Minolta XG-A - Prism Replacement?

William_Donald · Feb 1, 2025

Hello all.
So I just got this XG-A. I'm going through the cleaning process. I just replaced light seals and cleaned the view finder and mirrors. I'm totally new so I couldn't/ wouldn't know what each mirror / part is called.
Anyway, I cleaned what I could see but there's absolutely no difference in the dirt you see. It looks like a strip of tape or something was across somewhat of it. How would I clean this? What do I do? I used glasses cleaner but like I said, there's zero difference. What do I do from here?
I've been told I need to replace the prism. Is that correct?

If it is correct, I've searched Googles but there's different part numbers etc. I'm sure it's like old car parts, some are specific, some interchangeable.
Do all X models use the same prism? Only one model?
Do I have to get an XG-A for a parts camera?
Is it even called a prism? What's the proper part name?

Are there manuals on how to replace this? I have yet to find anything.
Other forums provid me with the useless "it's easy" then someone else says "it's complicated " but absolutely no one has answered me on how to repair it.
I cannot find a service manual anywhere.
Any help would be greatly appreciated.
(I'm trying to upload a picture but I keep getting an "oops! We ran into an error!" Message. I'll try to upload as a follow-up comment.

William_Donald · Feb 1, 2025

Images of the prism

xkaes · Feb 1, 2025

Welcome to the FORUM.

You'll find a lot of tape around the prisms in Minolta cameras, so that's nothing unusual.

One thing to keep in mind is wherever this dirt is, it won't affect the pictures. And the dirt could be anywhere. Replacing the prism should be the last thing to do. Even if you could find a replacement prism it's probably going to cost more that a replacement XG-A.

(1981) In 1978, Minolta had introduced XG-1, a streamlined XG camera for photographers with limited funds. Then, in 1980, they introduced the X-7, a streamlined XG camera for photographers with simpler photographic needs. By 1981, Minolta realized that they could merge the two camera together -- and produced the XG-A. The XG-A is essentially the same camera as the XG-1, but without the manual exposure control. Or it is essentially the same camera as the X-7, but with fewer feratures. Take your pick. The body styling and shutter speed dial are the same as that of the X-7-- it is simplified and lacks the normal manual speeds. The dial retains the X and B settings, so that electronic flash can be used with non-X units (the camera automatically sets the shutter speed to X with X-style flash units), and time exposures can be taken. The camera allows adjustment of the exposure through the normal +/- 2 EV exposure compensation dial.

xkaes · Feb 1, 2025

It looks like the dirt might be on the focusing screen. If you have the tools & time & talent you might be able to fix it, but there are lots of better XG cameras that you can get for close to the price of shipping. Here's a comparison table. The GREAT XG-9 can be found for $20 and has many more features.

http://www.subclub.org/minman/slrtable.php

William_Donald · Feb 1, 2025

xkaes said:
Welcome to the FORUM.

You'll find a lot of tape around the prisms in Minolta cameras, so that's nothing unusual.

One thing to keep in mind is wherever this dirt is, it won't affect the pictures. And the dirt could be anywhere. Replacing the prism should be the last thing to do. Even if you could find a replacement prism it's probably going to cost more that a replacement XG-A.

(1981) In 1978, Minolta had introduced XG-1, a streamlined XG camera for photographers with limited funds. Then, in 1980, they introduced the X-7, a streamlined XG camera for photographers with simpler photographic needs. By 1981, Minolta realized that they could merge the two camera together -- and produced the XG-A. The XG-A is essentially the same camera as the XG-1, but without the manual exposure control. Or it is essentially the same camera as the X-7, but with fewer feratures. Take your pick. The body styling and shutter speed dial are the same as that of the X-7-- it is simplified and lacks the normal manual speeds. The dial retains the X and B settings, so that electronic flash can be used with non-X units (the camera automatically sets the shutter speed to X with X-style flash units), and time exposures can be taken. The camera allows adjustment of the exposure through the normal +/- 2 EV exposure compensation dial.

So like I show in the pictures, is that the prism? That I see through the view finder?

xkaes said:
It looks like the dirt might be on the focusing screen. If you have the tools & time & talent you might be able to fix it, but there are lots of better XG cameras that you can get for close to the price of shipping. Here's a comparison table. The GREAT XG-9 can be found for $20 and has many more features.

http://www.subclub.org/minman/slrtable.php

So like I have in the pictures, the shot I have looking through the view finder, is that the focusing screen?
Or is that the plastic piece opposite the mirror?

bernard_L · Feb 2, 2025

That focusing screen / Fresnel lens is fragile. I would not use tissue. Only an artist brush and compressed air to try dislodge the debris. If it is removable, only water and dish- washing liquid; no solvent.

Andreas Thaler · Feb 2, 2025

I have this problem with a Minolta X-7.

Apparently the coating on the outside of the prism has come off due to a rotting adhesive strip.

Perhaps the reflective coating can be repaired with silver paint.

Otherwise, it is possible to install a replacement from another X-7. However, this might also have the problem.

Minolta X-7: Artefacts on the prism; view under the top cover

This beautiful Minolta X-7 has been sitting in my box of new acquisitions that I still have to check out for some time. Today I took a look at it. When I look into the viewfinder I see this interesting artifact. It looks like the remains of rotten foam and is reflected above the focusing...

www.photrio.com

Andreas Thaler · Feb 2, 2025

Here is the service manual for the XG-A:

https://www.minolta.suaudeau.eu/reparation/manuels/XG1%20XG1n%20XG-AService%20Manual.pdf

(From page 52 in the PDF.)

Andreas Thaler · Feb 2, 2025

The path to the prism (maybe also the mirror box has to be removed, see service manual):

A lot of work that requires experience, soldering skills and the right tools.

I don't think the camera needs to be readjusted after a replacement.

I have decided not to do anything about my X-7. But I will keep an eye on the problem to see if it progresses.

This should not affect the image result, even if the camera measures the exposure using measuring cells on the prism. The deviation should be too small for that.

More precise information would have to be obtained by measuring the exposure system or taking test shots.

With such extensive disassembling work there is always the risk of damaging something, so I would only replace the prism if the viewfinder image is severely affected.

With my X-7 the damage is almost unnoticeable when I hold the camera to my eye.

Andreas Thaler · Feb 2, 2025

William_Donald said:
So like I show in the pictures, is that the prism? That I see through the view finder?

So like I have in the pictures, the shot I have looking through the view finder, is that the focusing screen?
Or is that the plastic piece opposite the mirror?

Your first two pictures should show the part of the prism that is probably damaged. On the other pictures you see the focusing screen from below.

If you hold the XG-A to your eye, you will see the focusing screen from above. If no artefacts are visible here, the focusing screen is OK.

Andreas Thaler · Feb 2, 2025

William_Donald said:
Do I have to get an XG-A for a parts camera?
Is it even called a prism? What's the proper part name?

Individual parts are occasionally offered for sale on eBay, for example. They either come from dismantled cameras of the same type or, very rarely, from new stock, for example when a repair shop clears out its spare parts warehouse.

The best thing to do is to get a defective camera of the same type for spare parts. There are already parts for future repair projects.

„Prism“ is the correct term.

However, the problem may also exist here, so you should inquire beforehand.

William_Donald said:
Other forums provid me with the useless "it's easy" then someone else says "it's complicated " but absolutely no one has answered me on how to repair it.

It is neither easy nor impossible, but it is a lot of work, see above. Definitely not a project for beginners

But you could practice on another, similar and defective Minolta, then you will get an impression of how it works.

Andreas Thaler · Feb 2, 2025

Some impressions of my Minolta X-7 project, showing the removal of the top cover, the circuit board underneath and some of the tools used (see link above).

There is still a long way to go to the prism underneath.

Andreas Thaler · Feb 2, 2025

Maybe helpful if you should be new to repairing cameras:

Photo equipment: Basics for getting started with DIY repairs

As others I enjoy to report on my repair efforts here, but maybe someone would like to get into the topic? The desire is there, but there is still a lack of information on how best to start, what tools are needed and how much it might cost? That can be easily clarified. But it is even more...

www.photrio.com

William_Donald · Feb 2, 2025

Andreas Thaler said:
Individual parts are occasionally offered for sale on eBay, for example. They either come from dismantled cameras of the same type or, very rarely, from new stock, for example when a repair shop clears out its spare parts warehouse.

The best thing to do is to get a defective camera of the same type for spare parts. There are already parts for future repair projects.

„Prism“ is the correct term.

However, the problem may also exist here, so you should inquire beforehand.

It is neither easy nor impossible, but it is a lot of work, see above. Definitely not a project for beginners

But you could practice on another, similar and defective Minolta, then you will get an impression of how it works.

Wow, this is the answer(s) I've been hoping for. Detailed! Thank you so much!
I'm good with mechanical but I've never taken a camera apart like this.
I have to think on attempting this.
I wanted to try film photography. My mom loved it, my sister made it a career, I've been interested but never did much more than buy film and do the standard point and shoot.
I am, however, old enough (born in the 70s) to have grown up using film.

The XG-A I got on Ebay was really good. No nicks, scratches, abrasions. I got the original receipts, flashes, leather camera case, lenses, it seems such a shame to scrap it and start over.
I even went and bought old Minolta camera & photography books!

Too bad it could just be batteries. Haha!

Thank you so much for the detailed explanation!

Andreas Thaler · Feb 2, 2025

William_Donald said:
Wow, this is the answer(s) I've been hoping for. Detailed! Thank you so much!
I'm good with mechanical but I've never taken a camera apart like this.
I have to think on attempting this.
I wanted to try film photography. My mom loved it, my sister made it a career, I've been interested but never did much more than buy film and do the standard point and shoot.
I am, however, old enough (born in the 70s) to have grown up using film.

The XG-A I got on Ebay was really good. No nicks, scratches, abrasions. I got the original receipts, flashes, leather camera case, lenses, it seems such a shame to scrap it and start over.
I even went and bought old Minolta camera & photography books!

Too bad it could just be batteries. Haha!

Thank you so much for the detailed explanation!

With pleasure!

You could get a broken XG-A for little money and practice on it. Maybe you enjoy working with the screwdriver and would like to report here?

Good luck and much success!

Minolta XG-A - Prism Replacement?

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