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Re: [OM] OM 4Ti mirror lock up - but batteries are Ok.

Subject: Re: [OM] OM 4Ti mirror lock up - but batteries are Ok.
From: John Hermanson <omtech1@xxxxxxxxxxx>
Date: Thu, 27 Aug 2009 08:52:03 -0400
New silver oxide are usually 1.55 - 1.59V.  If you get good battery 
check and still get lockup ON EVERY SHOT, then there is a more serious 
problem. The only screws to tighten are the 4 on the bottom. The hole on 
the leading edge is supposed to be there.
___________________________________
John Hermanson  |   CPS, Inc.
21 South Ln., Huntington NY 11743
631-424-2121  |  www.zuiko.com
Olympus OM Service since 1977
Gallery: www.zuiko.com/album/index.html


Moose wrote:
> Fernando is having trouble with posts here and to John Hermanson 
> bouncing. Here at his request is his latest.
> =========================================================
> Hola Moose,
> 
> Thanks for answering :-)
> 
> "Machines take by surprise with great frequency" - Alan Turing.
> 
> Moose wrote: 
>>
>> Classic symptoms of two things.
>>
>> 1. Failing battery. Although most characteristic of non-silver oxide 
>> batteries, I could see this happening with silver oxides at just the 
>> right stage in their useful lives. Especially with the 303/357, with 
>> its long slow decline discharger curve (as opposed to earlier 357 
>> later 357/303).
>>
>> The why is simple. Battery load in metering, lighting test button, 
>> operating self timer, etc. is quite low. AND, none of these but the 
>> battery check cares much about the voltage.
>>
>> BUT, battery drain holding the second curtain open during exposure is 
>> quite high. AND, the exposure circuit is very picky about voltage, as 
>> insufficient voltage could mean mis-exposure. Voltage is checked just 
>> as maximum strain is put on the battery, it fails the test and the 
>> camera aborts the exposure.
>>
>> Unfortunately, the battery check light on the OM-4 series bodies is 
>> not very good. Check with a voltmeter.
> Done. My new Renata 357 batteries measured 1.5 dead-on.
> 
> just checlked a couple of almost new 357s
>> If voltage is below 1.5v, try another set. It doesn't matter if the 
>> batteries are "new", as manufacturing defects or time in the 
>> distribution channel crop up from time to time.
>>
>> 2. Poor electrical contacts in the battery circuit. This is most 
>> commonly loose screws holding the bottom plate on, but can be 
>> oil/corrosion where the plate makes contact or elsewhere in the circuit.
>>  
> Most probably this one may be the cause. Glad to have ruled out the 
> memory clear button and the self-timer left On.
> Removed the bottom cap after tightening to check if it was loose. It 
> admitted a less than one degree of tightening, not much.
> Removed the batteries, measured them, cleaned both at each one's 
> surface, inspected the batteries chamber and everything looked quite clean.
> Put the batteries again, tightened firmly and fired: it failed ... red 
> 1/60, fired again: it worked. Continued to shoot both with winder2 and 
> shutter release button, it didn't fail. Even took my time to check 
> shutter speeds using my TV set. Loaded the RDPIII. Shall wait until it 
> happens again ... :-(
>> The why is similar to above. At low current, there is little enough 
>> resistance through the problem spot that everything seems normal. With 
>> higher current, the voltage loss across the poor connection is great 
>> enough to lower the voltage too much for shutter operation.
>>  
> OhM rules !!
>> If truly fresh batteries and tightening the bottom plate screws don't 
>> cure the symptoms,
> How do I tighten those screws? Which one are they, btw? The black screws 
> which can be seen from the outside of the camera, at the farthest right 
> and left of the bottom plate - or something hidden inside the battery 
> chamber?
>> take the plate off and clean the bottom of the body casting around 
>> where the screw holes are, including use of a rough eraser, fine 
>> sandpaper or some such on at least one hole.
>>  
> Damn! - that might wear the paint off the black screws !! And I'd need a 
> crosspoint [destornillador] !.
> You're talking about my 'new' OM 4Ti :-)
> 
> BTW, this failure made me remember of very recent one I had.
> Strangely enough, I hadn't use my power amplifier since maybe the 
> beginning of June (nor had I used the 4Ti, which arrived on those days - 
> that is almost the whole winter).
> On August 24, I turned it On. No sound from the left loudspeaker, 
> everything else looked Ok.
> Did the usual troubleshooting: it was the power amp, no doubt.
> Time to buy a new one? Calmed down and thought a little (yes, I'm able 
> to think very clearly under stress).
> At its back, the Bryston 4B SST has three switches, only one of them was 
> suppressed in the newer 4B SST², the ground lift. The other two switch 
> the amp from balanced to single-ended inputs, and from individual 
> channels to bridged mode.  Switched those switches (amp *Off*) up and 
> down several times. Most probable, the balanced - single-ended selector 
> switch got dirt or moisten (we have cold an humid winters here). At 
> first, left channel didn't sound as loud as it should, repeated the 
> procedure and it's now as good as ever.
> 
> And all their screws are perfectly black ;-)
> 
> Fernando.
> --- does the idiomatic expression 'loose screws' mean something for 
> English speaking people?
>>
>>
>>
>>
> 
> 
-- 
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