32-377 Class 37 troubles

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bigfish
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32-377 Class 37 troubles

Postby bigfish » Sat Feb 10, 2018 5:44 pm

Hi.

My class 37 is usually a really reliable engine, but suddenly it has become problematic to the extent I can barely get it to move. I'm running it with a DCC chip, and there is obviously some sort of pickup issue as there is no power to the loco (no lights). If I push on the bogies gently from the side I get some flashes from the lights and a small amount of motion which stops again almost instantly. I have tried replacing the Chip, which made no difference although it now seems that the original chip does not work at all (could there have been some electrical issue that damaged chip and engine?)

I've taken the top off to inspect for obvious issues and to look at cleaning and I'm struggling to take the engine apart. I have the top off, and have undone the screws that attach the chassis to the weight body and I undid the screws holding in each bogie and they came loose. But I could not see any way to separate any of these parts without de-soldering the wired connections.

I'm a bit stuck now and would like some advice on how to troubleshoot this loco.

Regards
Martin

MickleoverTestTrack
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Re: 32-377 Class 37 troubles

Postby MickleoverTestTrack » Sat Feb 10, 2018 9:19 pm

OK so going by the number and google this is an older 8-pin. I have one in EWS livery that does the same although I've never investigated the cause properly. It does seem to be pickup related but also unlikely that the pickups would fail to connect on all 6 axles simultaneosly. Could be a broken wire or track on the PCB.

Have you got a digital multimeter with continuity tester on it?

Paul-H
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Re: 32-377 Class 37 troubles

Postby Paul-H » Sat Feb 10, 2018 10:31 pm

Get a multimeter and check pin 8 & 4 go connect to the rails, 8 to one and 4 to the other, set the meter on low ohms and look for a low resistance reading any thing other than a low say less than 10 would indicate a poor connection, either pickups on the back of the wheels or even dirty wheels, both flange and wheel backs should be nice and clean, but get dirty in use.

Paul

dan8400
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Re: 32-377 Class 37 troubles

Postby dan8400 » Sun Feb 11, 2018 8:32 am

I have two bachmann 66's with similar problems. Fine one minute, struggling the next. Wheels are clean, backs are clean.

I have an older 8 pin and a newer 21 pin.

They both used to be really reliable

Following with interest, let us know how it goes

Thanks
Dan
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Bigmet
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Re: 32-377 Class 37 troubles

Postby Bigmet » Sun Feb 11, 2018 9:46 am

No substitute for the slow plod through the electrical connections. If there is no power at all ever to lights or motor, most likely location is the 'power in' connections on the decoder socket as already mentioned as these are the sole common point connections to the rails. If you get brief power connection by wobbling a loco that's an intermittent connection, possibly more than one too...

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D605Eagle
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Re: 32-377 Class 37 troubles

Postby D605Eagle » Sun Feb 11, 2018 2:38 pm

I've had something similar happen with Bachmann Co-Cos running on DC, and it turned out to be very poor solder and wire connections between the pickup strips and the main circuit board. I replaced the wires with some new ones and not had any issues since.

dan8400
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Re: 32-377 Class 37 troubles

Postby dan8400 » Sun Feb 11, 2018 2:41 pm

That's worth knowing Eagle, thank you. It's something to eliminate for all of us

Thanks
Dan
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Mike Parkes
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Re: 32-377 Class 37 troubles

Postby Mike Parkes » Sun Feb 11, 2018 4:09 pm

Work back from the motor; first of all disconnect the decoder and apply 12v dc direct to the motor terminals, assuming the motor works okay the follow the circuity back via the 8 pin socket (plug in a blanking plug) to eventually the pick ups removing one wire from the motor to first available connection point (check the motor goes okay), remove the other wire from the motor to the first available connection point for the other side of the power supply (check the motor goes okay) and so on.

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Bufferstop
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Re: 32-377 Class 37 troubles

Postby Bufferstop » Sun Feb 11, 2018 5:16 pm

I'd agree entirely with the recomendation to check for continuity starting at the motor and working backwards to the decoder then on to the rails. If you have a blanking plug for the decoder socket it might be worth taking out the decoder and fitting it whilst you do your checking. Even so the fact that poking the bogies has some effect suggest you'll end up finding the problem in that area. Possibly a loss of tension in the pickups and a deterioration of the rear surface of the wheels.
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D605Eagle
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Re: 32-377 Class 37 troubles

Postby D605Eagle » Mon Feb 12, 2018 12:38 am

dan8400 wrote:That's worth knowing Eagle, thank you. It's something to eliminate for all of us

Thanks
Dan

No problem Dan. Always start at the power source and work your way forwards.

Bigmet
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Re: 32-377 Class 37 troubles

Postby Bigmet » Mon Feb 12, 2018 8:30 am

Something I forgot to mention with these all wheel drive and pick up twin bogie types: they are almost 'too good' in current collection. If you think about it, one bogie is the equivalent of an 0-4-0T or 0-6-0T in curent collection. So you can completely lose two of the wire pick up connections, one per rail, and the model will keep right on running! It's potentially only when the third wire pick up connection is lost or intermittent that the model becomes a non-runner.

This makes it worth checking all the connections between the pick ups and the main PCB. You don't want to fix just one, and leave potentially two others not working...

bigfish
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Re: 32-377 Class 37 troubles

Postby bigfish » Fri Feb 16, 2018 9:07 pm

Thanks all for your suggestions.

I got the multimeter out and started checking connections. There are two wheels on each side of each bogie that pickup, and so there is a left rail and a right rail feed from each onto the circuit board. 3 wires had resistances of about 1 ohm, and the 4th was a touch higher at 3-4 ohm. All pretty low I'd have thought. I did find it hard to get consistent readings with the multimeter, which I think was due to getting a good contact between the multimeter probes and the loco itself. I figured that if I got multiple readings then the lower readings could be trusted as poor contacts from the multimeter would only add to the baseline resistance.

I then swapped out the chip for a blank with the aim of testing from wheels to motor, and I found that the loco actually ran quite well on the track. So it all seemed to be working ok. I put the digital chip back in and again it actually seemed to run ok, with a few stutters on various parts of the layout. (points etc). Whilst running I lifted up one end and the engine stopped, whilst when lifting the other end the engine continued to run. So it seems that there is an issue via one bogie, although the connections from the wheels through to circuit board seem ok when tested with a multimeter. I'm wondering if there is some poor connectivity from some of the wheels that I'm misreading as poor contact between the multimeter and wheel. The wheels seem clean, and I would not expect them to be particularly worn because the overall usage on the engine has not been that great even though it must be getting on for 15 years old.

Maybe the act of removing the DCC chip and replacing it (re-seating it) might have improved matters.
I don't really know why contact via one bogie does not appear to work, even when the multimeter test shows decent connectivity.

I would like to clean the contacts between the wheels and the pickups. Is there a way to remove the wheels to do this?

Paul-H
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Re: 32-377 Class 37 troubles

Postby Paul-H » Fri Feb 16, 2018 10:37 pm

I wonder if a hi quality contact cleaner would help, as long as you don't get it everywhere as I don't know how paint safe it is, although given how it's used in hi end HiFi equipment without issue you should be ok.

If you can get it try Deoxit D5

Paul

Bigmet
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Re: 32-377 Class 37 troubles

Postby Bigmet » Sat Feb 17, 2018 12:26 pm

bigfish wrote:...I put the digital chip back in and again it actually seemed to run ok, with a few stutters on various parts of the layout. (points etc). Whilst running I lifted up one end and the engine stopped, whilst when lifting the other end the engine continued to run. So it seems that there is an issue via one bogie, although the connections from the wheels through to circuit board seem ok when tested with a multimeter...

Put a mark on the bogie underside that isn't picking up, to prevent any confusion! (It can be hard to remember once the body is off.)

What that means based on your testing so far is that the connection problem is on the circuit board, between the connections from the bogie end from which there is no track supply and the decoder socket.

One possibility is that the wires from the bogie that has no pick up are not connected to the correct terminals on the circuit board. I don't have a 37, but on Bachmann typically the pick up connections are marked up on the board 'L' and 'R' . So that's the first thing to check.

If that's good, and the connections are OK then the tracks on the board are broken so no current is reaching the decoder socket. Rather than go to all the trouble of tracing, I would just put in new wires to the connections for the other bogie, since those are definitely working.

bigfish wrote:...I would like to clean the contacts between the wheels and the pickups. Is there a way to remove the wheels to do this?

First up, sort out the connections on the bogie that isn't picking up. If that fixes the problem completely, you can leave the bogies alone: wiper pick ups tend to be pretty good at self cleaning unless operating in a very dusty environment. That you will be able to see by a ball of dust and fibres caught on the wiper tips, using a small torch to put plenty of light on the subject.

To remove the bogie frames to get access to the wheelsets and thus the wipers, first detach the pick up wires from the main board, then undo the pivot screw. That lets the bogie out of the chassis block, uncoupling from the drive shaft as it comes free. The bogie frame unclips from the central gear tower at the ends, usually lugs into apertures in the bogie frame ends (see the diagram). With the whole outer frame off the wheelsets lift out and the wipers are accessible. I do this fiddle-de-dee work every time on new purchases after first test running to confim all is basically well; mainly to make sure the wiper contact is very positive, often giving the wipers a little extra springy bend.


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