Dismantling a Braun 370 BVC flash.

[Roger th B]

I have the above flashgun. The fractional power control gives me full power on all settings above about 1/16th. I suspect that it's the wiper contacts; they need a clean. the trouble is that I can't get to them.

I have got as far as removing the front half of the case, but I cannot see how to remove the circuit boards from the rear half of the case, though I've managed to remove the transparent cursor.

Has anyone managed to get it apart? Is there anything that I need to look out for? I would ask Braun but they don't make flashguns any more.

[PhilW]

Be very very very VERY careful working on flashes. If you think how they work - as they power-up for a flash they are storing a whole lot of electrical hell in a capacitor somewhere - you really don't want that discharging into your body!!

Of course you may well know exactly what you are doing.... but if not... I wouldn't risk it (and I am well known for living somewhere near the "reckless" end of the risk averse scale )

[PeteRob]

I have the above flashgun. The fractional power control gives me full power on all settings above about 1/16th. I suspect that it's the wiper contacts; they need a clean. the trouble is that I can't get to them.

I have got as far as removing the front half of the case, but I cannot see how to remove the circuit boards from the rear half of the case, though I've managed to remove the transparent cursor.

Has anyone managed to get it apart? Is there anything that I need to look out for? I would ask Braun but they don't make flashguns any more.

be careful. these thigs have capacitors and can deliver a high charge. Not advisable to dismantle unless expert.

[Roger th B]

Blimey! That was quick! PeteRob and PhilW, thanks for your concern. I know about capacitors, and so I'm a wary fellow. There is no charge remaining in the cap, so no concerns there.

[Malcolm_Stewart]

I'm normally quite good at taking things apart, and getting them back together again (and working), but I was beaten by a Minolta 320(?) flash some years ago. It seemed to spring apart, and I had no idea where the pieces came from!

Have you tried Youtube? Someone might have filmed his attempts.

[Roger th B]

Nothing on Youtube. I looked there first.

[frank1]

Your chances are so remote on finding the information you're looking for. It's more than likely a flash that is rarely used by a lot of photographers. Most of us will not touch the insides of any flash at all. I doubt you'll find a solution to the problem as you probably know but hey no harm in asking. Might be the capacitor needs replacing and as Braun don't produce flashes any more you may not be able to it.

Just did a Google search there are some to be had but a flash as old as this. I wouldn't be buying one, more than likely they'll be in the same condition sooner or later. Alas nothing lasts forever, I've got an Elinchrom flash that needs the tube replaced. £200 or more to do it if I do that, how long before the caps need replacing.

Like yourself I want to do the job myself but the Flash centre have told me the tube can only be replaced by them and a spare part cannot be bought. Modern Elinchrom flashes have replaceable tubes which the owner can replace at a very small cost. So maybe it's time to face up to the inevitable if the light bulb was meant to last forever. Then suppliers would no longer be needed and that goes for longer lasting bulbs and I think we've been had on that one as well.

[Roger th B]

After some thought and gently trying various things I managed to get it apart.

There is no need to remove the cursor. One circuit board is at the back and there are contacts for the various controls that are on the back of the 'gun. It has a row of pins that a socket on the top board plugs into. Careful pulling removes the top board and the two side circuit boards that are joined to it.

The trouble seemed to be in the back circuit board. Some circuit strips and some contacts had green corrosion on them. This would have been caused by leaving the batteries* in until they had burst and sent noxious vapours out. The circuit board is three or four inches away from the batteries but still the damage occurred. Be warned!

I repaired anywhere that looked dodgy, resoldered some wires, and polished then wiped with solvent all the switch contacts.

If you remove the rear board, it's easier to reassemble if it's taken out through the back. Some clips hold the control panel into the back of the flashgun. This area is just full of tiny, easy to loose parts. I know, as when I knocked the soldering iron off the table and when I knocked it back on the table, I lost the ball bearing that allows to cursor to click into the right positions. It was about 3mm diameter, and in the end I used a bit sliced off the ink tube of a Bic biro. Lots of care and patience is required for reassembly of this bit.

I've just got it all back together, and it all seems to be working now.

*Really, the four 1.5 volt AAs that power the flash are not batteries but cells. The four together make a 6 volt battery. When you speak about a 12 volt car battery, you are referring to six 2 volt cells in a common case.

[Learning]

Well done. You won. This is a significant victory over the manufacturers who make things irreparable.
Edit. Really I'm not being facetious. You beat the buggers who designed this kt.

[Roger th B]

Learning, I see your point and I agree that many things are designed to be replaced, not repaired. I did win, but in a victory over whoever left the cells in until they burst, not over Braun, who made the flash in such a way that it could be repaired. It was my lack of specific knowledge of this model that made me struggle.

I didn't think for a second that you were being facetious.

(RANT ALERT)
It's not like the starter motor assembly on my car, that I had to replace because the solenoid contacts on the side of the motor needed a bit of filing, costing about an hour of my time. Instead I had to get an exchange assembly, because any parts that I could fettle or replace are under a crimped on cover, so costing two hours of my time including fetching it, and £40 or so.

Er, was this what you meant?

[PeteRob]

Well done. You won. This is a significant victory over the manufacturers who make things irreparable.
Edit. Really I'm not being facetious. You beat the buggers who designed this kt.

Let us not forget these are potentially dangerous things to take to bits. It would be foolhardy ti suggest the average person could fix one!

[AlexMonro]

Let us not forget these are potentially dangerous things to take to bits. It would be foolhardy ti suggest the average person could fix one!

A few years ago, when I worked as a development technician in a small electronics company, I came into the lab one morning and chatted to the other technician about what he was working on that day.

"Oh, just got to test this 5 kilovolt power supply." - typical of voltages found in flashguns.

"Watch it doesn't bite", I joked.

Half an hour of so later, there was a flash, a bang, and a yell from across the lab. I rushed over, frantically trying to remember my CPR training, but fortunately he wasn't badly hurt.

Which just goes to show that even people trwined and experienced with such things can get bitten.