Electrolytic capacitor replacement on a Minolta X-300s

[Andreas Thaler]

Of the 13 Minolta X cameras that are waiting to be checked here, see

Interested in Minolta X camera repair reports?

I'm currently working on the Minolta X series cameras to improve my repair skills. In particular, I would like to find solutions to the known problems of the Minolta X-700. For example, there does not always have to be a defective capacitor behind the LEDs in the viewfinder, which go out when...

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I was able to get candidate 1/13, a Minolta X-300s back to work

Issues:

- Camera cannot be wound up.

- LEDs in the viewfinder light up when the shutter button is tapped.

- Trigger pressed - LEDs go out, no shutter action


This problem can have various causes.

The easiest to fix is the failure of electrolytic capacitor C7 at the bottom of the camera.

The defective capacitor just needs to be removed and a new one soldered in.

So I'll start here and see how the capacitor is doing

The base plate can be removed after loosening four Phillips screws.

It is important to note that Minolta cameras use Japanese Phillips screws that comply with the Japanese Industrial Standard (JIS). Suitable screwdrivers should be used to avoid damaging the screw heads.

JIS (Japanese Industrial Standard)

JIS (Japanese Industrial Standard). Does your Phillips screwdriver \"cam-out\" and damage screws? If so, it may NOT be a US Phillips® screw - it may be a Read more

www.vesseltools.com

And actually, the electrolytic capacitor has leaked, electrolyte has already worked its way up to the soldering point via a connecting leg and corroded it.

The capacitor must be unsoldered.

The corroded solder joint will probably resist the hot soldering tip because the corroded layer on its surface inhibits heat transfer.

Beforehand, I measure the capacitance and ESR value of the capacitor. Both values provide information about the condition of the capacitor.

The meter indicates an open circuit.

Either the leaked electrolyte prevents contact with the measuring tip or the electrolytic capacitor has a high resistance.

Without contact, the capacity cannot be measured. Or the electrolytic capacitor no longer has any measurable capacity.

However. This electrolytic capacitor is defective and has had its time

I apply so called „solder honey“, a flux, to the corroded solder joint in the hopes that it will help the soldering tip make the solder fluid.

But no success.

Even scraping the surface with a scalpel does not help to transfer heat.

Therefore, I suck off the liquid solder on the right connection with the desoldering pump and cut off the left connection with the side cutters.

Both soldering points are now easily accessible.

With soldering honey and 20 degrees more soldering temperature I get the left soldering point liquid. Now I can remove the remaining part of the connecting leg.

Then I remove the corroded solder with desoldering braid dipped in flux and the desoldering pump.

Likewise the solder of the right soldering point.

I solder in the new electrolytic capacitor, the connecting legs of which I have previously shortened to fit using side cutters.

The cathode (negative terminal) faces out of the camera.

I unsoldered an electrolytic capacitor with 220 uF/4 volts.

Since I couldn't find this electrolytic capacitor (which is also slightly smaller in size) on the market, I solder in one with 220 uF/6.3 volts.

More volts of nominal voltage won't do any harm, less would be a problem.

The flexible circuit board shows that it is flexible But it is a gentle bend that does not kink the traces.

Soldering is not that easy here because the electrolytic capacitor barely fits into its compartment and the circuit board is thin and gives way when pressure is applied.

Main switch to ON, shutter button pressed and the shutter releases.

A check shows that all functions are there again

All information provided without guarantee and use at your own risk. It is possible that Minolta made different versions of the board with different connections.

 

[xkaes]

This is the best explanation & photos I've seen. Just great.

One question though. How do you know which leg on the capacitor is +? On mine there is a blue line on the side. Is that standard?

 

[Andreas Thaler]

This is the best explanation & photos I've seen. Just great.

One question though. How do you know which leg on the capacitor is +? On mine there is a blue line on the side. Is that standard?

Thank you

The polarity of a (new) electrolytic capacitor should be recognizable by the length of its connecting wires and a designation on the housing. In this case, the connecting wire of the positive pole (anode) is longer than that of the negative pole (cathode). The negative pole is also marked here with a light stripe.

The designation can differ; the manufacturer's data sheet or research on the web can help here.

Connecting the electrolytic capacitor with the correct polarity is important for the circuit to work. If connected incorrectly, an electrolytic capacitor can also break and, in the worst case, explode. Therefore, I strongly recommend wearing safety glasses when working with electrolytic capacitors and when soldering. Cameras in particular can surprise you with parts that suddenly pop out, but that shouldn't catch your eye.

Here is the position of electrolytic condensator C7 for the X-300/X-370 in the Minolta service manual, which also shows the correct polarity:

The picture is probably a tantalum capacitor, but the polarity of the connections should be the same as that of an electrolytic capacitor.


All information provided without guarantee and use at your own risk. It is possible that Minolta made different versions of the board with different connections.

 

[Dan Daniel]

Very nice presentation!

Background question for you. I'm not certain how many of these type of cameras you have worked on. It'd be interesting to see if you find that there are 'common designs' that keep pooping up across model lines, and even across manufacturers. Like the mechanical escapement in shutters- once you learn one, a lot of common problems are solvable. Maybe the location has changed or the specific orientation. I assume that electrical circuits will have the kind of recurring problems solved using similar circuits. And you'll probably see the transition to integrated circuits as you go along.

 

[Xylo]

I fixed two of these before. But in my case it was a hook on the film advance side that had slipped to the wrong position.

 

[Mark J]

Good work ! There must be many camera bodies that are disabled by this simple problem of capacitors that have a known lifetime.

 

[xkaes]

I was able to get a rare Sakar SL-90MD (AKA, Seagull DF-2 ETM and Zenit DF-2 ETM) for next to nothing because it was "dead". All it needed was this capacitor replaced.

 

[cmacd123]

on the X-700 there are TWO capacitors, one further up inside the body. I understand that the "lights go out" one on the X700 is the upper one.

 

[Andreas Thaler]

Very nice presentation!

Background question for you. I'm not certain how many of these type of cameras you have worked on. It'd be interesting to see if you find that there are 'common designs' that keep pooping up across model lines, and even across manufacturers. Like the mechanical escapement in shutters- once you learn one, a lot of common problems are solvable. Maybe the location has changed or the specific orientation. I assume that electrical circuits will have the kind of recurring problems solved using similar circuits. And you'll probably see the transition to integrated circuits as you go along.

Thank you

From what I've seen so far, the X cameras (700/500/300) are constructed similarly. This applies to mechanics and electronics.

Starting with the 300 as the basic model, more functions are added (e.g. exposure compensation, extended flash control, automatic program), which are implemented through additional ICs and more cables through the housing

The majority of switching takes place in the ICs, which is essentially only documented by block diagrams (what does which IC do). This means that these parts of the circuit can only be replaced on suspicion or following the available troubleshooting instructions.

What is very interesting is that on the X-700, for example, the manually adjustable times are stored as voltage values in a tantalum capacitor. I assume that this technology and other electronic solutions are implemented similarly in all X-cameras. Not least to save development and manufacturing costs.

 

[Andreas Thaler]

Good work ! There must be many camera bodies that are disabled by this simple problem of capacitors that have a known lifetime.

Thank you

Yes, the problem with defective electrolytic capacitors is typical for Minolta X cameras. But unfortunately a replacement does not solve all problems with the same or similar symptoms. Here I am trying to understand more.

 

[Andreas Thaler]

on the X-700 there are TWO capacitors, one further up inside the body. I understand that the "lights go out" one on the X700 is the upper one.

You're right, the X-700 has two more capacitors on the bottom of the board (C8, C9) that are responsible for controlling the magnets.

I recently replaced C8 on an X-700 that had already developed a leak. The electrolyte that escaped was still liquid. Therefore, I was able to clean the area on the circuit board with isopropyl alcohol and insert a new capacitor. The symptoms were the classic: LEDs on when the shutter button is tapped, pressing the shutter button causes the LEDs to go out, the shutter does not fire. The new capacitor fixed this:

Leaking electronic capacitor

Faulty capacitor removed and area cleaned

Soldering in a replacement

Defective capacitor with leaking electrolyte


I now check the electrolytic capacitors on every Minolta-X I own because they can still work even if electrolyte has already leaked and the area surrounding the circuit board is corroding. This can lead to the conductor tracks decomposing.

The Minolta XG-M seems to be particularly vulnerable here, as it has four electrolytic capacitors built into it.

In two examples, three electrolytic capacitors were already leaking and corrosion was spreading through cables and conductor tracks. The electrolyte is quite aggressive:

 

[maltfalc]

you can't measure the capacitance or esr of a capacitor while it's still connected to the circuit board, and if it's leaking, you need to scrub off the electrolyte with vinegar.

 

[Andreas Thaler]

you can't measure the capacitance or esr of a capacitor while it's still connected to the circuit board, and if it's leaking, you need to scrub off the electrolyte with vinegar.

The Peak ESR can, see

Peak Atlas ESR Gold ESR Plus model ESR70 | Peak Electronic Design Limited

Cleaning off liquid electrolyte with isopropyl alcohol works well for me.

 

[maltfalc]

The Peak ESR can, see

Peak Atlas ESR Gold ESR Plus model ESR70 | Peak Electronic Design Limited

Cleaning off liquid electrolyte with isopropyl alcohol works well for me.

"It can even measure ESR for capacitors that are in-circuit." that's not going to be true in all cases and you still can't measure capacitance. isopropyl alcohol won't neutralize electrolyte or break down residue and corrosion. you need vinegar to prevent your "fixed" camera from continuing to destroy itself.

 

[Andreas Thaler]

"It can even measure ESR for capacitors that are in-circuit." that's not going to be true in all cases and you still can't measure capacitance. isopropyl alcohol won't neutralize electrolyte or break down residue and corrosion. you need vinegar to prevent your "fixed" camera from continuing to destroy itself.

As I said follow the link to the Peak ESR and read what is written there. Believe it or not. Results in circuit are the same as of circuit. What should I tell you more?

The same is true for my „fixed cameras“

 

[mshchem]

You're right, the X-700 has two more capacitors on the bottom of the board (C8, C9) that are responsible for controlling the magnets.

I recently replaced C8 on an X-700 that had already developed a leak. The electrolyte that escaped was still liquid. Therefore, I was able to clean the area on the circuit board with isopropyl alcohol and insert a new capacitor. The symptoms were the classic: LEDs on when the shutter button is tapped, pressing the shutter button causes the LEDs to go out, the shutter does not fire. The new capacitor fixed this:

View attachment 352891

Leaking electronic capacitor


View attachment 352892

Faulty capacitor removed and area cleaned


View attachment 352893

Soldering in a replacement


View attachment 352894

Defective capacitor with leaking electrolyte


I now check the electrolytic capacitors on every Minolta-X I own because they can still work even if electrolyte has already leaked and the area surrounding the circuit board is corroding. This can lead to the conductor tracks decomposing.

The Minolta XG-M seems to be particularly vulnerable here, as it has four electrolytic capacitors built into it.

In two examples, three electrolytic capacitors were already leaking and corrosion was spreading through cables and conductor tracks. The electrolyte is quite aggressive:

View attachment 352895

View attachment 352896

View attachment 352897

View attachment 352898

View attachment 352899

What do you call the blue work mat/ where to buy?? This is fascinating to watch.

 

[Andreas Thaler]

What do you call the blue work mat/ where to buy?? This is fascinating to watch.

This is a silicone soldering mat made in China.

You can find them in different versions on Amazon, e.g

Premium Heat Resistant 932°F Silicone Soldering Mat, Large Anti Static Magnetic Electronic Repair Work Mat for BGA and Gun Soldering Iron, Workbench, Cell Phone Laptop Repair, 17.7'' *11.8 '' https://a.co/d/j4xTS4l

 

[Andreas Thaler]

"It can even measure ESR for capacitors that are in-circuit." that's not going to be true in all cases and you still can't measure capacitance. isopropyl alcohol won't neutralize electrolyte or break down residue and corrosion. you need vinegar to prevent your "fixed" camera from continuing to destroy itself.

And chemistry doesn't always help when it comes to crystallized electrolyte or battery acid. For example, to clean the corroded conductor tracks of the XG-M (see pictures above), I used a Dremel Stylo with a stainless steel brush. To solve corrosion, I use a descaling agent that works effectively and is odorless. But if the conductor tracks are already eaten away, the only solution is to repair them.

 

[cmacd123]

From what I've seen so far, the X cameras (700/500/300) are constructed similarly. This applies to mechanics and electronics.

Starting with the 300 as the basic model, more functions are added (e.g. exposure compensation, extended flash control, automatic program), which are implemented through additional ICs and more cables through the housing

yes the mechanical parts are very similar. depending on the market the model number could be 300 or 370 and also 500 and 570. I don't think any market got a 770. their is also a 370N with more plastic but similar features. Finaly Minolta had Shanghai Seagull build some cameras, and Seagull then was able to build a DF300 (apparently under A License) in both the metal and plastic versions, which they also sold to Private Label customers like CENTRON. the DF300 being more or less a X-370. (handy to know if you want a working spare X-370)

the 700 does have the "program Mode" while the other two are just "automatic" I believe one of the extra Caps is to store the exposure for the program mode to work.
the previous model did have an uncredited version of Program mode where if the controls are all set to green, the camera will ignore the stetting if needed to get a correctly exposed shot. The doenside is the reading is taken directly before the moror is raised, and so their is a bit of a delay between the time you release the Shutter and when the picture is taken.

 

[maltfalc]

As I said follow the link to the Peak ESR and read what is written there. Believe it or not. Results in circuit are the same as of circuit. What should I tell you more?

The same is true for my „fixed cameras“

did you read it? because i just quoted it to you.

 

[Andreas Thaler]

did you read it? because i just quoted it to you.

I did thank you.

 

[Andreas Thaler]

you can't measure the capacitance or esr of a capacitor while it's still connected to the circuit board …

I only now understood your comment.

Correct, the PEAK ESR only measures the ESR value of electrolytic capacitors that are soldered into the circuit, not the capacity. Here is the information from the manufacturer:

Peak Atlas ESR Gold ESR Plus model ESR70 | Peak Electronic Design Limited

Since the ESR value provides information about whether an electrolytic capacitor is still fit, for me this is the more important value for deciding whether the electrolytic capacitor can still remain in the circuit. The capacity value fluctuates anyway due to the high tolerance values.

If there are still problems, the electrolytic capacitor can be unsoldered and its capacity can be measured.

The device is a great help, even though I replace the electrolytic capacitors in the X cameras as a precaution anyway.

 

[koraks]

you can't measure the capacitance or esr of a capacitor while it's still connected to the circuit board

There are some caveats, but it can be done (evidently). Here's an informative video:

 

[Neofito]

excelent post, I think camera repairs have to start working more and more on electronics, is a pitty to lose all those wonderfulls 80s and 90s SLR. And their electronics are not the most advanced thing you can find in consumer electronics, is just that most of camera techinicians doesnt have an electronic background.

 

[Andreas Thaler]

excelent post, I think camera repairs have to start working more and more on electronics, is a pitty to lose all those wonderfulls 80s and 90s SLR. And their electronics are not the most advanced thing you can find in consumer electronics, is just that most of camera techinicians doesnt have an electronic background.

The mechanics of a camera are perhaps less intimidating than its electronics because you can see something of it, even in motion. But understanding the mechanics of a mirror box, for example, becomes confusing.

You should not forget that all mechanical components are the results of complex calculations that also determine their shape and appearance. Nothing there is a coincidence, even though it may seem like it.

Understanding and calculating electronics is not easy. I think the mechanics are even more complicated.