Trying to identify components in Yashica 35CC board

[extraniamiento]

Hi,
I'm trying to repair my Yashica 35CC which mostly fires at maximum shutter speed or at most shoots at slower speeds but erratically. The exposure arrows light up OK so it would seem it is only the part of the circuit driving the magnet which keeps the shutter open. I'm suspecting either a transistor or the timing capacitor. However, since this camera is different from the other yashicas (for which a repair manual exists) and there's very little information about its innards on the internet, I was wondering if someone can visually identify some components on the board (mostly the timing capacitor). I'm suspecting it is the green component (the little ball on the right could be a diode?). Not sure about the canister on the left. The three black ones are clearly the transistors and the other two 100nF ceramic capacitors.

Thanks!

 

[rfaspen]

The grey cylinder at left is a 1.5-ohm resistor. The green component appears to be a tantalum capacitor.

 

[rfaspen]

Cylinder on the underside could be either cap or resistor. My guess is capacitor considering the way it's connected with the pot on the board. The color code can be found on the net.

BTW, tantalum capacitors are known to "expire" much like electrolytic caps.
Test the green cap for short, then test it for a reasonable value. Might have to lift it first.

 

[JeffS7444]

Green device: Without being able to see it's markings, I'd guess it was a capacitor.

Don't assume the CdS photocell is okay either: With no light striking it, it's resistance likely should be measured in megohms. I've seen them fail such that max resistance was only 10K ohms or so, and meter reading was consistently high as a result.

 

[julio1fer]

Most likely failure point should be the moving contact in the potentiometer. Especially if the circuit behaves erratically. Hope you cleaned it before looking for anything else,

 

[extraniamiento]

Hi, I desoldered the green component (which is unmarked) and I'm not sure if it isn't actually a capacitor or if it is faulty. My multimeter can't get a capacitance reading (it keeps switching between uF and nF scales and never shows a value). I can set it to "diode" mode and see about 2.24v reading measured in both directions. As for resistance I get a value around 3.5k (mostly stable). Any ideas what could this mean?

The CdS cell is not faulty since as I mentioned the arrows indicating exposure behave as expected.

 

[extraniamiento]

Well, after some frustration I eventually decided to simply open up everything and desolder the board and follow where each cable is coming from. After some more inspection I directly tried to operate the electromagnet from an external power source to see if it was indeed capable of holding the shutter open. With 6V it wasn't possible so I measured resistance of the coil and got 125ohms. I started slowly raising the voltage until I got to around 7.5v and then the strength of the electromagnet was good enough to hold the shutter open. This equates to around 60mA.

Do you think it is possible for the coil to have increased resistance due to age? If it were actually 100ohm it would work at 6V as expected. I tried resoldering the leads but the resistance is still 125ohm. Any ideas? I suspect that if I fix this everything else will work.

 

[monopix]

The most common reason I see for erratic exposures in electronically controlled shutters is contamination of the electromagnet. Make sure the faces of the magnet and the armature are clean. It can make a huge difference.

 

[extraniamiento]

The most common reason I see for erratic exposures in electronically controlled shutters is contamination of the electromagnet. Make sure the faces of the magnet and the armature are clean. It can make a huge difference.

Thanks, I actually found something about this on some other forum and tried to use isopropyl alcohol on the magnet face and the shutter arm but it didn't make a difference. They also look clean and shiny.