[GreenKeys] Model 28RT puzzles

[Nick England]

What a great list! - Riceguys sent a wiring diagram, and Jim and Tom
also provided info that helped me get much less confused. OK, I think
it goes like this -
1) The capacitors hook onto the AC line to indeed provide power factor
correction - for the shaded pole motor that is located inside the tape
bin (oops, I took that bin off long ago and forgot that motor was
inside). The "extra" 3-pin cinch connector plugs into the bin motor.
2) The lamp transformer plugs into the AC line from the top deck - the
extra 2-pin connector wired to it feeds the caps and tape bin motor.
3) That leaves the TD clutch relay circuit connector hanging free -
This connector is in series with the AC line feeding the 48vdc relays
and it must have been hooked up to what?  - a big resistor? a light
bulb? a rectifier diode?

Many thanks guys. I'll post an update when I get it singin' and
dancin' - probably a candidate for a You Tube video.

cheers,
Nick

On Thu, Jul 22, 2010 at 7:28 PM, Nick England <navy.radio at gmail.com> wrote:
> I have finally moved my 28RT up on the bench to get running. I have
> photos of this unit at
> http://www.navy-radio.com/tty/28rt.htm
>
> Sidenote - For those not familiar with the 28RT, it is a FIFO - an LPR
> printing reperf followed by a tape bin and then an LAXD climbing head
> TD. Both have gear shifts so you can run signal in at say 100wpm,
> punch the tape which spills into the bin while the TD reads it back
> out at say 60wpm. Or vice-versa.
>
> My first step has been tracing all the wiring to see how some previous
> owner had set things up. I have most everything beeped out but I am
> still puzzled by a few  things so maybe someone on the list can help
> un-puzzle me. I got this 28RT from Don House and it may have been in
> the hands of one of you other guys at some point....
>
> Situation -
> #1) On the LPR/LAXD top deck there are two cables with 2-pin female
> Cinch connectors which are meant to run somewhere. One is factory
> wired 115vac from the on-off switch and the other is homebrew-wired in
> series with the two LAXD clutch coils, a toggle switch, the
> distributor stop switch and the 115vac line. The LAXD clutch coils
> (reader and distributor) are wired in parallel and according to the
> docs are supposed to operate on 48vdc (160ma ea.).
> #2) There are two 15 uf oil capacitors (rated 600vdc/330vac) mounted
> in the bottom of the base (near the tape reels). They are wired in
> parallel and the leads run up to a 2-pin male Cinch connector mounted
> on the lamp transformer bracket (see #3 below). These are pretty
> clearly factory items - brackets, wires in plastic tubing, etc.
> Homebrewer has added a 3-pin female Cinch connector in parallel with
> the factory male 2-pin.
> #3) There is a bracket on the upper part of the base with a
> transformer whose secondary feeds 3 small lamps. The primary is
> connected to a cable with a 2-pin male Cinch connector. Bracket,
> cable, etc. all appear to be factory items. Homebrewer has added a
> 2-pin female Cinch connector in parallel with the factory male.
> #4) Note - There is also a 4-pin Cinch connector that carries leads
> from a tape-out switch on the reels - it all looks stock and obvious
> in function.
>
> Photos of these cables are near the bottom of
> http://www.navy-radio.com/tty/28rt.htm
>
> Now the 64,000 baud question - where should those two cables from the
> top deck go? and why?
> A) The 115vac cable from the top deck clearly hooks to the capacitor
> connector - so the two caps are in parallel with the AC line (really?
> power factor correction?)
>
> B) The other (home-brew) cable from the top deck evidently goes to the
> lamp transformer primary so it is in series with the TD clutch coils.
> That's weird.
>
> It is NOT posible to swap these two cables - the homebrew cable in the
> top deck is too short to reach the capacitor plug.
>
> And what about those extra home-brewed connectors? - one in parallel
> with the caps and one in parallel with the lamp transformer primary.
> What might they have gone to?
>
> I am assuming that this isn't random re-wiring by Mr. Homebrewer -
> other stuff in the signal circuits make sense and the caps and
> transformer are clearly factory items - but for what?
>
> Any suggestions or info greatly appreciated. I really like to
> understand why/how gear is originally constructed before I go in and
> make my own mess of things.
> Thanks gang,
> Nick K4NYW
>