VM144 - led constantly illuminated, flickers on ring

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1

Hello, I bought the preassembled VM144 and wanted to use its relay output, upon connecting it to the telephone I found the led illuminated constantly and the led flickered from dull to bright when the telephone rang but the relay never activated.

I double checked that the unit had 12v supply and I checked the rj11 wiring (2 inner wires to pin 2 and 5 of a BT socket). I also removed all telephone extensions and connected the device to the master socket but the led lights up constantly (even without the psu connected)

Can you advise a solution to get the led to light up only when the phone rings and to be able to get the relay to activate

thanks
lifeoreilly

2

Are you using the item on a classic PSTN line, for which is was designed?
Nowerdays, there are a lot of ‘simulated’ PSTN lines, which are actually digital lines converted to analog, to allow the use of a classic telephone set.

3

It is a standard BT telephone line provided over a pair of copper wires for which I have a standard telephone plugged in.

I have two lines - one is telephone only and the other has vdsl and telephone. I have tested the product in both lines and it does the same. - I would guess that as vdsl is on one line then it would be a standard analogue line

4

Do you have a multimeter?
If you do, can you please measure what DC and what AC level you get from the line when idle. (nothing connected to the line).
It would also be nice if you could measure the levels when the phone is ringing.

5

I measured the following when the phone was idle:- 49.7v DC and 0v AC

and the following during ringing:- fluctuating between 48.3v and 53.4v DC and fluctuating between 110v and 140v AC

6

Since there is no AC present in idle conditions, the led should not light unless there is something wrong with the unit.
There are different options:
You can return the unit to your distributor for exchange or refund.
You could open the unit and check if you can spot a problem.
If you provide LINKS to HI-RES and SHARP pics of both SOLDER and COMPONENT side, then we can take a look and maybe provide some feedback.
You will not loose your warranty if you open the unit.

7

I opened the item up and there appears to be three points that are not soldered.

url to image:- zen107635.zen.co.uk/IMG_0685.JPG

The two in the middle do not have any component connected and the one on the top right is for one of the legs of the 105K 400V capacitor.

Is a component supposed to be connected there or is that a surplus item on the board?

8

We have the impression that one leg of the 400V cap is not soldered.
Can you please check this?
A picture of the component side would help.

9

yes - the leg isn’t soldered to the board - it has no contact

10

Sorry to read that this is the case.
For some unknown reason this has not been noticed by QC, for which we apologize.
There are two options, either you can solder it yourself or you can return the unit for refund/exchange to your distributor.

11

I soldered the joint however the led still lights up so I am guessing there must be something else wrong with the unit - I will return it to the distributor for a replacement

12

Sorry that you had to go through all this trouble. This is really unusual.
Please keep us informed.