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Re: [OM] OM-4 Not Firing Flash

Subject: Re: [OM] OM-4 Not Firing Flash
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Tue, 23 May 2000 20:07:38 +0000
If I recall correctly, the OM-4 will not fire the flash if there is already
enough ambient light without it.  It's one of the challenges trying to get
an OM-4 to produce fill flash in anything but Manual Mode.  Look in the
viewfinder doing what you did before under the same lighting conditions.
If the shutter speed diamond hovers around 1/60th or faster, the flash may
not have fired.  Suggest testing two things:
(1)  Set the OM-4 ASA dial to ASA 25, put the OM-4 in Auto Mode, set the
lens to f/16, put the flash in TTL-Auto, and fire the flash in a very dark
room.
(2)  Put the OM-4 in Manual Mode at 1/60th shutter speed, put the flash in
Manual Mode, and fire the flash in a very dark room.  It should produce
full flash output.

If both of these fail, it is possible someone bolted an old high-voltage
aftermarket flash unit to the hot shoe and fried the electronic switching
that fires the flash on the center contact.

The old strobes were made in the days of mechanical relay contacts inside
the camera body that fired the flash by shorting the center contact to the
camera body (sides of the hot shoe).  Some of these old strobes have a high
voltage between the center contact and the side contacts.  Because the
camera bodies made at the time the flash was used a mechanical relays to
fire them this didn't matter.  With electronic shutter and exposure
control, most modern bodies short the center contact to the camera body
using electronic switching and assume the flash has a low voltage and
current across its contacts.  An old strobe with a high voltage across its
contacts can fry the electronic switching inside the camera body.

-- John

At 22:16 5/23/00 , Dave wrote:
>Hello all,
>I need some advice......
>I've just picked up on impulse an OM4 to go with my OM40 based outfit.  It
>was a very good price at Jessop's, in Glasgow (Scotland) at £260.
>Garuanteed for 12 months, c/w 50/1.8.
>I remembered from the list the battery check test, ie if the beep turns off
>after 30 seconds it's an upgraded board less prone to drain, and together
>with Jessops expert staff (the UK list memebers will detect irony there, i
>reckon...) we tried to get the camera to emit a beep.  It wouldn't make any
>noise at all, regardless of the position of the rotating switch around the
>self timer light.
>Otherwise the camera seemed to work fine.  All the LCD's are intact, the
>aperture preferred auto works fine with sensible exposures.  Spot, multi
>spot, highlight and shadow bias worked sensibly, and all in all it gave the
>impression of being a well looked after, fully working OM4.  If a little
>quiet....
>When I got it home, I mounted both my T20, set it to auto, turned on the
>flash, took a picture....but the flash didn't fire.  Tried with the T18.  No
>flash.  "The camra didn't go bang!" explained my three year old helpfully.
>Flash ready light blinks, goes out after the shutter is released, and the
>LCD's charmingly inform me "under", then the raedy light goes back on.  But
>no flash.  Not on manual either, at 1/60s or below.
>Many questions:
>1.  Have I forgotten to do something stupidly obvious which means the flash
>wont go ...em...bang!
>2.  Whats with the lack of noise, is that and the flash failure related?
>Does it mean the camera is gubbed and should go back?
>3.  I've got a horrible feeling that something has fried under the top plate
>causing this.  Can my local Olympus approved repaire deal with this
>economically, or should I take it back for my money back?
>what do you think?......
>Dave


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