[ARC5] BC-454 Conversion

[Unserviceable but Repairable]

Gud advice so far, but unaddressed....

output xfrmr:  think 2000 ohms tapped @ 600 ohm.  If @2000, just use output
               xfrmr fm a ' tube table radio' (read AA5) for speaker match

Not asked:   Spotting bad bypasses.  

             Here's a general post I did months back.  On command rx-en, 
             lift jumper between 2 vertical wire wound resistors.  Then 
             you may 'try it @ home'

             (those wire wounds are a 'shunt acroos B+' mentioned below)

  Merry,

    Marty


-------------

 From milsurplus-bounces at mailman.qth.net Mon Aug 27 06:52:28 2007
 Received: from mailman.qth.net (mailman.qth.net [63.238.179.60])
 	by fracas.netboobie.org (8.13.4/8.13.4) with ESMTP id l7RAqSqK017712
 	for <cosmoline at aa4rm.ba-watch.org>; Mon, 27 Aug 2007 06:52:28 -0400 (EDT)
 Subject: Re: Capacitor question 
     |
     |
     |
 >> .... The parts list
 >> says
 >> they are mica even though some are as high as .01 mfd (10,000 mmfd).
 > Are they really mica?  - Probably not.  Break one open, and look.
 >
 > Are they reliable?  - Papers are probably NG.  Micas are possibly
 > tolerable.  I probably wouldn't resort to wholesale replacement of micas
 > unless I started finding leaky ones.
 >
 
 complete agreement
 
 I'd add this tho.  Make sure no filament supply.  Apply more than design
 B+ to rx thru a current limited supply.  Like 400vdc w. seriesed 25K
 resistor.
 
 Measure drop across resistor & if zip, you & the purported micas are fine.
 If big drop, look @ ckt. for shunt across B+ line.  If found then lift it
 & try again.
 
 If drop still there, start rattling thru all B+ isolation resistors to
 ferret bad bypasses.
 
 I reported this months back as a fast way to revive a long-dead BC-455. 
 Found only one bad "in-can" bypass.
 
 Recent example is a BC-224 fm weeks back.  Old one, BC-224h by RCA - sn
 98.  Must have been in a lean-to for years.  Lotsa outside mud.  But
 after lifting RF gain ctl fm gnd, NO drop across current limiter R!!!
 
 She was listening to a classical mix on 1690AM right away.
 
 BUT prior bug-a-boo.  BIG ONE.  Former owner rewired for 6vac & getting
 it back to work on 12vdc (yes dyno) took my 1st ever need for set's wiring
 diagram.  Don't think I cudda w/o it.  THANKS BAMA/edebris for
 having it!!!
 
 Oh and prior guy no dummy - grounded B- BUT removed 41 and pinned out
 audio to outboard amp.  Something presumably w. better audio iron.
 So think he used 224 as hi-fi s-w tuner
 
    Marty the 'rm
 
 
 
 
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