The Journey Begins

smoke665

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So after the initial inspection, watching a ton of video, and gathering tools I'm close to starting resurrecting the Yashica Mat LM. Still have a couple things coming tomorrow that I'll need. As I proceed, I thought it would maybe interesting to others to document as I go.
tools.webp



Day 1 - Removed the top/focus screen. there are 4 tiny screws on the outside rim that hold the top in place. The slot is pretty small, but they weren't difficult. Inside showing the mirror has an accumulation of dust but the interior isn't bad. At the top/right of the mirror is a little black spring clip you have to push down slightly to pull the mirror back and up (be careful it's easy to deform this spring clip or scratch the back of the mirror as you remove it). The mirror is smaller at the bottom than it is at the top so it will lift out once you slide it back a touch. The mirror was of course dusty but not overly bad. It cleaned up nice, I blew out and cleaned the interior, including the focus lens inside (left).

20240320_183217_resized.webp


The focus screen was my first BIG mistake. If you look at the photo, it's held in by two spring clips (one top/one bottom) which slide under a small folded over metal tab. The metal tab on the bottom was only holding on by a thread. When I pushed down on the spring clip, the tab gave way completely. So now there's nothing to secure the spring hold down. %^&$%^& . The focus screen is actually two pieces, a top glass with grid lines and Fresnel plate. You have to be gentle with both, but they cleaned up fairly easy. The tab is an issue???? I'm going back to town today to get some Metal Epoxy to try and bond the tab back in place. I don't think I can solder it and hold. If the epoxy fails, if there is enough clearance outside I'll drill a small hole and insert a screw to catch the clip.
20240320_183203.webp
 
Ok, just pulled my for-parts EM out of the shoebox.

The grid ground screen goes in first with the ground side down (to the mirror).
Then the fresnal the smooth side down to the mirror.
 
Ok, just pulled my for-parts EM out of the shoebox.

The grid ground screen goes in first with the ground side down (to the mirror).
Then the fresnal the smooth side down to the mirror.
Is the ground side the one "with the grid lines", or the opposite side. I have the side with the grid down toward mirror

I'm pretty sure the freznel has the grooves down toward the mirror, so you're saying I've got it upside down?
 
Yes, the grid screen is ground on the bottom ... OK, yes down towards the mirror.
On mine the freznel side goes towards the ground screen ... shiny side towards mirror.
 
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Well update on the journey......there's been no progress on the camera. I decided that rather than proceeding blindly, I needed to do a little study on the process. I've watched a lot of videos, and stumbled across this site Learn Camera Repair: Home which has a wealth of documentation and information. Hopefully I'll be able to proceed again shortly.
 
@smoke665, that site is great for links, docs, and also the free Nat Cam tech course material ... if you join the Facebook Group you will find many people who can provide advice ... including Bob Sara, he is a trained Yashica TLR tech and has no problem helping people fix their MATS.
 
Latest update on the journey, I was able to resolve the issue with the tabs holding the focus screen. Got everything cleaned up, but it doesn't seem to be focusing on anything but at infinity?
 
Before I started on the focus issue I decided to tackle the shutter problem (since I had to open up the camera). The Yashica Mat shutter and aperture sits in a separate block that comes off the camera with 4 screws. The front cover comes off with 5 screws. The shutter assembly is held in by a threaded tube on the taking lens, that is unscrewed from the back. I didn't have one of those fancy little barrel wrenches, but I did have a small strap wrench that worked just fine. Once I got everything apart and could see what was happening, I didn't need to go further. The shutter was fine, but the wonky little arm mechanism was just slightly bent. A little adjustment with a pair of needle nose pliers, and the shutter is working fine. Everything back together and on to the focus issue, which I hope is just as easy to fix.
 
Did you figure out the focus??

Sadly no. I completed cleaning and adjusting shutter, it's working good. Removed both taking lens and focus lens for good cleaning. When you remove the outer ring on the focus lens it just drops out. While out I did a close inspection of the outer tube and the inner lens. I can't see any way to adjust this lens. The documents I have (different model) says there's a set screw that you back off and screw the tube in/out, but there's no set screw, and doesn't appear the lens housing tube is meant to move. I'm wondering now if you have to shim the focus screen to adjust focus.

Before I adjust anything though I need to fabricate a screen to check infinity focus on the taking lens. There's also the possibility that the focus knob is off as the infinity marks don't line up when they should.

The biggest issue has been time, I've had to much other stuff going on.
 
Hmm, as I have finished restoring my Minolta's I've got no cameras to fix ... I can pull out the EM that I have and check out the focus adjustment this weekend. The Focus knob is just fixed on by a nut ... I think.
 

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