Help with Sunpak 522 repair

SOldBear · 05-09-2009, 03:58 PM

I have a Sunpak 522 without sync cord and battery holder. I just bought a complete but non-working 544 for the parts.

Now I'd like to repair the 544.

The problem is that it fires intermitttently. It charges up OK, but takes any where from 2 to 50 (mostly 3) times to push the "test" button to fire it. I use the "test" button to make it simple. The symptom is the same when I connect the flash to a camera's PC terminal with the sync cord.

Is the flash reparable with basic tools and electronic knowledge? I have a non-working Sunpak 522 to act as organ donor if needed.

Any pointer is appreciated. Thanks.

Ratmagiclady · 05-10-2009, 06:56 PM

Hrm, I did a little bit of poking around out there, it seems some of these models are prone to failure of that type, ....haven't found anything about why. Is the head modular in any way? I think I'd start from the bulb and look for loose connections there.

SOldBear · 05-11-2009, 12:37 AM

Originally posted by Ratmagiclady

Is the head modular in any way? I think I'd start from the bulb and look for loose connections there.

No, the flash is not modular. I think the only Sunpak model is modular is 622.

I opened up the head and looked around - everything is clean and solid. I think the cause of failure is electronic (component failure), not mechanical (corrosion, solder joints coming loose, wires broken,...).

Ratmagiclady · 05-11-2009, 10:01 AM

Originally posted by SOldBear

No, the flash is not modular. I think the only Sunpak model is modular is 622.

I opened up the head and looked around - everything is clean and solid. I think the cause of failure is electronic (component failure), not mechanical (corrosion, solder joints coming loose, wires broken,...).

Hrm, well, it's good troubleshooting to start there with intermittent problems, at least.

I asked about the modularity cause some of the older Sunpaks and a few Vivitars had some trouble with the connectors wearing out, once upon a time, usually with the shoe mount models and the interchangeable heads, when they had sort of an Atari-cartridge like card connection, and you could get problems like that. There's sometimes little things you can do with that.

I suppose the next question is if you feel capable of repairing little circuit boards, or maybe trying to swap out components. (This is generally outside my depth)

Do you know what's wrong with the parts-522?

kalaci · 05-30-2009, 02:50 AM

The flash is fired the rather ordinary way: a small SCR discharges a 33nF cap - charged to about 180V - across the primary of the trigger transformer. The secondary 6kV pulse ionizes the xenon gas in the tube and, as the uprising voltage on the anode of the series thyristors exceeds the dU/dt value of the CR3JM-8, they open, thus allowing the main cap to be started discharging. The test knob is of spartan simplicity and can be corroded. I'd start to troubleshoot with that.

SOldBear · 05-30-2009, 10:38 AM

Originally posted by kalaci

The flash is fired the rather ordinary way: a small SCR discharges a 33nF cap - charged to about 180V - across the primary of the trigger transformer. The secondary 6kV pulse ionizes the xenon gas in the tube and, as the uprising voltage on the anode of the series thyristors exceeds the dU/dt value of the CR3JM-8, they open, thus allowing the main cap to be started discharging. The test knob is of spartan simplicity and can be corroded. I'd start to troubleshoot with that.

Thanks for the pointer. But...

I know it's not the 33nF cap. I replaced it.

It's not the test button either. I once bypassed it with a jumper.

The symptom remains the same.

I don't think it is the SCR. I can "hear" it closing with the test button.

The inside of the flash is as clean as a whistle: no corrosion, no loose wire, ....

05-09-2009, 03:58 PM	#1
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206	Help with Sunpak 522 repair I have a Sunpak 522 without sync cord and battery holder. I just bought a complete but non-working 544 for the parts. Now I'd like to repair the 544. The problem is that it fires intermitttently. It charges up OK, but takes any where from 2 to 50 (mostly 3) times to push the "test" button to fire it. I use the "test" button to make it simple. The symptom is the same when I connect the flash to a camera's PC terminal with the sync cord. Is the flash reparable with basic tools and electronic knowledge? I have a non-working Sunpak 522 to act as organ donor if needed. Any pointer is appreciated. Thanks.

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05-10-2009, 06:56 PM	#2
Ratmagiclady Veteran Member Join Date: Nov 2008 Location: GA Photos: Gallery \| Albums Posts: 13,563	Hrm, I did a little bit of poking around out there, it seems some of these models are prone to failure of that type, ....haven't found anything about why. Is the head modular in any way? I think I'd start from the bulb and look for loose connections there.

05-11-2009, 12:37 AM	#3
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206 Original Poster	Originally posted by Ratmagiclady Is the head modular in any way? I think I'd start from the bulb and look for loose connections there. No, the flash is not modular. I think the only Sunpak model is modular is 622. I opened up the head and looked around - everything is clean and solid. I think the cause of failure is electronic (component failure), not mechanical (corrosion, solder joints coming loose, wires broken,...).

05-11-2009, 10:01 AM	#4
Ratmagiclady Veteran Member Join Date: Nov 2008 Location: GA Photos: Gallery \| Albums Posts: 13,563	Originally posted by SOldBear No, the flash is not modular. I think the only Sunpak model is modular is 622. I opened up the head and looked around - everything is clean and solid. I think the cause of failure is electronic (component failure), not mechanical (corrosion, solder joints coming loose, wires broken,...). Hrm, well, it's good troubleshooting to start there with intermittent problems, at least. I asked about the modularity cause some of the older Sunpaks and a few Vivitars had some trouble with the connectors wearing out, once upon a time, usually with the shoe mount models and the interchangeable heads, when they had sort of an Atari-cartridge like card connection, and you could get problems like that. There's sometimes little things you can do with that. I suppose the next question is if you feel capable of repairing little circuit boards, or maybe trying to swap out components. (This is generally outside my depth) Do you know what's wrong with the parts-522?

05-30-2009, 02:50 AM	#5
kalaci New Member Join Date: May 2009 Location: Budapest Posts: 2	The flash is fired the rather ordinary way: a small SCR discharges a 33nF cap - charged to about 180V - across the primary of the trigger transformer. The secondary 6kV pulse ionizes the xenon gas in the tube and, as the uprising voltage on the anode of the series thyristors exceeds the dU/dt value of the CR3JM-8, they open, thus allowing the main cap to be started discharging. The test knob is of spartan simplicity and can be corroded. I'd start to troubleshoot with that.

05-30-2009, 10:38 AM	#6
SOldBear Veteran Member Join Date: Feb 2009 Location: Alameda, CA Posts: 3,206 Original Poster	Originally posted by kalaci The flash is fired the rather ordinary way: a small SCR discharges a 33nF cap - charged to about 180V - across the primary of the trigger transformer. The secondary 6kV pulse ionizes the xenon gas in the tube and, as the uprising voltage on the anode of the series thyristors exceeds the dU/dt value of the CR3JM-8, they open, thus allowing the main cap to be started discharging. The test knob is of spartan simplicity and can be corroded. I'd start to troubleshoot with that. Thanks for the pointer. But... I know it's not the 33nF cap. I replaced it. It's not the test button either. I once bypassed it with a jumper. The symptom remains the same. I don't think it is the SCR. I can "hear" it closing with the test button. The inside of the flash is as clean as a whistle: no corrosion, no loose wire, ....