replacement / mending for broken flash unit
Posted 03/07/2009 - 13:28
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Are you using Alkalines? I have found this same sympton on an old flash of mine as rechargables operate at 1.2 volts the batteries were not pushing enough power to charge the flash. Alkalines at 1.5 volts solved this problem.
Bodies: K5IIs, K7, MZ5n, LX, MV
Lenses: DA*16-50, DA18-55WR, DA18-135, DAL35, M50 F2, A50 f1.4, FA50 f1.4, DA*50-135, DA55-300, Tamron 70-300, DFA 100 WR Macro, M135 f3.5, Sigma 120-400 APO DG HSM, Tokina 500 f8.0
Flash: Metz 58, Metz 48
Accessories: BG4, Pentax right angle finder, Pentax mirror adaptor lens, O-ME53 Viewfinder Loupe
Auto 110 System: Auto 110, Winder, 18mm, 24mm, 50mm, 70mm, 20-40mm, AF100P, 1.7x telecon
Lenses: DA*16-50, DA18-55WR, DA18-135, DAL35, M50 F2, A50 f1.4, FA50 f1.4, DA*50-135, DA55-300, Tamron 70-300, DFA 100 WR Macro, M135 f3.5, Sigma 120-400 APO DG HSM, Tokina 500 f8.0
Flash: Metz 58, Metz 48
Accessories: BG4, Pentax right angle finder, Pentax mirror adaptor lens, O-ME53 Viewfinder Loupe
Auto 110 System: Auto 110, Winder, 18mm, 24mm, 50mm, 70mm, 20-40mm, AF100P, 1.7x telecon
Posted 03/07/2009 - 18:39
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I second Mannesty's warning about the voltages inside flashguns.
As to the alkaline/NiMH thing, although the open circuit voltage of an alkaline is higher, so is it's internal resistance. This means that as you start to draw current the voltage of the alkaline will fall away faster, and at some point the voltage of the NiMH will exceed that of the alkali battery. This is why a flashgun which takes 6 seconds to recharge on alkalis may only take 4 seconds with NiMHs.
As to the alkaline/NiMH thing, although the open circuit voltage of an alkaline is higher, so is it's internal resistance. This means that as you start to draw current the voltage of the alkaline will fall away faster, and at some point the voltage of the NiMH will exceed that of the alkali battery. This is why a flashgun which takes 6 seconds to recharge on alkalis may only take 4 seconds with NiMHs.
Posted 03/07/2009 - 19:10
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It could be the batteries they need to be quite powerful. My old Sunpak 5000 used to charge up in 7 secs with Sanyo Cadnica Ni-Cads. Lesser batteries take twice as long and cheap batteries just never quite manage to bring the green light on.
shim
shim
Posted 04/07/2009 - 17:15
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Comments taken on board, thanks.
I know all about getting a belt off circuits - got the T shirt.
I'm using Alkali batteries but I have found that they have lasted for ages in the past - incredibly more than with my two previous ancient designs.
I guess there's no dice with a £40 repair, somewhere then?
I know all about getting a belt off circuits - got the T shirt.
I'm using Alkali batteries but I have found that they have lasted for ages in the past - incredibly more than with my two previous ancient designs.
I guess there's no dice with a £40 repair, somewhere then?
Posted 05/07/2009 - 23:53
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I managed to mend it. A wire to the flash tube has come adrift as the zoom mechanism had moved back and forth. Not for the squeamish as a repair job. So many loose wires and four separate circuit boards. All hand soldered plus loads of screws. Assembly costs must be enormous compared with mobile phones and PDAs.
What is the pttl experience like? Is it significantly usefull? Using the flash on manual an referring to the histogram of a test shot works pretty well in any case.
What is the pttl experience like? Is it significantly usefull? Using the flash on manual an referring to the histogram of a test shot works pretty well in any case.
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86 posts
17 years
It's powerful enough and has given some good results imho. BUT I'm sure I could have got something better.
And now it's bust - the firing circuit, I think. The motor works and the inverter whistles a nicely rising note at switch-on but neither the test button nor the camera will make it flash.
It went intermittent near the beginning of my first wedding (aaargh) and then stopped completely.
I would like to get it repaired but haven't found anyone interested (in Brighton).
Two questions then: Is there anywhere who could do that sort of repair in the UK and, failing that, is there a more compatible unit which won't cost more than about £100?
I may look inside and have a tinker - you never know,it could just be a loose wire or an obviously cooked component.