How to fault find an Urmet analogue coax video system

This article will help you fault find an Urmet analogue coax video system.

Fault - NO CALL

  • Check connection from PS terminal (call tone output) of 789/5 power supply to common side of call buttons. (For multi entrance systems contact Technical Support)
  • Measure the voltage between the entry panel camera terminal R1 and the common of the call buttons. It should be 19V DC
  • On the monitor bracket measure between terminals R1 and CA. When the call button for that monitor is pressed the voltage should be 19V DC (only while the button is pressed)


  • If the fault is isolated to one monitor, check connections 1,2 and 6 of that monitor
  • If the fault is common to all monitors measure the voltage between the – and + terminals on the speaker/mic unit in the entry panel. The voltage should be 6V DC. Check that the polarity is correct
  • To test the operation of the speaker/mic unit proceed as follows – Remove the wires in terminals 1A and 2 of the speaker/mic (leaving the wires in – and + connected). Connect a monitor on a short cable directly to the speaker/mic as follows:-
Monitor  Speaker/mic
 - (minus)

When you lift the handset you should have speech between the test monitor and the entry panel. If you do the fault lies in the wiring of the system.


  • The lock release output from the 789/5 power supply is 12V AC @ 1A. There is a relay inside the power supply (SE1, SE2 & SE3) that can be used to control a lock release. If you are using a DC release, a separate DC power supply will be required
  • Measure between the ~0 and ~12 terminals of the power supply. The voltage should be at least 12V AC. Remove the two connections from the lock release; connect your meter to the two wires, when the lock button is pressed on the monitor your meter should read 12V AC while the button is being pressed
  • To test the lock release circuit of the power supply, first remove any wires that are in the AP terminal. Use a short link of wire to touch the R1 connection to the AP terminal. When you do this you should hear the relay inside the power supply clicking. Use a meter to test the SE1, SE2 & SE3 relay output connections

Fault - NO VIDEO

  • The monitor will not switch on unless it rings. If there is no call to the monitor rectify this fault first
  • If the monitor screen lights up but there is no picture measure the resistance between terminals V3 and V5 (coax) on the camera in the entry panel. The reading should be between 75 and 80 ohms. (Check first that you have fitted the 75 ohm resistor between terminals V4 and V5 in the monitor bracket)
  • Press a call button on the entry panel and measure the voltage between R1 and +TC on the camera in the entry panel. It should be 18V DC with R1 being 0V. Check the polarity is correct
  • If the monitor rings but the screen does not light up, measure between terminals R1 and R2 on the power supply (R1 being 0V). After the call button is pressed you should read 18V DC. This is the supply voltage to the monitor and will stay on for about 45 seconds. If this voltage is not present, disconnect all wires in the R2 and +TC terminals, switch off the mains supply for five minutes, switch the mains back on and repeat the test. If you now have 18V DC it is likely that there is a short circuit in the wiring
Mark is the author of this solution article.

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