KX-T: kxtd 408

[Larry]

Thats a different picture.  You have 4 dead digital ports in a row.

There are two protectors along the edge of the board that protect the 
digital ports in groups of 4.

The protectors are either micro fuses (look like axial resistors without 
color bands) or auto resetting ptc's (look like small disc capacitors 
with a bright finish).  More than likely, one of the four ports is 
shorted.  With no power to the KSU,  read the resistance between each of 
the digital pairs, one will likely have a much lower resistance.  Find 
the shorted component in that port.  Look for components that look like 
they were over-heated, shorted caps (esp disc), shorted pulse coil (both 
sides of the digital pair goes thru the coil) 

Looks like it's port 3 from your test, the other three ports should have 
a few volts on them.  You did have all the station cables disconnected 
when you ran your test?  A short in the house cable will take down the 4 
ports. 

Look for burnt traces around the protectors.  btw, fuses don't reset, 
ptcs latch off until power is removed.

Good luck

-l     

Lancia Ersatzteilservice C.C. wrote:
> Dear Larry
>  
> thank you for helping here
>  
> I did measure the digital part of the  8 extensions:
>  
> 1)  voltage spike every 2 seconds
> 2) dito
> 3) dead
> 4) voltage spike
> 5) 14.9 V
> 6) 14.9 V
> 7) 14.9 V
> 8)  14.9 V
>  
>  
> all the analogue parts are working... ie. I can connect analogue 
> phones on all extensions
> but system phone only on 5-8
>  
> now that looks like a hardware fault to me...
>  
> however can this be fixed or do I have to replace the whole pabx ?
>  
> Thanks Felix