absolutely brilliant, i shall test this myself tomorrow
Scalextric and this community owe you a lot
Scalextric and this community owe you a lot
DPR - the solution
2
OK, I've been head down on this for a while trying to bottom the issue.
Here are my findings, and a solution.....
To start with lets dispell a few myths:
Axle proximity has nothing to do with this. I've tried with the chip on the roof and it still happens. Equally proximity to the track has no effect.
Missing ferrite man is not the cause. My best "faulting" car has both in place at guide and motor.
Powerbase is not the cause, I've had this with 4PB, stock V1.5 6PB, and PB-Pro-SHA
So a few thousands of laps later what have I found?
With no LC in the circuit you have no problem. So we do have an electrical noise problem. Trials with the chip isolated shows it is not an inductive effect from axle, passing LC coils etc, it has to be noise that is conducted up the wires, i.e. picked up from the rails.
First thoughts were that a corrupt data packet causes the runaway or stopping. As the occurance of the fault always happened immediately after crossing an LC I thought it was possibly the break in the current at some critical point in the read sequence. Or the other thought was that the processor was getting a reboot and then defaulting to zero or full throttle.
Wrong.
I lashed up a DPR with a 470uF capacitor across the 5V supply to the chip.
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That made a bit of difference to the time to the fault, but it would still happen. And reset would take a 5 second lift off the track. So we can be sure that the processor still had juice and didn't brown out.
A discussion with Adrian Norman pointed towards the XLC exit being part of the issue. Sure enough the braids on my Porsche 997 were quite spread. I pulled them in close to the guide. Magic! problem disappeared completely.
Now as I had a PB-Pro SH I had no worries about shorts so I splayed the braids out wider and ensured a good short on every passing. Enough to dim the display. I could now get very consistent faulting behaviour from my car. With the extra capacitor mounted it allowed the car to run for 20 laps rather than 6, but it still only postponed the inevitable.
So where is the problem? On the exit of the LC is a place where the joining lane rail gets very close (about a mm). Solution? Insulate the last 5mm of the rail by painting with a black enamel paint at the positions I have marked in red on the photo. Or keep your braids very very tidy.
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Riko
Here are my findings, and a solution.....
To start with lets dispell a few myths:
Axle proximity has nothing to do with this. I've tried with the chip on the roof and it still happens. Equally proximity to the track has no effect.
Missing ferrite man is not the cause. My best "faulting" car has both in place at guide and motor.
Powerbase is not the cause, I've had this with 4PB, stock V1.5 6PB, and PB-Pro-SHA
So a few thousands of laps later what have I found?
With no LC in the circuit you have no problem. So we do have an electrical noise problem. Trials with the chip isolated shows it is not an inductive effect from axle, passing LC coils etc, it has to be noise that is conducted up the wires, i.e. picked up from the rails.
First thoughts were that a corrupt data packet causes the runaway or stopping. As the occurance of the fault always happened immediately after crossing an LC I thought it was possibly the break in the current at some critical point in the read sequence. Or the other thought was that the processor was getting a reboot and then defaulting to zero or full throttle.
Wrong.
I lashed up a DPR with a 470uF capacitor across the 5V supply to the chip.
That made a bit of difference to the time to the fault, but it would still happen. And reset would take a 5 second lift off the track. So we can be sure that the processor still had juice and didn't brown out.
A discussion with Adrian Norman pointed towards the XLC exit being part of the issue. Sure enough the braids on my Porsche 997 were quite spread. I pulled them in close to the guide. Magic! problem disappeared completely.
Now as I had a PB-Pro SH I had no worries about shorts so I splayed the braids out wider and ensured a good short on every passing. Enough to dim the display. I could now get very consistent faulting behaviour from my car. With the extra capacitor mounted it allowed the car to run for 20 laps rather than 6, but it still only postponed the inevitable.
So where is the problem? On the exit of the LC is a place where the joining lane rail gets very close (about a mm). Solution? Insulate the last 5mm of the rail by painting with a black enamel paint at the positions I have marked in red on the photo. Or keep your braids very very tidy.
Riko
1 - 20 of 133 Posts
Bravo Riko! Very well thought out with a simple solution. Thank you.
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Awesome! I feel MUCH better about buying some DPR cars now. I can solder OK, but if I can avoid it, I sure will. I'd much rather put some paint or tape on those rail points.
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2
Magnificent Riko, thanks for all the hard work.
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Collected this thread into SSD 101 already, hope everyone will post their results. I'll order in a DPR tomorrow and have a go myself, the Chapparal has just been waiting. Mike's experience scared me off DPRs completely!
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Similar problem on the clcs?
Paul
Circuit TrustChrist
Collected this thread into SSD 101 already, hope everyone will post their results. I'll order in a DPR tomorrow and have a go myself, the Chapparal has just been waiting. Mike's experience scared me off DPRs completely!
Similar problem on the clcs?
Paul
Circuit TrustChrist
Sterling work through Riko.
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I have no DPR chipped cars, as yet, and i was avoiding them, due to the bad press.
Does this problem only occur as they pass over these XLC exit points?
Why does this not affect the saloon and F1 chips then??
I have no DPR chipped cars, as yet, and i was avoiding them, due to the bad press.
Does this problem only occur as they pass over these XLC exit points?
Why does this not affect the saloon and F1 chips then??
2
But....and it's a big but as zipp has asked, why does the DPR chip act in this way and not the Saloon or F1 chip
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That's the question I have tried to answer and failed on several times.
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Rich
That's the question I have tried to answer and failed on several times.
Rich
2
The "real" solution to this one has eluded me. Have on two occasions now spent several hours on it.
The boards are electrically identical. There is one small capacitor missing on the DPR board but fitting it makes no difference.
I even resorted to swapping processors between a Saloon & a DPR board. Again no difference so it's not firmware.
I have hacked about the DPR board to isolate the input & output wiring from the board again no difference. Remember that the F1 board has a track adjacency problem that makes it more susceptible to motor interference than the Saloon board.
So unless I am missing something that leaves a layout problem, that was not fixed by taking the input & output tracks off the board.
One day when I have nothing else to do, could be a long time, I will get to the bottom of it. I feel it must be something to do with the input signal routing that my hacking did not isolate fully?
Why on earth Hornby don't just put an engineer on it and sort it I do not know? The DPR boards rightly have a very bad name.
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Not fixing it is leaving the whole DPR concept in jeopardy. Not because of the DPR concept which is sound, but because of some silly electrical problem.
So well done to Riko for the fix, but with respect it's not a solution. It's like have a make of car with very harsh suspension and fixing by making all the roads smoother.
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Rich
The boards are electrically identical. There is one small capacitor missing on the DPR board but fitting it makes no difference.
I even resorted to swapping processors between a Saloon & a DPR board. Again no difference so it's not firmware.
I have hacked about the DPR board to isolate the input & output wiring from the board again no difference. Remember that the F1 board has a track adjacency problem that makes it more susceptible to motor interference than the Saloon board.
So unless I am missing something that leaves a layout problem, that was not fixed by taking the input & output tracks off the board.
One day when I have nothing else to do, could be a long time, I will get to the bottom of it. I feel it must be something to do with the input signal routing that my hacking did not isolate fully?
Why on earth Hornby don't just put an engineer on it and sort it I do not know? The DPR boards rightly have a very bad name.
So well done to Riko for the fix, but with respect it's not a solution. It's like have a make of car with very harsh suspension and fixing by making all the roads smoother.
Rich
3
A pound to a penny they were just using CLCs in their test circuit.... Or their braids were brand new and tidy.
Nice simile Rich:
QUOTE (RichG @ 2 Mar 2009, 10:07) <{POST_SNAPBACK}>So well done to Riko for the fix, but with respect it's not a solution. It's like have a make of car with very harsh suspension and fixing by making all the roads smoother.
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A bit like taking GT-R down a potholed road? And the solution? Don't go down a potholed road!
But seriously they could not have designed the system to cope with shorts like this. It probably takes out V1.2 6PBs as well. I would say this solution is the same as filling in the potholes - they were never intended to be there....
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The important thing is ..... it works
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Riko
Nice simile Rich:
QUOTE (RichG @ 2 Mar 2009, 10:07) <{POST_SNAPBACK}>So well done to Riko for the fix, but with respect it's not a solution. It's like have a make of car with very harsh suspension and fixing by making all the roads smoother.
A bit like taking GT-R down a potholed road? And the solution? Don't go down a potholed road!
But seriously they could not have designed the system to cope with shorts like this. It probably takes out V1.2 6PBs as well. I would say this solution is the same as filling in the potholes - they were never intended to be there....
The important thing is ..... it works
Riko
I am sure that changing track pieces that cause braid shorts is a good thing all round. Remember in the early days with a 1.2 Powerbase the same problem existed on the CLC's and caused the Powerbase to overload. I fixed this with some Sellotape, without which the set would have been in the loft by Boxing Day.
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However there is still a major problem / difference with the DPR chip. I assume you are running with the ferrite man on the slot guide? Try taking it off, you won't need to run over a CLC to see the car take off.
So yes making a change to reduce shorts / sparks is a good thing but the Saloon & F1 board cope well with them wheras the DPR chip does not. Must be worth finding the difference?
Rich
However there is still a major problem / difference with the DPR chip. I assume you are running with the ferrite man on the slot guide? Try taking it off, you won't need to run over a CLC to see the car take off.
So yes making a change to reduce shorts / sparks is a good thing but the Saloon & F1 board cope well with them wheras the DPR chip does not. Must be worth finding the difference?
Rich
3
That'll be me then!
You's guys really are "Crazy" in the nicest possible way, Riko how many laps did it take you to find this information
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If it was me I'd have just stuck in a saloon chip and have done with it. I must admit it's a great find and I may even consider buying my first dpr chip some time this year, now you have sussed this, lets face it this fix won't do any harm to the other chips either win win !
See you soon
You's guys really are "Crazy" in the nicest possible way, Riko how many laps did it take you to find this information
See you soon
3
QUOTE (RikoRocket @ 2 Mar 2009, 12:53) <{POST_SNAPBACK}>A pound to a penny they were just using CLCs in their test circuit.... Or their braids were brand new and tidy.
Riko
Probably new braids. You got me curious, Riko, so I had a look back at the Scaley Nurenburg thread and their demo circuit did have an apparently unmodified xlc in it:
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Got to wonder how much Scaley is just free riding on Rich, Riko, and other SF guys' engineering skill.
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Oh well, that's my cynical lawyer side.
The neat thing for all of us is watching you guys work to make digital better!
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Paul
Circuit TrustChrist
Riko
Probably new braids. You got me curious, Riko, so I had a look back at the Scaley Nurenburg thread and their demo circuit did have an apparently unmodified xlc in it:
Got to wonder how much Scaley is just free riding on Rich, Riko, and other SF guys' engineering skill.
The neat thing for all of us is watching you guys work to make digital better!
Paul
Circuit TrustChrist
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