> Do you have film in the camera? In TTL Auto with the OM-2[n,S] and
> OM-4[T,ti], it meters off the film. The reflectivity of the pressure plate
> isn't nearly that for film, often indicating under-exposure when it should
> have put out sufficient light.
Yes, this is what I thought was the problem initially, so I got a cheap roll of
colour film and put it in. There is still the same problem.
> You've almost got it, but not quite. Of the three contacts, the large
> center one is obviously the flash trigger. One of the other two smaller
> ones is the flash ready and exposure OK contact. This is the one that is
> used by the OM-10 and OM-1n to light up the LED in the viewfinder. The
> second of the two smaller ones is the "flash quench" contact used for
> TTL-OTF. It signals the flash to shut off when the body metering has
> sensed sufficient light from the flash. This is why the switch is in the
> same position as for "Manual" operation on the back of the flash. Unless
> there's a quench signal from the camera body before a full dump occurs, the
> flash gives a full dump.
I managed to work this out. I used a thin piece of plastic to stop the T32
touching the quench contact (one on the left). The flash then behaved normally
in "Normal Auto" with the Autocheck light flashing.
> First, if the camera has no film in it, get a roll of the cheapest film you
> can find and load the camera with it to use it as a "scratch roll." I
> sometimes forget to do this, and end up wondering for a couple of seconds
> why the same thing happens to me when testing a flash that supports TTL-OTF
> control.
Done this, still the same problem.
> If it still occurs with film loaded, then the problem could be in the T-32,
> in the OM-2n accessory shoe (you are using a Shoe 4, right?), or in the
> OM-2n itself. At this point it's an ambiguity group. You'd need another
> "golden" T-20 or T-32, and another "golden" Shoe 4 to isolate it further.
I had a further look at the flash (sorry, I didn't do this properly first time
round). It exhibits this behaviour:
In Manual GN32, not on a body, when the test button is pressed, the autocheck
light remains off (correct behaviour).
In Manual GN16, not on a body, the autocheck light blinks after the flash
regardless of if the "O" in "Olympus" is covered. This is wrong - if it was
meant to flash (which I don't believe it is), then it shouldn't with the "O"
covered.
In all normal auto modes, the autocheck light blinks unless I put my finger over
the "O", suggesting all three of these are working normally.
So, it seems to be some kind of problem with the switch (possibly?).
I had these ideas for fixing it:
I assume that the TTL socket on the side of the T32 (small 5 pin connector)
derives flash quench from the OM 2n if it is working properly. If it isn't, then
the quench is simply when the flash shuts off. If I use an oscilloscope to
monitor the "flash sync" and "flash quench" signals, when on and off of the
body, in manual, and auto modes, I should be able to see timing differences. If
not, then the flash is at fault.
I also assume the Hot Shoe 4 is just connected straight through, so I will do a
continuity test on it.
I don't know what exactly signals things on the hot shoe, either a circuit
closing or a voltage, but I could monitor this on the OM 2n to see if that is a
problem.
I have a broken T32 here as well (very broken that is, no flashing), which looks
like someone unskilled tried to fix, so that could be used for parts once I have
drilled out the screw holding it closed (it is completly mangled after whoever
last opened it).
Thanks very much for the help, it's greatly appreciated.
Andrew.
--
Andrew Tierney
urbex@xxxxxxxxxxxx
www.urbex.org.uk
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