[AMPS] Blow TL922

[Helmut (DF7ZS)]

Quite a succesful weekend working on my TL922...

I replaced the 470uH L2's with a R 27 Ohm and
a 1000pF C. There is already a 220pF C in place.
The Zennerdiode ZX 7,5 was replaced by a 6.8 V
1 watts type and a MJE 3055 (100V 10A) transistor.

The strange effects on the IP meeter turned out to be
a few blown resistors around the meeter. The 0,68 O.
was OK, one 1 O was blown and the 1.5 K near the
IP meeter also.  After replacing them the meeter was
still kind of missreding (might got a hit also) so we had
adjust a litle with a other R parralel to the 1.5 K.

We tested Voltages first without tubes and later with
tubes. One test QSO later went well to.

The baby is back online.

Thanks to all the usefull tip's and hints.

I'll do some of Rich's circuit improvements as the
next step. The heating Voltage measures 5.51
Volts ... a bit high.

I am quite confident that the L2's were blown by
a shorted tube on a first incident and did not got
replaced. After replacing the defective tube the
TL922 had about 20 hours on duty and the secound
incident happend on standby. We were not able
to figure out what happend here .... .

Thanks again and have a great week !

73sss

            Helmut (DF7ZS)
____________________________________________
<A>bort, <R>etry or <I>nfluence with larger hammer !

-----Ursprüngliche Nachricht-----
Von: Helmut (DF7ZS) <df7zs@gmx.net>
An: AMPS@contesting.com <AMPS@contesting.com>
Datum: Donnerstag, 24. Februar 2000 13:37
Betreff: [AMPS] Blow TL922


>
>Hi there.
>
>I have a TL922 by Kenwood and the folowing happend to it:
>
>On Standby-Mode (after some minutes operation) I heard
>a loud "bang" . As I looked on the panel the IP-Meter was
>showing 500mA. Remember the Amp is set to STANDBY
>not to operate nor the PTT is hit.
>
>My guess was maybe a missreading so I pushed the PTT
>and sended out a short burst via mike. The Power meter
>showed that the AMP is delivering about 1000 watts as
>normal. Back to standby - the IP reading is still 500mA.
>
>I turned the thing off.
>
>Any Ideas what happend ?
>Anyone had a simular problem in the past ?
>I am also seeking for a Service Manual to
>download or faxpoll.
>
>Thanks for any help !!!
>
>73sss
>
>            Helmut (DF7ZS)
>____________________________________________
><A>bort, <R>etry or <I>nfluence with larger hammer !
>
>
>
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>


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