Chip reverting to 3

[mikeg]

I have a loco that for 15 years has been No 67 but a month ago it stopped and although I cleaned the wheels and checked the pickups it appeared to be dead. I put it on the programming track and read the address and it came up as 3, I tried it and it ran so I reset it to 67, tried it and was running OK. I ran it on my layout and worked as it should, I tried to run it this morning and it again appeared dead tried 3 and it ran, I reset to 67 and it ran but when I reversed it nothing so checked it on my test track which is switchable from running to programming, checked Cv1 it was 3 so changed it to 67 and it ran, reversed the controller and it didn’t run so checked CV1 again and it was back to 3!

The chip is a TCS T1 has been used for years but it has not been used for several months. The first time was using a Z21 and the test track is a P2.

Has anyone any idea what could be wrong, I think that it may be time to do a reset but it was to cold to spend time with the temperature 3 degrees C.

 

Hope somebody can help, regards Mike  

[RAF96]

Many older chips tend to revert to default settings after a long power down period. A refresh of the address will wake them up again.

 

It may be that you should think of retiring them in favour of more modern chips with better capability, etc.

[mikeg]

An update I have found that the chip changes back to default either when the track power is turned off or when tripping a frog juicer. I can change the address and it will run on that address until the power is turned off. When I tried a reset my Z21 said there was no response from the chip but my P2 would change the address back to default but neither would change the address with POM mode. On any address the loco responded and runs as it should so I have decided that its not worth changing the chip, I will just change it to the correct address at the start of a running session as the programming track is always available by the layout.

 I have another loco with a TCS T1 that’s still working that has been out of use for longer but has a single digit number 9 and worked as soon as it was placed on the track. I have been trying all of my locos to make sure that I haven’t any problem with not being used, and especially the sound fitted ones are not too loud.

regards mike 

[Hairy Bear Digital]

Hornby R8215 were known to do this as a design fault.

Steer clear of them if that's fitted.

[mikeg]

Its a TCS T1 which when bought was one of the best chips around. I now only use Zimo and wouldn’t touch Hornby with the proverbial pole I tried a TTS and was impressed with the sound but it has no guts kept stopping when I got to step 4/5 on the throttle in a class 14 by Heljan.

regards mike 

[mikeg]

Further to my previous posts I have found that the loco changes back to 3 when it hits a frog that has a frogjuicer so does the way the juicer is connected make any difference to the frog polarity that could cause a short? 

The loco was running with address 67 so had accepted the number but as soon as it hit the frog stopped and then ran as 3! I was able to repeat the process with the same result but only on the one point. I have not changed the juicer as all my other locos run through it with no problem.

Has anybody any idea what the problem is? I am tempted to buy a new Zimo MX600 to replace the TCS and use that for coach lighting.

 

regards mike 

[Nigelcliffe]

Two moderately long-shot suggestions before replacing the decoder. 

 

a)  If RailCom is "on" in the Z21, consider turning it off if you're not using it.  

 

b) Try fitting a "snubber" (or two) to the DCC bus.  A snubber is a small resistor and capacitor (a few pence).  Or some DCC brands will sell you one for a few pounds.    Just sometimes its the "ring" from the short circuit which upsets some older decoder designs causing a reset.  

 

 

[Brian]

As suggested by Nigel above.  The cause is the short circuit or the power surge at switch On/Off producing a momentary spike on the DCC rails/bus and causing the older and "fragile" decoder to reset to its factory default. Most (if not all?) modern decoders have now overcome this.

 

Fitting a resistor and ceramic capacitor across the DCC bus pair or the rails if no bus is used will help.

The components and how to is shown here if its of help? Link to Bus Filter

[mikeg]

Thanks Nigel and Brian I will try to fit one each end of my layout, one end already has a connector so will be easy to do. The other end is a fiddle yard with five roads so I think I will fix it to the bus connection at the yard entrance point.

Will post once I have got them installed and tested, probably after Xmas.

 

regards mike 

[mikeg]

I have been able to install one unit on the lefthand side of my layout and it appears to be have solved the problem, I have used components that I had and not sure of the value of them but they fixed to the end of the bus wires.

 I tried the loco with the TCS chip and it ran through the points without stopping and has kept its address.

 

thanks for your assistance 

 

regards mike