Hornby 31 TTS Chip

Discuss Hornby Model Railway products and related topics here. This includes (Lima, Rivarossi, Jouef, Electrotren).
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dubdee1000
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Hornby 31 TTS Chip

Postby dubdee1000 » Sat Sep 23, 2017 11:23 pm

Thought id share my experiences of this.

I have a mix of 31's - 31270, the original Hornby release and a few lima bodies sitting on the new style chassis that I got from modelspares

I thought id have a go at fitting the tts chip in them. With these, the easiest is to remove the fan - the speaker fits very neatly in its place, you can even use the same screw holes. There isn't enough space for the decoder to fit between the PCB and the roof, so it needs to be taped under the pcb where there is room.

Now the fun and games.

I have a Lenz system and fair to say it doesn't like tts chips. The lack of CV2 on the tts chip makes it grumpy and it'll throw up and ERR message. Whilst some cv's can be reprogrammed, its hit and miss whether the chip takes it. Sometimes it does, sometimes not. Setting a speed curve is a nightmare. Motor control is on cv150, 151,152. The default values are 0,8,8. Not on mine though. CV 151 was 0. That may have explained the lumpy running, but try as I might, I could not change the cv's.

I rang Hornby. They said they knew about this. Their advice - buy an Elite.

When you've been burned once.....

So I rang what is now my local model shop, Model Railways Direct, who advised me to bring everything in and we'd have a play.

Turns out the problem is with the Lenz

Both the Bachmann and Gaugemaster Decoder Doctor could read and write the cv's, albeit the latter could not write a 4 digit address easily. After a chip reset, we found that cv 151 was 0 and 152 was 16. This is not what the manual says they should be. We set cv150 to 0, cv 151 to 8 and cv 152 to 8 and read them back - all ok.

This has cured the lumpy running and its now silky. A bit of a shame that I ended up buying the Gaugemaster unit, but it did the job and as i'm planning to buy a few tts, it was worth it.


Moving on, I fitted a 21 to 8 pin adapter to a Bachmann 37 and tried the tts decoder - works fine, though same lump running at slow speed so it might be the same cv issue. I'm wondering trying them a heljan unit. These are power hungry and I wonder whether the tts will chuck out enough juice to supply them. MRD say that if the chip blows, providing I have installed it properly, Hornby will replace it.

Now to wait for the 37's!

GWR_fan
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Re: Hornby 31 TTS Chip

Postby GWR_fan » Sun Sep 24, 2017 2:32 am

dubdee1000 wrote:Thought id share my experiences of this.......... I'm wondering trying them a heljan unit. These are power hungry and I wonder whether the tts will chuck out enough juice to supply them. MRD say that if the chip blows, providing I have installed it properly, Hornby will replace it.
....!



Regardless of what you have been informed if you exceed the capacity of the decoder then I will be surprised if Hornby honour the warranty. You admit that the Heljan locomotives are power hungry. TTS chips have been successfully fitted to Bachmann locomotives but you are risking failure with the Heljan models.

As regards rewriting TTS chips, I have had no issue with NCE.

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dubdee1000
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Re: Hornby 31 TTS Chip

Postby dubdee1000 » Sun Sep 24, 2017 9:25 am

Yup. I was a bit surprised. I'm reluctant to try it. Haven't read anywhere of people using these chips in heljan, but then again, just because I haven't read of people doing it doesn't mean it's never happened

Bigmet
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Re: Hornby 31 TTS Chip

Postby Bigmet » Sun Sep 24, 2017 9:44 am

I might suggest the 'scientific' approach to asssessment of the TTS decoder for a Heljan model. Measure the 12V DC stall current of the Heljan model. If it is much the same or higher than the rated motor output of the TTS decoder, then don't fit it.

However, the last time I looked at the spec of the TTS decoder it was 500mA sustained motor supply, 800mA total (motor/sound/lights). The Heljan diesels with their usual big motor are typically in the range 400 - 700mA for the motor alone. That's 'no go'.

Easy enough solution, fit a 1 amp+ decoder to run the motor, and the TTS to run sound alone. Still way cheaper than an ESU or Zimo sound decoder.

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RAFHAAA96
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Re: Hornby 31 TTS Chip

Postby RAFHAAA96 » Sun Sep 24, 2017 10:33 am

The TTS decoder is self protecting against overload on the motor circuit but not on the function outputs so be aware that your Heljan may cause it to cut in and out but if you overload it with lights then it may be lights out for good.
Rob
RAF Halton Brat - 96th Entry
http://www.halton96th.co.uk

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dubdee1000
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Re: Hornby 31 TTS Chip

Postby dubdee1000 » Sun Sep 24, 2017 11:18 am

I had a look at another tts chip i bought yesterday that i test fitted into the bachmann 21. Straight out of the box, lumpy slow speed running.

Read cv 150 - 0 (as it should be)
cv 151 - 0 (it should be 8. )
cv 152 - 0 (it should be 8. )

Reprogrammed the cv's to what they should be out of the box - all good, slow running is bang on.

So looks like QC might be a bit suspect on these chips. Similar issues on my other 31 tts chips with cv's 151 and 152. The chips came from different retailers. Easy to remedy generally, but some controllers seem to struggle.


FTR :

(from the box)

BEMF
Long address supported ( know some have had issues with this)
1 aux function output (f18 or f25)
Max cont motor current 500mA
Peak motor current 1 amp (no function load)
Function output current max - 100mA (unprotected)
Decoder max continuous 800mA (motor and functions)

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RAFHAAA96
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Re: Hornby 31 TTS Chip

Postby RAFHAAA96 » Mon Sep 25, 2017 2:11 pm

Re the TTS limited function currents...

I installed an Express Models lighting kit to a TTS Class 37 and the headlight plus two marker lights plus two rear lights was over the function limit so the decoder started playing up - dodgy sound, odd lights, and poor motor response, so I thought it was a gonner. Then after doing the big Ohm's Law sums I installed an additional 1K ohm resistor in the blue wire feed and bingo everything went back to normal.

I was lucky I suppose in that the initial overload that had caused the decoder to play up had not caused irreversible damage and when I fettled the function current limit I managed to get back all the decoder facilities working as advertised.

Rob
RAF Halton Brat - 96th Entry
http://www.halton96th.co.uk


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