Payphone interlocks

This is perhaps the most obscure, specialized question I have ever asked.

Dear people who own or have opened payphones:

As you know, you put the Real Key in the right, then you put the Giant Skate Key in the left to pull down the interlock teeth. And you can't re-latch the interlock teeth unless the front of the case is properly seated.

Well a friend and I spent literally an hour failing to seat the case. We can't get the fucker to latch. The bottom left is poking out by less than .5mm. Maybe something is bent but I can't tell what.

Is there a trick I'm missing?

Because my plan B at this point is to find someone with a welding torch to cut the interlock teeth off and "secure" the thing with a single screw.

Please save me from committing this atrocious act of mutilation.


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17 Responses:

  1. Would pictures of mine, or a video of mine help? I think ours are the same base model, though I don't have the handset amp button.

    There's a lip around the bottom of mine, and I can't engage the teeth unless the interlock is open. On the other hand, I can't remove my skate key unless the interlock is closed.

    • I put some pics at imgur. I swear I've run into this before, though, and it was just that the skate key was in the wrong position... Like Ryan, though, I cannot reproduce it in my kitchen.

      • Ryan Finnie says:

        Not relevant to jwz's question, but FYI: When I bought my phone, it didn't come with real locks. That's good, since many phones on eBay come locked but without keys, and apparently drilling out the locks is borderline impossible (public payphones are hard to destroy, imagine that). I did eventually buy replacement locks but never installed them, out of fear I may lose the keys.

        I also have the solenoid assembly, but use a piece of wire to hold it open, so coins drop straight through to the coin box. In theory it could be made to work as intended (holding the coins until the call is accepted, then giving it a control signal to open the solenoid), but I seem to remember it's not something my ATA adapter could generate.

  2. Ryan Finnie says:

    I cannot reproduce on the phone in my, err, kitchen... but here's some photos if it'll help. Interlock open (, closed (, and 3/4 view open ( The paint removed on the bottom latch (and a little on the top, but not the middle) suggests it's really making contact with the inner locking plate, so maybe you could shave that down.

    • jwz says:

      Yeah both yours and Michael's are what mine looks like, except dirtier and with more scrape marks.

  3. Karl says:

    The lock and arms are fully disengaged, and you're only trying to get the top cover arms engaged? And you can fully engage and disengage the arms using the T-bar when the top cover is removed? And you have fully disengaged them before you attempted to assemble the phone? And the same top cover was assembled to the rest of the case and engaged properly before you started?

    Something changed to make it not able to engage again. Did you drop it or bend something?

    One little thing is blocking the assembly, the problem is that you can't see it during assembly.

    Make sure nothing loose is blocking the arms. Tape down wires, sweep out screws, broken plastic bits, lint etc.

    Make sure the lock and the arm assembly are firmly attached and aren't wiggling out of place.

    Make sure the cover is straight at all times while you slide it on. If you can't engage the arms, bump it lightly with a rubber mallet in several places to align it, attempt again, repeat. Usually it is easier when the phone is upright, sometimes it helps to put it on its back.

    I've tried marking the parts with chalk or grease pencil and seeing what rubs off, but I've never gotten anywhere with that.

    You might be able to saw off the arms one by one until you find the one that's catching, hopefully before the last one.

    • jwz says:

      Yup, all of this. The root of the problem seems to be that when I slide the cover on, it doesn't seat evenly. The bottom left corner sticks out just a hair farther than the right. I can't see anything blocking it, and I can't imagine how anything could have bent, every single thing being cast iron and all.

      It was always hard to get it to latch, but now that's advanced to "impossible".

      • Nick Gully says:

        Could you shrink the cover with dry ice or leave in the freezer overnight, just to give yourself another fraction of a mm?

      • Karl says:

        One more thing, try gently frobbing the tbar during assembly. The top case must be square and level with the rest of the chassis at all times, but jiggling the arms sometimes helps to mush everything together. You kind of need three hands for this. It may be easier to have the phone on its back as you do this. In general I find it easier to keep everything square with the phone upright, that's how it's meant to be assembled, but the gravity assist sometimes makes it easier to ease in.

        • jwz says:

          So of course, after telling everyone "we spent an hour and couldn't get it back on!" I tried again a few days later and it went on smooth as butter.

          But I hadn't re-assembled the computer, so I get to try again tomorrow. What will the future hold?

  4. Mark E Crane says:

    I came back to this thread hoping for a resolution and was not disappointed.

    • jwz says:

      Oh, it's not over yet. I came in today to put it back together, and it was finicky again but I did succeed... except that the reason that I opened it up in the first place was that the keypad was flaking out. I thought I had fixed that. I was wrong. It went from "half the buttons don't work" to "press any button and it goes koo koo krazypants for 15 seconds". So that's great.

      I am not good at this hardware shit.

      • BHN says:

        This is how hardware behaves when it is lonely and needs some attention, jwz. Your payphone just wants some cuddle time.

      • I think "committing this atrocious act of mutilation" is the right thing to do. Though probably an angle-grinder would suffice.

        Given that its purpose is to be a cool-looking enclosure for some entertaining hackery, some major surgery is justified. I can't remember previous discussion of this object, but I guess it is no longer guarding a precious box of quarters against roaming gangs of crowbar wielding pilferers.