[GreenKeys] 28ASR slow release relay - Update

[John, W9DDD]

Still trying to figure out the best approach for connections. (a lot of 
the problem revolves around the fact that the TU puts out 60ma loop, the 
default having been 20ma with the line relay involved.  Since it does 
that by means of current limiting rather than dropping resistor, I don't 
want to mess with that.)

LESU13 drawing tells me how I can remove the SR relay.

But, the SR relay appears to give you local copy of your tape punching 
it the K-T position.  Do I need that? I don't know how well I type 
blindly.  I was good on the iron horse back in the day, but I think the 
PC has ruined my touch typing skills. No real incentive to type it right 
the first time. Do I have a different cam with the LESU15 vs. LESU13?

One option I'm considering it bringing out a pair of wires for the 
selector magnets, a pair for the keyboard contacts and a pair for the 
LXD. Forgetting about all the "features", OR ...

There was a WE 63C1 (SB-6/UG) already attached to the ASR cabinet when I 
got it.  I could use that as a way to have the normal paths be as 
original and use patch cords to re-route?

I'm getting close to figuring things out.  Colored pencils are helping.

John, W9DDD

On 8/8/2020 3:26 PM, Jerry Murphy wrote:
> 
> 
> 
> 
> 
> Hi John:   Does your machine have the slow release relay or are you just
> wondering what it does?  I've never encountered one but I do know that they
> are not necessary for the proper operation of a standard, no frills machine.
> 
> Do you know what LESU your machine has?  The most common LESU found in ASR
> sets is the LESU13.  I'm fairly certain that the LESU13 is called the 28F
> LESU when used in Bell System service.  The actual and schematic diagrams
> for the LESU13 can be found at navy-radio.com.  Here are the links:
> 
> http://navy-radio.com/manuals/tty/wd/wd-tty-3292.pdf
> 
> Actual wiring diagram for the LESU13.
> 
> http://navy-radio.com/manuals/tty/wd/wd-tty-3294.pdf
> 
> Schematic wiring diagrams for the LESU13.  Pages 1, 4, 5 and 6 pertain to
> your machine.  Pages 2 and 3 have information on the LCXD and LBXD
> transmitter distributors and are not needed.  The left half of page 4 has
> information on the LAXD transmitter distributor while the right half has
> information on the LXD transmitter distributor.  Your machine has the LXD
> transmitter distributor.
> 
> Take a look at the WD for the LESU7/184.  It is a no frills LESU for a KSR
> or RO without a line relay.  Look at terminal block A inside of the LESU.
> It shows the strapping and wire placement for connecting the signal line
> directly to the selector magnets.  The selector magnets are wired for
> 60 ma. signal line current.
> 
> Here's the link to the LESU7/184 actual wiring diagram:
> 
> http://www.navy-radio.com/manuals/tty/jh/ttyman9/drawings/2874wd.pdf
> 
> Here's the link to the LESU7/184 schematic wiring diagram:
> 
> http://www.navy-radio.com/manuals/tty/jh/ttyman9/drawings/2875wd.pdf
> 
> If you remove the line relay socket and change the wiring and strapping on
> the A terminal block so it matches the A terminal block on the LESU7/184,
> then you should be OK.  You MUST remove the strap that connects terminal
> C20 to terminal C21.  This removes power coming from the local rectifier
> that went to the selector magnets when the polar relay socket was installed.
> The C terminal strips are mounted on the cabinet above the LESU.
> 
> On the LESU13, there is a red wire which goes from terminal 8 on the A
> terminal block to terminal 9 of the S terminal block.  It is not shown
> on the LESU7/184 schematic because it is not there.  It is OK to leave
> the wire in place on terminal 8 of the A block as it has no effect on
> proper operation.
> 
> Check your wiring before you power up the machine.  Go over the schematics
> carefully to make sure there are no opens or shorts in the signal line
> wiring.  Good luck with your project.
> 
> Jerry Murphy
> 
> 
> 
> 
> 
> -----Original Message-----
>> From: "w9ddd at tapr.org" <w9ddd at tapr.org>
>> Sent: Aug 8, 2020 10:51 AM
>> To: greenkeys at mailman.qth.net
>> Subject: [GreenKeys] 28ASR slow release relay
>>
>> Anybody know the purpose of this relay?  I'm trying to simplify the LESU wiring while still  keeping it close to standard.  I mostly just want to bypass the polar relay socket. Never found a WD for an ASR that didn't use the polar relay.
>>
>> John, W9DDD
>>
>>