55020 decoder problems

PhilP

PhilP

G Scale, 7/8th's, Electronics
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Have a Mallet with a pair of these, and a 'naked' 6500x soundcard in it..

Loco runs under analogue.
DIP switches are (all) off.
Sound module 'did not work'. - But if I connect it up, and use F8 it does! ;)

The loco will NOT run under DCC control. No lights, sound, anything..

Pulling out a 55020, and connecting track and motor, same result. UNLESS, I set CV 1 (address, in my book) to the default value of '3'. Then I can run the motor.

Have tried writing 55 to CV 55, it appears to 'take'. - Though if you query it, CV 50 = 0.
Resetting the decoder this way does NOT appear to reset the address.

I can set the decoder address to any value between 1 and 22, and it reads back correctly. However, I am unable to get any output at any address except '3'.

Any ideas??
PhilP.
 
A few suggestions.

Disconnect the sound card as well. That also contains a decoder, make sure you are only programming (and reading back) one decoder at a time.

Turn off the loco lights.

If the problems still persist in programming the address remove power from the loco. Replace the loco on the track and read back the address, is the address the same as before? Does the address that reads back respond to commands to move?

Can you change CVs successfully if you try Programming on the Main?
 
Thanks for the ideas Cliff..

Decoders removed from engine.. Just track and a motor.. Address programmed, and read back with new value (1,2,4 to 22). All power off. Power on, read back address.. Back to track-power, and nothing, no movement..
Set address to '3', and can drive the motor. - 4 wires, motor, decoder, central station. Nothing else. Both decoders OK.
Sound decoder works as I would expect. - Think they had not tried F8 to turn it on, it is 'switching speed' after all! ;)

The fact it does not work (motor decoders) 'outside' the loco, rules out a motor-block being back to front (short circuit), and it works analogue with the decoders in the loco.
There *could* be a fault on the mainboard in the loco I suppose? But why do the decoders not respond to any address except '3'. - That suggest a fault in the logic on the decoders??
 
Does the 55020 allow direct programming or is it register programming only (i.e. put cv no into CV6,then required value into CV5) ?

Don't think it has a "switching speed" mode !
 
Both decoders behave the same way..
I HAVE directly programmed the address into all three devices. Connected everything up, and it works on address '3'. :o :D :D :D

I had not thought about register programming..
I had assumed this was a 'feature' of the older MTS kit, but suppose it makes sense for the decoders to behave in that way as well??
BUT, why would they show the changed address if directly programmed, but not respond to it I wonder??

**
Just re-read a downloaded copy of the 55020 leaflet.. It does indeed look like you have to write the CV number to CV 6, follows by the desired value to CV 5.
Not something I have had to do before..

Just got time to try this..
 
Very strange..

It would appear (despite what my Digitrax tells me) I am probably not able to program these decoders at all..

All works on address 3, though I need to tweak the soundcard starting point etc.

It would appear that I am not able to do register programming using a Digitrax Zephyr.. I will email Digitrax support to confirm this.. :(

Thanks for your input peoples, and thanks Mark for pointing me in the right direction.. Always learning!

Cheers,
PhilP.
 
Speaking from personal experience, if the loco is to be used on a hilly railway, ditch the 55020s. They don't have back EMF, and big trains can run away.

They also work on a lower frequency than later decoders, and you can sometimes hear them (well, the motors) buzzing.
 
I had wondered about the motor frequency. - Well state of gearboxes, really..
I think this has been a 'shelf queen'. - wheels show little, if any wear, and it takes a third of a throttle before it gets moving.. The drive is 'noisy', but now reckon that is motor frequency.
Might be worth suggesting replacing the whole lot with an XLS, or just the two 55020's with an XL..

Thanks Tony.
 
The 55020 runs at 75Hz and was produced by Lenz and as was said by Tony, they don't have feedback from the back EMF so a good replacement would be to replace the whole lot with a Massoth XLS
 
Railway42 said:
The 55020 runs at 75Hz and was produced by Lenz and as was said by Tony, they don't have feedback from the back EMF so a good replacement would be to replace the whole lot with a Massoth XLS
Click to expand...
.. And then put the rest on evilBay, marked-up as *RARE* ..

;) ;) :D ;D ;D

I did (supposedly) find a way of writing CV's without first reading them..
Appeared to do what it said on the tin, and got the three pulses back each time, but the address would not 'take'.

This may be another case of my Digitrax and LGB/Massoth not quite understanding each other!!?? ::)
 
Phil, dont blame Massoth with the 55020 decoder it was made by Lenz! :D
 
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