Re: KX-T: Power Supply for TVS 200

[Paul H. Gusciora]

Michael

Looking at the service manual for the KX-TVS200 / KX-TVS204

The full-wave bridge rectifier for line power formed by diodes D21-D28 are likely to be the components that fail first. Two diodes in series (21-22, 23-24, 25-26, 27-28) form each leg of the bridge. Usually, if one is trying to achieve a higher PRV, one must bypass the diodes with capacitors and resistors to equalize voltage drop. Since the circuit only has to handle 120 VAC (or 240 VAC) which is easily handled by a single diode, it is likely that the diodes are in series here to prevent failure in case (when) one of the diodes fails in shorted mode (milliseconds prior to opening because of excess current).

Recommendation:

1. Check all diodes D21-D28 in the bridge for short circuit conditions.
2. Look at one of the good diodes in the D21-D28 series for hints about replacements. It is likely that they are 1N200x equivalents (1 A forward current, x indicates PRV: 1==50V, etc. )

BTW: I had similar problems identifying relays and Zener diodes in the KX-A46 battery backup system so that I could understand the charge /dishcarge characteristics. I had to open the box to find identifying markings on the relays. I also had to connect external power to elucidate the voltage of a Zener diode.

Good luck,

Paul H. Gusciora
San Rafael, CA


From: "Michael Karaman" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Organization: The Phone Network, Inc.
Subject: KX-T: Power Supply for TVS 200
Date: Tue, 21 Jan 2003 16:56:26 -0500

Does anyone have an out of service TVS200 with a good power supply???? I
have a unit with a blown power rectifier and Pana parts cannot identify it.
Emailed a picture and everything, only a new one avail. I know it's only a
couple dollar part but I need a number. Haven't sent it to ATL for repair,
that's my next option.

Michael Karaman
President
The Phone Network, Inc.

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