Zimo MX648R decoder

[pushpull33]

Hi all.

Hope someone can help before I ring the prouder of the decoder and make a fool of myself.

 

Just fitted a Zimo MX648R decoder to an EFE Adams class 02. It has been hard wired making doubly sure of connecting wires correctly (I'm not a beginner as have fitted many decoders) This one however has presented me with a problem.

All the sounds function correctly and it travels forwards but nothing in reverse.

I have tried a reset with 0 and 8 but still nothing in reverse. The loco ran perfectly on DC before fitting the decoder but now I have this problem. As a note; if leaving the dc option active it does the same thing, forwards but nothing in reverse. Normally I turn the dc option off but was just testing if the same problem occurred.

Is it me our is it a faulty chip ? Or can some Cvs be changed to rectify this.

Any advise greatly recieved.

[Nigelcliffe]

Either decoder fault, or loco fault.   Hard to be sure which.   Could be a contact from motor wires to pickup wires (anywhere from decoder all the way to loco).  

 

Suggested test:  disconnect the motor leads, and attach those to an independent, known good, motor.  See if that motor now runs correctly or not.  

 

( For hard-wire jobs, I check decoders before installing.  A free-standing motor is all that's needed, though there are several sources of "decoder testers" which offer a neater way of checking things ). 

 

- Nigel

[pushpull33]

42 minutes ago, Nigelcliffe said:

Either decoder fault, or loco fault.   Hard to be sure which.   Could be a contact from motor wires to pickup wires (anywhere from decoder all the way to loco).  

 

Suggested test:  disconnect the motor leads, and attach those to an independent, known good, motor.  See if that motor now runs correctly or not.  

 

( For hard-wire jobs, I check decoders before installing.  A free-standing motor is all that's needed, though there are several sources of "decoder testers" which offer a neater way of checking things ). 

 

- Nigel

Thanks, will try another motor. Should have tested it first but came from a good source and is the first decoder of many that has failed.

[Ray H]

What happens if you swap the orange and grey wires?

[pushpull33]

45 minutes ago, Ray H said:

What happens if you swap the orange and grey wires?

I tried that and it just enables it to run backwards but then nothing forwards.

[Nigelcliffe]

23 minutes ago, pushpull33 said:

I tried that and it just enables it to run backwards but then nothing forwards.

 

OK, that's a useful bit of information. 

 

Are you absolutely certain there is no electrical path from either motor terminal to pickups (with decoder not connected to the motor) ?  Could be via suppression components manufacturer fitted, or other routes ?   ( Or do the test on another motor suggested earlier, which would confirm things).    If no electrical path, then I'd say its pointing to a faulty decoder, which does happen sometimes, so refer back to supplier. 

 

 

- Nigel

Edited October 17, 2021 by Nigelcliffe

[WIMorrison]

May be related - or maybe not - but I have a loco fitted with a MX638D that will only run in reverse after having been switched off for a period if 'initialised' by running on DC. After making the motor run on DC for 10 secs in reverse the loco will happily run on DCC in both directions all day, until you switch the layout off and come back the following day when I need to go through the cycle again - never worked out what causes this

 

[pushpull33]

2 hours ago, Nigelcliffe said:

 

OK, that's a useful bit of information. 

 

Are you absolutely certain there is no electrical path from either motor terminal to pickups (with decoder not connected to the motor) ?  Could be via suppression components manufacturer fitted, or other routes ?   ( Or do the test on another motor suggested earlier, which would confirm things).    If no electrical path, then I'd say its pointing to a faulty decoder, which does happen sometimes, so refer back to supplier. 

 

 

- Nigel

Hi Nigel.

Thanks for your help. Deffinatly no connection between pick-ups and motor wires and other factory suppression gubbins had been removed, leaving solely, two wire from pickups and two from the motor.

I have also just tested the decoder on a separate motor and the same thing happens, only runs one way.

Has to be the decoder !

This is the fourth Adams 02 I have fitted but 1st to give me problems.