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Tx2 Transmitter - 'DelTang' R.C. Problem
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 Posted: Sun Jul 25th, 2021 02:57 pm
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Geoff L
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1.
 
Seemingly, problem is with a Tx2 transmitter,
with erratic response to centre-off speed control.

Grounding pins-3&4 made some improvement,
grounding pin-7 didn’t.

Various calibrations have been tried.


Loco control is fine in one direction,
but it maintains initial setting in the other.
 
ie. speed at where knob is turned to at take up,
with no acceleration/deceleration, and stops at centre-off.

Initially it kept going, before grounding pins-3&4.


The Rx. responds correctly to another Tx. of similar construction,
and another Rx. responds similarly to the errant controller.

Changing the pot has made no difference.


The LED on the Rx. behaves peculiarly.

It goes out as the speed control is moved,
but goes solid at centre position.

It would seem that transmission is lost when speed is applied,
although loco is partially controllable in this condition.

Difficult to see, as Rx. is beneath board feeding track,
and I can’t see the loco and Rx. at the same time.


Only motor control and 'Selecta' are connected.


I should be grateful for any suggestions,
as to what else I might look at to resolve this problem.



2.

The on/off switch LED contact has been damaged.
Is there an alternative location it could be fitted, please ?



Thanks in anticipation,

Geoff


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 Posted: Wed Jul 28th, 2021 07:55 am
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fallen
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Hi Geoff,

Problems like this are always interesting.


Two thoughts:

Have you tried it with a new battery ?


It may be the floating inputs are causing problems.
You have grounded pins-3&4.

I would suggest grounding pin-6 also,
as this can cause confusion, if left to float.


Keep us posted.

Frank


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 Posted: Thu Jul 29th, 2021 10:36 am
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Geoff L
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Thanks Frank.

Posting a query often results in a solution being found,
even before any responses !


I had tried a new battery,
and I had grounded the other pin(s) with no discernible improvement.

However, the track power was supplied by 11.1v Li-Po,
and replacing this with a conventional 12v supply, resulted in perfect running.


The puzzle was that if battery power was low (which I didn't unfortunately check)
why it did not affect running in both directions, or give an indication.

Possibly because the resistance goes from 0-10K,
and not from mid-point to 0 and 10K ?


I would appreciate any info re the LED,
to save the controller being left switched on.


Geoff


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 Posted: Sat Jul 31st, 2021 07:51 am
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fallen
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Hi Geoff,

Glad you have it sorted.


If you want to mount an LED in the case, to replace the one in the switch,
you just wire it in place of the one in the switch.

There is a circuit here:

http://www.deltang.co.uk/dt-tx21b-v207p6.pdf

The switch LED is at the far right.

The wire from pin-8 goes to the new LED, instead of the LED in the switch,
and the other wire of the LED, goes to the negative supply.

You do have to get the LED the correct way round though.


Frank


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 Posted: Sat Jul 31st, 2021 07:16 pm
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Geoff L
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Thanks Frank


What I am not able to do,
is make the connection at pin-8.

But would like to use the LED in the switch.


Geoff


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 Posted: Mon Aug 2nd, 2021 04:39 pm
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fallen
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Ah.

Just to clarify,
you can make the connection to the LED terminal at the switch,
but not to pin-8 on the transmitter board ?


Then you can connect to the positive power lead to the transmitter board instead,
but you must put a resistor in series with the LED.

The value will depend on the battery supply voltage,
but its not critical.

If you have a 9v battery then 470 or 330 Ohm one would be a good starting value,
lower battery voltage would need a lower resistor, perhaps 220 or 150 Ohm.


If you do this it will work to indicate the power is on,
but you will not get the flashing signals for binding or low battery voltage.

Frank


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