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Author Topic: Dapol HST 125 power car - More problems  (Read 10007 times)

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Offline grahame

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Dapol HST 125 power car - More problems
« on: October 17, 2015, 11:29:53 AM »
While I love this model and the detail,  it has been far from trouble free. Some time back I reported this problem which appears to be very wide spread.

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=17621.msg175720#msg175720

I never got a proper response from DCC supplies..pretty dismissive. Well here is something else going on. Not related to the other but perhaps it is?

! No longer available

The power car runs very erratically..starts, slows down speeds up then stalls. If I turn it upside down and let the split chassis pick up directly from the track it runs perfectly. in this video towards the end that is me varying the speed of the loco with controller, very smooth. Even with a bit of load on the wheels it does not falter. This certainly suggests power pick up with the bogies which I have cleaned fanatically every way I know how. Any one seen this problem, solved it? Only recently started to see this. I can pick it up after a stall, turn it upside down and it runs perfectly. Is there an intermittent short perhaps in the bogies?
« Last Edit: October 17, 2015, 11:32:58 AM by grahame »

Online Dr Al

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Re: Dapol HST 125 power car - More problems
« Reply #1 on: October 17, 2015, 12:32:58 PM »
It sounds like the same problem as you originally had. You really really need an ammeter to see what current it's drawing (you can get a vague feel if something's not right if it's hot) - the Dapol surging motor syndrome seems to recur a lot on any motor that has it. I assume that vid wasn't full power - if it was then it looked slow - there's definitely a problem.

It may be that when you run upside down there is just enough lack of load that it doesn't quite heat up and perform as you see on track.

Need current figures to conclusively diagnose though.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

“We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.” – Dr. Carl Sagan

Offline robert shrives

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Re: Dapol HST 125 power car - More problems
« Reply #2 on: October 17, 2015, 08:19:38 PM »
Hi
A recent HST I got had bent pickups on the chassis - I guess when bogie twisted in to fit so the contct on edge of strip - the spot of conductive grease not touching anything useful at all - By straightening up so it worked as designed  all a lot better.  Worth a check -  The bogie pick up is the weakpoint on all diesel designs  - where steam locos win! 

I have hardwired the old Farish 158 spring contact system. The Dapol 153/156 suffers same issue with a compresed srping no pickup plus losing same when talking bogie out. The current Dapol chassis is inspired by the Kato/ Lifelike chassis with a springy pickup strip bent down to contact with a curved section off the bogie pickup strip point contact being better for pickup and rotational resistance.

Surging/ high current windings in the Dapol motors is a problem for some but not had an issue but I have been playing with an NQP 67 with blown diodes - it is possible that the motor issue is giving high current issues beyond the capacity of components - some later work as 200v 5A capable parts fitted. So off to check this as well.   

Hope that is of help
Robert

Offline Only Me

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Re: Dapol HST 125 power car - More problems
« Reply #3 on: October 17, 2015, 08:52:00 PM »
Running any dapol or farish model upside down is not recommended as you will chew up the gears and cause yourself more issues eh @Dr Al



Offline scruff

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Re: Dapol HST 125 power car - More problems
« Reply #4 on: October 17, 2015, 09:14:29 PM »
That's very true Only Me.. Any diesel from Farish or Dapol with pull out bogies should not be run upside down because the Large cog at the top of the bogie and the worm drive mesh tightly and cause damage.
Guess how I found out??? :dunce: Then I read the instructions!! :censored:

Grahame, have you tried cleaning the wheel backs, pickups by the wheels and the contacts where the power transfers from bogie to body with IPA. I had a Dapol 86 with transit grease all over the bogie/ body contacts, cleaned them and straightened the contacts and it runs like a dream now..

Cheers
Mark
« Last Edit: October 17, 2015, 09:29:21 PM by scruff »

Online Dr Al

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Re: Dapol HST 125 power car - More problems
« Reply #5 on: October 17, 2015, 11:53:29 PM »
Can't say that running upside down is something I've ever had any trouble with myself - though I've specifically avoided with the Farish 60 and 66s where the meshing with the worm is known to be slacker than some and others have posted problems doing this. Never seen an issue with Dapol so far or other Farish and have run Farish 37 and 47 upside down for quick wheel cleans no problems.

Cheers
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

“We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.” – Dr. Carl Sagan

Offline sparky

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Re: Dapol HST 125 power car - More problems
« Reply #6 on: October 18, 2015, 08:01:38 AM »
I would look very carefully at how the tips of the wheels sit in the pick up strip and give them a good clean out...the other problem I had with the dapol arrangement of the axle ends sitting in the contact strip was that one of the actual wheels themselves came loose on the axle and was sliding slightly along the axle causing  an intermittent power drop..it was a class 56 wheel which I replaced and now works fine.

Offline grahame

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Re: Dapol HST 125 power car - More problems
« Reply #7 on: October 18, 2015, 11:26:10 AM »
It sounds like the same problem as you originally had. You really really need an ammeter to see what current it's drawing

Cheers,
Alan

Thanks for your comment..I will get hold of an ammeter and take some current readings. Will post when available.

Offline grahame

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Re: Dapol HST 125 power car - More problems
« Reply #8 on: October 18, 2015, 11:31:23 AM »
Grahame, have you tried cleaning the wheel backs, pickups by the wheels and the contacts where the power transfers from bogie to body with IPA.
Cheers
Mark

Ah ok..so the power is picked up by wipers on the back of the wheel, yes? I wasn't sure about this. Sometimes it is the axle tips, with split axles...and the pickup is just inside the sideframe of the bogie. Will also check.

These bogies have been cleaned in an ultrasonic bath with degreasing solvent which is totally harmless to plastic of any kind.

Offline grahame

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Re: Dapol HST 125 power car - More problems
« Reply #9 on: October 18, 2015, 11:43:44 AM »
Hi
A recent HST I got had bent pickups on the chassis - I guess when bogie twisted in to fit so the contct on edge of strip - the spot of conductive grease not touching anything useful at all - By straightening up so it worked as designed  all a lot better.  Worth a check -  The bogie pick up is the weakpoint on all diesel designs  - where steam locos win! 

Hope that is of help
Robert

Many thanks..yes I will try bending that copper strip down a bit, with bogies off, to make it press harder against the copper pickup tab on the bogies. That is on my list of things to try.

Offline grahame

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Re: Dapol HST 125 power car - More problems
« Reply #10 on: October 18, 2015, 03:50:00 PM »
If all else fails I will separate the split chassis and investigate the motor. i have not done this on the Dapol power car yet. Any one have photos/diagrams of what it looks like inside?

Online Dr Al

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Re: Dapol HST 125 power car - More problems
« Reply #11 on: October 18, 2015, 07:19:02 PM »
Ah ok..so the power is picked up by wipers on the back of the wheel, yes? .

The Dapol HST uses the pin point axle bearing pickups to take power from wheels to pickups. The wipers on the chassis block then take power from these to the chassis block.

HTH,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

“We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.” – Dr. Carl Sagan

Offline sparky

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Re: Dapol HST 125 power car - More problems
« Reply #12 on: October 18, 2015, 08:39:55 PM »
Purely coincendentatily but I am having a running session in my garage and posting from my old net book...just had to clean my HST exec power car (both bogies) as lights flickering and dropping power....dirt on the points of the axles and cleaned out the small indentation they sit in and everyone immediately much better.

Offline grahame

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Re: Dapol HST 125 power car - More problems
« Reply #13 on: October 18, 2015, 11:49:47 PM »
...just had to clean my HST exec power car (both bogies) as lights flickering and dropping power....dirt on the points of the axles and cleaned out the small indentation they sit in and everyone immediately much better.


How do the bogies come apart to give access to the axle points? Thanks

Looks like we gently pry here (red arrows)

« Last Edit: October 19, 2015, 12:03:34 AM by grahame »

Online Dr Al

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Re: Dapol HST 125 power car - More problems
« Reply #14 on: October 18, 2015, 11:51:46 PM »
How do the bogies come apart to give access to the axle points? Thanks

The bogies pull out from the chassis block. They then have a sideframe which unclips (front and back) from the main internal moulding. Unclipping this will remove the pickups and wheels, and from there you can remove the wheelsets from this sideframe.

HTH,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

“We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.” – Dr. Carl Sagan

 

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