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Bengi
Tinkerer
Username: Bengi
Post Number: 28
Registered: 11-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 22, 2010 - 02:12 pm: | 
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Well, the subject is pretty selfexplanatory: the flash (tested several, from the Pentax,to Starblitz to Metz) flashes only if connected to the FP plug, no way with X and hotshoe.
I removed the top plate and noticed that if I touch the metal parts of the camera AND the flash sync contacts the flash ready light on the flash switch off, sort of short?
Ben |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 61
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 27, 2010 - 10:32 am: |
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Get the Petnax MX Service manual at http://www.robertstech.com/files/mx_sm.pdf . It includes a schematic. Note that it is not 100% error-free, someone decided to "improve" it by retyping the scanned text, and errors were made.
The wiring for the flash sync goes all over the place, through various connections between different parts of the camera body. You probably need to pull the bottom plate and the front of the camera. You'll need a ohmmeter for troubleshooting. There are some spring contacts between the front plate assembly (with the PC jacks) and the body of the camera that may not be working. There may also be failed solder joints, possibly from a prior repairer who was not competent with a soldering iron. (Soldering tiny wires to PC board pads isn't easy.) Or some wire may be mis-connected. |
Don
Tinkerer
Username: Don
Post Number: 61
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 29, 2010 - 06:39 am: |
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If the top is still off, try bending the flash contact by the viewfinder up slightly. If someone worked on the camera before, they may have bent it down a bit so it does'nt make contact w/the top cover. Or there could be oxidation on the 2 contacts. |
Bengi
Tinkerer
Username: Bengi
Post Number: 29
Registered: 11-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 09, 2010 - 02:03 pm: |
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thanks, but is it normal the symptom that I describe in the second sentence of my post? I mean, with the top cover off should the camere trigger the flash connected to the X plug?
Ben |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 62
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 12, 2010 - 01:42 pm: |
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What a flash sync does to fire the flash is to short the inner and outer contacts of the "PC" flash connector, or to short the contact in the middle of the flash shoe to the shoe itself.
You need an ohmmeter, the basic ability to read a schematic, and the service manual.
Alternative is probably a $40 service bill at http://www.pentaxs.com. Or have Eric do a full CLA. |
Bengi
Tinkerer
Username: Bengi
Post Number: 30
Registered: 11-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 23, 2010 - 11:46 pm: |
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I have played around and realized the top cover has something wrong: with top cover off, the camera triggers the flash whenf I press the shutter button with a metal tool. I have bended the contacts and now one is broken. Will probably look for a top cover on eBay,
thank for the suggestions, what a great forum,
I wish and your dears serenity and peace,
Ben |
