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Discussion Starter · #1 ·
I was wondering if anyone has had similar experiences with N scale decoders.

The Equipment.Power Cab, Dapol Hymec, Digitrax DN125IN

The Scenario
Loco runs well with DC
Works okay when decoder first installed (plug in)
Works eratically over following weeks (twiddling with the decoder seems to bring it back to life temporarily)
After a faultless running session does not respond next day. Lights are on but loco does not respond to controller in any way
Try to program decoder "on main" or program track and all I get is "cannot read CV"

I handle my models extremely carefully and cannot see anything I may have done to damage the decoders.

This has happened with 2 DN125IN and 2 DN125 (wired) out of a total of 6 decoders I have purchased over the last 3 months (66% faulty). Obviously I will be returning them, but this seems a very low quality control to me.

Would this be similar to the level of returns experienced with 'OO' decoders or with other manufacturers?
Are Digitrax decoders lower quality ?

Could anyone suggest similar replacement decoders (other than Lenz gold - too expensive)?

What is your experience with Digitrax in N Scale?

Thanks

Billy R
 

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QUOTE (Billy Rivers @ 21 Sep 2008, 10:18) <{POST_SNAPBACK}>I was wondering if anyone has had similar experiences with N scale decoders.

The Equipment.Power Cab, Dapol Hymec, Digitrax DN125IN

The Scenario
Loco runs well with DC
Works okay when decoder first installed (plug in)
Works eratically over following weeks (twiddling with the decoder seems to bring it back to life temporarily)
After a faultless running session does not respond next day. Lights are on but loco does not respond to controller in any way
Try to program decoder "on main" or program track and all I get is "cannot read CV"

I handle my models extremely carefully and cannot see anything I may have done to damage the decoders.

This has happened with 2 DN125IN and 2 DN125 (wired) out of a total of 6 decoders I have purchased over the last 3 months (66% faulty). Obviously I will be returning them, but this seems a very low quality control to me.

Would this be similar to the level of returns experienced with 'OO' decoders or with other manufacturers?
Are Digitrax decoders lower quality ?

Could anyone suggest similar replacement decoders (other than Lenz gold - too expensive)?

What is your experience with Digitrax in N Scale?

Thanks

Billy R

Hi Billy,
Welcome to the forum


I use Digitrax decoders wired/plug in / drop in board types in both my British and American N gauge locos without any problems, the only problem i have had is a bad install on my part leading to decoder damage.

On your Hymek did you check the contacts on the chassis and clean the wheels/track while trying to programme it ?
as on the Dapol class 66 in N gauge pick up is through contacts touching the chassis insides i would presume Dapol have made the Hymek similarly.

Wheel blackening though good looking does not help with communication to the control if this is the case here and consideration should be given for it to be removed where it contacts with the track.

The loco will work well on DC but DCC is more demanding on levels of contact and cleanliness, and a good install will pay dividends every time.
 

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QUOTE (upnick @ 21 Sep 2008, 10:49) <{POST_SNAPBACK}>Wheel blackening though good looking does not help with communication to the control if this is the case here and consideration should be given for it to be removed where it contacts with the track.
A problem we have often come across - best way we have found to remove it is to run the locomotive on DC for a while (either on a rolling road or track).
 

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Discussion Starter · #4 ·
QUOTE (upnick @ 21 Sep 2008, 19:49) <{POST_SNAPBACK}>On your Hymek did you check the contacts on the chassis and clean the wheels/track while trying to programme it ?
as on the Dapol class 66 in N gauge pick up is through contacts touching the chassis insides i would presume Dapol have made the Hymek similarly.

Did not check any contacts or clean wheels as I assumed they were okay as running on DC is excellent. Will check this out

Thanks
 

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If the lights are working then the current is flowing between the track and the decoder and the decoder processor and the decoder components driving the lighting circuits are OK. There may be high resistance in this circuit preventing the motor working in which case Upnick's suggestions will help. Inability to read the CVs on the programming track could be because the decoder needs to draw current through the motor in order to communicate with the command station.

However I think it is more likely that there is a problem between the decoder and the motor. Do you get any volts on the motor contacts when trying to move the loco? Have you tried the six decoders in the same loco or do you have six Dapol Hymeks or is it some other combination? There may be an intermittent short or open circuit in the motor circuit (orange and grey wires).

I've also had problems with two Bachmann/Farish motors going short circuit though I've never heard of this problem with Dapol (I don't have either this loco or this decoder). This had very similar symptoms to yours. At first running was intermittently poor, possibly because the short was only present in some rotational positions so was only a problem if it stopped in that position. Later on the motor went completely dead and in one case fried the decoder's motor drive, but the lights were still OK. To check for this problem remove or isolate the motor completely from the loco and check that the resistance between the contacts remains above about 25 ohms as you turn the shaft very slowly by hand. You might get similar symptoms if the motor simply needs more current than the decoder can supply.

I use Zimo MX620s with Farish locos, they are better than Lenz Gold Minis and can be cheaper but only by a little bit. Reports on here suggest the latest TCS with back EMF are pretty good too. There is also the Lenz Silver Mini of course.
 

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I had a problem after installing a Digitrax drop-in decoder. The lights were working, but the loco wouldn't respond to the controller. Took it apart and had a close look. The motor contacts on the decoder weren't connecting properly with the motor. Bent them out a little and everything was fine.
 

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QUOTE (poliss @ 21 Sep 2008, 13:23) <{POST_SNAPBACK}>I had a problem after installing a Digitrax drop-in decoder. The lights were working, but the loco wouldn't respond to the controller. Took it apart and had a close look. The motor contacts on the decoder weren't connecting properly with the motor. Bent them out a little and everything was fine.

Motor contacts can be a problem with some drop in decoders ... with NCE they provide two slots for the always too short contacts to pass through, i resolved this by soldering two short lengths of brass to the motor contacts and clipped them off after passing through the board.

Last night after testing a drop in decoder loco i found the chassis contacts not to be touching disassembled the chassis and glued some 10 thou patches under the four contact areas shimming it up to the chassis reassembled and now its fine
.
 

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Discussion Starter · #8 ·
QUOTE (upnick @ 22 Sep 2008, 03:29) <{POST_SNAPBACK}>Last night after testing a drop in decoder loco i found the chassis contacts not to be touching disassembled the chassis and glued some 10 thou patches under the four contact areas shimming it up to the chassis reassembled and now its fine
.

Thanks for the posts and advice.

I don't think I will be disassembling the chassis, glueing patches or anthing so extreme on a new model. Surely it should be manufactured properly so as not to require such measures. I will check that the decoder pins are contacting in the socket but even that will be pretty hard with my ageing eyesight.
Still waiting to hear back from the supplier as to whether he has found the decoders to be faulty.

Thanks

Billy R
 

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[quote name='Billy Rivers' date='23 Sep 2008, 11:02' post='62676']

"I don't think I will be disassembling the chassis, glueing patches or anything so extreme on a new model."

**This was a drop in decoder Billy and it is common practice to fit American locos this way with board decoders ...... disassembly of the chassis is needed on
two new locos i received yesterday. **

"Surely it should be manufactured properly so as not to require such measures."

** The boards are manufactured to tolerances and it can happen the chassis is that little bit shy of the contacts touching**
 
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