Motor overcurrent

[Neil -349476]

Hello,

I’ve got “ motor overcurrent “ .

what does it mean and how do I fix it.

cheers.

[96RAF]

If it is a true motor over-current then your motor may be unserviceable or it may need some maintenance. You could carry out a motor stall current check with a suitable rated multimeter to find out but you need to unplug the decoder and fit a DC blanking plate. Do not try it with the decoder in circuit else it will simply overload the decoder and could damage it.

It may be the fault was caused by a temporary overload and should reset by power cycling the app. If it happens again see earlier.

Although it says to reload the sound profile this fault would not in my opinion need you to do that.

[South Coast Flyer]

I have the same on Falcon - deleted the decoder and reinstalled three times to no avail so am sending back to Margate for fixing - all other locos work fine on the track so am assuming it’s not a problem with the layout

[sotars]

I had the same problem, the A4 from the Easterner train set. Worked fine on the transit controller. As soon as I inserted the chip and tried to run it under default settings, nothing worked but on checking I got the "overcurrent message". Sent it back to Hornby (Loco and Next18 chip). It was returned as repaired and working. Put it on the track and again nothing. Overcurrent message returned. Put blanking plate back in Loco runs fine on transit controller again.

I had already sent the Loco and original decoder back as it would not accept any downloads. It was returned as fixed as above. So Loco is back in box and chip is sitting on the shelf. Don't think I will be continuing with my planned layout build now in TT120.

[Rallymatt]

I had this on one of my failed TT 120 locos too, replaced under warranty.

[Neil -349476]

Spoke with Hornby and am sending the chip back.

Anyone know what would cause the issue ?

cheers.

[Rallymatt]

The logical explanation would be the motor has being trying to draw more current than the decoder is rated for (1amp) Modern motors in good health draw much less than that, the TT:120 ones have been measured 240-300 milliamps. Drag in the transmission, failing motor, short circuit could all cause ‘over current’ demand. When I experienced it, it was a seizing motor, the decoder shut itself down to protect itself.

[South Coast Flyer]

As a follow up to this I just received my Falcon back from the paramedics in Margate - with replaced chassis and decoder which sounds as if this error is pretty terminal…

Hopefully all sorted now

[Greg-1325485]

I have had this problem... three times, once with Falcon (sent back and repaired) and twice with Trigo (now back at Hornby and awaiting its return). I have asked Hornby what causes this fault but have had no definitive reply. From what I have seen on other posts it's a problem with the motor but no one seems to know what causes it. It doesn't seem to be an issue if locos are controlled with an analogue controller. I'm thinking of going down the analogue route despite losing the advantages of DCC and sound.

[96RAF]

3 hours ago, Greg-1325485 said:

I have had this problem... three times, once with Falcon (sent back and repaired) and twice with Trigo (now back at Hornby and awaiting its return). I have asked Hornby what causes this fault but have had no definitive reply. From what I have seen on other posts it's a problem with the motor but no one seems to know what causes it. It doesn't seem to be an issue if locos are controlled with an analogue controller. I'm thinking of going down the analogue route despite losing the advantages of DCC and sound.

As already stated using it as analogue, the controller simply provides the extra current. It has no smarts to know if this is more or less or normal.

With a decoder in, the app detects the current draw and cries for help.

Either the motor is obviously drawing more than it should or the app sensitivy is too tight.

[ColinB]

This fault it appears to be coming up over and over again and before everyone jumps in, there are at least 3 posts about it. The overcurrent is going to be derived from a bluetooth message from the HM7000 decoder back to the smart device because the smart device(pad or phone) is not in control of the DC power supply used to power the track. Perhaps if it is possible, could one of you guys just test it on DCC only (no HM7000 involvement) if you have a suitable DCC controller, to see if the loco actually works with the HM7000 fitted. If it does work could you please report back.

It is possibly the way Hornby monitor the motor current, they are not filtering it properly as they seem to fix it by changing the motor. Trouble is the HM7000 triggers an overcurrent condition sets the flag in bluetooth so I imagine the App then sets the motor current to zero via another bletooth message back to the decoder. That is just a calculated guess from my experience with signal controlled control systems. The decoder could be doing current limiting on its own by using foldback to reduce the current to zero, but I doubt it as it would need a pretty chunky resistor on the decoder.

A bigger issue is as motors get old they generate more noise, so just replacing the motor is not a solution.

Edited July 21 by ColinB

[LTSR_NSE]

Considering more than one analogue user has had these type of locos simply expire - personally I’d suspect the motors more the the decoders/app.

However I certainly don’t disagree with @96RAF that sensitivity might be too great.

[ColinB]

12 hours ago, LTSR_NSE said:

Considering more than one analogue user has had these type of locos simply expire - personally I’d suspect the motors more the the decoders/app.

However I certainly don’t disagree with @96RAF that sensitivity might be too great.

I never have noticed it with my HM7000 but on TTS I had one loco that would constantly lose sound, I spent about a week trying all the techniques I know to reduce noise. In the end I gave up. I eventually moved the TTS to another loco and bought a Zimo sound decoder as a replacement. Both locos worked perfectly with their respective sound decoders. I could have changed the motor in the brand new Duchess but as it was new, I didn't want to. I have a similar issue with my DigiKeijs it occasionally trips out on start up, which it didn't until I changed the firmware to the new arrangement. I mailed the guy that designed it and he explained they had put some extra protection in which was what was causing it. He had a fix to disable the check, but in the end now I know the cause so I just put up with it. I suppose I am different, we once had an issue with the engine control of a Zeta engine mainly because of the way the engine was manufactured. In the end we were told to fix it in software, as there was no way they were going to redesign the line. So I suppose I have totally different attitude.

It needs sorting, as I am sure this may be one of many reasons decoders get returned. Interesting to see though if they work ok on DCC only, which could imply a binary flag is getting set improperly on power up.