Profoto D4 Pack wont fire. What could be wrong?

The studio i am currently at has a Profoto D4 pack that is currently out of commission and we don't really know what is wrong with it. The pack lights up and turns on just fine when plugged in and the strobe heads also power up when plugged in. Everything on the pack lights up perfectly, however, the problems start when you try to fire the heads. The pack can't seem to fire the strobe heads. We've tried multiple heads and the result is all the same: the pack wont fire the heads. I know it's very hard to diagnose an issue like this without cracking the unit open, but what could be wrong with it? I feel like repairs on this pack would probably break the bank, but it is a very expensive power pack and it's a shame to just watch it sit in a corner and not get used.

Could be anything from a dry joint or loose wire to a broken EHT transformer, capacitor, diode..... almost anything.

 

"I know it's very hard to diagnose an issue like this without cracking the unit open..."

 

You're right. And it's impossible by remote control over this thread!

Check the fuses and look for any thermal cutout that needs resetting.

 

Beyond that: Do not open the pack and attempt a DIY repair.

There are lethal voltages and current inside that can throw you across a room, give you a severe burn or even stop your heart!

Send it to Profoto to repair. Its the cost of doing business. Do not attempt to fix yourself. At the very least get the estimate and then decide if it will break the bank or not.

I've never used a D4, but taking a quick look at the user manual, it appears that it can be configured for two different style light heads.

 

Check how it's set up like so: put the pack in standby by pressing the "on/standby" button. Then simultaneously press the "slave" and "set" buttons; the display should show either "Pro" or "Acu." If it's wrong for your head style, check the manual for the procedure to reset, page 17 under " Configuration."

 

Aside from this, I don't know how much troubleshooting you've done, but the normal routine for a pack would be to start out with a known-good light head (one that you have seen flash with a different pack) attached to the pack. Turn on the pack and see if the "ready" light comes on within a few seconds (this is a good indicator that the charging circuits are ok). Finally, try to trigger the pack to fire. The most reliable way to do this is to press the "test" button. If no flash occurs make sure that all other sync connections are disconnected (a shorted sync cable can prevent the test button from working).

 

I would do two other things: try plugging the head into a different receptacle (in case one is "dead,"), making sure that the outlet is not set to standby, etc. Finally, if still no flash I'd inspect the pack's receptacles closely to see if any pins have been melted/burned back (this has happened on plenty of older packs when someone didn't have a light head fully plugged in; the flash partially burns back a connector in the light head cable; the photographer then tries the now-defective cable in a different pack receptacle until they have damaged every receptacle). You won't be able to fix the receptacles yourself, but at least you'll know what is wrong.

Just a guess. Check the dials/switches to make sure they are not "stuck" in between setting. Make sure it clicks into position. The happened to me once.