Un readable decoder

[sb67]

Got my first decoder problem. I've a loco with an unknown decoder, it runs with my Bachmann EZ command ok but when I use my power cab it can run but when I try to change cv's, even the address, I get the cannot read cv message. I've done a factory reset and also a recovery program but to no avail.

Anybody got any ideas what could have happened?

Steve.

[Ray H]

Can you confirm whether the loco/decoder still responded (as loco No. 3) after the factory reset?

 

I often get cannot read CV messages but they're usually down to dirty track or dirty wheels.

[NIK]

Got my first decoder problem. I've a loco with an unknown decoder, it runs with my Bachmann EZ command ok but when I use my power cab it can run but when I try to change cv's, even the address, I get the cannot read cv message. I've done a factory reset and also a recovery program but to no avail.

Anybody got any ideas what could have happened?

Steve.

 

Hi,

 

According to a document I've just read DCC decoder reset is not standardised so putting the value 8 decimal into CV 8 may not always work.

 

What's the loco and manufacturer - I've had some not connecting to the tracks reliably enough due to pickups/dirty wheels problems and others where the connection to the motor is intermittent (so the decoder can't communicate back to the command station when in programming track mode)?.

 

Also what recovery program did you use - just curious since you said the decoder is unknown?.

 

Regards

 

Nick

Edited June 8, 2017 by NIK

[johnb]

Down in the depths of the NCE Powercab menus is a decoder reset option. I've used it occasionally when setting Cv8 to 8 fails. It's worked for me on three occasions. How it knows what to reset to what I haven't a clue!

 

John

[10000]

Early Hornby decoders often failed to read on the Powercab

Open it up and have a look at the decoder - see if it has a blue dot on it.

[sb67]

I used the recovery program which is No 7 in the programming options and it did respond to address 3 but ran really slow, then I tried to alter cv's and it decided not to read them. I've looked t the decoder and indeed it has a blue dot on it, does that mean it's the early Hornby type? If so is there any options?

Steve. 

[johnb]

Seems like it could be an early Hornby. Easiest option is take it out and replace with a decent one. I generally use three or four function ones from TCS or Digitrax and they do fine for what I want. As you will have seen others have other preferences Zimo, Lenz, ESU and so on. Depends on what you want to do with the loco, if it's fine control for shunting and so on then those latter are probably better if usually a bit more expensive.

 

Like the command station preferences everyone has their own likes and dislikes. I've a couple of Lenz and they are very good, but I got them at a bargain price. I can be a bit of a tight walletted type, but having a largish collection, price tends to veer me towards the cheaper ones. Personally I don't feel the need to pay that bit more if I don't need to for my operation.

 

Beware of the ultra cheap ones though, I did that a while ago, and regretted it! They were sensitive to short circuits and sometimes having a variety of operators on exhibition duty they sometimes got the points wrong and the layout shorted. That scrambled the chip, OK it could be reset easily enough after the show, but having three chips revert to id 3 out of ten or so in service was a real pain!

 

John

[RFS]

Blue dot means it's a Hornby R8249 which is their current version.  Earlier Hornby ones (eg R8215) have a red dot. 

[sb67]

I think I'm learning that you get what you pay for with decoders. I've fitted a Lenz, Zimo and ESU decoder to various locos and they all run great. I put a Hattons 21 pin Decoder in a class 25 and that isn't too bad but nowhere as smooth as the others.

Steve.

[sb67]

Also, might seem silly but which end of a diesel should be forwards?

Steve.

[johnb]

Officially diesels have a No1 end and a No2 end. I think (only think!) that No2 end is usually the radiator fan end. No1 end is probably not called front in real life as far as I know

 

Mine is an end to end layout with EMUs, a DMU and several assorted locos. For appearance purposes I vary the way round the stock runs onto the layout, for example I make sure that not all two car EMUs have the brake end the same way round. I then set the chip so that which ever way round they are the 'forward' direction is always from the fiddle yard to the buffer stops. It means twiddling CV29, but that is easy with a Powercab as on setting up a chip it asks which direction you want the unit to run. I then put an orange dot underneath to indicate 'layout front'. Similarly with locos, similiar locos are set to have different orientations.

 

Learnt that tip from operating a friends exhibition layout where it didn't matter which was the official 'front/forward/No1 end' of anything, just ensuring that all 'dots' faced the bufferstop end of the layout.

 

US locos are a bit different in that the designated front is usually shown by a small 'F' on the underframe at the appropriate end.

 

John

[Pete the Elaner]

Officially diesels have a No1 end and a No2 end. I think (only think!) that No2 end is usually the radiator fan end. No1 end is probably not called front in real life as far as I know

Mine all run radiator first when set to forward, so I think rad is at no.1 end.

Electric locos have their pantograph at no.2 end.

What about dual-engined diesels such as Deltics & Westerns which are more symmetrical? I guess you leave the lights on & they should go white lights first!

[beejack]

I used the recovery program which is No 7 in the programming options and it did respond to address 3 but ran really slow, then I tried to alter cv's and it decided not to read them. I've looked t the decoder and indeed it has a blue dot on it, does that mean it's the early Hornby type? If so is there any options?

Steve. 

 

which CV's are you trying to change?

From memory with the Hornby R8249 you can only change  CV's 1, 2, 4, 17, 18 and 29. Trying to read any other CV's will result in the cannot read error.

[sb67]

I couldn't change 2, one of them was 3. Sounds like I cant change the ones I want. I've also got a Hornby decoder that is showing on!y PAG mode not sure what that is.

Steve.

[devondynosoar118]

PAG is paged programming mode, this from the DCC wiki-

"Paged Mode

Paged Mode introduced the term "CV" (Configuration Variable).

 

It is very slow when reading back the CVs.

 

To read a CV, a number is sent to the decoder. If the response is negative, the number is incremented by one, and the process repeats until a positive response is received from the decoder. This process can repeat up to 256 times.

Reading the complete CV set of a decoder will take a long time. Every CV will be tested sequentially in this manner."

 

I would bin that old decoder, newer ones from decent makers perform much better and are easier to set up in my experience.

[Pete the Elaner]

which CV's are you trying to change?

From memory with the Hornby R8249 you can only change  CV's 1, 2, 4, 17, 18 and 29. Trying to read any other CV's will result in the cannot read error.

I have a few R8249s. They don't have many configuration options but they all seem to respond correctly & I have never had any of them do something unexpected.

I can definitely change some CV29 settings as well as address them with 2 or 4 digits & CV3 &4 for acceleration/deceleration. They do not support advanced consisting.

I think they accepted CV8 value 8 for reset.

[peterfgf]

Mine all run radiator first when set to forward, so I think rad is at no.1 end.

Electric locos have their pantograph at no.2 end.

What about dual-engined diesels such as Deltics & Westerns which are more symmetrical? I guess you leave the lights on & they should go white lights first!

The radiator end is No.1 end.  I use the drawings in The Diesel Impact on British Rail by Tufnell as a guide (a highly recommended book by a BR traction engineer).

I've also had problems with Deltics and Westerns: on a Deltic there is an access hatch at the side of one nose which differentiates the ends (unfortunately I can't recall which); and I never did sort out which end is which on a Western.

Peterfgf

[devondynosoar118]

Westerns have a "Devon" end and a "Cornwall" end, that's probably the source of your confusion. Generally clotted cream or a pasty placed on the locomotive will determine which is which.