[Collins] Re: 75S3 Questions

[Jim Brannigan]

Antique Electronic supply had new replacement capacitors for the B+.  The 
cans are too small to restuff.

I tore down my 75s3B, removed the PTO, meter, tubes, mechanicals, etc and 
gave it a good cleaning and greasing.
As part of the project, I opened the meter and painted the inside case with 
some left over white ceiling paint.
It helped some...

Jim



> On Tue, 2008-02-12 at 15:28 -0500, Bill Stewart wrote:
>> Man, what a great response to my questions. Many thanks to all who
>> responded.
>>
>> I have shut the receiver down, except for some testing. In previously
>> looking around the rcvr, I did note that there were only five of the 
>> paper,
>> tubular capacitors...all Sangamo and I believe either .1 or .05's. They 
>> will
>> be replaced. The coupling cap to the grid of the 6BF5 is a disc. I think
>> disc caps usually hold up ok, but will check the 6BF5 grid bias.  Also,
>> someone mentioned the bias rectifier being a S/T cube...that's what I 
>> have.
>> I will replace it with a 1N4007, same as used for the B+ diodes.
>
> Mount a two terminal without ground terminal (solder tag) strip in place
> of the selenium and mount the new diode on that. There's a strong chance
> that will cool both the 6BF6 and the power transformer, though the tube
> will alway be fairly hot. Hence the dark spot on the cabinet lid over
> it.
>
>> It does
>> have 150vdc B+. I think the fuse-block diode mounting was orig with this
>> rcvr since the mounting nuts have some loc-tite on them.
>
> Shouldn't have been loc-tite, but a colored lacquer also on the solder
> connections. The inspector put a drop on each inspected and passed
> solder connection.
>>
>> The B+ 'lytic in my rcvr is a Sprague with twist lock tabs, 183-1764-00 
>> (may
>> be a Collins in-house number).
>
> That IS the Collins part number. The 183 group was all electrolytic
> capacitors.
>
>> It is 40/40/40 uf @250vdc. It is about 1 inch
>> in dia. The ones I found at Surplus Sales was 40/40/20 at 450vdc 1.5 in. 
>> dia
>> and another was 40 at 350vdc and 40/40 at 300vdc 1 3/8 in. dia. I'm not 
>> sure
>> if either of these would fit the chassis slots for the twist tabs. Anyone
>> know for sure. I may try my hand at restuffing first.
>
> They did come in different mounting diameters and the big ones won't
> stuff into a small hole even with a big hammer.
>
>>
>> I did receive the manual on cd today and its the forth edition, 1 jul 
>> 1963.
>> It's not the exact manual for my rcvr but will do for a while.
>
> Probably for 3B/C. Won't match your receiver several places. Was hard to
> read. I wrote the next edition.
>
> The right manual should be down loadable from CCA manuals.
>
>> By the way,
>> if anyone needs to copy this version of the manual, let me know and you 
>> can
>> borrow my cd.
>>
>> On the S-meter illumination, I noticed the inside of my S-meter is black.
>> The inside of my 30L1 meter is white.
>>
>> Guess that brings me up to date for now. I have some other questions re: 
>> hum
>> and some squealing at close to max volume. These problems may go away 
>> after
>> I re-cap so will hold off on these questions.
>
> Signs the big electrolytics are bad (as are the couple little ones).
>>
>> Again, many thanks for all the help...it IS a real nice rcvr...73 de Bill
>> K4JYS
>>
>>
>
> -- 
> 73, Jerry, K0CQ, Technical Advisor to the CRA
> All content copyright Dr. Gerald N. Johnson, electrical engineer
>