Old Seven Pin Pendolino Decoder not responding to Controller Commands - SOMEWHAT RESOLVED

[Will Hay]

Can someone kindly take a look at this circuit board configuration and tell me if there appears to be something adrift?

I bought a second pendolino set some time ago to utilise the extra carriages and dug this out today, to see how it performs before I sell on ebay.

When I read the decoder the unit zooms backwards and doesn't respond to the controller request.

[96RAF]

The only thing I can say for definite is that is a factory fit 7-pin version of the basic R8249 decoder, also found in 4 and 6-pin variants.

[Will Hay]

Yeah, I did some research in advance of posting and saw a couple of similar threads on this very forum.

I don't have a means to independently test the decoder but given its activity when my controller sends a request, would that suggest the decoder is fine?

All L, R & M wires appear present and correct.

Presumably it's fitted correctly?

I think I read that I could remove the decoder and bridge some pins to test on DC, that might determine if the decoder is at fault?

I think I have an old hornby dc controller somewhere, although; does my power track section need to be a certain type?

[96RAF]

Standard bridge for DC - jumper red to orange and black to grey.

Not special track connector required.

To ascertain correct fitment, red pin should be continuous with either/both TR, black pin with either/both TL. Orange and grey with M+ and M-.

If reversed lights simply wouldn’t work.

[markp123]

I don't think there's anything wrong with your circuitry. I have exactly the same DCC fitted Pendolino as yours and try as I might I could not read or write to these decoders on my programming track (albeit I have a non-Hornby setup). I believe these 7-pin decoders were Hornby's first attempt and are quite old now. Probably like the Select controller and not fully NMRA compliant.

My solution was drastic as I snipped off the old decoder and wired the 7 wires up to an 8 pin socket harness. (The 7 wires map exactly to the 8-pin colours where the green is missing.). Once a modern 8-pin decoder is fitted it now programs and performs perfectly.

So in summary I believe it's the decoder that's the problem and not the circuit board.

[Fishmanoz]

Why don’t you swap the decoders between your Pendolinos and see if the problem follows the decoder or stays with the loco?

Mark, your comment re Select and NMRA compliance is now years out of date, at least for later firmware versions - it is compliant.

Does anyone have anything beyond anecdotal about performance of 7-pin 8249s? I’d have thought an 8249 is an 8249 is an 8249 and the number of pins is irrelevant?

PS. Robwill, not meaning to pick on you but I’m still on my thread title hobbyhorse. What your title says to me is “I have a problem with my DCC Pendolino but I’m keeping it a secret until you open my thread”. What I would have titled this is “Pendolino Decoder Not Responding Correctly to the Controller”. With that title, I get a reasonable idea what you problem is and whether I have anything to contribute and, for people with decoder problems in future, a forum search on Pendolino Decoder will get them a far more targeted response to this and similar threads.

[96RAF]

@mark

The 7-pin decoder was specific to early factory DCC-Fitted Pendos. It was not used in any other loco and soon dropped in favour of the NEM652 8-pin socket.

@fishy

My notes show absolutely no difference of the decoder twixt the pin variants. The only performance issues are those gripes identified and fettled as the firmware of the basic decoder was developed over the years, e.g. lights jamming on with certain CV29 values or adding better programming support for alien controllers.

Early versions were a tad flaky and the actual firmware version can ID’d by the size and position of a blue paint spot or not on the MCU.

A specific 6-pin version of R7150 was remapped for the Terrier motor but this can only be sourced as spare part X13567 not retail.

Edit - digging deeper into my notes I see there was a 7-pin version of the old R8215 decoder for the Pendo and as seen in RobWills photo it has a red paint spot on the MCU confirming it is indeed one of these old and known to be unreliable very early decoders (v1.21). Normal suggestion at this point would be to replace it, but if it still works, it still works.

[Will Hay]

Why don’t you swap the decoders between your Pendolinos and see if the problem follows the decoder or stays with the loco?

Mark, your comment re Select and NMRA compliance is now years out of date, at least for later firmware versions - it is compliant.

Does anyone have anything beyond anecdotal about performance of 7-pin 8249s? I’d have thought an 8249 is an 8249 is an 8249 and the number of pins is irrelevant?

 

 

A fine idea, apart from the fact that my running Pendolino has a decoder socket, and an eight pin decoder fitted.

Mark,

Mine is also non-hornby, insofar as I use a Z21 controller.

I wonder if a select would be more successful and our problems are specific to the fact that we use better controllers than the select or elite?**

Thank you everyone, it looks like I'll be putting a socket in.

 

 

** 😄😄😄😄😄😄😄😄 Willie Wyndoop

 

 

 

 

[markp123]

My 7-pin decoders also have the red paint spot - so it makes sense it's early firmwire that's incompatible with other manufactuers (rather than my suggestion of NMRA compliance).

@Will - I found my 7-pin decoders would respond on the track OK. It's just that I couldn't program them to change their CVs etc. I don't have an Elite to confirm if this would have worked or not.

[Will Hay]

Ah, that's good to know.

On the assumption that's it's still programmed as 03 I should be able to ascertain if it's running okay.

Thanks.

[ColinB]

I suspect it is as someone said early decoder that has ageing issues. I had a brand new decoder that did exactly that, which was traced down to an issue with the connections. Admittedly it was a Next18 type connector but it could be still bad connections. Could it be one of those crimped connectors has gone slightly open circuit.

[Will Hay]

A test of the cheeky monkey using address 03 has proved fruitless, which means it's either not been allocated 03 or the decoder is faulty.

Thanks again to everyone.

[Fishmanoz]

RobRAF, thanks for those notes, explains a lot. I wondered about firmware, had no idea 8215s were involved.

Given that either way, blue or red spot, this is a design issue, I’d be asking HCC a question or two, despite the age.

RobWill, that explains why someone of your experience hadn’t tried swapping.

Mark, given you have red spot, it’s more than a firmware issue as per Rob's advice, it’s a known old poor performance decoder.

[Will Hay]

RobRAF, thanks for those notes, explains a lot. I wondered about firmware, had no idea 8215s were involved.

Given that either way, blue or red spot, this is a design issue, I’d be asking HCC a question or two, despite the age.

RobWill, that explains why someone of your experience hadn’t tried swapping.

 

 

I'm confused.

As I've outlined, the setup in each pendolino is different, as is each decoder.

Without changing the seven pin to an eight pin, which is extreme if indeed it isn't faulty, I really don't know what I should have swapped to successfully test 👍

[Will Hay]

The previous owner had put a small sticker on the underside of the locomotive with the reference 002.

Having tried that it runs perfectly fine.

Maybe I should have tried that earlier [no need to quote this with "yes" raffo, it was rhetorical].

It would therefore appear that my useless, utterly rubbish* Z21 controller can't read this older, Hornby decoder.

*magnificent.

[96RAF]

@will

It would therefore appear that my useless, utterly rubbish* Z21 controller can't read this older, Hornby decoder. *magnificent.

You controller is far too modern to have been around when that old R8215 was in service circa Dec 2007.

It may however be able to interrogate the decoder using REG mode.

[Rog RJ]

The R8215 decoders had a number of problems and one of them was that they could not be read from. They were also only able to have a 2 digit address.

[Will Hay]

RJ.

The designation written under the unit is 002. Relevant, given your comment re. two and three digits?

Raffio.

Surely don't call me Shirley, if it was made *after* the decoder it should accommodate the limitations [of the decoder]?

I'm outraged*

Thanks for the suggestion re. REG.

I've no idea what that means but I'll do some research.

Thanks again.

*I'm not outraged.

[Fishmanoz]

RobWill, clearly what I wrote is not reading as intended. I asked if you’d tried swapping. You confirmed you couldn’t due to the 7/8-pin difference. So I said no wonder you didn’t try then, because you couldn’t.

Glad it’s working now, even if only sort of.

[96RAF]

@willie or wontie

I doubt many kit manufacturers, other than Hornby, even bother to test with, never mind cater for compatibility to other manuf’s kit.

They just build to ‘conform’ with NMRA regs and may not even submit their kit for NMRA testing and warranty due to cost.

Hornby do have a stack of alien controllers and other brand decoders that are used as check mules when introducing new or modifying their own existing kit.

[Will Hay]

Fish and Raf...

... 👍