I have an older, but little used, Mehano Mountain that I hard-wired for DCC with sound, using the Digitrax SDH167D decoder. Basically, the loco refused to work, despite exhaustive checking of the wiring. According to an ‘error code’ of flashing headlight, there is supposed to be a short-circuit through the motor wiring, yet, if I fit a non-sound decoder in place of the SDH167D, the loco runs just fine.
It’s been suggested that the non-sound decoder is less fussy than the sound chip. Maybe so. The motor wiring is not at fault, so perhaps the problem is in the motor itself. Anybody out there ever seen this?
Welcome to the forum, modelmaniac99!
Did the locomotive run OK before you put in the decoder?
Very well indeed; and it still does with the non-sound decoder.
I would suspect the decoder. Do you have another sound decoder you could try?
Well, so did I, but…
I didn’t explain that there was a lot of other curious behaviour surrounding the installation. In fact, I tested the SDH167D in another loco and in a decoder tester, where it worked perfectly. Later, the behaviour in the Mountain became so odd that my local dealer agreed to send the chip back to Digitrax (although that has not happened yet). I have a spare SDH167D but, frankly, don’t want to risk damaging it. Meanwhile, I am having a hard time getting around to EVEN MORE checks of the loco wiring.
Yesterday, I measured resistance across the motor at 80 ohms. When compared with several other model motors, this figure hardly looks like the short-circuit suggested by the ‘error code’ I mentioned. I have yet to compare this figure with another, identical, Mehano Mountain.
Hi there and welcome to the forum!
I have installed a few of these decoders and they can be finicky. Have you tried a reset? I prefer to do a reset with the Digitrax sound loader - maybe your hobbyshop is equipped with one if you don’t have that. Otherwise, your motor may be drawing too many amps. Can you check that?
Simon
Thanks snjroy and others for the welcome.
Yep; tried resetting by all means known to ordinary mortals, including JMRI, and I believe my friendly local dealer also put it on his sound loader.
Although I’m pretty sure I checked the motor stall current before installation, it’s something I can look at again, so that’s a good call, for which thanks.
Just for grins – did you check and stone the commutator and ensure the brushes and springs were good? Impulse noise might be causing trouble.
I stopped short of opening the can type motor for fear of wrecking it completely. When I have workshop time, I plan to compare resistance and stall current with an identical loco. Overall, I expect I’ll abandon the sound decoder and simply let the Mountain get on with a silent one. There are plenty more things to fix!