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Author Topic: Help please for poor running  (Read 684 times)

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Offline daversmth

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Help please for poor running
« on: July 03, 2017, 03:53:00 pm »
Hi All,

I have two multiple units that are exhibiting the same bad behaviour. One is a Farish DMU101 371-511, and the other  Farish  EMU 4CEP 372-675. Both were bought as used on ebay, and have had little use. Both have  Bachmann 36-558A DCC decoders fitted ( I fitted them after purchase ). I have a large momentum value set for slow speed ramp up.  Both worked perfectly for quite some while. But now both are exhibiting the same unwanted behaviour where, when DCC ramps up the power to the motor, the train does not move, and after a few seconds the 1.5A current limiter of the control is triggered. So it seems like something is jammed up and causing the motor to draw a lot of current. I see the same behaviour with both the dmu and the emu.

I stripped down the emu completely, could not see anything broken or dirty, reassembled it, but with no change in behaviour as a result.

I reprogrammed the decoder, during which process the train lurched forward slightly in small steps as the instructions were written to it.
This seemed to free the movement and the unit worked for a short while before failing again with the same problem.

I tried both the dmu and emu on DC, and they both run fine.

After a lot of experimentation, suspecting that a "sudden kick" will get the motor to start but a slow ramp up will not, I have managed to get both units running with DCC, with a low value of momentum to get a rapid ramp up of power applied to the motor.

The DMU runs perfectly with this set up unless I run at too high a speed in which case it again causes a 1.5A cut out on the controller.

The EMU still sometimes sticks on startup but will run if left for 20 or 30 seconds.

Has anyone seen similar issues or  have any advice how to "properly" resolve these problems.

I am happy to completely replace all the innards of both units if that is what is required as the bodies are perfect.
If this is needed, could anyone advise what I would need to order to do so ?
Or is there some other solution related to decoder set up or a maintenance issue of the motor/gears etc ?

Thanks in advance

Dave



Offline ntpntpntp

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Re: Help please for poor running
« Reply #1 on: July 03, 2017, 05:25:05 pm »
When you say "ran ok on DC" do you mean with the decoder still fitted or with it removed and replaced with a blanking plate (I'm assuming these are plug-in decoders?)

To me it sounds a bit like could be split gears.   Can you hear any sort of clicking sound?
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline daversmth

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Re: Help please for poor running
« Reply #2 on: July 03, 2017, 06:26:06 pm »
Hi,
Thanks for the reply.
When I say ran in DC I meant with the decoder replaced by a blanking plate.
There is no undue noise when the units are running.

Offline Malc

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Re: Help please for poor running
« Reply #3 on: July 03, 2017, 08:32:43 pm »
I believe there is a CV that sets the start current. It may need adjusting to give a bit of a kick.
I'm not sure if life is passing me by, or trying to run me over.

Offline daversmth

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Re: Help please for poor running
« Reply #4 on: July 03, 2017, 08:43:31 pm »
Thanks for that.
I see that CV 65 is kickstart.
I will look into it.

Offline daversmth

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Re: Help please for poor running
« Reply #5 on: July 03, 2017, 08:55:20 pm »
CV 65 is not supported on the 36-558a decoder but I have other types fitted to other locos so will try to find one that supports it.

Offline PLD

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Re: Help please for poor running
« Reply #6 on: July 04, 2017, 07:37:20 pm »
I tried both the dmu and emu on DC, and they both run fine.
When I say ran in DC I meant with the decoder replaced by a blanking plate.
There is no undue noise when the units are running.
That strongly indicates there is no mechanical issue with the units (motor fault, bearings, split gear etc); which points towards something electrical. It could be the chips, it could be the controller or it could be the wiring in between... have you tried any other DCC fitted locos on the same track & controller? If so, how did they perform?? If they also performed badly I'd be suspecting the controller, if they are OK, it suggests the chips in these two units.

Offline daversmth

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Re: Help please for poor running
« Reply #7 on: July 04, 2017, 08:16:16 pm »
Thanks for the reply, other dcc locos run fine on the layout.  My suspicion is that Dcc control is more sensitive to a  mechanical problem than DC control. I have exhausted my attempts to find any fault and am beyond my frustration endurance level so will pack them off to a repairer now if I can find one.

Online RailGooner

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Re: Help please for poor running
« Reply #8 on: July 04, 2017, 08:47:42 pm »
If loco 'L1' fitted with DCC chip 'C1' performs poorly and loco 'L2' fitted with chip 'C2' performs without error, what is the result of swapping the chips between the locos? How does loco 'L1' perform when fitted with chip 'C2' and how does loco 'L2' perform when fitted with chip 'C1'?

Basically, does the problem running follow the chip or stay with the loco?
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Offline daversmth

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Re: Help please for poor running
« Reply #9 on: July 04, 2017, 08:59:41 pm »
Thanks for that. I have a new decoder arriving in a couple of days for a new loco so I will try it in these 2 units first to see what hapoens.

Offline lil chris

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Re: Help please for poor running
« Reply #10 on: July 04, 2017, 10:30:23 pm »
I have gf class 108 two car unit,  I fitted a better chip in the powercar( DZ125) and just used one of those gf 36-558 in the trailer car for the lights.
Lil Chris
My layout here East Lancashire Lines
http://www.ngaugeforum.co.uk/SMFN/index.php?topic=29492.0

Offline amsie

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Re: Help please for poor running
« Reply #11 on: July 05, 2017, 02:13:22 am »
Good advice by Chris.

I had no end of problems with the Hornby VEP using cheapo Bachmann decoders.  By chance I put a Loksound decoder into the VEP and it ran like a dream.  Perhaps a better decoder will give you the faultless running you require.

Offline daversmth

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Re: Help please for poor running
« Reply #12 on: July 05, 2017, 09:41:28 am »
Thanks once more for the advice. I will try a different decoder when it arrives.

Offline daversmth

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Re: Help please for poor running
« Reply #13 on: July 06, 2017, 04:25:04 pm »
So I tried a different decoder and I still see the same behaviour.
The EMU, for example, either refuses to run at all and triggering the controller current limit cut out when I try to start it, or if it runs, it will suddenly stop after a while, again triggering the controller cut out.
It seems to me that something mechanical is jamming.
I have completely disassembled everything once but could see nothing obvious.
Tempted to do the same again but without knowing what everything should look like when "normal" it is hard to know what the problem is.

Offline austinbob

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Re: Help please for poor running
« Reply #14 on: July 06, 2017, 04:35:40 pm »
As PLD stated earlier in the thread its unlikely the problem is mechanical if all is ok on DC. BUT..is all really ok on DC, have you measured the current required to start the loco up. Should only be a few 10's of milliamps. If much more than this there may well be something a bit stiff or something wrong with the motor...
 :beers:
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