Help Me Get My GTE 120B Phone Working?

[olePigeon]

Hello,

I'm new to the forums.  I've scoured the forums as best I can, but I'm unable to progress further with my phone.

My situation:  I purchased a new-old-stock GTE 120B that had been pre-configured with a landline adapter kit, but it had no internals.  I also didn't like that it uses a regular electronic telephone ringer and not the pay phone's ringer.  Also, the half-height keypad doesn't have volume control, and it's very quiet (both receiving and sending) with no way to adjust it.

I do not have a POTS.  I'm using the phone with a Cell2Jack adapter.  It's powered by a 5v USB cell phone charger (this could be the problem.)

Over time I've purchased a full-height keypad, ringer, coin mech, relay, and "dumb" chassis motherboard to complete the phone.

I would like to get it working in its stock configuration if possible.  Judging by what other have said, I suspect the Cell2Jack can't provide enough power.  It works fine with the conversion kit, but if I try to use it with the actual payphone innards, it doesn't work.  I can't get a dial tone and the keypad doesn't respond.  I do get click when the receiver is pressed (not from the switch itself, but over the speaker), but no dial tone that I can hear, and no tones from the pad.  Although I don't know if keypads are interchangeable, so that could be a whole other issue.

I have it jumpered for "emergency pre-pay" per the instructions sheet, and I set the switch to 25 cents (20 + 5.)

I would appreciate any advice or suggestions.  I'm including a link to high res pictures.

Thank you.

[dsk]

May this help: https://www.classicrotaryphones.com/forum/index.php?topic=11987.msg127249#msg127249  ?

[olePigeon]

May this help: https://www.classicrotaryphones.com/forum/index.php?topic=11987.msg127249#msg127249  ?

Oh, thank you!  I figured I needed something to supplement it.  I'll have to ask other people for some help as I'm not very good with reading schematics.

I was also looking at a cheap scratch-built payphone controller.

[olePigeon]

According to this thread, I should just be able to plug it in?  Or am I reading it wrong?

If so, then perhaps there be an incompatibility with my Cell2Jack versus an actual phone line?

[olePigeon]

I may have to put this away.  I'm afraid I don't have the skill to build anything like this.  Thank you for linking to your project.

Without real POTS, I think my Cell2Jack is too underpowered to even use it as a regular telephone.

[leejor]

I have one of the Cell2Jack adapters, and even though I don't use it on a regular basis, it I've found that it seems to support just about any regular old telephone that I've plugged into it. If the keypad isn't working, then i suspect another issue, either wiring, or a bad keypad.
Standard coin phones used + and - 110 to 130 volts DC, to collect or reject the coin. The phone should work as a "normal" phone but will not be able to deal with the coins. These phones required a special payphone line with a connection to the equipment capable of sending these voltages.

A lot of "newer" coin phones rely on a current reversal to indicate an off hook as a signal to collect the coin(s). In many cases, this requires a special linecard, capable of providing this signal. This all depends on the type of switch at the central office.

[Stan S]

All the above comments are interesting however they have nothing to do with solving your problem. If you really have put the payphone in the prepay mode the coin trigger in the hopper must be in the down position or the payphone will be completely dead. Make sure you wired the coin relay properly then make sure the coin trigger is down. That simulates an initial deposit.

[Stan S]

I might as well add that your payphone (when you get it working) will only function like a standard desk set. You have no high voltage to trigger the coin relay. For your payphone to work 100% you need a payphone controller between the cell2jack and the payphone.

[Stan S]

Additionally all of the above assumes the payphone is in the COIN FIRST MODE. If you put it in the DTF DIAL TONE FIRST MODE it should come to life without an initial deposit.

[olePigeon]

I bought a another chassis for it on the offchance my original wasn't working, and it's the exact same behavior.

So I guess I just don't have the right equipment to get it working. :/

[Stan S]

Exactly what is your payphone NOT doing and what is it doing.

[olePigeon]

Apologies fore extremely long delay.  I am not ungrateful for the help, I appreciate it immensely.  We started the new school year and I've been very busy, so my hobbies were sidelined.  I also forgot my password during that time and apparently the answer to my secret question.  Forum doesn't send Password Reset emails (or at least I never saw it in my inbox or junk mail.)  Took me forever to guess my password after it locked me out for increasingly longer periods of time, but I figured it out and managed to set it.


OK, what it's NOT doing:

* No dial tone.
* Keypad doesn't even make tones when buttons are pressed.

What it IS doing:

* I can hear the receiver click when I lift the headset and toggle it.

Some additional background and troubleshooting steps I've taken:

* I've purchased two separate motherboards for the phone.  Both were "unknown working condition," and both are in rough shape.  It is entirely possible I simply bought two junk boards.
* I also purchased a new (different) keypad, but the behavior is unchanged.
* I even dragged the 20 pounds of phone into my office and plugged it into the POTS normally for the FAX machine.  I had wondered if my Cell2Jack didn't provide enough power to the phone for it even act as just a regular phone and detect a dial tone.  Unfortunately it still didn't work.


Please let me know if any additional pictures will help.  Closeups of anything specific you'd want to see.

If anyone knows of common failure points on this particular board, perhaps I can repair it.  I do have a multimeter and can check for continuity and voltages.  I find it peculiar that both boards exhibit the exact same behavior.

I'm also willing to purchase a known-good board if anyone has one.

Thank you for the help.

[olePigeon]

Some progress!  At least more progress than before, which previously was absolutely nothing.

Looked at the schematic some more.  I had it set to Emergency Pre-dial, but I noticed that that requires a battery hooked up to the coin slot (and I don't have one.)  Not sure if that mattered, so I set it to Regular Pre-Dial.  Unfortunately still nothing.  Looked on the forum and some people said that it's polarity sensitive.  So I rotated the jumper block (didn't think to bring a screw driver) 90 degrees, and I got a dial tone!  Granted, it was very quiet (even when set to max volume) and it had a constant clicking sound, but it was there. And I could dial on the keypad.

Grounding is of course wrong when I do that.  So when I get home I'll try swapping the polarity on the block terminal so the grounding is correct.  Hopefully that'll get rid of the clicking sound.

[olePigeon]

Some further progress.  If I disconnect the coin mech it stops the clicking sound and I can hear the dial tone, even though it's faint.

I can not transmit, however.  No keypad, no voice.

[olePigeon]

The cable from the keypad / receiver to the chassis is extremely temperamental.  My keypad is new-old-stock, so I'm inclined to believe it's the chassis.  I already sprayed it with some deoxit which helped a tiny bit.

I'm gonna take the chassis out and reflow all the solder, check the resistors, diodes, capacitors, etc.