I am only too happy that you are thinking this through before potentially wasting money on an unsatisfactory solution
Originally Posted by: Rwill 
So first dumb question - for a 76493 is that one and a half switches on either a control box or keyboard?
No, you really have to reserve 2 pairs (not one and a half)
This relates to my prior comment about "This unit is frustratingly useless for 3/4 aspect signals"
How the 72760 works is that send a pulse for a particular aspect BUT the buttons are latchon/latchoff type.
Setup = 76493 set to address 1/2
So if you set a 76493 to Amber (2nd button on 72760 down) and then set the signal to green (1st button down - Note 2nd button still shows green!)..
If you now want to set it to amber again you have to toggle the 2nd button off then on (Note 1st button light does not change and is thus also misleading) . In doing so any device with half its address on 2Red will be affected.
For 2 aspect signals this is "OK"
Quote:
Second Q -Where would the control box get its power or is it just a brown and red from the line?
Absolutely not from your 6021 brown/red
By design you need to buy a 66361 for power
Quote:
Third Q - for all the points raised is a 72760 a workable and sensible solution?
I personally do not think so.
For the price of a single 72760+66361 you would be well on your way to getting a 2nd 6040 (all be it 2nd hand)
Quote:
.. should I ditch the 6021/keyboard set up in favour of a mobile station 2?
Absolutely not ditch!!.
By all means consider a MS2 for its more modern locomotive capabilities (mFX, DCC, FX(81-255), LokCard) but I would keep your 6021/6040 for just the accessories anyway
(Totally separate Brown/Red wiring buses).
RE....
Quote:
.. I like the good solid click feeling of control 80f and keyboard ...
DITTO !!
RE...
Quote:
I also have an irrational longing to find a 6043 memory and see if I can master that.
Personally , I think this is an excellent challenge.
However, be aware that the 6043 has a battery that will have expired (unless serviced) and just as probably leaked - corroding the circuit board.
If you do find a 2nd hand one do not buy it sight unseen. Only buy it if the battery hasn't already leaked AND replace the battery anyway!
Re:
Quote:
I am worried about the natural expiry of the 6021 over time - we have a sticky number 2 and the reversing knob seems to need quite a bit of force to action.
This may be a driver towards a MS for loko control, however I would still retain the sub-system for your accessories.
You may find that a bit of maintenance, (contact cleaner on the keypad contacts) and a check of the shape of the reversing contacts will allow for another 30 years of service. Failing that, a second (second hand) 6036 Control80F may be worth considering.
"Click" aside the MS is OK for a throttle, as long as you do not have to juggle screens if you also have your accessories connected to it
Note: However, if your trains are of a generation where you have lighted carriages with old, power hungry, bulbs, the 6021 does still provide more power than the MS.