# Digitrax SDH164D Problem, what are your thoughts ?



## oldSmokey (Jul 31, 2011)

I bought a SDH164D decoder and installed it in my loco (just plugged it in really)
I then placed it on my program track and set the address, I did not
change any other CV's and I was using the speaker that came from 
Digitrax with the decoder. The loco made it around the layout only
once, it let out a high pitch squeal and then no sound at all.
I then placed it on the program track and done a reset (cv8=8),
still no sound, so I got my PR3 and programing track setup and using
Decoder Pro tried to program it, without success, Decoder Pro states
no loco found.
I sent an Email to Digitrax and told them what I had done etc, they
advised me that the decoder was faulty and if I sent it back that
they would replace it, so I posted it back to them, and a month later
I received a new one (living in Australia and posting both ways take
time). I put the new decoder in, programmed the address and guess what
??, it made it around once and exactly the same thing happened, no sound
cannot program it from Decoder Pro etc.
Strange thing is, I can do a reset or program in an address it has
motor control but no sound, if I hold the speaker to my ear I can
hear the engine sound F2 the Horn, also F1 Bell.
So again I contacted Digitrax and explained again, they told me
the decoder was faulty, I told them it was getting expensive me
posting decoders back and forward to the States, they told me not
to worry about sending it back, they would send me a new one.
in the mean time I bought a QSI decoder and set it up in my loco
and it has been running great ever since.
I received my new Decoder from Digitrax but I'm a bit hesitant about
trying to use it.
Looking on the Web, the SDH164D has had a lot of problems, with one 
shop giving away selling the as they have too many faulty ones coming
back at them.
My DCC System is the Digitrax Superchief 8A with the DT402 Throttle.
I have found Digitrax to be a really great company to deal with I'm glad I decided to go Digitrax when I went to DCC.

I was just wondering what are the thoughts of other members and if
they have had problems.


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## NIMT (Jan 6, 2011)

Old smokey, 
I would have said that you had a short that was causing the problem but if you've installed another type of decoder and it works then it's likely that they do have a problem with the decoder design.
I think I see a pattern arising here! Several people are seaming to have the same issues.
You still have the decoder with no sound right? Do you manually program in the CV's? I use a PR3 and a computer to program my decoders. It might be that when you do a reset it turns down the volumes, it does have 8 different volume controls!
The CV numbers are 58 = 15 ,135 = 0 ,140 141,142,143,145 = 64
That will give you max volume
135 is mute volume you could try and raise that to 255 to see if it's just stuck on mute.


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## oldSmokey (Jul 31, 2011)

Hi NMIT,

Thanks for your reply, if I try to use the PR3 and my computer I
cannot read the decoder type with decoder pro it just says no loco
found, I have also tried Train Programmer from Railroad & Co, and
it cannot find a decoder also, I have tried the digitrax sound loader
program without success. If I put it on the program track I
can read some cv's. There is a IC on the decoder that gets very hot
too hot to touch after awhile, I'm thinking that this is the amp
chip and hence no sound. Digitrax told me that they don't repair
the decoders and I didn't find out anything about the circuitry
as to if the ic is an amp.
I will try and put it on the program track and see if I can program
the cv's you mentioned and see how I get on.


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## NIMT (Jan 6, 2011)

I suspect that your right and it is the audio amp that is fried, getting too hot is not a good thing!
I don't know of any way to "protect" the decoder from it happening again.
I think they have a bad set of chips or just a bad design, they are great about getting it taken care of, I hope that digitrax makes it right for you!
Sending you a new chip is all well and fine unless the one they send just has the same problem as the original!


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