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MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 08, 2005 - 03:00 pm: | 
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Hi all
I took my ME Super out of the cupboard after a couple of years rest (playing with these fangled digital thingies). The exposure LEDs worked OK, but I thought I'd change the batteries as a precaution against leakage. Big mistake, as now the LEDs don't work at all. Right batteries, right voltage, right way round but it's dead. Any ideas as to what it could be please? |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 08, 2005 - 05:45 pm: |
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First try cleaning the contacts with an abrasive contact cleaner.Pay particular attention to the inside of battery cap where it touches battery.Long term storage with batteries fitted can lead to severe 'oxide' formation on plated contacts,even if batteries do not leak.
If this does not work then you will require the help of somebody who knows the Pentax circuits.I only have experience of Canon slr.
Best of luck,Glenn. |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 09, 2005 - 01:11 am: |
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Glenn, thanks for your suggestion. The contacts looked clean when I took the batteries out, but I will give it a go.
Mike |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 09, 2005 - 11:25 am: |
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OK, now I really am confused! I cleaned the contacts but still no LEDs. Then I fitted a flash unit (Pentax AF200S) to the hot shoe. When I turned the flash unit on the exposure LEDs came on and worked correctly! When I turn the flash off they stopped working...
Does that give anyone any clues as to the problem?
Mike |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 09, 2005 - 04:58 pm: |
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Mike,
This may sound silly, but remove batteries from flash and repeat the above.The LEDs will a,work b,not work, obviously.If a,the feed circuit from battery is OK and some other circuit or wire is faulty.If b,this suggests that power is coming from flash unit and the camera feed circuit is at fault.This could simply be a dirty/corroded main switch or a corroded wire.Many cameras use a simple transistor to 'regulate' supply from battery,before feeding camera circuits.These transistors can fail.
If somebody can give the source of a good circuit diagram,I may be able to pin point the fault for you.
Glenn |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 12:32 pm: |
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Glenn
I tried your test and the answer was (b). The LEDs only work when the flash unit batteries are installed and it is switched on. Is the main switch in the shutter release mechanism? I found a service manual for this camera on the internet and if it's a simple job I might have a go.
Thanks,
Mike |
Don
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 03:10 pm: |
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To test the main sw. w/o disassembly, short the middle w/the outer MD teminal in the base. If the display works now, you have problem w/the main sw. To fix, you'll need to remove the top. It's not hard to get the top off as there are no wires going to the hot shoe, only a pressure connection but the wind cap screw & the ret. nut under it are both lh thread. Adj of the sw is done via an eccentric on the top wind side edge. The manual should be of help. Don |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 03:33 pm: |
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Don, is the MD terminal the row of three contacts for the wind motor? If so, does it matter which outer terminal I short the middle to?
Thanks.
Mike |
Don
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 04:46 pm: |
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Sorry -- should've been clearer on this. Yes & use the 1 closer to the end.
Don |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 05:04 pm: |
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Thanks Don. I appreciate all the advice I'm getting on this forum (my first visit!).
Mike |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 10, 2005 - 06:21 pm: |
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Mike,
I think with Don's help you might solve problem.As I said Canon are my area.In the official A series repair manuals there is always a simple yes/no type action list.This allows one to pinpoint the faulty part or circuit more easily.I would think that there will be a Pentax manual that has a similar diagram in it.If switch is OK and nobody comes up with another possibility for problem ,find a fault checking diagram and just do a logical elimination.Sometimes it points to quite a simple repair that even a novice can do.We all have to start somewhere if we are working on an unfamiliar camera,the logical approach can save a lot of headaches.
Glenn |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 10:30 am: |
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OK, making progress now. Don's test shows that it is a faulty switch. A friend has just given me an old ME Super body with working exposure meter to practice on! I've got the top cover off and traced the wiring, but the manual doesn't say how to service the switch. Do I need to take it apart to clean it?
Mike |
Don
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 11, 2005 - 01:13 pm: |
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Mike -- look at the camera from the front -along the top edge on the wind side. Where the body stops, you should see a small black crosspoint screw. Just to it's R. is the main sw. eccentric. It's been almost 20 yrs since I did this so I dont recall if you have to loosen the crosspoint screw or not to turn the eccentric so try turning it slightly. If it moves, then see what happens when you push the release rod. If not, loosen the cp screw & then try. If that does'nt do it, then theres a prob w/the front platecircuit bd. If needed, I can send a scan
of the exploded view. Part 0-A129 is the front circuit bd. Pentax might call it something else. There are 4 connections going to it. The bare wire 1 is the main sw. You can find the board by looking at the front from the top. its the part w/3 bent over tabs. But getting at them can be tricky.
Don |
MikeD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 12, 2005 - 10:56 am: |
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Thanks for that Don. I found the screws and checked the operation of the switch. The movement seemed to be OK, but there was no current passing through the contacts. I decided to clean them, but as they appear to be gold plated I didn't want to use anything abrasive. I managed to feed a strip of paper in between the contacts then drip some isopropyl alcohol onto it and wiggle. Presto! I now have a working exposure meter again.
Thank you (and Glenn) for your patient advice.
Mike |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 12, 2005 - 12:38 pm: |
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It was a pleasure,glad it all worked out and was a simple fix.
Glenn |
