Hook Switch help on cradle Decotel phone

[meganul]

Hi! Would appreciate any and all help on this issue! Sorry if any of my vocabulary is incorrect, I am completely naive to the telephone world.

I'm building an audio guestbook for my sister's wedding in early September. Using a deco tel phone (pictured below). I've wired the phone to a Teensy Microcontroller to run code that allows a voice message to play when the hand set is lifted, and then a recording to occur through the microphone. The code should shut off when the handset is replaced onto the hanging hook switch.

I've successfully wired everything to the phone and the code works seamlessly. My issue is that when I replace the handset to the cradle, it doesn't trigger continuity between the hook switch contacts, so the code never shuts off. I can manually depress the hook switch plunger and trigger the handset to be "replaced".

I think my issue is related to the spring that connects the hook switch to the plunger. I have tried tightening the existing spring, and tried replacing the spring with 4 different new springs without any luck. Not sure if there is a separate issue with the hook switch contacts, or if im just not yet successful in the right spring tension that will allow the phone to depress the hook switch to just the right spot. Any advice would be greatly appreciated !!!! 

TLDR; need help with lethargic hook switch on cradle decotel phone

[HarrySmith]

Welcome to the forum!
I am sure we can figure this out.
Pictures of the inside moving parts of the switch hook might help.
I for one am not familiar with the insides of those phones.

[meganul]

Attached a few photos of the inside of the phone.

The gold piece in the housing is connected to the cradle which depresses the white plunger. I notice that the phone only "hangs up" when the cradle/hookswitch is depressed just slightly above a completely depressed position. If the spring is too loose, placing the phone on the cradle allows the hook switch to fall quickly to the bottom, bypassing the section that the contacts create continuity.

If I depress the plunger manually without involving the cradle portion at all, the phone goes on on off the hook easily with one quick press of the plunger.

Not sure if I will find a spring with the exact amount of tension required to allow the cradle to depress perfectly, or if I'm over-simplifying my problem.

really appreciate any thoughts!

[TelePlay]

Is this the hook switch plunger?

[FABphones]

Did it function correctly before the additional wiring was put in? The spaghetti of wires may be causing an obstruction when the phone is closed up. I would lace those (it will look neater too).

[paul-f]

My issue is that when I replace the handset to the cradle, it doesn't trigger continuity between the hook switch contacts, so the code never shuts off. I can manually depress the hook switch plunger and trigger the handset to be "replaced".

I think my issue is related to the spring that connects the hook switch to the plunger. ...

Welcome to the group!

In addition to the spring, consider all other mechanical components that connect the cradle to the hookswitch. In some phones, the space between the plunger and the housing becomes clogged with dirt and grime. If it's binding, try cleaning with a good cleaner or degreaser (that doesn't dissolve plastic). Also check for damage that may have been caused by slamming the handset down too forcefully. Slightly bent parts can increase friction. Make sure the cradle returns smoothly to the up position when the handset is lifted.

[meganul]

Is this the hook switch plunger?

Yes, this is the hook switch

[meganul]

Did it function correctly before the additional wiring was put in? The spaghetti of wires may be causing an obstruction when the phone is closed up. I would lace those (it will look neater too).

The phone was functional in the sense that it turned on and created noise when I plugged it in, however I never used it as a phone because I don't have a telephone line and I didn't technically need it to work as a traditional telephone since I was adding a computer processor to it. Most of the nest of wires are pre-existing. I can also see into the housing and don't see a physical obstruction between the cradle and the plunger mechanism.