# How to replace digitrax DH 123



## musicwerks (Jan 4, 2012)

Hi all,

I just installed a digitrax dh123 into my HO bachmann fairbank morse train master. It is my first attempt to install onto a older split frame DC engine (non dcc ready)

I just realized that the dh123 is lousy and my engine can't run slow and reponse is still not comparable to newer decoders even after adjusting speed table on jmri.

A) does Dh123 has bad reviews, anyone has used it before?

B) there is a harness attached to the decoder. Can I take out the DH123 and replace with a tusnami sound decoder? Is the harrness universal ? I am considering changing to a Diesel sound decoder

Kiong


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## waltr (Aug 15, 2011)

Did the Loco run slow with just DC before installing the DH123? If not then a newer decoder may not improve the running.
A) The DH123 is a good, simple decoder that has worked fine in several Locos for me. I keep a couple around for quick tests.
B) I'm unsure of the pin for pin comparability of the DH123 and Tsunimi decoder connectors. Hopefully, some else will know and answer your question.


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## britblad (Jan 2, 2012)

you have to cut the plastic back on the tsunami and unplug it but i think that voids the warranty but they will plug right in


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## musicwerks (Jan 4, 2012)

*The loco runs perfect before installation*

The loco runs v well and smooth on DC . After the dh123d, I need to raise to 50 odd steps just to start the engine.

Thanks for updating the tsunami warranty and fitting

Thanks


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## musicwerks (Jan 4, 2012)

It can't run really well at low speed now, it's not as smooth as I want to


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## Rusty (Jun 23, 2011)

Will the more amp booster help?


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## Southern (Nov 17, 2008)

musicwerks said:


> Hi all,
> 
> I just installed a digitrax dh123 into my HO bachmann fairbank morse train master. It is my first attempt to install onto a older split frame DC engine (non dcc ready)]I just realized that the dh123 is lousy and my engine can't run slow and reponse is still not comparable to newer decoders even after adjusting speed table on jmri.


The trouble that you have having with the decoder is in the settings. Check to make sure that the speed table is clicked on. JMRI will let you adjust the spped table and not write to the decoder until it is checked off above the speed table.



musicwerks said:


> A) does Dh123 has bad reviews, anyone has used it before?


No, it is a good low end decoder. i have put a lot of them in old DC locos and after tunning them with JMRI they work great, they run slower, and smother than they did in DC.



musicwerks said:


> B) there is a harness attached to the decoder. Can I take out the DH123 and replace with a tusnami sound decoder? Is the harrness universal ? I am considering changing to a Diesel sound decoder
> 
> Kiong


Yes both decoders have a MNRA 9 pin plug under the edge of the shrink wrap.


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## musicwerks (Jan 4, 2012)

Thanks guys.

Southern...I adjusted the speed tablebut... yeah I forgot to tick the use speed table. Now it runs well and quite smooth on low speed. I like the mars light function that is available in the DH 123D. 

Come to think of it, DH 123 is quite good for the price.


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## waltr (Aug 15, 2011)

Ok, great.


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