DRV and Multiplexor problem

[azamtim 0]

hi,

recently installed a 8 channel DVR (pc based) with 7 cameras and multiplexor (quad).

The problem i'm having is when I connect them all up, the cameras that connect to both DVR and multiplexor act weirdly:

- 1 camera is no image on both;

- 2 cameras is no image only on DVR, works on multiplexor;

- 1 camera works on both;

nothing wrong with cameras as I've been swapping them around.

when i unplug cameras from multiplexor they all work fine on DVR and vice versa.

the signal(cable) is split with BNC T-connector

 

My guess is that the camera psu in not giving enough power to support another device in the chain (multiplexor).

 

the PSU is 8channel 12V 5 AMP

 

Anyone came across similar situation?

 

Any help appreciated.

Thanks,

Tim

[Soundy 1]

It's nothing to do with the camera power supply, the cameras simply don't like the load presented by splitting the signal that way. What model DVR and MUX are you using? Most will have a set "daisy-chain" outputs along with the inputs that will load the cameras properly. If not, you may need some sort of proper signal splitter.

[azamtim 0]

Hi Soundy,

 

thanks for your reply!

 

the multiplexor is FS-204 "4 Camera Duplex Colour Multiplexer"

more at http://www.henrys.co.uk/cctv/cmp043.htm

 

the DVR card is Kodicom KMC8800

 

If what you're saying is true how come 1 camera works on both, 2 on MUX and 1 doesnot work at all ?

 

thanks for your help,

Tim

 

It's nothing to do with the camera power supply, the cameras simply don't like the load presented by splitting the signal that way. What model DVR and MUX are you using? Most will have a set "daisy-chain" outputs along with the inputs that will load the cameras properly. If not, you may need some sort of proper signal splitter.

[Soundy 1]

Are they all the same make/model camera? Where are the T-connectors (at the DVR or the MUX)? If you run the camera through the T, but don't connect the T to device, do those cameras still work fine?

[azamtim 0]

hi,

the T-connectors are by the DVR, all cameras are same make and model.

Did not quite understand the last question...

If i unplug the MUX from t-con the camera shows up on DVR fine.

[crirvine 0]

THINK THIS WAY you have a pipe with water running in it you put a y on it now 1/2 the water runs in each pipe most cameras allow you to adjust the video output level of the camera. In electronics when you split a signal with a T that is a 3db loss or 1/2 of your signal. This is all basic electronics.

 

Soundy he might be having video out level low and needs to set the video output of the camera to 1 volt peak to peak. Most of the dvrs I see like the video a little higher than a crt monitor. The only problem is most people do not have a video meter like fm systems meter to set cameras with.

[Soundy 1]

Yup, your problem is definitely caused by splitting the signal. It may also be complicated by iffy BNC connections or cheap/dirty T-cons causing additional signal loss.

 

I haven't actually seen any cameras that let you change the output level or at least, have never had the need to look for the capability), but it's something you could look into. Double-check that none of your connectors are dirty, and possibly re-terminate the coax runs.

[azamtim 0]

What can you guys recommend then?

 

Thanks,

Tim

[crirvine 0]

What are the model cameras you are using I see the card you have does not have video out how far are the coax runs on the cameras what type coax are you using cheap coax can creat signal loss. are you using crimp on conectors or twist on rca conectors.

[azamtim 0]

Hi,

 

Coax - RG59 (quality one)

from cameras to DVR - about 15M

from DVR to MUX - about 10M

cameras - cheap ones, cannot remember the make

twist-on connectors

 

What are the model cameras you are using I see the card you have does not have video out how far are the coax runs on the cameras what type coax are you using cheap coax can creat signal loss. are you using crimp on conectors or twist on rca conectors.

[Soundy 1]

Twist-ons could be a part of your problem - they work just fine IF they're installed properly, BUT they can be tricky to get on right; getting a solid connection with them is far more sensitive to the cable being stripped back properly.

 

Others here will be able to point you at an electronic video splitter (I've never used one, personally), or you could replace the MUX with one that has ins AND outs on each channel (often called "looping inputs"), that will let you properly chain the signal through it.

[crirvine 0]

Soundy you are correct about the best and most cost effective choice now would be a new mux that allows loop through as it would cost more to replace the cameras to get what you need.

[Soundy 1]

A used color quad should go relatively cheaply... or for that matter, even a used 4- or 9-channel color simplex or duplex mux would suffice. Are these color or B&W cameras? If B&W, you could even go with a B&W mux for probably next to nothing.

[azamtim 0]

Thanks Soundy,

 

I think thats the best option!!

I never thought of sending the signal through MUX first (silly me)

I've always used to just split the signal in between with T-connector...

But what you've suggested sounds like a proper way of doing it.

 

The MUX i've got has in and out BNC female so it should be ok

 

I use color cameras with IR leds.

 

 

Thanks for your help!

 

A used color quad should go relatively cheaply... or for that matter, even a used 4- or 9-channel color simplex or duplex mux would suffice. Are these color or B&W cameras? If B&W, you could even go with a B&W mux for probably next to nothing.