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DC locos will not run on simple track

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I have a problem where DC locos will not run whereas DCC locos run well on the same track. The track layout is a small Peco Setrack Starter Pack oval with two turnouts and two short sidings. The track is clean and in good condition. It was working fine in DC until recently. No alterations have been made since then, except that I have started to use it for DCC operation (but not at the same time as DC).

DC Electrical Arrangements and Operation

A Bachmann mains plug in transformer supplies 16V AC to a basic Bachmann rectifier/controller. This, in turn, supplies variable DC to the track via a Bachmann supplied lead with its terminals soldered to the underside of the rails. The position of these terminals in the main oval is such that power is supplied to the sidings when the turnouts are manually switched to the appropriate position.

With no locos on the track, power available measured between the rails at any point is in the range 0-25 VDC depending on the position of the basic controller and the direction switch.

With a single loco on the track there is no voltage measured between the rails and no response from the loco regardless of the position of the controller.

This last operation was carried out on two occasions with a Hornby class 08 diesel loco, and a Hornby Class 56. Both locos had their 8 pin decoders removed and replaced by 8 pin decoder blanks.

DCC Electrical Arrangements and Operation

The DCC set-up is exactly the same as DC except that the basic Bachmann rectifier/controller is removed and replaced by a Bachmann E-Z Command Control Centre. For simplicity, there is no booster incorporated in this set-up.

The Hornby class 08 diesel loco and the Hornby Class 56 loco were fitted with decoders and worked perfectly. A Hornby class 08 diesel loco with sound also worked perfectly. All three locos were on the track at the same time.

Conclusion

I’m baffled. I have checked the track, equipment and electrical connections thoroughly but I cannot see a logical answer.

The problem is the same when I try the locos on a single length of Peco Flex Track and on a rolling road.

All help and suggestions would be much appreciated.

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Don't like to be the bearer of bad news but the symptoms suggest a high resistance joint in the DC circuit or a faulty DC controller

If you measure the volts at the DC controller terminals & they go to zero with load then the problem is in the controlled 

If the volts stay constant at the DC controller & drop to zero at the track then the problem is in the wiring from the controller

John

 

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59 minutes ago, bkk-bkk said:

I have a problem where DC locos will not run whereas DCC locos run well on the same track. The track layout is a small Peco Setrack Starter Pack oval with two turnouts and two short sidings. The track is clean and in good condition. It was working fine in DC until recently. No alterations have been made since then, except that I have started to use it for DCC operation (but not at the same time as DC).

DC Electrical Arrangements and Operation

A Bachmann mains plug in transformer supplies 16V AC to a basic Bachmann rectifier/controller. This, in turn, supplies variable DC to the track via a Bachmann supplied lead with its terminals soldered to the underside of the rails. The position of these terminals in the main oval is such that power is supplied to the sidings when the turnouts are manually switched to the appropriate position.

With no locos on the track, power available measured between the rails at any point is in the range 0-25 VDC depending on the position of the basic controller and the direction switch.

With a single loco on the track there is no voltage measured between the rails and no response from the loco regardless of the position of the controller.

This last operation was carried out on two occasions with a Hornby class 08 diesel loco, and a Hornby Class 56. Both locos had their 8 pin decoders removed and replaced by 8 pin decoder blanks.

DCC Electrical Arrangements and Operation

The DCC set-up is exactly the same as DC except that the basic Bachmann rectifier/controller is removed and replaced by a Bachmann E-Z Command Control Centre. For simplicity, there is no booster incorporated in this set-up.

The Hornby class 08 diesel loco and the Hornby Class 56 loco were fitted with decoders and worked perfectly. A Hornby class 08 diesel loco with sound also worked perfectly. All three locos were on the track at the same time.

Conclusion

I’m baffled. I have checked the track, equipment and electrical connections thoroughly but I cannot see a logical answer.

The problem is the same when I try the locos on a single length of Peco Flex Track and on a rolling road.

All help and suggestions would be much appreciated.

Do any of the locos work if you disconnect all power supplies and with the blanking plate in place, connect a 9 volt battery across the track?

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Some DCC chips won't allow DC running unless they're 'told'. You need to change one of the CVs to do that - a question with which someone else will need to help you. Also, as an afterthought, is the blanking plug the right way around (been there, done that!)?

 

Cheers,

 

Philip

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2 hours ago, John ks said:

Don't like to be the bearer of bad news but the symptoms suggest a high resistance joint in the DC circuit or a faulty DC controller

If you measure the volts at the DC controller terminals & they go to zero with load then the problem is in the controlled 

If the volts stay constant at the DC controller & drop to zero at the track then the problem is in the wiring from the controller

John

 

Think that's you answer - you could carry out a check by taking two wires from the controller and applying them direct to the wheels of the loco which would eliminate any questions re the track and connectivity. If they ran fine that way - then need to work through the connections starting from the back of the controller an onwards. If they won't run with the direct wires - controller is on the blink.

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Posted (edited)

 

wrong thread

Edited by WIMorrison
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Many thanks for all your helpful suggestions which I read with interest and tried in the latest fault finding exercise.

I’ve come to the conclusion that it is the DC controller that is at fault, so I have binned it.

However, I do need a replacement DC controller but I don’t want to spend too much and air freight charges are often more than the cost of the item being bought.

Low and behold, the DCC controller has a DC function (https://www.bachmanntrains.com/home-usa/images/E-Z_Command_instructions.pdf bottom of page 6). I tried it today and it works but I think it is only a temporary solution. So I will use that when needed instead of buying a new DC controller.

Another interesting point was the suggestion to use a 9V battery to check that the locos were operational. Obvious when you think about it but in the heat of the moment these ideas tend to get overlooked. So I bought a 9V battery today and was pleasantly surprised when the Hornby class 08 with decoder blank ran perfectly on the track with the battery connected. Likewise with the Hornby class 56 on my rolling road.

While I was in the hardware store buying the battery I noticed that they also had 12V rechargeable batteries. These were much larger than the 9V battery, probably about 10x10x15 cm. I will check next time on prices and method of recharging. But I wondered if these would be a good cheaper substitute for the DC controller as I could salvage bits from it and use them for speed and direction control. Any suggestions on this last idea?

Many thanks again.

Brian (bkk-bkk)

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1 hour ago, bkk-bkk said:

But I wondered if these would be a good cheaper substitute for the DC controller as I could salvage bits from it and use them for speed and direction control. Any suggestions on this last idea?

Might/might not work depending on where the fault is. If you can disconnect the rectifier component from the speed controller and try connecting that to the 9V battery - it would prove the concept. If it worked you might want to spend bit more effort on it.  Alternative might be worth speaking to these folk and seeing if they have something, maybe used, at a modest price -  http://zughaus.yolasite.com/

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4 hours ago, bkk-bkk said:

 

Low and behold, the DCC controller has a DC function (https://www.bachmanntrains.com/home-usa/images/E-Z_Command_instructions.pdf bottom of page 6). I tried it today and it works but I think it is only a temporary solution. So I will use that when needed instead of buying a new DC controller.

 

Hi,

 

The DC function, using address 10 for a single DC loco is NOT A GOOD IDEA, you may very well destroy the motors in any analog loco's that you try this with. Bachmann do warn about this in the manual. I'd stick to a 9V battery for DC testing.

 

Regards,

 

John P

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On 29/06/2020 at 08:21, Philou said:

Some DCC chips won't allow DC running unless they're 'told'. You need to change one of the CVs to do that - a question with which someone else will need to help you. Also, as an afterthought, is the blanking plug the right way around (been there, done that!)?

 

Cheers,

 

Philip

 

I think you've mis-read the problem. The issue was that non-fitted locos did not run.

Blanking plates are rotational symmetrical too, in the sense that they are the same when rotated 180 degrees so the 'wrong way' should be fine.

 

 

4 hours ago, bkk-bkk said:

 

Low and behold, the DCC controller has a DC function (https://www.bachmanntrains.com/home-usa/images/E-Z_Command_instructions.pdf bottom of page 6). I tried it today and it works but I think it is only a temporary solution. So I will use that when needed instead of buying a new DC controller.

 

 

Sounds like you mean address zero. Some frown on this & as a result, not all systems support it. You should be ok running DC locos for short periods, but do not leave them idle on the layout because there is still power running through their motors & they are not moving in order to dissipate the heat.

 

Are you thinking of using the charger as a controller or the 12v battery? I am guessing the charger? It would need to have an output of at least 1/2 amp.

How many locos are still on DC? I would prefer to convert these if possible.

I expect you will fit decoders to them sooner than you expect anyway. I know mine seemed to breed after I started in DCC.

It is still useful to have the ability to test with DC though.

 

How well is railway modelling supported in Thailand? I visited Hua Hin a few years ago. I understand the station is a very nice building but I don't think my GF would have appreciated visiting it. I think I would have passed through it a couple of years later on the sleeper train to Surat Thani but it would have been dark then.

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Guilty as charged - scanned it too quickly and missed the bit where the decoders had been removed. However, it did beg the question (in my mind) why would you want to run them without the decoders when they will operate on DC (provided always the CV has been tweaked) which sent me on the wrong path :(.

 

Anyway, glad to see the problem has been overcome.

 

Cheers,

 

Philip

 

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Hello again everyone

Many thanks for your continuing input. This is the first time that I have used any forum where the conversation has continued beyond the first question and reply.

 

First a summary of the current situation. This is followed below by answers to specific questions and suggestions.

 

First the reason for the exercise. I have about 25 OO gauge diesel locos, all periods from BR blue through to sectorisation and privatisation. They have all been in storage for about 10-11 years and some of them need minor repairs. They are all fitted with DCC decoders, including 4 with sound, and were always intended to be operated on DCC. Due to a fragmented lifestyle over the last 15 years caused by 5 house moves and 2 major illnesses I have never been able to complete a layout successfully apart form the current Peco Starter set oval with 2 sidings.

 

The reason for using DC to get things moving is because I am not sure of the status of most of the locos as they have been in storage for so long, so DC is a starting point to ensure things are mechanically and electrically fit for purpose without putting decoders and sound systems at risk. Once DC is satisfactory and repairs are complete, then I will move on to DCC as a final check for each loco. After that they will be listed for sale on eBay with a statement that they work correctly and are DCC ready or DCC fitted as appropriate (ie, the same status as when I bought them new) so that buyers can be confident in what they are paying for.

 

Regarding running a DC loco from the DCC controller. I tried it today for about 20 seconds and the loco definitely didn’t like it. So I have discontinued doing that.

 

The idea of using a 12V rechargeable battery is just that, an idea at the moment. First I will need to check on prices when I go shopping next week. If cost isn’t a problem I will try and modify the defunct Bachmann DC controller by removing or bypassing the rectifier, then if that’s successful, back to the shop and buy the battery and recharger. The plan is to use the battery as the DC power source and recharge it as necessary.

 

Finally, I have bit the bullet and ordered a new Bachmann DC controller on eBay which was listed at a very reasonable price with free delivery from Florida to Thailand. (Breaking news the guy has emailed to cancel as I didn’t request postage costs despite the fact that he promoted free international postage in 2 different places on his listing.)

 

Footnote, railway modelling in Thailand seems to be just me. Although there must be more I haven’t come across others and I haven’t heard of any sort of community organisation. However there is a shop (Zug Haus) in Bangkok which JimFin mentioned earlier in this thread. Their website looks a bit out-of-date 2014 seems to be the last update. I have sent them an email anyway requesting assistance. Will report on the outcome later.

 

Another footnote, the station in Hua Hin is quite attractive but will soon be bypassed I believe as a “high speed” line is being built from Bangkok to somewhere south of here (Surat Thani?). Much of the local groundwork appears to be complete and some of the catenary supports are in place but no sign of any track yet.

 

Apologies for being so long-winded but I think and plan and do all at the same time and usually not in the correct order.

 

All the best Brian (bkk-bkk)

 

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30 minutes ago, bkk-bkk said:

 

Footnote, railway modelling in Thailand seems to be just me. Although there must be more I haven’t come across others and I haven’t heard of any sort of community organisation. However there is a shop (Zug Haus) in Bangkok which JimFin mentioned earlier in this thread. Their website looks a bit out-of-date 2014 seems to be the last update. I have sent them an email anyway requesting assistance. Will report on the outcome later.

 

 

I have also passed a sign for a model shop in Silom before. It seemed to be upstairs so I expect it was a small place but I did not remember seeing it last year when I was there. It was closer to Sala Daeng BTS than it was to Silom MRT: if you exit Sala Daeng BTS facing the Silom Centre & walk at street level towards Silom MRT it was on the right.

That is all very well if you go to Bangkok for any reason. It makes London seem quite calm!

 

If there is no commercial support, there is a little you could do to model Thai railways: they have some class 158s but they run on metre gauge track, so re-gauging them to TT would make them more accurate than OO.

The Suvarnabhumi link uses trains similar to UK class 360s, but with large air con units on the roof, so it is a shame Bachmann's class 350 tooling has not been modified to cope with 360s too. I am not sure how interesting a layout the airport line would be though. Being 50' in the air would make things more difficult & a bit awkward to hide the entrances to your fiddle yards.

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With your defunct controller the symptoms seem to indicate a high resistance joint in the controller

Could be as simple as a dry solder joint or loose joint. Depending on your skill level you could try resoldering all solder joints in the controller

If you can open the controller try measuring the voltage (load & no load) in several places (eg after the rectifier) if the voltage drops significantly

then the fault is before that point

If it is (as you suspect) the rectifier then replacement rectifier are cheap & fairly easy to get (could be replaced with 2 diodes)

The rectifier may be made of 4 diodes, these could be replaced with any 1Amp 100V or greater diode eg 1N4004

If you decide to try to repair the controller then post a couple of pictures of the circuitry & someone here may be able to spot the fault or give some clues as to where to look

John

 

 

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Hello John

 

Thanks again for your help.

 

I've progressed beyond fault-finding mainly because I don't really have the necessary skills and I probably would have to buy replacement parts from overseas where postage costs would be prohibitive.

 

I’ve kicked off my alternative plan and bought a 12V battery. Next job is to modify the controller for 12V DC input. I have disassembled the controller into four major parts and photos are enclosed of the result.

 

Figures 1 shows the 4 major components laid out in the order top to bottom and Fig 2 shows the same items turned over.  Figure 3 is a PDF and shows both sides of the PCB alongside each other. Orientation can be taken from components D1 and D2 which are identified on both sides of the board. Figure 4 is just for interest and shows ECB Q1 and Q2 in more detail.

 

The only items that I will need to use in the circuitry are the input jack, potentiometer, direction switch, and output jack. However I will need to retain the PCB and the three other major components (both halves of the case plus the aluminium plate) so that I can reassemble it for use.

 

My plan is to:

 

1.     reconnect the three wires of the potentiometer to the PCB

2.     use new wiring soldered to the terminals of the existing components (input jack, direction switch and output jack) on the PCB to create the circuit

3.     figure out which components on the PCB (capacitors, diodes, etc) will be redundant and whether to bypass them somehow or just remove them to prevent hazards

4.     use the wire from the redundant transformer to connect the 12V battery to input jack 1. (I'm guessing the soldered joint nearest the red LED is positive and the other one is negative.)

5.     use the existing wire to the track plugged into outlet jack 2 for operation

 

I would appreciate any guidance that you can offer on items 2, 3, 4 above.

 

Best regards

 

Brian (bkk-bkk)

 

figure 1 dc controller major components top to bottom (right way up).jpg

figure 2 dc controller major components top to bottom (upside down).jpg

figure 4 dc controller pcb (underside showing ecb q1 & q2).jpg

figure 3 dc controller pcb (top and underside).pdf

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Connect the battery to the terminals marked 'ac input', it doesn't matter which way round. You will have a very smooth output, no ac ripple, but it should work.

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If you are planning to use the pot as a speed controller then I don't think it will last very long

The pot is probably 5k or 10k & is unsuitable to directly power a loco

Looking at the circuit the thermal overload (see drawing) looks to be open

there are 3 resistors R4, R5, & R6 that seem to be missing. see drawing

These resistors are in series with the transistor output & may be part of an overcurrent protection 

1179074487_bachmanncontroller.png.3e91ff0ed08201036ac1aad1d5ab722c.png

 

This controller looks like it uses split dc power 

In forward the voltage goes from 0v to (+)12V & for reverse it goes from 0v to (-)12v

 

Do the following at your own risk

You could power up the controller with the overload reset & measure voltages

Brown to blue 12VAC (this could be 18V depending on your power supply)

Blue to red 12v dc positive

Blue to black 12v dc negative 

red to black 24v dc positive

if you get voltage reading similar the above then the power part of your controller should be OK & you can try the following remembering Do the following at your own risk

 

Solder a wire across R4 (or R5 or R6) reconnect the pot, make sure the overload is reset & power up

1 of 2 things may happen 

1 it will work

2 More of the magic smoke will escape & it wont work

 

John

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21 hours ago, cliff park said:

Connect the battery to the terminals marked 'ac input', it doesn't matter which way round. You will have a very smooth output, no ac ripple, but it should work.

Cliff if I understand the circuit properly then connecting DC to the AC input wont work

For anybody interested this is the circuit (assuming I have made no mistakes) 

1035940841_bachmanncircuit.png.6e0a459c4816a819fa746ab6dc0fec92.png

 

The power transistors symbols for Q1 & Q2 are not completely correct, suspect 1 is PNP & other is NPN, not sure of Emitter or collector of Q2

Transistors Q3 &Q4 are SMD,s &as such the best I can do is show a representation on them

John

 

 

 

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Hello John

 

This is fantastic. Thank you for taking the trouble to make the circuit diagram. I’ve abandoned the idea of battery operation and am now fully into AC fault-finding mode (until the magic smoke appears). I have taken some more photos:

 

Figure 2.1 shows a side view of the thermal overload showing that it is actually open. How is this reset?

 

Figure 2.2 shows a close up of R4, R5, R6

 

They are very difficult to see against the background of the dark parts of the PCB. They are very thin so I have used light from the side to try and highlight them but my phone is not up to the job and I don’t have a decent camera. I have viewed them through a strong magnifying glass and they each look like a smear of congealed grease. There’s no visible markings and all three look the same. The spaces between them look smooth just like the rest of the dark parts of the PCB.

 

THIS IS WHERE REALITY KICKS IN AND I REALISE THAT THESE THREE RESISTORS APPEAR TO HAVE BURNT OUT OR MELTED. I HAVE NO IDEA WHAT THE Y LOOKED LIKE BEFORE THE PROBLEM APPEARED.

 

I’ve included answers to your remaining points but I fear that rectifying this problem will be outside my capabilities. So please skip to the final paragraph if required.

 

Figure 2.2 also shows the two items that you circled in red.

 

The circled item below and to the left of Q4 is a mystery. It is also shown in Figure 2.3 in the best close-up that I could get. There is nothing in that location on the other side of the board.

 

Figure 2.4 close up of output jack

 

The second circled item, between R4 and the yellow component (234), is connected to the top left of the output jack.

 

Figures 2.5 & 2.6 show a close up of the undersides of Q1 and Q2

 

When the controller is assembled Q1 and Q2 are bolted to the aluminium plate with a thin piece of isolating material between the component and the plate. Incidentally, I had to split the nut of the screw holding Q2 as I couldn’t get access to the head to stop it rotating. I will replace it with a BA bolt and nut during reassembly so that I can insert  a thin piece of metal into the slot in the head of the bolt to prevent rotation.

 

Bearing in mind that my objective with DC operation is a brief check of the basics of each loco (motion and lights) before moving on to DCC for final operational checks:

1.      Is it feasible to continue with the original plan and convert the faulty controller for DC battery operation? if so what size potentiometer should I use if a change is required? and what modifications should I make to the PCB?

2.      I have a car battery charger (Figure 2.7) which has a built-in controller. Could I use that to supply DC direct to the track or rolling road?

 

Best regards

Brian Gledhill (bkk-bkk)

 

PS. Only figures 2.1, 2.2 and  2.7 uploaded  (10 Mb limit exceeded). Figures 2.3, 24. 2.5 and 2.6 to follow if required.

figure_2.1_dc_controller_pcb_(side_view_''fuse'').jpg

figure_2.2_dc_controller_pcb_(close_up_r4,_r5,_r6).jpg

figure 2.7 dc controller pcb (car battery  charger).jpg

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Posted (edited)

Resetting the thermal overload. Pushing down on the copper contact near the top (marked FUSE) might reset it

 

 

Resistors R4 R5 R6 are missing , the pieces with the red arrows point to what is left of one of them & i have put the pieces back where I think they came from.

Resistors R4 R5 R6 were 3 resistors in parallel. By paralleling resistors you can get a low resistance that will handle more power than a single resistor 

Say you need a 0.33ohm 3watt resistor then three 1ohm 1 watt resistors will work

spacer.pngr456.png.99f70a34508eea28bfbde344f6225ae5.png

The transistors Q3 & Q4 (yellow circles) look like they are cooked

As i said previously Do the following at your own risk

reconnect the pot 

reset the overload

solder a piece of wire or a big blob of solder across R4 R5 or R6 (where the grey rectangle is)

You may also need to remove Q3 & Q4

connect AC to the input terminals & give it a go (measure the output voltage with a meter before you run a loco)

3 hours ago, bkk-bkk said:

Is it feasible to continue with the original plan and convert the faulty controller for DC battery operation?

I don't think the circuit in the controller will work with a DC supply 

 

3 hours ago, bkk-bkk said:

I have a car battery charger (Figure 2.7) which has a built-in controller. Could I use that to supply DC direct to the track or rolling road?

Maybe.

the output of the charger may only give 6V or 12V which will run your locos at 1/2 or full speed

John

 

 

 

 

 

Edited by John ks

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