[NJARC] Grounding question PS

[Scott Roberts]

Also just found a 68 ohm resistor in place of the bus wire across terminals 8 & 12 on the rear wafer of the AVC-Off-MVC switch.

Gonna remove it, put the bus back in...

Scott



--- On Sun, 2/15/09, Scott Roberts <ng19delta at yahoo.com> wrote:

> From: Scott Roberts <ng19delta at yahoo.com>
> Subject: [NJARC] Grounding question
> To: "NJARC Radio Club" <njarc at mailman.qth.net>
> Date: Sunday, February 15, 2009, 1:59 AM
> Visit our web site - See http://www.njarc.org
> _______________________________________________
> This may sound like a simple question, but I do need an
> answer, although I am pretty sure I know it already...
> 
> I am working on my BC-348-P, which I got at the swapmeet
> back in August or September at Info Age.
> 
> I had thought I had corrected all the modifications made to
> the set, and returned it to original shape. However, I still
> get a loud hum over any and all settings. I have been
> starting to check voltages and resistances at the tubes with
> the I-56-A test set.
> 
> Anyway, I just found a change I missed- The dial lamp
> circuit has been heavily modified- The power in lead has
> been moved from the AVC-Off-MVC switch, front wafer,
> position 1, and moved to the  VT-86(217, First I.F.) tube
> socket terminal 7. Continuing through the circuit, the
> original series arrangement of the lamps has been changed to
> parallel, and resistor 503(the flat 60 ohm dial lamp
> resistor) has been bridged across with a piece of bus wire.
> 
> Could these changes, having been left unnoticed &
> intact, be the cause of the overriding hum? I am about to
> restore the circuit, as I would anyway, but wanted to see
> what you guys think.
> 
> I'll let you all know the results(hopefully positive
> & hum free) after i complete it and test the unit again.
> 
> I am still not sure the neon tube in the oscillator plate
> voltage regulator, (id 218, 2J991, or 2V991, JAN-991) is
> operating properly, and wonder if it could be related to
> either, or both issues- the convoluted lamp wiring, or the
> hum...
> 
> Thanks!
> Scott
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