Braun F900

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David
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Returning to photography after 2 decades of being really busy. Resurrecting a Braun F90O which I bought some 40 years ago new which needs some TLC. Needs a replacement battery and ideally if I can lay hands on one a service/repair manual. Last time it was used it did work but the batteries being dead and no longer available, have toyed with making up my own battery pack. Anyone out there that can help with this. The battery does not ned to fit in the original casing as the intended use will be in a static situation. A service manual would be very useful in case there is a component failure e.g., capacitor that may need replacing.
 
I first used this chap about fifteen years ago - it's nice to know he's still going. He works from home, but his turnaround was always good and I never had a problem. He's done more packs for me than I can remember - I never found anything he couldn't do. All at a good price too. :cool:

Strikalite - the rechargable battery specialists

Strikalite provides an extensive range of batteries in all formats for all applications
www.strikalite.co.uk
 
Definitely find out what the trigger voltage is before you decide whether it’s worth having it repaired, you don’t want to fry your camera.
I never had much luck with old auto flashes on modern cameras, and tbh for the cost of a new battery, and any other repair that might be needed, a modern TTL replacement is probably better vfm.
 
Thanks for your replies much appreciated. I am very much in the have ago to repair sort of chap saved me a lot in the past and learnt a lot on electrics and electronics making darkroom equipment like timers' temp controllers and even a processor when such things were very expensive that was over 50 years ago. A copy of a service manual would be great if I could lay my hands on one, as if needed, I think I could effect a repair myself if I had one. I did build a small mains power pack which demonstrated flash worked but it took a long time to charge up as it was probably not powerful enough. Now am very conscious of the fact that there is too much consumerism in the world and do not want to add to it if I can avoid it. So, it may end up being a new unit in the event, But the Braun is very powerful and very fast though I would like to get it up and running off a battery pack if I can. Good point about the trigger voltage I would not drive it direct off the camera but via remote trigger anyway.
 
As Phil says watch the trigger voltage if your using it on digital. I cant find a voltage for that model but quite a few Brauns had a trigger voltage between around 11v and 21v with a few over 200v. Most makers of modern camera suggest the cameras are safe up to around 10v, although there is some debate as to wether anything over 6v is safe. There are variations from model to model of camera and flash as well. I have two metz45 one is fine, the other an earlier model is 600v very not fine, and I used to get a decent zap of it in wet weather.
Making a battery pack should be simple enough, you can buy ready made battery holders, it's more about finding out the required output from the original pack then just buying a suitable holder and battries, and a bit of soldering.
Personally I'd just buy a new budget flash gun and save myself the hassle and the risk. Be a bummer to save a hundred quid on a flash and blow up a K's worth of camera.
 
If my small amount of research is correct, you only need 8v of battery, I bet you could find something designed for rechargeable tools (even if you had to use something to limit the power).
 
Thank again great info. The link from Steven states trigger vols is 22V. If needed can use a slave trigger that will operate the F900 off the built-in camera flash or an accessory in the hot shoe that does the same thing. That link also has a diy battery pack of 7 1.2v NImh stuffed into the original battery pack look like c size so possibly not 3.8ah. Braun did do a NIcad pack and I wondered whether a Nimh would do, and someone has. Really like your photos, Steven. The original pack was 8 v 3.8ah can get 2x4 v sealed LA at 4 ah which would do but they won't fit in the casing. I have found the original wet barix batteries and having ago to see if can kick them into action with some tablets and battery acid but guess they may be too far gone.
 
Well most modern rechargeable AAs run at about 1.2 ish volts, so I’d have a go at wiring a simple 4 pack of those for relatively peanuts.
 
Don't think AA will be powerful enough ones I have got are only 900 mAh. Don't believe they can be made to the power I need. But the comment Phil made has reminded me that I have 4 1.2 v 4Ah "c" which go in a laser level I have, and I also have 4 spares of dubious age/capacity. I'll see what i can learn from that trial. Just need to get an 8 cell holder and make up a dummy cell (dowel with a nail through it) to go with 7 of the rechargeables.
 
Have made good progress with this. I used 8 cells 1.2v Nimh with a voltage reduction board I had made up years ago and delivered 9.1 V. The battery pack I made up was delivering 11.5V to my circuit when checked voltage all the 1.2 v C cells were around 1.45V not measured them before thought would have been 1,2V. I measured voltage and current and was clear the flash unit was taking a lot of current 7.1A and taking a bit longer to charge up that I remember but my meters were telling me that the voltage was slow to rise after initial take so that explained that. I then got a 12v 10ah motorbike battery coupled that to my voltage regulator and with the extra power in the bigger battery was able to deliver the volts much quicker to the flash, The amps now gone up to 8.3. Flash now operating as I remembered it. Tested the triggering with a conventional film camera in case I busted my digital and worked. Used a remote trigger connected to the flash and used the on-board flash on the digital to set it off and that has worked. Have a remote sensor for the flash which extends the useable aperture value and that worked. All need to do is tidy stuff up so it is conveniently portable. I am not bothered too much about the 12V m/bike battery as most of my intended use will be indoors and I can just fit a 8cell pack of C batteries in the original flash battery housing if need greater portability. I have gone into the detail here so if someone comes along a lot later there is something to go at. One issue remains which have experienced years ago with flash units and that is sync leads. I have 2 curly longish leads and neither of these will trigger the flash whereas a short plain lead does. When I extended the short lead with another standard cable that did not trigger the flash. Think there is a reason for this somewhere in my mind but cannot recall. Anyone got any idea.
 
Assuming the leads are ok resistance is about the only other likely issue. have you checked the trigger voltage?
 
As above, my only thought would be a v low trigger voltage that fails to make it on the long journey.

Which is the exact opposite of my first post on here, so… that proves we never stop learning.
 
Or just use cheap radio slaves, which are better/ safer than using a cable.
 
Thanks for the replies. I measured the trigger voltage at the socket of the flash head, and it is 25V. At end of the lead was no volts fiddled around with the contacts and got voltage so was bad contact between the "spade" 2 prong ends going into the flash head. As all the leads were failing reckon the contacts inside the flash head are tarnished with no use, All my leads work now but putting an extension on them does not work, guess Steven right there. Thanks for the VD link. I am very familiar with doing the calcs with mains and I used those formula for gauging the wires on the flash. Not come across the elv calcs before has no need really. Have just finished putting the unit back together got my voltage regulator in the battery housing and the battery sit outside. Have effectively now 2 battery packs the "c" cell and the motor bike battery. Except will need to rescue the C cells when need to use my laser level. When I bought a replacement battery over 30 years ago it was almost twice what I paid for the motor bike battery which has 2.5x the capacity of the original. I don't really need to use extension leads as have 2 remote flash triggers but will look into radio slaves. Not got into setting the camera for flash I guess there will be TTL on it not got that far with the manual yet.
I am on a big learning curve with my digital camera they have come a long way since my film days. A computer wizard would probably sail through.
Thanks for your help one and all.
 
For completeness to close off the flash voltage query later found out from Nikon support that my D 7500 will take up to 250v with a rider that is with compatible Nikon flash units. I later found reference to this in an on line manual that has more info than the printed manual which is comprehensive in itself.
 
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