Help with Rx - ESC - Sound Mystery

[WKDOR]

I have two locos with supposedly identical controls (19.8v battery, Deltang Rx102, GScale Graphics Enhanced Railboss, Phoenix P8). Both run beautifully.

But one drives me potty because it can't stop ringing its bell from start up to shutdown every few seconds - without any manual triggers!

The only way to stop it is to disconnect the bell trigger wire ESC to P8 OR turn the bell down to 0% volume but I don't want to lose 50% of my premium sound triggers.

This is what I have done so far:

Tried tweaking all the Phoenix Bell parameters
Changed from one triggered sound (bell) to another (water fill) - exactly same problem with water fill
Reloaded software from original Phoenix ROM files
Reset everything to factory default settings
Treble checked wiring Rx-ESC-P8 is identical to its twin

Any other suggestions please?


mike in Despair

 

[PhilP]

Are the Rx102 and Phoenix negative rails tied together?
Are you using a 1K resistor in the trigger feed between the Rx102 and the P8?
Which pin on the Rx102 are you using for the trigger?
Are you *sure* that trigger wire isn't trapped anywhere?

That will do for a start..

 

[Neil Robinson]

The only way to stop it is to disconnect the bell trigger wire ESC to P8 OR turn the bell down to 0% volume but I don't want to lose 50% of my premium sound triggers.

Changed from one triggered sound (bell) to another (water fill) - exactly same problem with water fill

The above leads me to suspect that the offending trigger wire is permanently grounded at the ESC end.
Swapping P8s between ESCs should confirm if the fault is with the ESC as I suspect or the P8.

It may be due to a solder bridge between pcb tracks or a single stray strand of wire

 

[WKDOR]

Many Thanks Phil and Neil

That will keep me busy for a while. I'll report back when we have some daylight.

mike

 

[Tony Walsham]

Phil, if the P8 uses the same power supply as the ESC, the two parts will be automatically grounded together.

Mike, It could be the Rx102 although I doubt it.
You might try connecting the ESC triggers channel cable to a different channel on the Rx102.
The Rx102 requires an interface to convert the servo signal to an ON -OFF trigger using a transistor or FET. The Rail Boss does that. So, given that you cannot trigger a sound system direct from an Rx102, I would be looking at the trigger device on the ESC.
Connect something else to the sound trigger on the RailBoss, like a bulb of suitable voltage. If the bulb works properly the fault will be in the P8.

 

[WKDOR]

Thank you very much too Tony. Its always great to have an alternative (i.e. upside down) perspective!

Further info as requested Phil. Yes everything is powered from one battery pack so ESC and P8 are grounded together (see Del's wiring diagram for the P8 here: http://www.gscalegraphics.net/uploads/2/5/7/7/25776635/sound_board_wiring_enhanced.pdf )

No there is no 1K resistor (which I have done for the Rx65 installs), where would it go?

I have started with Tony's suggestion. Tried a working 3.5v LED connected to ESC Bell terminals 15 positive and 14 negative - no light on power up and none on the bell trigger. Same negative results when tried with a buzzer that works at 1.5v.

I'm not sure whether this conclusively points to the Railboss ESC as suggested by Neil and Tony. If the trigger is shot (everything else works fine), how is it that am I able to turn the Bell off in Phoenix Manual control mode - until it turns itself back on again a few seconds later?

Your expert views would be very much appreciated before I decide whether to swap out the ESC.

All the best

mike

 

[PhilP]

Right...
Having a 'picture', and going back to post #1.. - Always helps to check what the original question/problem was...

The P8 is obviously working as it should be, as if you remove the trigger, the bell stops. - Prove this by triggering bell with wire between ground and C2-4 on the P8.
This will prove P8 working, so we move back down the chain..

Assuming P8 OK:
There must be a 'stray' earth on the wire feeding it..
Now, that could be a whisker from a soldered joint, a circuit board resting on something metal.
OR it *could* be something in the configuration of the Rx102, or Railboss telling it to make a noise..

Trace the wire (still disconnected from P8) to the RailBoss.. It IS B+ 15 isn't it?
Any stray whiskers here? - also, how are 14 B- and 16 W- commoned? Check for whiskers here as well.

You need to see what is coming out of the RailBoss.. - To me it looks like you could put a meter across 15 B+ and 14 B-. Toggling whatever on your Tx should cause you to get / not get a reading on the meter. This will be inverse to what you think, as you ground the trigger to fire the bell.

Bell 'on' on Tx will give no reading(or very low). Bell 'off' should give a higher reading.

**Can you confirm I have this right please Tony?**

 

[PhilP]

I have also just looked at the RailBoss manual...

The triggers can be configured as momentary, latched, and also as a random event..
So a little to check there as well..

 

[WKDOR]

Very Many Thanks indeed Phil

We have voltage measurements for you taken at the ERB board screw terminals:

For the Whistle: 17W + 16W -. Power ON NO R/C = 2.55v. Power ON bound R/C Idle sounds = 2.55v. Sound triggered = 0.05v

For the Bell: 15B + 14B -. Power ON NO R/C = 0.00v. Power ON bound R/C Idle sounds = 0.00v. Sound triggered = 0.01v

The whistle works fine.

Is this conclusive please?

All the best

mike

 

[Tony Walsham]

Mike.
As you were using an LED I take it you did use a resistor in series with the LED? Plus you had the polarity of the LED the correct way around. The short lead of the LED to the trigger and the long lead to the plus voltage.
I prefer a bulb as they are non polarised and will work either way round.
It is possible the switching transistor has been damaged. They can go full ON all the time internally.
If you wire in an LED without a suitable resistor you will kill switching transistors.

Phil,
The only reading you should get is from the Phoenix trigger. It will probably be around 5 volts on the trigger wire all the time.
it will only sound when the open collector transistor actually takes the Phoenix output to ground.

 

[WKDOR]

Very Many Thanks Tony

Yes, Yes and Yes. LED was supplied pre-wired by RCTrains of this parish. I had tested it first.

Can you please comment on my voltage readings? Yours may have crossed with mine somewhere over the South Pacific.

All the best

mike

 

[PhilP]

Looks like output on RailBoss is dead..

Tony, was talking RailBoss outputs for meter readings..

 

[WKDOR]

Very Many Thanks for the diagnosis Phil that is what I was suspecting too.

Best

mike

 

[Tony Walsham]

Hello Mike.
Sorry, but I have no idea what the readings you get refer to.

 

[PhilP]

Hello Mike.
Sorry, but I have no idea what the readings you get refer to.

Tony, he has measured across the outputs of the RailBoss (pair for whistle, and pair for bell)..
He gets a voltage reading on the whistle when 'off', no voltage when 'on'.
He does not get a voltage reading on the bell outputs, when either 'off' or 'on'.. Conclusion: output transistor on the RailBoss has blown.*

*There is still a slight possibility the RailBoss is not programmed correctly, but I am not familiar with RailBoss, so am unable to advise on this.
PhilP.

 

[WKDOR]

Many Thanks Phil that's a much better summary.

Sorry Tony I was trying too hard. The "17W" type references are to the terminal labels on the Railboss wiring diagram. I put the results in a table that would have been much clearer but then discovered that the forum wouldn't let me attach/insert an excel file. Hence my convoluted sentences.

So the diagnosis looks very likely your suggestion:

"switching transistor has been damaged. They can go full ON all the time internally"

Should I assume that its not likely to be economically repairable?

mike

 

[Tony Walsham]

Hello Mike.
My suggestion would be to get in touch with Del Tapparo at G Scale Graphics and explain to him what is happening.
Del has always been very helpful to me.

 

[WKDOR]

Many Thanks Tony

That's what I have just done. Yes Del has always been very helpful.

Best wishes

mike

Hello Mike.
My suggestion would be to get in touch with Del Tapparo at G Scale Graphics and explain to him what is happening.
Del has always been very helpful to me.

 

[ge_rik]

If all else fails, you could trigger the bell directly from the Rx102 ( provided it's v110-3 or later). You'd need someone with a Prog3 or Prog4 to reprogram one of the pins on the Rx102 to on/off but it would be a cheaper option than replacing the Railboss if everything else on it is working OK.

Rik

 

[Del Tapparo]

Very Many Thanks indeed Phil

We have voltage measurements for you taken at the ERB board screw terminals:

For the Whistle: 17W + 16W -. Power ON NO R/C = 2.55v. Power ON bound R/C Idle sounds = 2.55v. Sound triggered = 0.05v

For the Bell: 15B + 14B -. Power ON NO R/C = 0.00v. Power ON bound R/C Idle sounds = 0.00v. Sound triggered = 0.01v

The whistle works fine.

Is this conclusive please?

All the best

mike

Hi Mike - It looks like the Bell output of the Enhanced RailBoss is either shorted or is being driven on via some upstream failure. Most likely it is shorted. I can certainly repair it if you are willing to foot the shipping costs. Better yet, you have had many good years of service. Perhaps it is time to update to the RailBoss 4 system with the convenience of a transmitter you can put in your pocket, no external receivers, no stick radios, no calibration procedures, etc. RailBoss 4 R/C