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Discussion Starter · #1 ·
I have converted all my 35 locos to DCC and they all run well despite some "dodgy conversions " on the earlier Bachmann Locos. The one issue I seem to struggle with is the top speed. I have, on the bigger locos ( A4's -Princess Royals ) been setting CV5 to 255 but the top speed still seems a little slow on a lot of these models. I had a shorting problem on a Hornby A4 and decided to remove the chip to test it. I re-tested after diagnosing the fault ( poor soldering from new) on standard DC and the top speed was much faster. This set me wondering if I am missing a trick.
Is there a real difference between the top performance of DC v/s DCC or is there some voltage drop in the chip that does not allow the same top speed.
Any advice appreciated as I have quite an incline on one of the circuits and need a bit of momentum to "hit the summit"
 

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Hi StMartins

A lot of early locomotives had an unrealistically high top speed

The old analog controllers sometimes put out 17-18v at full voltage (especially the Fleischmann ones)

DCC voltage for HO or OO should be around 14v some DCC Systems (euro ones have higher voltages 16-18v)

The motors have about 1 volt less than the track voltage.

If you are having issues with lack of pulling power , it could be that the motors magnets are not as strong as they were
they can be re-magnetized though.

Regards Zmil
 

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Discussion Starter · #3 ·
Thanks Zmil
the voltage on the old analogue control units is an interesting one, never thought of it that way.That could be the reason for the noticeable difference, I still have my "tester" will check the voltages to see how near they are to 12V .Maybe DCC is more realistic but if this is the case it does seem very slow. Incidentally it is the newer locos that seem to be slower the new Hornby Britannia & the A4's. Its interesting to note there is another similar posting today dare I say could it be the new Hornby chips?
 

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I have to admit I noticed that with one of my conversions that was done by Chuffers in Guisborough a year ago.

It's a Graham Farish Low Emission 66952 but with pcb board unlike the low emission ones that Dapol do with the 6 pin chip.

Chris at the store basically gave me the loco as a christmas present and it was tested in store on dc and it had a high top speed like most of the Farish range but when he chipped it which was with one of the Hornby R8215 chips I find that it's top speed is now relatively slow. I thought it might be something in the chips settings that might have been altered before I got it but after doing a factory reset it is still the same. The loco is running ok it just doesn't have the top speed that the rest of my locos have and I don't really wanna tamper with it seeing as it has a sentimental value to me.

I just can't work out what is causing the such a low top speed. Running the 66952 one and the Farish Eddie the Engine 66 together the eddie does have a higher top speed than the 66952 model.
 

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*** I can't comment on the chip in relation to speed as I will not install hornby chips but it may well be.

The top speed of loco's on DC is always over fast, and a slight drop with DCC is an advantage not a negative really... I do understand that a significant change isn't acceptable though!

I usually install TCS T-1 or MC-2 in those locomotives when we do not add sound, and to get realistic running quality in a simple way almost always end up lowering top speed CV5 to about 190 and setting mid speed CV6 to 120 to give good acceleration rate and realistic top speed.
 

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Discussion Starter · #6 ·
Thanks for all the feedback.
I have looked at Zmil's comments and the DC controller is punching out 14.5 volts on max top speed settings. Having tested the voltage on the Prodigy its around 14V so not a big difference. I have Digitrax 123 decoders in the Hornby "Firth of Tay" and Bachmann "Windward Islands" and they both run at a realistic speed. I removed the Digitrax chip from "Windward Island" and swapped it for the new R8249 chip and the difference is really noticeable with the same settings the top speed is definitely slower. It looks as if I will need to use the new Hornby chips on the freight locos and the Digitrax and ZTC chips on the "Passenger Locos".
Its interesting how helpful the forum is as the comments prompted me down this route whereas I think I would have just accepted it before without thinking there maybe an issue.
 

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I wouldn't do that. I'd forget the Hornby decoder and consign it to a land fill. Get yourself a TCS DP2X-UK if you have somthing like any Hornby loco that is DCC ready or even if it comes DCC fitted I junk them and refit the TCS decoder. For Bachmann locos I use the TCS M1-P as in some Bachmann locos the fitting is a bit tight in the likes of a K3 or 4MT. For diesels use a TCS T-1 which has basic lights or or a T4X which has 4 lighting functions or a T6X which has 6 lighting functions. If you want sound see Richard.
Here's the link to TCS http://www.tcsdcc.com/ . I have loco that in real life while designed for a top speed of 80mph rarely got above 45mph. I control this by the addition of a custom speed table. The only problem this creates is that if I double head or require a pusher, the 2nd loco must be similarly treated orthe locos will fight one another.
If your Prodigy has a serial or USB port for a computer connection then I would suggest you try Decoder Pro http://jmri.sourceforge.net/ This program will aid in setting up most decoders and is easy to upgrade best of all it's free.

Charles Emerson
Queensland
Australia

QUOTE (stmartins @ 1 Dec 2008, 15:57) <{POST_SNAPBACK}>Thanks for all the feedback.
I have looked at Zmil's comments and the DC controller is punching out 14.5 volts on max top speed settings. Having tested the voltage on the Prodigy its around 14V so not a big difference. I have Digitrax 123 decoders in the Hornby "Firth of Tay" and Bachmann "Windward Islands" and they both run at a realistic speed. I removed the Digitrax chip from "Windward Island" and swapped it for the new R8249 chip and the difference is really noticeable with the same settings the top speed is definitely slower. It looks as if I will need to use the new Hornby chips on the freight locos and the Digitrax and ZTC chips on the "Passenger Locos".
Its interesting how helpful the forum is as the comments prompted me down this route whereas I think I would have just accepted it before without thinking there maybe an issue.
 
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