R8247 v1 points decoder issues - Now recovered after a full failure.

[STB]

I am just annotating a few notes when my R8247 decoder failed apparently completely this week.

I was running a loco that in the end proved to be far too troublesome and was shorting out every couple of minutes.

One of these shorts seemed to have fried the R8247 as when I tried to change a point - nothing happened.

The points used are PL-11 red to pos, green common and black neg.

Tried to read the CVs in Railmaster and it came up not recognising the chip ID or said it was 25.1 and port numbers were 16000 something...

I had applied a DCC id of 50 for ports 197 - 200.

Tried to reset the decoder back to factory CV 8 to 8.

Nothing.

Used the spare Elite to try to reset - again nothing.

Unwired the controller and put it on the shelf and resigned myself to saying it was fried good and proper.

Next day, tried again. Wired up the controller to the DCC bus and ran the controller to the PROG on the e Link.

Read the CVs... hmm success Hornby 12.1 recognised and the port numbers came back correct.

Wired back up to the track and , yes the points worked again.

________________________________________________________________

I think , I may have mis wired it up incorrectly the weeks before, but up to the point failure it was working - so a bit strange.

Don't give up hope basically.

[96RAF]

Likely the unit had been affected by the shorts but that you had been trying to reset it on the main which is not supported in RM. All programming has to be done on the Prog output with the unit disconnected from the layout bus.

It could be that your Elite Prog output has blown, hence why the eLink worked - try reading a loco address on the programming track to check.

Reading back accessory decoder addresses in RM is notoriously unreliable and it pays just to refresh the address by rewriting it.

From memory the V1 acc decoder is v1.21 so your version number seems correct. V2 is v1.35 again from memory as it is a while since I delved into this. Now they are on the layout and working I tend to leave well alone.

[STB]

I put a second PL-11 point on.. using next port in line 198... the thing stopped working... took it off .. back working... then used next port 199.... working!

Is it possible a blown port from the shorts? Oh well.... just lucky it is not a throw in the bin job at least.

And , yes, I am leaving well alone now!

[Chrissaf]

I had a R8247 damaged by loco track shorts (now replaced). I fitted a 'snubber' to my track BUS located close to the R8247 connection position. R8247 issues are now a thing of the past and no longer affected by shorts.

A 'snubber' is a filter wired across the DCC feed to the track / decoder. The snubber filter is a 100 ohm 1 watt (2 watt preferred) resistor wired in series with a 0.1uf ceramic disc capacitor rated at 50 volts or better (100 volts preferred).

[96RAF]

How about the third and fourth ports, are they unresponsive as well. If so read this about a bug the Select induces on R8247.

http://www.halton96th.org.uk/page16.html

Scroll down to Known Faults.

If alter a reset the second and subsequent ports work until you select the first port then it more or less confirms the death by flutter snag.

If you are using RM then you could hive off your points onto a secondary bus and run the eLink as Controller B just for your points, leaving the Elite as Controller A for locos.