[ARC5] BC-455 - intermittant LO.

[Rich Post]

Found a never-soldered resistor in a BC348 affecting the critical output
tube bias.
<http://www.ohio.edu/people/postr/bapix/BC348Q_3.htm>

and here's my saga on a basket case BC342 that finally led to a variable
cap mounting screw that was too long.
<http://www.ohio.edu/people/postr/bapix/BC342.htm>

Factory defects are not a new phenomenon.

Rich KB8TAD


On Tue, May 26, 2015 at 10:10 AM, J Mcvey via ARC5 <arc5 at mailman.qth.net>
wrote:

> These radios have been tinkered with so much over the years that anything
> is possible:
>
> I had a LO failure due to a mico-shard of metal that got into the LO gang
> section for plate circuit and shorted it out. This particular gang has b+
> for the osc plate on it. I never did see the offending shard, but I was
> able to blast it out with an air nozzle.
> I had to disconnect the gang to verify the short.
>
>
>
>      On Tuesday, May 26, 2015 6:03 AM, Sheldon Daitch <SDAITCH at bbg.gov>
> wrote:
>
>
>  Similarly, I had an old Spotmaster cart machine which would occasionally
> fail to stop when the cart recued.
>
> It worked most of the time, so until it quit totally, I never opened it
> up, but when I did, I found a lead on a transistor on the stop cue sense
> board which had never been soldered.
>
> A spot of solder cured the problem.
>
> 73
> Sheldon
>
>
> -----Original Message-----
> From: ARC5 [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Kenneth G.
> Gordon
> Sent: Monday, May 25, 2015 7:23 PM
> To: Leslie Smith
> Cc: ARC5 at mailman.qth.net
> Subject: Re: [ARC5] BC-455 - intermittant LO.
>
> Les:
>
> Concerning your intermittant LO: during a refurbishment of an R-25/ARC-5,
> I discovered a "no solder" joint in the coil-box, yet the joint had been
> painted with a dot of red "inspection" lacquer which all other joints had
> been.
>
> This was a factory fault.
>
> Soldering that joint eliminated the intermittant LO problems I had
> experienced with that receiver.
>
> Do remember that the LO voltage is quite low. Therefore, any such fault
> could have more effect that it would in a rig with higher voltages.
>
> Ken W7EKB
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