[R-390] R390 B+ Current?

Fri May 24 17:13:36 EDT 2019

Hi Jacques,

The state of the 6082's were new in box but I am suspecting they failed.  My
tube tester (NRI Model 70) doesn't have a listing for the test settings for
the 6082.

I will check C608 but I think I did already.  R615 is spot on.  I've also
replaced the four 47 ohm resistors since they were burned, as well as R625
and R626 which were charred beyond recognition.  After doing all that, the
receiver worked for a few days, B+ was normal, no hum.  The resistors I
replaced are still good.  Also, the resistors for the 6BH6 are good also.

I may rig up a test setup to measure the Gm of my stock on 6082's to test
them.

I'd like to measure the leakage on my B+ like you suggest.  How is that
done?

Thanks!
John

-----Original Message-----
From: Jacques Fortin <jacques.f at videotron.ca> 
Sent: Friday, May 24, 2019 8:58 AM
To: jgedde at optonline.net; 'r390a' <r-390 at mailman.qth.net>
Subject: RE: [R-390] R390 B+ Current?
Importance: High

Hi John,

What is the state of the 6082s ?
Have you a tube tester to test those ?
Whatever the output voltage you got, the plate of the 6BH6 (V607) normally
have to be a few volts BELOW the output.
If C608 is leaky, this will reduce the output voltage for sure because it
will make the 6BH6 grid raising higher than it should.
Expect it to be leaky anyways: I do not see any original one that was
faultless.
Check also R615: I once found one that was measuring almost 1 meg. Replace
it by a 1W part.
When all is in order, you should get 180V out ± 3V and the Hum Balance
should work (provide a minimum output hum setiing).
BTW, it is easier to debug when it give you lower than expected voltage than
the reverse !

170mA is within the spec: the transformer is rated at 200mA DC !
But if there was no leakage test done on the B+ rail, to detect any leaky
cap., it can be that you draw more current than the designed value.

Any other question, just ask !

73, Jacques, VE2JFE

-----Message d'origine-----
De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la
part de jgedde at optonline.net Envoyé : 24 mai 2019 07:49 À : 'r390a'
<r-390 at mailman.qth.net> Objet : [R-390] R390 B+ Current?

I'm still having trouble with the voltage regulator.  Low B+ and a hum.
There's plenty of input voltage available, but the output isn't right.
Right now I have a 180V bench supply feeding the radio through the B+ test
point and all is working but the current is seemingly high.  I see about 170
mA.  Does this sound right?  It may well be, but I want to make sure I'm not
trying to fix the wrong thing.

John

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