[MRCA] BC-474 Cap Pack Mystery!

[J Mcvey]

 Those are some nasty looking caps. Probably have 50k leakage .The radio should come to life once you get all those old caps replaced.Then again, there are always "secondary problems" too.
    On Tuesday, July 1, 2025 at 02:32:44 PM EDT, Ray Fantini via MRCA <mrca at mailman.qth.net> wrote:  
 
  <!--#yiv7875857849 filtered {}#yiv7875857849 filtered {}#yiv7875857849 p.yiv7875857849MsoNormal, #yiv7875857849 li.yiv7875857849MsoNormal, #yiv7875857849 div.yiv7875857849MsoNormal {margin:0in;font-size:11.0pt;font-family:"Calibri", sans-serif;}#yiv7875857849 span.yiv7875857849EmailStyle17 {font-family:"Calibri", sans-serif;color:windowtext;}#yiv7875857849 .yiv7875857849MsoChpDefault {font-family:"Calibri", sans-serif;}#yiv7875857849 filtered {}#yiv7875857849 div.yiv7875857849WordSection1 {}-->
Ok, another project. The BC-474 transmitter receiver. Not my radio just doing it for someone else. Got the radio in and started by removing the Ham radio modifications like a different receiver power cable and the like. Pulled a couple capacitors in the receiver and they were questionable so decided maybe it’s time to replace most, at least the ones associated with RF and AF bypassing, coupling and AVC filtering. The smallest amount of leakage in a AVC filter has a huge effect on the AVC action.
 
The more I worked on the radio the more it became apparent that I was not able to find a lot of the capacitors, then the discovery! A thing called the CAP Pack, C10, C17 and C18 and a couple of the screen bypass capacitors all live in the cap pack. 
 
Looks like a IF Transformer and located right next to one of the IF cans.
 
Attached are a couple pictures of the cap pack and what was removed after I melted away some of the wax its sealed in.
 
Heat gun works for that. Any leaky capacitors in a battery radio are an issue. Remember that all the time the B Battery is connected the B+ bus in the radio is hot and any leakage will kill the battery when not in use.
 
Somehow the 474 has somewhat of a following so posting this information for anyone who may also work with this radio.
 
Will be posting more as work progresses, maybe video too. Still have a bucket full of BC-654 video that I have to edit.
 
  
 
Ray F/KA3EKH
 
  
 ______________________________________________________________
MRCA mailing list
Home: http://mailman.qth.net/mailman/listinfo/mrca
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:MRCA at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20250701/0ea74dbf/attachment.html>