Pentax ZX-5n Flash Capacitor Unit

Written By: Sam Gustafson

Comments: 4

Difficulty

Moderate

Steps

Time Required

3 minutes

Introduction

How to remove the two flash capacitors and the PCB they are attached to. A donor part from another camera will be needed.

Tools

Step 1

Push down on the screw to depress the spring loaded hinge and release the door.

Step 2

Remove six 5.3 mm #00 screws.
Remove one 3.4 mm #00 screw.
The short screw has a machine thread and screws into the plate underneath. The rest screw into the plastic body.

Step 3

Remove three 5.3 mm #00 screws (the bottom-most screw is not always present).
Remove one 7.3 mm #00 screw.
Remove the remote trigger cover.

Step 4

Remove one 3.4 mm #00 screw.
Remove two 5.3 mm #00 screw.
Gently lift up on the flash housing to help remove the cover if necessary.

Step 6

Slide the eye cup up and off to access the screws underneath.

Step 7

Remove two 5.3 mm #00 screws by the eyepiece.
Remove one 6.8 mm #00 screw in the battery compartment.
Remove one 7.0 mm #00 screw near the take up spool.

Step 8

Lift the cover so it is just free of the body. It is still attached by several wires.

Step 9

Use a 1kΩ-10kΩ resistor to discharge the capacitor. Place the resistor between the blue wire, exposed in the previous step, and ground.
The flash capacitors store energy at a very high voltage. Failing to discharge the capacitors properly could result in personal injury and/or damage to the camera.

My camera doesn't have the same yellow connection point (is it apart of the camera or your own). I was wondering if there was any other way to discharge the flash capacitors? And how do I know when I've completed the step, any sound cue? Thanks in advance.

tarek tarek -

The yellow piece you see in the picture is a resistor covered in heat shrink tubing. When you discharge the capacitors, you are making a connection between the high voltage pin and ground, which allow the energy to flow out. The resistor is there to slow the current and have a safer discharge. If you don't have a resistor in the range listed, picking something higher will still allow a safe discharge but it will take longer. With a 10 kOhm resistor, it usually takes about 10 seconds to fully discharge. I check the voltage with a meter to make sure it's at a safe level. There isn't really an audible or visual cue to know whether it has discharged.

Sam Gustafson -

Step 10

De-solder the green, blue, brown and black wires from the flash PCB.

When soldering the connections, what temperature would you recommend?

tarek tarek -

I'm not sure what the optimal temperature is. My soldering iron is set at 380 C but that might be a little on the high side.

Sam Gustafson -

Step 11

Move the top cover to the side to access the battery connections. It is still connected by a flex cable.
De-solder the indicated joints. Use a solder sucker on the tabbed connections.
Pull the black wire from the battery flex to get more slack in the connection to the top cover.
Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

Step 12

Desolder the flex cable connecting the top plate to the camera body.
Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.
The top cover can be completely removed at this point.

Step 13

Use a solder sucker to de-solder the four posts from the flex circuit.
This is the most difficult part of the repair. Patience and persistence are required.
Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

Step 14

De-solder the marked connections.
Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

Step 15

Remove one 4.3 mm #00 screw.

Step 16

Gently pry up the plastic carrier under the flex circuit. It may catch slightly on the battery contact tab.
Pay close attention to the connections around the four through-hole posts as you lift the flex. Make sure that no solder is left over and that it pulls away freely.
This metal tab is lightly held in place with lacquer and can easily come loose. Keep an eye on it.

Step 17

Remove one 3.3mm #00 screw.
Remove one 3.9 #00 screw.
De-solder the red wire.
Peel off the black tape. Leave it attached to the wires.

Step 18

Gently peel the flex circuit from the surface of the capacitor.
There may be additional adhesive underneath the larger capacitor.
Lift the two capacitors and the flash PCB out as a single unit.
The double sided tape used to secure the capacitors can be softened with isopropyl alcohol if necessary.

Conclusion

To reassemble your device, follow these instructions in reverse order.

Author

Sam Gustafson

Member since: 02/09/22

3233 Reputation