebastianMoran]

After reading all the comments, I adopted a strategy of leaving the broken Yashica GTN on the shelf to see if it got better. It did not.

The camera is now off to Mark Hama who recently transformed a Pakistan-sourced GX into a perfect operating machine for me with very reasonable turn-around.

 

[ColSebastianMoran]

This is way old, but here's the conclusion of the story.

I sent the camera to Mark Hama who did his usual magic and I now have a perfect GTN. Mark has the advantage of having parts, and I'm sure he knows just which part to replace for this pattern of symptoms.

Earlier, working from the circuit diagram, I had hoped to find a loose connection, or a bad capacitor, or whatever that I could fix myself. Maybe this could ultimately have been a possibility, but it would not have been easy.