Flickering Leds on KX-T7730 - cable problem?

[AlexArusha]

When I lift the receiver of my KX-T7730 set, the Leds flicker, and I have to punch buttons repeatedly to get a digit. It is connected to a KX-TA308 via 2 pairs of an STP cable, about 15 metres long.

1. When I connect the set to the KX-TA308 via the short original lead, it works without a problem.
2. When I use another KX-T7730 set on the STP cable, same problem.
3. When I connect to another jack of the KX-TA308, same problem.
4. When I ground the shielding of the STP cable, no improvement.
5. When I use regular 2 pair phone wire, same problem.
6. The weirdest of all: some days (2 days a month?) it just works.

Alex.

 

[rivet]

it sounds like a fault on the PSU

try this remove all exts from the board
then just plug 1 ext in see if it works ok
then just adding until it goes faulty

i had this happen on 3 sites and the supplier changed then and said it was a fault with the version of system.

 

[AlexArusha]

Thanks for your suggestion.
I tried it: I removed all extensions but the flickering one - no improvement. I wonder if it'd be the PSU - because it works on that short lead without a problem. I'm using Shielded Twisted Pair to rule out EMI.

I just got a break-through: when placing a 3.3 nF capacitor across the signal pair, flickering stops and I can dial without a problem. Hope this'll be a lasting solution.

 

[cwc3]

try using normal cat 3

 

[AlexArusha]

Thanks cwc3,

Tried that - see my point 5 above. I started out with Cat5 cable, when the problem started I switched to Cat3, then tried STP.

 

[cwc3]

you have a bum unit i'dd say

 

[AlexArusha]

Yes cwc3,

I agree with you. Where I am it'll take a week or 3 for a new unit to arrive, so I'm happy that my capacitor trick works.

 

[cwc3]

yeah if they knew that you were doing that it would void
the warrantee.

 

[AlexArusha]

The PABX is three years old. A small capacitor across a cable would void a warranty?