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Repairing a Videx Speaker Unit Module

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Mikel

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Hi

I would like to save £50 or so and see if it may be possible to repair this unit. It is a Videx 836-1 Speaker Unit Module that enables communication via a remote phone link between a pair of gates and our house nearby. The fault occured after a lightning strike some time ago and after some helpful assistance from Videx technical support I have managed to fix all the problems except just one.

The problem is that nothing is heard at the phone handset (at the house) when anyone speaks into the microphone (although communication the other way is fine) I have eliminated the cable as an issue and checked all the voltages on the unit and they all as spec For instance when the handset goes off hook the DC voltage of 8V across the mic pins drops to 0.47 as expected. Videx sent me another mic to try so I know this is not the problem. Not being an expert in this area I was wondering how complex this could be to fix and whether I could even augment the current PCB with something I could knock up myself. I can send a photo of the PCB if needed

Many thanks
 
Is it a 2 way system? If so, your speaker may be what's bad. Try replacing the speaker in both sides of the unit in addition to the mic.
 
The way this works is that there is a telephone handset in the house that when off hook transmits speech properly to the speaker in the unit However the mic in the unit does not transmit speech to the handset receiver Videx tech support seemed to think the handset receiver is OK because of the voltage drops when the handset is taken off hook Also I can here some AC hum from the receiver suggesting that this is OK
 
Each end has both a speaker and microphone.

Now you have verified that all circuitry works, and the wires between everything is good, right?
If so, the only things that could still be broken are the mikes or speakers...

House microphone --> Remote speaker
House speaker <-- Remote microphone

So we know the house microphone and the remote speaker are good, because we CAN talk TO the remote.
Either the house speaker or the remote microphone is broken, because we CANNOT talk TO the house.

I think you said the remote microphone has been replaced, so that only leaves the house speaker to be the bad part.

A photo could help too :)
 
Last edited:
Each end has both a speaker and microphone.

Now you have verified that all circuitry works, and the wires between everything is good, right?

Actually I said that I had eliminated the wiring. Videx tech support asked me to check various voltages on the board which I did and they said these were as expected Whether this means the circuits are OK I do not know I suspect not but would like to check if possible They think the unit is at fault because the voltage drops when the receiver is taken off hook

I have attached a photo of the board if this helps I have arrowed 3 items of interest

1 Component D1 is connected between the mic and the pin out to the handset
2. What I think is a capacitor and marked MIC on the board (part hidden in photo) is connected across the mic leads
3. A volume control (VR in photo) connected to one of the mic connections

What do you think the components involved with the mic are and maybe I can check if these are OK or not?

Thanks

Videx.JPG
 
Same problem with videx 836

Hi
my father has the same problem as mikel with his videx 836-did this ever get resolved please and if so how do i fix it?
Regards
 
Miracles do happen

Hi
Thanks for the reply.
Funnily enough my mate came up and tried swapping two wires and it didn't work-As we were giving up it sparked into life!!!
It seems ok now-Would you credit that?
Regards
 
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