[Heathkit] Popping DX-40

[cemilton at aol.com]

 Bill,

Did you check the rectifier socket for carbon tracks???  Just a thought.

Otherwise, you've done what most of us do......... Unfortunately, the power tranny in the DX-40 does give problems.

Gud luck

73
Chuck
W4MIL

 

 

-----Original Message-----
From: Bill Stewart <cwopr at embarqmail.com>
To: heathkit at mailman.qth.net
Sent: Thu, Oct 29, 2009 11:13 am
Subject: [Heathkit] Popping DX-40













Good morning all, 

I have a DX-40 which constantly puts out a popping noise in the rcvr. Its about 
2/sec and varies....once in a great while it will stop. But I can flip back to 
tune, then to standby and it cranks up again. It does NOT do it in the tune or 
off  position...all other positions it does. I have run an antenna input wire to 
a test rcvr and probed around and it seems to be maxing out around the 
electrolytic area. But this is not a very good test due to coupling to the 
wiring. When carefully listening under the chassis, by ear, I can hear a slight 
arcing but can't tell just where its coming from...being careful not to stick my 
ear on something hot. All tubes are removed except the 5U4GB. Here's what I 
have tried so far: 



Replaced the 5U4GB 

Sub'ed the lytics 

Re-soldered 5U4GB socket connections 

Disconnected DC load coming off the center of the bleeder/lytic connection 
and the load coming off the output side of the choke and also the 1Kohm/.005 cap 
hooked onto the ctr tap lead 



The xmtr does work, as I made a couple contacts with it yesterday. 



None of the above cured the problem. I'm beginning to get that feeling that its 
the power trans. Anyone had a similar problem and what was the outcome? I 
vaguely recall something about raising the trans. above the chassis with plastic 
spacers and screws (internal arcing to the case?)....was this the solution to 
this problem? Another question...if it is the trans., can anything be done at 
this point, before a complete failure, to fix the trans....such as heating it up 
to move the tar around (probably not a good idea). Any suggestions would be 
helpful. 

Thanks...73 de Bill K4JYS 

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