Heljan class 15

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GeraldH
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Re: Heljan class 15

Postby GeraldH » Sat Jun 25, 2016 9:20 pm

Thanks for the advice so far. This is now becoming a bit of a saga. I took what I thought would be the easy way out and bought a new Heljan motor with flywheels attached from Howes, unfortunately that is not the end of the story...

I fitted the motor, which curiously seemed to run in the opposite direction to the original, despite me connecting the marked + terminals of both motors to the + terminal on the locos PCB. The loco ran, perhaps a fraction slow, but the resistor was still getting very hot. In the end I decided to stick the body on and put the loco on the night mail train - possibly a bad idea. Half way up the second gradient it just stopped and died. No visible smoke or smells this time, but it's dead as a dodo :( . I'll have to strip it down again and have a look, but I suspect that the new resistor has fried.

I could buy a new Class 15 for the chassis and sell the spare body and dead chassis. Alternatively I could bypass the PCB and wire the pickups direct to the motor and see what happens. It would be a shame to lose the lighting though... :(
Gerald H - BNR Correspondent :)

My layout: http://www.newrailwaymodellers.co.uk/Fo ... hp?t=28854

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GeraldH
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Re: Heljan class 15

Postby GeraldH » Sun Jul 03, 2016 7:31 pm

Just had a look inside the Class 15 and it is the new resistor that has fried. Odd that its the same resistor (of the pair) on the PCB that has gone each time...
Gerald H - BNR Correspondent :)

My layout: http://www.newrailwaymodellers.co.uk/Fo ... hp?t=28854

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Bufferstop
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Re: Heljan class 15

Postby Bufferstop » Sun Jul 03, 2016 10:42 pm

Is it a resistor or a choke (inductor coil) part of the interference suppression circuit. If it's the latter it could be wired out, the diodes would then keep the lights working. I'm in the process of building a new control panel, one of the improvements I was determined to include is an ammeter and voltmeter which can be switched into the feed from one of the controller's. It means three extra cores in the lead from the handheld, but the meters can be switched out by just one single pole c/o switch. If a loco is running but struggling the current will show that all's not well.
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Bigmet
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Re: Heljan class 15

Postby Bigmet » Mon Jul 04, 2016 9:00 am

GeraldH wrote:Just had a look inside the Class 15 and it is the new resistor that has fried. Odd that its the same resistor (of the pair) on the PCB that has gone each time...

As 'Bufferstop', I'd want to try bypassing it with a piece of wire, and then give it an extended running test.

Personally with little use for lights on locos - you couldn't see the lights on the pilot scheme diesels other than at night, and train spotting at night was not generally compataible with my parents ideas of attendance at mealtimes and bed times! - my usual recourse with any circuit troubles in locos is to rip it all out and make my own direct connections between pick up and motor. Nowadays of course hard wiring a decoder into the circuit, and this too is often much easier once the manufacturers bulky circuit board has been removed.

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Bufferstop
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Re: Heljan class 15

Postby Bufferstop » Mon Jul 04, 2016 9:58 am

Thinking about it a very low value wirewound resistor, wound in the "right" way is going to have nearly as much reactance as a coil made for the purpose, so what you call it is accademic. Suppression circuits are a requirement for the manufacturers, but only needed by the user if there is a problem. Can motors and semi open cans usually generate little rf interference and it is usually badly maintained models in a poor mechanical condition which generate noticable rf. I've operated all types of motors in a loft shared with a TV aerial without problems even at 30miles from the transmitter. For a year or so I worked next door to the RFI investigation teams and shared "kettle space" with them. I got talking to them about model railways and TV interference. Their comment was that it was usually "some tight a**** so and so trying to get BBC2 on a coat-hanger", and they simply told 'em "get a proper aerial, then call us if you have problems" I suspect today they would add "and that will be fifty quid please!"
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Bigmet
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Re: Heljan class 15

Postby Bigmet » Mon Aug 08, 2016 9:35 pm

I bought a couple almost immediately the model first came out, and the lights were way too bright during DC test running ahead of decoder fitting. So I would guess that they are all much alike. (Had to wind the controllable light output down on the DCC decoder to a very small setting to make the realistically dim.)

No idea about the circuit board wiring. At least with the switched lines to operate the lights coming from the DCC socket, you can install resistors there using the internal void that enables a decoder to be installed.

Bigmet
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Re: Heljan class 15

Postby Bigmet » Thu Aug 11, 2016 8:56 am

You'll need the 22K, or even all three in series. Those LEDs run on a dribble of current. You are making progress, which is good. I have been known to use Pentel spirit marker inks to dim and change colour tone on LEDs where I cannot get them quite right. (Still too bright on step 1 of 255 from the decoder! - had that happen, so added filtering as well.)

I have to say that light control is an asset on DCC. Turning them down low or off is my usual choice, but they have been very useful for assessing layout wiring faults as they flicker nicely when the loco is standing, if there is anything dodgy in the way of connection conductivity. The heavy all wheel drive and pick up chassis of a large CoCo gives good confidence that pick up is rock solid, so if there's flickering visible, it's on the layout or its wiring. A good 'cheap and dirty' test tool.

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GeraldH
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Re: Heljan class 15

Postby GeraldH » Fri Aug 12, 2016 9:36 pm

Bigmet wrote:
GeraldH wrote:Just had a look inside the Class 15 and it is the new resistor that has fried. Odd that its the same resistor (of the pair) on the PCB that has gone each time...


As 'Bufferstop', I'd want to try bypassing it with a piece of wire, and then give it an extended running test.

Personally with little use for lights on locos - you couldn't see the lights on the pilot scheme diesels other than at night, and train spotting at night was not generally compataible with my parents ideas of attendance at mealtimes and bed times! - my usual recourse with any circuit troubles in locos is to rip it all out and make my own direct connections between pick up and motor. Nowadays of course hard wiring a decoder into the circuit, and this too is often much easier once the manufacturers bulky circuit board has been removed.


Howes have kindly provided me with a new PCB. If my soldering is up to it, I will put the new board in and see if it cures the resistor frying issues. If it doesn't, I will wire the motor direct to the pickups, drop the lighting and see what happens. I''ll report back when I've done it, but somehow sitting indoors soldering during the summer doesn't seem that attractive :) .
Gerald H - BNR Correspondent :)

My layout: http://www.newrailwaymodellers.co.uk/Fo ... hp?t=28854

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GeraldH
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Re: Heljan class 15

Postby GeraldH » Wed Oct 05, 2016 10:57 am

I finally got around to soldering in the new PCB. It was pretty fiddly work, but I got there in the end. The loco has survived two or three operating sessions, so fingers crossed it's now fixed. The only component on the old board that could have had a problem seems to be the capacitor[?] which comes between the resistor and the motor. Could a faulty capacitor cause a resistor to burn out? It seems to have, but I'm no electronics guru...
Gerald H - BNR Correspondent :)

My layout: http://www.newrailwaymodellers.co.uk/Fo ... hp?t=28854


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