Hasselblad A70 Service guide/manual/repair advice

This seems to be one of those things to have fallen through the cracks of the internet.

A lot of A70 backs out there aren't fully functional(even if they will mostly work). A lot have issues like the frame counter not resetting or not properly advancing to the first frame.

I have one such back that I made the mistake of tinkering with, and now it's REALLY broken-I know my own stupid mistake(it's not the only A70 I have, but all of mine have some sort of ill...) and I honestly can't make heads or tales of how to get it working. In fact I've wasted a decent bit of film(fortunately nothing rare, but no 70mm film is cheap these days) thinking it was fixed and then finding it still had an issue. Basically on this particular one, I fixed it so it will reset to zero when you pull the insert out, but now won't lock advance unless you manually turn the counter to frame 1, the white "advanced" flag never shows(which keeps it from firing), and the frame counter does not seem to advance.

This one may be parts now, but I'm hoping it can be saved.

As a bigger question, though, does anyone have the service manual for these? There's really not much in the way of instructions on the internet. The back service manuals I have cover the standard roll film backs(C type, A12, A24, etc) but not the A70. Even the instructions one finds don't actually cover the A70-they cover the 100/200 back, although they're close enough to get you there.

This may help,
link to manual on learncamerarepair.com;
Hassleblad Film Magazines Service Manual

bdial said:

This may help,
link to manual on learncamerarepair.com;
Hassleblad Film Magazines Service Manual

Click to expand...

I can only save it as web page. Thank you.

It’s not downloadable until you pay $2.58 USD

Here is the info on the 70mm back from the previously mentioned pdf.

Thanks everyone for the information. I actually already had the above linked PDF(I bought all the Hasselblad ones they have) and it does have the diagrams, but I was hoping there was some more detailed information along the lines of what's provided for the regular roll-fill backs.

In any case, I THINK I actually have this one working. I had a 6ft piece of developed film that was mostly blank(my own fault...) so I've been running that through the back just to test it. These backs are nearly impossible to test without film, as they rely on film winding around the sprocket wheel(or whatever you've replaced it with-plastic wheel with rubber ring in both my backs to allow any perf type) to interact with wind-on and stop it correctly. I worked it a bunch with the side plate off, something you CAN'T do without fogging film if it's loaded.

The issue I was having was related to the wheel that engages camera wind-on and transmits this to the film advance. This works similarly to how it works in a standard A12 back. It's two gears stacked on top of each other, and they "unlock" in the A70 when the counter mechanism tells them the film has been wound far enough. Like in a standard back, when in need of service, they can slip prematurely and in this case the film just wasn't winding far enough.

If this had been an A12 back, I'd have had badly overlapped frames.

It's been disassembled, cleaned, and carefully and sparingly oiled, and seems fine...