How to fix the broken pc sync port on a Lens: Mamiya-Sekor SF C 150 F/4 for the RB67?

[Certain Exposures]

The problem

I have a Mamiya Sekor C medium format lens with a problematic PC sync port.

Edit: My lens is a Mamiya-Sekor SF C 150 F/4 for the Mamiya RB67.

The PC sync port "works" because the lens will activate a flash at all shutter speeds with a PC sync cable connected. However, the PC sync port does not allow the entire male PC sync cable head to fit inside the female PC sync port; i.e., a light touch or tug can remove the PC sync cable. I have a second lens, and its PC sync port has "resistance" similar to a 35mm SLR's PC sync port.

Things I've tried

1. Shining a flashlight into the PC sync port: there's no obstruction inside the PC sync port. Also, the broken port looks identical to the working one.
2. Attaching and removing the PC sync cable (with gentle pressure) repeatedly: the PC sync cable meets resistance well before you can fully seat the PC sync cable.
3. Using air: putting compressed air through the PC sync port made no difference.

Do any of you have recommendations for what to try next?

 

[Kino]

Sounds like the internal contact, which should slide along the edge of the male portion of the PC connector has been pushed/bent down into the path of the pin and is blocking the insertion. It could be pushed far enough down you can't even see the contact and it blocks the pin, but retains the ability to fire the strobe.

You could just strap it down with a velcro strap while you shoot, otherwise it's probably going to take disassembling the lens to put it right.

Another strange fix would be to buy a sync cord just for that lens and try trimming the center post down incrementally until it sits flush but still makes contact and then crimp the outer ring down a bit to get it to hold on during use.

Not ideal but...

 

[BrianShaw]

I don’t know about that brand, but noticed on another brand that there appeared to be a rubber o-ring of sorts in the PC port to make the connection tight. I seem to recall that the o-ring wore out and got crammed on the bottom of the PC port. I have no idea if this is your situation but you might want to look for a similar obstruction.

 

[reddesert]

What kind of lens? There are a lot of different Mamiya lenses that have a "C" on them. I am guessing that you are talking about a lens for RB67, but there are other kinds. It matters a little because the way the PC sync port is mounted is different, so the difficulty of servicing would be different.

It seems likeliest that there is an obstruction and you're not seeing it; probing the port with a pin or needle may be informative.

Depending on how often you use the PC sync, I would consider a variant of Kino's solution, get a short PC extension cord, gently crimp it to stay on, and tape it to the lens to serve as a strain relief.

 

[MattKing]

@Mamiya_Repair may be able to help with your question.
I agree though - which lens?

 

[MattKing]

Thanks for the lens details - I've included them in your thread title.

 

[Certain Exposures]

Thanks for the lens details - I've included them in your thread title.

Thank you.

Thanks for the replies so far, everyone. I will consider them and follow up. I may include photos at a later time.

Please feel free to add anymore thoughts if you're reading this.

 

[Mamiya_Repair]

Your problem is caused by the plastic liner inside the PC terminal becoming damaged, this is very common. Mamiya put this liner in the PC terminals of early (up until around 1979) C lenses. Solution is to have the socket replaced.

 

[Certain Exposures]

....Solution is to have the socket replaced.

....it's probably going to take disassembling the lens to put it right.

How would either of you rate the difficulty level of taking apart the lens enough to replace the PC sync port?

 

[Sirius Glass]

Replace the PC port or send it to KEH and let them fix the problem.

 

[Kino]

How would either of you rate the difficulty level of taking apart the lens enough to replace the PC sync port?

I've dabbled in a lot of amateur camera repairs, but I wouldn't touch that with a 10 foot pole...

 

[Alan Edward Klein]

The problem

I have a Mamiya Sekor C medium format lens with a problematic PC sync port.

Edit: My lens is a Mamiya-Sekor SF C 150 F/4 for the Mamiya RB67.

The PC sync port "works" because the lens will activate a flash at all shutter speeds with a PC sync cable connected. However, the PC sync port does not allow the entire male PC sync cable head to fit inside the female PC sync port; i.e., a light touch or tug can remove the PC sync cable. I have a second lens, and its PC sync port has "resistance" similar to a 35mm SLR's PC sync port.

Things I've tried

1. Shining a flashlight into the PC sync port: there's no obstruction inside the PC sync port. Also, the broken port looks identical to the working one.
2. Attaching and removing the PC sync cable (with gentle pressure) repeatedly: the PC sync cable meets resistance well before you can fully seat the PC sync cable.
3. Using air: putting compressed air through the PC sync port made no difference.

Do any of you have recommendations for what to try next?

Use masking tape to hold it in place when shooting.

 

[Sirius Glass]

I've dabbled in a lot of amateur camera repairs, but I wouldn't touch that with a 10 foot pole...

A good camera repair person is your best friend and worth the money. Send it off to KEH for the repair.

 

[Mamiya_Repair]

How would either of you rate the difficulty level of taking apart the lens enough to replace the PC sync port?

While I don't know your level of skill with small parts, this repair is actually trivial, no lens disassembly needed, only removing two screws holding the PC terminal base to the lens and then screwing in a new terminal and lining up the spring contact.

 

[Kino]

While I don't know your level of skill with small parts, this repair is actually trivial, no lens disassembly needed, only removing two screws holding the PC terminal base to the lens and then screwing in a new terminal and lining up the spring contact.

Good to know! Lenses are incredibly variable as to how hard repairs can be.

I stand corrected!

 

[Certain Exposures]

Just an update...I don't have an update! I have not abandoned this repair though. I'll keep you posted. Thanks for all the replies so far.

 

[Certain Exposures]

Update: the PC sync no longer works. Unfortunately, I discovered this fact on a shoot . The replacement part is on my list of things to order once I can. Thanks again.

 

[Certain Exposures]

Do any of you have recommendations for where to purchase this PC sync port replacement part? How much is it worth? I’m keeping an eye out for broken 150 SF lenses that have the part intact.

 

[MCB18]

Do any of you have recommendations for where to purchase this PC sync port replacement part? How much is it worth? I’m keeping an eye out for broken 150 SF lenses that have the part intact.

Bill from Mamiya Repair (@Mamiya_Repair, already on this thread I see) may have it. I’d email him and see if he does.

 

[Certain Exposures]

Bill from Mamiya Repair (@Mamiya_Repair, already on this thread I see) may have it. I’d email him and see if he does.

Ok, thank you.

 

[Certain Exposures]

Update:

I fixed my PC sync port. I purchased the replacement part from Bill at Mamiya Repair and installed it myself.

The replacement fits a pc sync cable like a glove and fires properly on all speeds.

Thank you to everyone that replied.

 

[BrianShaw]

Yay!

 

[Certain Exposures]

Mods, could we add "[Solved]" or something to indicate that the problem was resolved to the title? I look for that when I'm doing searches.

Yay!

 

[MattKing]

Mods, could we add "[Solved]" or something to indicate that the problem was resolved to the title? I look for that when I'm doing searches.

We don't, as a rule, do that here. There are lots of such threads, and it isn't unusual to have them evolve over time, and reveal more than one solution.

 

[Certain Exposures]

We don't, as a rule, do that here. There are lots of such threads, and it isn't unusual to have them evolve over time, and reveal more than one solution.

Okay