[Boatanchors] TCS Receiver Revival Updated- Part 2.

[David Stinson]

TCS Receiver Resurrection, Part 2.
(Posted widely because these concepts can
be applied to many BA rigs.)

Removing the IF/Det/Audio Modules for R0ebuild.

Most of the resistors and caps in the four modules 
are going to need replacing.  It looks daunting,
but it's not so bad if one follows these steps.

Stage location reminder:
https://goo.gl/photos/Drx2a5s1m26CbgLf8

To do this repair, you need to remove the 
2nd IF, Detector/BFO and Audio modules from 
the receiver.  There is no need to remove the 
1st IF module; once we have the first three out, 
you can repair that module in situ.
You will also need some good Corona Dope, 
both for strengthing old wire insulation and for
insuring your IF and BFO coils survive power-up.
More on that later.
https://goo.gl/photos/hU6Tg4N9KAahRk3m6
I got this a the local Frys store.  Not cheap, but
it does a job nothing else will do.
http://www.frys.com

Now that sounds daunting, but it's really not that 
bad if you're patient. You have to remove them
in a specific way because of their interconnection; 
you can't reach all the parts or get a soldering iron
everywhere you need to fix them without disassembly.

Remove the rear panel (if not already off).
Use the two spline wrenches from the rear panel
to remove the BFO Pitch knob and the cabinet latch
from the side near the modules.  
There is an index mark on the BFO shaft but you'll
need to add another to tell which way is "up."
Loosen the two screws on either side of the 
panel where the BFO shaft comes through.
Do not remove them- just loosen them.
Remove the screws securing the modules to the 
side panel.  Remove the handles and screws 
securing the side panel and remove the panel, 
exposing the modules.
https://goo.gl/photos/KRm6VKrnmHqgR59aA

A wiring harness connects to terminals on 
each of the phenolic boards used in the 
individual stage modules. Lacing cord 
secures the wires from the harness to each
board. Cut the laces on the first three modules
from the front. Leave the lace and harness on
the 1st IF module at the rear intact.

Before removing the harness wires, 
mark each wire and each terminal 
so you can get reconnect them correctly.
Do this carefully and double-check; 
an error will be a big pain to find and fix.  
You may need to try a couple of methods
of marking before you find one that works well
for you.

Unsolder the wiring harness connections
from the first three modules.
Important: These wires are old and may fray
if handled carelessly.  If they begin to fray,
coat with Corona Dope and let dry.

There is one wire from the harness into 
the Audio module that is down on the side,
connected to the inside end of C-235.
https://goo.gl/photos/ArtKcpzL36GWDr146
https://goo.gl/photos/YUscrcHo7yNAwDAR7
It is a pain to reach with an iron.  Make sure 
you have the correct wire, going from C-235,
into the wiring harness.  In the TCS-12, this is
a long wire going to the harness on the side of 
the modules.  In the TCS-13, it's a short wire
(and a pain!) going into the harness above 
the modules.  Mark and cut this wire; 
we will install a "pigtail" on that cap (and one
on the wire if needed) so they can be easily 
reconnected when you reassemble.

There are two wires going through rubber 
grommets in the shield between the 2nd IF
and the Detector/BFO module.  There is
one wire going through a grommet in the
shield between the 2nd IF and the 1st IF,
which is "trickier" to reach.  
https://goo.gl/photos/Zs4AK5XAJ1Hj5vJr8
https://goo.gl/photos/j1KCJyGep5aKd9818
These wires must be unsoldered, marked for 
return and pulled through the grommets so 
the 2nd IF module can be removed.
I recommend you "Corona Dope" all three
of these wires before you try to move them.
They may fray when you pull them through
the gormmets.  The dope will help hold the
clothe/fiber insulation together.

There are two bare-wire busses running between
the four modules:
https://goo.gl/photos/NfBvCqZXPh6v1t3Z7
The filament voltage buss can be unsoldered 
from the 1st IF and 2nd IF module terminal 
boards and the end bent upward to clear.
The ground buss will have to be cut in two 
places and bent out of the way. 
https://goo.gl/photos/7TnZZ3pPYA1pwi7u8

The 2nd IF module must come out first.
If the wire harness has been marked and unsoldered,
the three grommeted thru-hole wires disconnected
and the two busses handled, remove the remaining
two screws holding it and remove the 2nd IF module.  
Now remove the four screws holding the Detector
and Audio modules, move them straight back into
the space vacated by removing the 2nd IF and 
take them out as one interconnected unit.
https://goo.gl/photos/gQqgQL7Hfnz9432J6
https://goo.gl/photos/SwUyfeSMMuct4zW37
This should leave the 1st IF still mounted on the
chassis.  You have room to work on it without
removing that one.

In Part 3, we will seek and replace baddies
in the main chassis, then tackle rebuilding
these modules.

GL OM ES 73 DE Dave AB5S