Unusual Spotmatic problem

[resummerfield]

I would send the camera to Eric Hendrickson (pentaxs.com) for an evaluation. I've sent him several, and he does excellent work on the older models, and his fees are very reasonable.

 

[John Koehrer]

There's a bulb lever under the top cover that's only allowed to engage when the camera is set on..............you got it, .......B.

It's likely to be old lubricant at the pivot of the lever. Pretty simple fix when you get the top cover off and the Spotmatics are one of the easiest cameras to do this with.
One problem though, the screw holding the counter dial is SOMETIMES a left hand thread.

 

[AgX]

One problem though, the screw holding the counter dial is SOMETIMES a left hand thread.

.

You mean, there are variations on threading orientation between samples of the same model?
I never thought of that.

 

[oreston]

Yes, but apparently you can tell from the camera's serial number. It's supposed to be a LH thread above # 4000000. Who knows why they would introduce a seemingly pointless change like that. Perhaps something to do with Asahi adopting ISO manufacturing standards? Just a guess.

.

You mean, there are variations on threading orientation between samples of the same model?
I never thought of that.

 

[oreston]

Thanks for everybody's input on this. I tend to think it's most likely a small mechanical fault in the camera itself. Applying Occam's razor, it may well just be the bulb lever as John Koehrer - suggests in which case the whole motor drive thing might be a red herring.

I'm going to be taking off the top plate to do one or two small tasks anyway (cleaning out the finder and lubricating the sticky meter switch). While I'm in there I'll see if I can identify the bulb lever and if I can get to it I'll lubricate with a drop of clock oil and see if that resolves the issue. I have a PDF of the service manual.

As discussed earlier in the thread, I'm probably not going to get this camera CLA'd at this stage. If I was, I wouldn't be sending it to Eric as unfortunately I live too far away here in England. That's fine as we have Harrow Technical, who also do good work and who I've used in the past.

 

[lxdude]

Yes, but apparently you can tell from the camera's serial number. It's supposed to be a LH thread above # 4000000. Who knows why they would introduce a seemingly pointless change like that. Perhaps something to do with Asahi adopting ISO manufacturing standards? Just a guess.

Changes like that are usually done to address an issue of some type. LH threads are usually used because of problems with RH threads coming loose.
Sometimes engineering changes are done as part of a greater design change, or because of a change in assembly or adjustment method. When the product is made in comparatively low volume, changes may occur later in the run, as an issue might take a while to show up.

I have a very early Pentax MX. The body casting is significantly different from the later MX I have. They redesigned the casting for whatever reason- maybe cost, maybe strength, maybe to simplify assembly...

 

[Sirius Glass]

Changes like that are usually done to address an issue of some type. LH threads are usually used because of problems with RH threads coming loose.
Sometimes engineering changes are done as part of a greater design change, or because of a change in assembly or adjustment method. When the product is made in comparatively low volume, changes may occur later in the run, as an issue might take a while to show up.

Yeah, wot he said.

 

[oreston]

Just to update this, I went under the hood and found what I correctly assumed was the bulb lever under the shutter release plate. Following lubrication and a little gentle adjustment I now have a working B setting!

I cleaned out the finder, lubricated the meter switch and fine-adjusted the meter sensitivity while I was under there. I'd already replaced the light seals and freed the corroded battery cap, so I now have a smooth, fully working extra camera body.

All in all, a very satisfying few hours' work

 

[shutterfinger]

Congratulations on doing a good job.

 

[Bill Burk]

Great! Happy to have another mystery solved...

 

[benjiboy]

I will try and be gentle with you by asking when, if ever are you going to use bulb flash and if so where are you going to get the flash bulbs from?

"B" signifies "Brief Time", and is nothing to do with bulb flash.

 

[Bill Burk]

Wowie catz, benjiboy. At first I thought you were nuts but looks like you might be right.

The bulb they named the setting for was the bulb at the end of a rubber hose that you squeezed to open the shutter... And back then there were no Zirconium or Aluminum filled flash bulbs... Its usage as Bulb may have even predated Edison's light bulb...

 

[AgX]

What sense would the designation "brief time" make? As the counterpart to the "T" Setting?

Perhaps, but was there "T" as early and as common as "B"?


I rather stíck to "B" = rubber Bulb

 

[lxdude]

I rather stíck to "B" = rubber Bulb

After hearing and seeing it described that way for 40 years, I concur.

 

[Chan Tran]

After hearing and seeing it described that way for 40 years, I concur.

Yes I think B stands for Bulb too. Never heard of brief time until Ben said it.

 

[MattKing]

Wikipedia gives two possibilities: B for Bulb, as in the pneumatic release, and the German word Beliebig (Eng: any time). It certainly wouldn't suprise me if there was a German root.

 

[AgX]

I hear this "beliebig" explanation for the first time, but it would make sense.
In german engineering literature B is explained as "rubber ball".

 

[benjiboy]

Yes I think B stands for Bulb too. Never heard of brief time until Ben said it.

I was told it meant "brief time" by my mentor when I started to be interested in photography more than sixty years ago Chan, but I think on reflection It's wrong and your right it would have been "bulb" for the pneumatic bulb releases they used in the early days of photography.