Nikon Speedlight SB-E for the Nikon EM: Disassembling, assessment condition, decision service

[Andreas Thaler]

As the third and final sub-project in my Nikon EM series, I will try to get a small SB-E system flash for the EM up and running again.

In the battery compartment, there is severe corrosion of the contact springs due to leaked battery electrolyte.

This is probably the most common error with flash units that have been put away without removing the batteries first.

I cannot clean the contact springs thoroughly from the outside, and I also suspect that the electrolyte has spread to the circuit board. So I have to open the flash.

This time I have the service manual to hand and will hopefully manage opening without damage, unlike an earlier attempt:

Nikon Speedlight SB-E: Dissection

I was actually looking forward to the restoration of this little flash to the Nikon EM. Damage to battery acid in the battery compartment gave rise to hope for a major cleaning operation behind the battery contacts, with patching and soldering work on the circuit board. Externally in mint...

www.photrio.com

Because of the long period of time without batteries, the flash capacitor will no longer have a dangerous voltage.

Nevertheless, I will treat the device as if it had just been fully charged, so with the utmost caution.

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A word of caution

What we as DIY repairers WITHOUT electronics training should definitely not do is work on devices with high voltage.

This includes all electronic flash units like this SB-E Speedlight, cameras with built-in electronic flash units and devices that are powered by mains voltage.

This poses a potential risk to health and life.

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Whether I clean the contact springs or replace them remains to be seen. I still have the parts from my previous section of an SB-E.

We‘ll start soon!

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See also

Nikon EM: Check and clean, issue with automatic shutdown of the exposure meter

The Nikon EM with its exclusive winder MD-E and the flash unit SB-E will be my next main project this year. With a focus on technical exploration, service and repair. Nikon EM: carefree photography The EM from 1979 was Nikon's attempt to make SLR photography accessible to customers with less...

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Nikon winder MD-E for the Nikon EM: Troubleshooting

After taking care of my well-used and dirty Nikon EM https://www.photrio.com/forum/threads/nikon-em-check-and-clean.208703/ today I'm taking a look at the corresponding winder MD-E. In a quick first test at the EM the winder doesn't work. So let's take a closer look at it. The...

www.photrio.com

 

[Andreas Thaler]

Opening the SB-E and looking inside it is also interesting because it has obviously been tampered with, as the pry marks on the casing show.

This means I will handle the flash even more carefully, as the previous intervention will no longer guarantee its operational safety.

I will proceed as follows:

1. open the housing as per the service manual,
2. checking the flash capacitor for possible residual voltage,
3. check and clean/replace the contact springs,
4. reassemble,
5. and only then will I insert the batteries, try to load the flash capacitor and test the function. (But that depends on what the inside of the circuit board looks like and whether there are any attempts visible to repair it. In this case, the flash goes straight into the spare parts box and is not charged.)

The plastic housing insulates and therefore protects me from possible electric shocks.

This does not apply to the contacts in the flash shoe, which I will check for any voltage.

When the flash is charging, I have to test it on my Nikon EM.

There is a certain risk to the camera's electronics if the flash no longer works as Nikon intended due to the presumed botched job beforehand.

So it's an interesting project that requires some thought.

 

[Andreas Thaler]

Disassembling, check for voltage

I managed to open the case this way. However, this SB-E is no longer in its original condition and some of the plastic clips used to lock the case were broken off.

Main switch with corroded contacts.

Broken plastic clip and lever marks.

Battery chamber cover with corroded and filed contacts.

The flash capacitor (black) with red and black cables. When charged, high voltage is present at the two cable connections (but be careful, not only there).

Therefore, I measure the voltage here ...

… which is 0 volts as expected.

After such a long time, the capacitor has completely discharged.

Two screws, one missing.

These contact springs located in the battery chamber are severely corroded.

In this condition, they can already break because the leaked battery electrolyte attacks metal.

In order to remove the main board, the three contacts must be pressed in. They are held in place by springs.

The main board is partially detached.

 

[Andreas Thaler]

This cover plate above the smaller circuit board is attached with three screws. One of them is located under a rubber pad.

The cover plate is removed.

The flash capacitor is glued to its holder.

The electronics are detached from the front housing part.

Three trim potentiometers, accessible from the outside via the nameplate.

The component side of the smaller board with an IC.

The flash capacitor.

The component side of the main board.

The contact springs in the battery compartment are now accessible for cleaning. To do this, they can be desoldered from the main board.

The neon lamp for the flash ready indicator.

The photodiode to control the flash power.

Power transistor and electrolytic capacitor.

Coil

 

[Andreas Thaler]

Mitsubishi high speed switching thyristor CR3AMZ

Yellow: one of two transformers.

According to the service manual, the gray component should be a 2.2 uF capacitor.

In the middle the second transformer.

Rotten foam

Layout and circuit diagram.

In the service manual there are two construction versions.

Assessment of the condition, decision service​

• I will not attempt to service and put this SB-E into operation because the device has obviously already been worked on unprofessionally (leverage marks on the housing, broken plastic clips, missing screw).
• Even if I can clean the contacts, I have no confidence that the circuit will work properly.
• And I don't want to tinker around with it, as the flash is powered by high voltage.
• Last but not least, there is also the possibility that the flash could damage the circuit of my Nikon EM due to a malfunction.
• That's why the remains of this SB-E are going into the spare parts box.

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All information provided without guarantee and use at your own risk.