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Re: [TenTec] How Much Damage From Reversed Polarity?

To: tentec@contesting.com
Subject: Re: [TenTec] How Much Damage From Reversed Polarity?
From: doc <kd4e@arrl.net>
Reply-to: kd4e@arrl.net, tentec@contesting.com
Date: Sun, 09 May 2004 20:14:21 -0400
List-post: <mailto:tentec@contesting.com>
I have lifted the damaged zener, no effect.

I am going to replace the transistor with a 2N2222
per the recommendation of Tentec.

Will advise later in the week when I again have a few
minutes to work on the rig.

Thanks to all for the helpful advise and encouragement!

73, doc kd4e

Bert Braun, DD5XL wrote:
doc schrieb:

There is no visible damage to anything that I can
see on the little circuit board to which the power
connector is soldered.  No smell of something
burned either.

I am looking at the schematic 4-32 in the Op Manual.

Any suggestions as to which device(s) is(are) most
likely to have failed, please?


Check the D2 16V zener diode.
If its shorted, the relay will never close. D2 and Q2 act as overvoltage protection, a shorted diode will cause a overvoltage protection even when the supply voltage is in range.
If you are sure providing the right voltage, you may simply cut off the diode. If it was faulty, the TRX will work as usually without the diode, but overvoltage protection is disabled, so be careful with your power supplies!



73 de Bert


--
Thanks! & 73, doc kd4e
West Central Florida
Drake, Heathkit, Kenwood, TenTec, Yaesu
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