K1000 flash issues

I posted a few days ago that I have a pentax K1000

which I bought with some issues. I've cleaned the lens

internals to allow it to function properly, I cleaned out the

cameras mechanism and straightened out the base

plate. I cleaned out the prism replaced the seals ect.

 

But I was messing with a flash on it the day I got it

before I did anything and noticed the flash with fire when

I advance the film. I changed flashes and it stopped. So I

tried the flash on an other camera and it functioned fine.

Now that I have fixed this camera I put a 3rd flash which

uses a cable. And once you hit the shutter release it fires

but it will keep firing as it charges even if you aren't

touching the camera. Clearly something isn't right with

this. Any ideas?

The hot shoe is not firing the flash at all now...

<p>Not sure if this is a factor, but can you name the flashguns you used.</p>

Gemini 4700, Vivitar auto thyristor 225, auto flash DX-

700, and I'm not sure what my dad's is

<p>Does the hotshoe flash have 1, 2, or 3 contact points? I'm wondering if a setting on the flashgun using a programmable setting is an issue.</p>

A single. I suppose that could be the problem but just

assumed it was the camera when one flash that worked

even if it had issues stopped working when no settings

changed.

 

The camera is currently disassembled and being

completely overhauled I have not spotted any issues

internally so it may very well be due to the flashes.

<p>If it has a single connector on the flashgun I really can't image that's the problem. It was just a thought.</p>

 

<p>You say you changed flashes and it stopped. Does this mean your problem is no longer reproducible?</p>

<p>I believe the electronics in play here are very simple. On the flashgun's hotshoe foot I believe it just bridges the single contact on the bottom of the foot and the contact between the grooves that the hotshoe's two sides engage. So you should be able to fire the flash by shorting these two contacts. This I have done before.</p>

<p>Similarly, I believe the cable does something similar, the inner and outer conductor on the cable are temporarily bridged to fire the flash. I would think you could test-fire the flash and cable by carefully shorting these as well (though they're a bit smaller so probably harder to do; I haven't tried this).</p>

<p>Thinking about how this works...if you can do these tests...you should also be able to test the socket or hotshoe on the camera. There should normally be no continuity between the center contact on the hotshoe and the two metal bars on the sides of the hotshoe (that the flash unit foot engages when mounted). When the shutter is triggered, this circuit should briefly be closed. If continuity remains well after the shutter has been tripped, I would think there is a problem in the camera's innards.</p>

<p>These innards (x-sync contacts, wiring) seem to be described at length in the <a href="http://pentax-manuals.com/manuals/service/servicemanuals.htm">K1000 service manual</a>. My quick skim suggests that there are two sets of contacts -- one (FP) that is only closed when the mirror goes up, and another (X-Sync) that is opened when the shutter is cocked but closes when the shutter is fired.</p>

 

<ol>

<li>mirror down and shutter un-cocked: X-sync closed, FP open.</li>

<li>advance film, shutter cocked: x-sync open, FP open</li>

<li>shutter button pressed, mirror up: X-sync still open, FP now closed</li>

<li>shutter fired and curtains all the way open: X-sync now closes - both contacts are closed so flash fires</li>

<li>mirror returns down, X-sync still closed, FP opens to break circuit so flash won't fire again</li>

</ol>

<p>Given this scheme, I would think the most likely scenario for undesired flash firing would not be when cocking the shutter (as this should open the X-sync contact that was already closed and break the circuit) but more likely that the FP contact does not get opened when the mirror returns. This doesn't quite match your description though. The problem you described several days ago mentioned a lever that was rubbing due to a dent, and a mirror that doesn't always go all the way down. I wonder if there's an extra short here somewhere due to the lever rub and that the FP circuit isn't being opened because the mirror isn't going all the way down.</p>