Mamiya RZ67 Shutter Speed Issue

[kinumim]

Just got a new Mamiya RZ67 and having some issue with the shutter speeds. 1 out of 5 times (ish) the shutter speed is wrong and seems to fire at 1/400. The problem persists between 2 of my lenses. I have so far switched out the battery and cleaned the electronic contacts (although I don't know if I did a very good job). Has anyone else had this issue?

 

[awty]

Just got a new Mamiya RZ67 and having some issue with the shutter speeds. 1 out of 5 times (ish) the shutter speed is wrong and seems to fire at 1/400. The problem persists between 2 of my lenses. I have so far switched out the battery and cleaned the electronic contacts (although I don't know if I did a very good job). Has anyone else had this issue?

These cameras were heavily used by professional photographers, hard to find a good body with out any issues.
Many things can cause this, one of my bodies had trouble cocking some lenses, after spending a lot of time trying to fix I ended up just getting another body.
It maybe that it just needs a little lubrication and some use to get it working again.
If you take the film back off, turn the little switch on the side to M it will fire. Put it on a slow speed and fire it while looking through the lens. If it looks like it is only opening to 400th every 5th or so go it maybe and electrical fault or maybe the firing button is not locked in the downward position....maybe.
If it dosnt let you cock because the lens hasn't fired then it can be a mechanical issue.
Lots of things can go wrong with these cameras and there isnt much in the way of spare parts or people willing to repair them.
Good luck, they do have awesome lenses.

 

[wiltw]

The RZ67 uses the Seiko electronically timed shutter. If there is no battery power to the timing circit in the body, the shutter defaults to a mechanical shutter speed, in this case 1/400.

So the fact that the shutter sometimes defaults to 1/400 indicates a possible shakey connection in the path from A) the timing circuit in the body B) thru the bellows wiring C) to the lens mount D) to the lens contacts D) thru the lens wiring to the shutter

The fact that you have issue with 2 lenses and (I presume) not others would seem to indicate wriing thru the bellows to the contacts in the mount are not the issue, but that two of your lenses may have a contact problem A) at the lens mount, or B) internal wiring within the lens. I suggest taking a pencil eraser to rub against the lens contacts, blow off the contacts thoroughly, and try.