Zimo MX63R decoder running slow

[34theletterbetweenB&D]

Among my mostly Lenz fitted locos, a few 'difficult' chassis have got Zimo MX63R for their extra adjustment. One of these is a Bach 9F which started too fast on step 1 with a Lenz silver. The lower starting output possible with the Zimo fixed that. But today, she no start on step 1, and eventually needed CV2 increased to 20 to get a creep at step 1. Half an hour later, and CV2 had to be reset to 35 to get the loco to start at step 1. Top speed noticeably well down now also, by about 35%.

 

Tried decoder resets, no change. Tried chassis alone on 12V DC, fine, still runs at the maximum speed it did when new. Tried chassis with a Lenz silver, it starts too fast on step 1 with this decoder on minimum output (which was the reason this chassis got a Zimo), and the top speed is as it was when new, scaling about 80mph. Put the Zimo decoder in another chassis, same sluggish performance. Even after some time running on either of the chassis the Zimo decoder is cool, there is no burning smell or discolouration: current draw of these chassis on DC is only 110 - 180mA.

 

Anyone seen similar? Any other possible therapies? Or do I just accept that its magic moonbeams are leaking away, and put it in a loco that wasn't that quick?

[Adrian Wintle]

I would think it was a mechanical issue rather than a decoder one. Check the mechanism for dirt and for proper lubrication. This issue may be masked by the higher start of the Lenz decoder. Depending on the logic used in the decoder, a lower top speed may be expected if the start voltage is increased. Also, check that back emf isn't masking an issue.

 

Adrian

[34theletterbetweenB&D]

Don't think it can be mechanical, the effect travelled with the decoder to a second chassis. Pretty much resigned to this being the decoder gradually turning its toes up...