[Kenwood] TS-940S Dead

[Dennis Younker NE6I]

A heartfelt thank you to those that emailed me with suggestions.

I was doing some more troubleshooting tonight and was getting quite a few 
voltage measurements that didn't make any sense. Eventually, I pulled 
connector J5 on the AVR board to make some more measurements. I hadn't 
pulled this connector previously. Once again, I was getting measurements 
that didn't make sense to me. They were quite a bit lower than expected. 
Scratching my head, I plugged the connector back in and turned the radio on 
to continue making measurements. VOILA! The radio came right up and is 
operational.

Moral to the story, and I know to do this but didn't follow my own normal 
policy, carefully unplug and reseat ALL connectors on a suspect board as one 
of the first things you do when troubleshooting!

73, Dennis NE6I

-----Original Message-----
From: kenwood-bounces at mailman.qth.net
[mailto:kenwood-bounces at mailman.qth.net] On Behalf Of Dennis Younker NE6I
Sent: Sunday, December 08, 2013 7:46 PM
To: kenwood at mailman.qth.net
Subject: Re: [Kenwood] TS-940S Dead


As a follow up to this, it was suggested to me that the AVR board might have

problems. A little closer inspection makes me think that it is the source of

the motorboating sound. Not sure why that board would make such a sound but
maybe someone can enlighten me.

Page 85 of the service manual list the various voltages and points to check
on this board. What I am finding is that the +10 and +5 VDC points are all
measuring about +2 and +1 VDC respectively. All other voltages are good. It
appears on the schematic that both voltage supplies are derived from
connector 6 on the board, and Q104 and D10-D13. I have 18 VDC at pin 2 of
this connector, and I'm assuming this is good when unloaded (plug is removed

from the connector on the board). Does this point to Q104 as the culprit or
should I be looking at something else? Connector 6 and its connections are
right on the fold of my manual so some of those lines are difficult to make
out.

--Dennis NE6I

----- Original Message ----- 
From: "Dennis Younker NE6I" <ne6i at cox.net>
To: <kenwood at mailman.qth.net>
Sent: Sunday, December 08, 2013 2:48 PM
Subject: [Kenwood] TS-940S Dead


>I was doing a little operating today with one of  my faithful 940s. I
>had a
>made a few contacts, took a break (45 mins to an hour), and came back to
>tune around some more. While listening to a QSO, the 940 suddenly went
>dead. Lights out. Nothing but a sort of motor boat sound coming from it. I
>powered down, unplugged things, powered up. Same thing. With the covers
>off, I don't see anything obvious. No burned components that I can see, no
>burnt smell, fuse on rear panel is good. The motor boat sound seems to be
>coming from the left rear (when viewing from the front of the transceiver).

>And it seems to be coming from beneath the power transformer, of all
>places.
>
> Does anyone have any suggestions on what to look for?
>
> --Dennis NE6I
>
>
>
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