LX won't change to manual mode

huge10 · 06-13-2021, 02:12 PM

If I turn the shutter speed dial off the automatic setting (to one of the manual speeds) camera stays in automatic mode. Any of you has encountered this and knows what causes this? And can tell how to remedy it?

Regards,

Wim

andrewd · 06-13-2021, 02:31 PM - **1 Like**

A while back I bought a second LX as a backup, which had problems with the manual shutter speeds. Not quite the same as your problem. Mine had very inconsistent shutter speeds (eg 1/60 sounding more like 1 second for a few shots, and then normal etc). Interestingly when the mirror was locked up all the manual speeds consistently fired at X synch speed (no slow speeds at all). Auto mode seemed to work correctly.

I contacted Robin at Harrow Technical who serviced my first LX. He advised that there is a high chance that there is a faulty shutter speed control circuit. Replacement circuits are no longer available, so he would need to find one from a donor body. He recommended returning the camera so that is what I did. The fault is a known weakness of the LX and can effect both early and late models.

Since your problem is a little different I recommend contacting one of the specialist LX technicians directly to get their expert opinion. Please keep us posted.

**aslyfox** · 06-13-2021, 03:25 PM

I agree you need to find a specialist but just in case

here is the pdf of the service manual

https://learncamerarepair.com/downloads/pdf/pentax-lx-service-manual.pdf

LesDMess · 06-13-2021, 09:17 PM

Does the meter work in A mode? If so, when you meter a long exposure - 1 second and above, does it expose that time correctly? When you switch to manual mode - like 1 second, does the meter work correctly?

Wasp · 06-14-2021, 02:06 PM

Originally posted by aslyfox

I agree you need to find a specialist but just in case

here is the pdf of the service manual

https://learncamerarepair.com/downloads/pdf/pentax-lx-service-manual.pdf

The manual is interesting and intimidating at the same time. Opening one of these up is not for the faint of heart.

I was wondering about component level repair of the electronics but the manual is silent on that - not even a circuit diagram. There is one small clue. Part T100 in figure 4 seems to be the main board. The drawing shows the outline of an IC on it. This was probably made for/by Pentax from what is now unobtanium.

Huss · 06-14-2021, 05:15 PM

Originally posted by huge10

If I turn the shutter speed dial off the automatic setting (to one of the manual speeds) camera stays in automatic mode. Any of you has encountered this and knows what causes this? And can tell how to remedy it?

Regards,

Wim

Hey Wim. Sorry to hear about your issues. Out of curiosity was this camera working for you at any time? Or did you buy it broken?

huge10 · 06-15-2021, 12:58 PM

Originally posted by Huss

Hey Wim. Sorry to hear about your issues. Out of curiosity was this camera working for you at any time? Or did you buy it broken?

I bought it with this issue. It has very clean outside looks. Would be nice if it could be reapired.

Huss · 06-15-2021, 01:33 PM

Originally posted by huge10

I bought it with this issue. It has very clean outside looks. Would be nice if it could be reapired.

Should have asked, in the A mode - does it work properly? Exposures/shutter timing seems correct?

huge10 · 06-16-2021, 12:55 AM

Originally posted by Huss

Should have asked, in the A mode - does it work properly? Exposures/shutter timing seems correct?

Didn't test it with film, but long times sound correct.

Lord Lucan · 06-16-2021, 01:42 AM

The LX has two different manual modes. At speeds of X (1/75 sec) and faster, it is mechanical. At lower speeds it is electronic. They are largely independent of each other except for using the same shutter, which you know works because it works in Auto. So does your LX fail to work in both those different speed ranges? If so, I would suspect the speed selector dial is simply not turning the contact mechanism below, which is staying in Auto despite turning the dial.

**aslyfox** · 06-16-2021, 03:45 AM

just in case it is needed, here is a pdf of the LX manual

http://www.pentax-manuals.com/manuals/mf/mfmanuals.htm

huge10 · 06-16-2021, 11:58 AM

Originally posted by Lord Lucan

The LX has two different manual modes. At speeds of X (1/75 sec) and faster, it is mechanical. At lower speeds it is electronic. They are largely independent of each other except for using the same shutter, which you know works because it works in Auto. So does your LX fail to work in both those different speed ranges? If so, I would suspect the speed selector dial is simply not turning the contact mechanism below, which is staying in Auto despite turning the dial.

I checked with the service manual. There is a switch near the film advance mechanism that switches from auto to manual. Wish me luck in getting in there and see if something is wrong there.

LesDMess · 07-04-2021, 09:19 AM

Originally posted by huge10

I checked with the service manual. There is a switch near the film advance mechanism that switches from auto to manual. Wish me luck in getting in there and see if something is wrong there.

Good luck!

06-13-2021, 02:12 PM	#1
huge10 Forum Member Join Date: Mar 2018 Location: Apeldoorn, The Netherlands Posts: 62	LX won't change to manual mode If I turn the shutter speed dial off the automatic setting (to one of the manual speeds) camera stays in automatic mode. Any of you has encountered this and knows what causes this? And can tell how to remedy it? Regards, Wim

06-16-2021, 03:45 AM	#11
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,583	just in case it is needed, here is a pdf of the LX manual http://www.pentax-manuals.com/manuals/mf/mfmanuals.htm Last edited by aslyfox; 06-16-2021 at 05:06 AM.

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06-13-2021, 02:31 PM - 1 Like	#2
andrewd Senior Member Join Date: May 2021 Posts: 238	A while back I bought a second LX as a backup, which had problems with the manual shutter speeds. Not quite the same as your problem. Mine had very inconsistent shutter speeds (eg 1/60 sounding more like 1 second for a few shots, and then normal etc). Interestingly when the mirror was locked up all the manual speeds consistently fired at X synch speed (no slow speeds at all). Auto mode seemed to work correctly. I contacted Robin at Harrow Technical who serviced my first LX. He advised that there is a high chance that there is a faulty shutter speed control circuit. Replacement circuits are no longer available, so he would need to find one from a donor body. He recommended returning the camera so that is what I did. The fault is a known weakness of the LX and can effect both early and late models. Since your problem is a little different I recommend contacting one of the specialist LX technicians directly to get their expert opinion. Please keep us posted.

06-13-2021, 03:25 PM	#3
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,583	I agree you need to find a specialist but just in case here is the pdf of the service manual https://learncamerarepair.com/downloads/pdf/pentax-lx-service-manual.pdf

06-13-2021, 09:17 PM	#4
LesDMess Pentaxian Join Date: May 2011 Location: Santa Cruz, CA Photos: Albums Posts: 3,235	Does the meter work in A mode? If so, when you meter a long exposure - 1 second and above, does it expose that time correctly? When you switch to manual mode - like 1 second, does the meter work correctly?

06-14-2021, 02:06 PM	#5
Wasp Pentaxian Join Date: Mar 2017 Location: Pretoria Photos: Gallery Posts: 4,661	Originally posted by aslyfox I agree you need to find a specialist but just in case here is the pdf of the service manual https://learncamerarepair.com/downloads/pdf/pentax-lx-service-manual.pdf The manual is interesting and intimidating at the same time. Opening one of these up is not for the faint of heart. I was wondering about component level repair of the electronics but the manual is silent on that - not even a circuit diagram. There is one small clue. Part T100 in figure 4 seems to be the main board. The drawing shows the outline of an IC on it. This was probably made for/by Pentax from what is now unobtanium.

06-14-2021, 05:15 PM	#6
Huss Veteran Member Join Date: Apr 2020 Posts: 629	Originally posted by huge10 If I turn the shutter speed dial off the automatic setting (to one of the manual speeds) camera stays in automatic mode. Any of you has encountered this and knows what causes this? And can tell how to remedy it? Regards, Wim Hey Wim. Sorry to hear about your issues. Out of curiosity was this camera working for you at any time? Or did you buy it broken?

06-15-2021, 12:58 PM	#7
huge10 Forum Member Join Date: Mar 2018 Location: Apeldoorn, The Netherlands Posts: 62 Original Poster	Originally posted by Huss Hey Wim. Sorry to hear about your issues. Out of curiosity was this camera working for you at any time? Or did you buy it broken? I bought it with this issue. It has very clean outside looks. Would be nice if it could be reapired.

06-15-2021, 01:33 PM	#8
Huss Veteran Member Join Date: Apr 2020 Posts: 629	Originally posted by huge10 I bought it with this issue. It has very clean outside looks. Would be nice if it could be reapired. Should have asked, in the A mode - does it work properly? Exposures/shutter timing seems correct?

06-16-2021, 12:55 AM	#9
huge10 Forum Member Join Date: Mar 2018 Location: Apeldoorn, The Netherlands Posts: 62 Original Poster	Originally posted by Huss Should have asked, in the A mode - does it work properly? Exposures/shutter timing seems correct? Didn't test it with film, but long times sound correct.

06-16-2021, 01:42 AM	#10
Lord Lucan Pentaxian Join Date: Sep 2017 Location: South Wales Photos: Gallery Posts: 2,977	The LX has two different manual modes. At speeds of X (1/75 sec) and faster, it is mechanical. At lower speeds it is electronic. They are largely independent of each other except for using the same shutter, which you know works because it works in Auto. So does your LX fail to work in both those different speed ranges? If so, I would suspect the speed selector dial is simply not turning the contact mechanism below, which is staying in Auto despite turning the dial.

06-16-2021, 11:58 AM	#12
huge10 Forum Member Join Date: Mar 2018 Location: Apeldoorn, The Netherlands Posts: 62 Original Poster	Originally posted by Lord Lucan The LX has two different manual modes. At speeds of X (1/75 sec) and faster, it is mechanical. At lower speeds it is electronic. They are largely independent of each other except for using the same shutter, which you know works because it works in Auto. So does your LX fail to work in both those different speed ranges? If so, I would suspect the speed selector dial is simply not turning the contact mechanism below, which is staying in Auto despite turning the dial. I checked with the service manual. There is a switch near the film advance mechanism that switches from auto to manual. Wish me luck in getting in there and see if something is wrong there.

07-04-2021, 09:19 AM	#13
LesDMess Pentaxian Join Date: May 2011 Location: Santa Cruz, CA Photos: Albums Posts: 3,235	Originally posted by huge10 I checked with the service manual. There is a switch near the film advance mechanism that switches from auto to manual. Wish me luck in getting in there and see if something is wrong there. Good luck!