Fixed LED issues
Today's final inspection of the XD revealed that in mode A (aperture priority) when the aperture ring was turned, all the LEDs in the viewfinder glowed dimly and flickered.
In mode S (shutter priority) the LEDs disappeared and the lower red triangle for over-range lighted up. Tiny movements of the aperture ring solved the problems, but not reliably.
Obviously a contact problem above the bayonet ring, where wipers and contact tracks are located.
So I disassembled the bayonett area of the XD to have a look.
First, I checked the conductive and resistance tracks with wipers for entering the smallest aperture on the lens into the camera's exposure metering system.
I cleaned it with electronic cleaner and bent the wipers a little so that they have stable contact.
I also worked the tracks with an eraser, here the tracks for entering the preselected aperture. Some coating came off in the process. But it was the gold plating!
But none of this solved the problem.
So I looked at the wipers on the ring for the aperture transmission.
I can't see anything unusual here, the two contact brushes show no wear and are neatly aligned.
I removed the ring (in the picture on the right) from a second XD-7 that worked and put it into the XD to test it. And now the LEDs light up in the viewfinder as they should.
So it was the ring!
I'll look at what doesn't work here later.
Both brushes are electrically connected to one another. The upper one runs along a resistance path and the lower one transfers the voltage to the camera. The whole thing works according to the principle of a variable resistor.
I gave the XD-7 its ring back with polite thanks
Here are three things to look out for when disassembling/assembling:
There are two tabs at the bottom of the plastic cover of the bayonet. I partially broke off the left one.
The two tabs engage with the front cover. Therefore, the base plate must be removed before dismantling the plastic cover.
The spring for the aperture transmission ring must be on the outside. It takes a bit of practice until it obeys you.
Now I want to look for a replacement for the ring.
This XD-7 had to give it away.
The decision was not difficult for me.
The camera has a dent on the top cover, the inner panel of the mirror box is no longer attractive (
Schneideritis) and it looks very used.
It is also the version with shrinking leather. You can recognize this series by the lever for the exposure compensation wheel. It points towards the front of the camera.
Since I need a spare parts donor for future projects anyway, I removed the ring.
The wipers on the ring look very worn, but the important thing is that the XD is happy.
And it is, all LEDs are behaving normally again and are stable after replacing the ring
Excellent teamwork today!
