[Collins] Looking for 75A-3 Manual

[Dr. Gerald N. Johnson]

On Mon, 2008-12-01 at 15:31 -0600, Dennis pharr wrote:
> Hello all - I'm looking for a downloadable manual for the 75A-3 (round
> emblem - SN 1715). I don't see a manual for the 75A-3 listed in the
> Tech Archives section on any of the Collins Collector websites. I'm
> beginning to think there weren't too many 75A-3's produced, so the
> manuals are not too plentiful? 
> 
> I acquired the 75A-3 at a hamfest recently and would like to get it
> playing. But, I want to check out the power supply caps first to make
> sure they are still OK before applying power. I realize the power
> supply caps are easily found and tested in the unit, however I hate to
> poke around in these old receivers without some kind of documentation.
> The unit appears to be completely original with no mods. Any help
> anyone could provide in locating a downloadable manual for the 75A-3
> would be greatly appreciated.
> 
> Thanks
> 73
> WD5JWY
http://www.collinsradio.org/75Asur.pdf says there were two distinct
75A-3 manuals and the 75A-2 was a fair amount different.

There is a Dec 1974 edition reproduction manual on epay:
http://cgi.ebay.com/Collins-75A-3-manual-w%2F19%22-foldout-schematic-%
BBR%B2_W0QQitemZ350124839547QQcmdZViewItemQQimsxZ20081113?
IMSfp=TL081113121010r8966

or at radio reprints: 
http://www.radioreprints.com/descriptions/75a3.htm

Or at Vintage manuals:
http://www.vintagemanuals.com/manual.php?
manufacturer=Collins&model=75A-3

or Tannenbaum:
http://www.agtannenbaum.com/c_cat.html#COLLINS

Or:http://www.w4qcfmanuals.com/manualsA-C.html

Or surplus sales:
http://www.surplussales.com/cgi-bin/cart.pl?name=
(PUB)+COL-75A-3&price=49&custom1=75A-3
+Manual&return=http://www.surplussales.com/Manuals/man_col2.html


Google shows many in response to the search on Collins "75A-3" manual.

As for the receiver, look out for molded oil paper capacitors, they are
leaky. Electrolytics are not to be trusted, need to be replaced before
applying power. Tighten all the tube socket and ground lug screws. Clean
the tube pins and sockets with small amounts  of DeoxIT, dropper bottle,
not spray. Same thing for switch contacts. The DeoxIT works better with
some motion of the contacting parts to scrub off the loosened oxides.

Some tubes will be on the weak side, and some of the resistors will have
shifted value out of tolerance.

Its possible for the mechanical filters to have problems by now, whether
from age or shock while stored.

Ceramic and mica capacitors are often OK, but they can fail. Just they
aren't so prone to failure that shotgun replacement is justified. The
black beauty oiled paper capacitors and the electrolytics are so surely
bad that blanket replacement saves much troubleshooting time and
cleaning when the electrolytics spew their content under the chassis.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer