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Truma c3402 / 6002 spark generator - ignition transformer


Hughmer

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Forgive me if this has been covered, I tried a few search strings and found Mark Hymer's remarkable and very useful thread Truma Boiler 3402/6002 PCB FIX, But his was a different problem

 

My Boiler isn't igniting. and I'm confident that it is the "little blue box" (the ignition transformer) that generates the HT spark(s). Full story below if you're super keen,

BUT the purpose of this post is to determine if anyone knows the whereabouts of a suitable ignition transformer part 49 on the Truma diagram.

Needless to say I have tried to source the kosher Truma part but as they obsoleted the boiler in 2012 it seems all the spares have been bought.

 

Does anyone know if is there another part that will do the trick?. 12v in > 18kv @ 3 or 5Hz out

Similarly, my electrodes look ok at the moment but if they fail, snap, wear out, - can one get spares?

 

 

Full story

I have the boiler out and have organised a gas supply.

Fans start, the gas valve opens, 12v appears on the blue box but i only get one spark

I understand the blue box should generate about 3 or 5 sparks / sec, - until the ionisation probe detects a flame

 

The gap between the spark electrodes is bout 6mm (Pretty close to truma's tech booklet) also pictured

Closing the gap makes no difference to frequency of spark. - i still only get one at a time, - i.e. by dissing and reconnecting the 12v supply.

 

 

 

 

 

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Hughmer

 

I can’t argue with your diagnosis, but it might be worth mentioning the problem I had in the early 2000s with the Trumatic C-3402 EL heater that was fitted to my Herald Templar.

 

On Day 1 of a March trip to France the heater became very difficult to light (on gas) and by Day 3 lighting had become impossible.

 

I later took the motorhome to Truma UK’s HQ and, when the heater had been dismantled, it was found that the ceramic insulation on the gas-ignition electrodes had cracked, preventing sparking from taking place at the tip of the electrodes and within the gas envelope.

 

Leisureshopdirect advertise some spares for C3402/C6002 appliances

 

https://www.leisureshopdirect.com/gas/water/truma-heaters/trumatic-c-6002-c-3402-spare-parts

 

including these parts

 

https://www.leisureshopdirect.com/gas/caravan-gas-water-heater/truma-heaters/trumatic-c-6002-c-3402-spare-parts/12v-ignitor-trumatic-c3402-c6002-c4002

 

https://www.leisureshopdirect.com/gas/caravan-gas-water-heater/truma-heaters/trumatic-c-6002-c-3402-spare-parts/truma-ignition-plug-left-for-the-trumatic-c6002-c3402

 

(I ’tweaked’ your diagram image for extra clarity...)

 

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Ha you beat me to it

Ive been looking at the DCZ1/12 which is exactly that ... for fridge pilots.

Similar spark rate too

The only snag is that the fridge unit is a single pole HT relying on Chassis earth for return.

Also found a Dutch thread

https://camperforum.nl/viewtopic.php?t=8452930&start=14

discussing a cheaper multi pole spark unit, but it still requires earth return

 

The Truma unit s 2pole HT (spark is between 2 individual electrodes, rather that Electrode & Chassis)

 

I guess someone will know if its safe to ground one of the truma electrodes ...

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Derek

Thanks for the info

The difficulty with LSD is although they advertise Truma stuff all stock is spoken for.

I have inspected my ceramics and they look very healthy, no signs of fracture. AND I can get one spark from the unit through the 'trodes each time I connect 12v So methinks// if the insulators allow 1 spark, surely they'd allow more if more were delivered...?

It seems to point to the transformer.

I'm tempted by the IGB60 unit (quite common on narrow boats to replace 240v sparkers in domestic appliances) but as my 6002 is a chassis earth HT return, I'm still uncertain about whether it's safe to ground one of the 'trodes

 

I'm cautious because the Truma igniter also has a separate earth terminal tagged to the boiler chassis. So 5 terminals in all.

 

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You also asked about replacement electrodes, so this advert may be useful if you should need them.

 

https://www.southdownsmotorcaravans.com/34020-60800-truma-ignitor-plug-kit-screws-truma-spare-parts.html

 

The Truma Part Number for the DCZ unit is 34010-14100 and a GOOGLE-search retrieves several hits across several countries. However, you may want to check with Truma(UK) whether this part is actually available nowadays.

 

(I came across a 2019 thread on an Italian forum asking about replacing on a Trumatic C6002 an ‘old type’ spark-generator box (which evidently was black in colour, 50Hz and cost about €130) with the later (blue) 35Hz box that cost about €45. It was said that the black generator sparked successively (eg. click-click-click) whereas the blue box produced a stream of sparks. Replacing the 50Hz unit with the 35Hz unit proved to be successful.)

 

 

 

 

 

 

 

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  • 3 weeks later...

Derek & Alan

Thanks for your earlier responses. Things get weirder. The spark gen was OK.The problem was

 

DIRTY CONTACTS! (well oxidation on the 12v spade connectors)

 

Now, it 's more like the stream of sparks that Derek described. Lesson learned, so in future I'll make it a rule to check connections (and fuses) are tight

 

So now the weird bit. The boiler fires up in the workshop on a stand-alone leisure battery, but now it's back in the van it's not working. The van's on EHU, batteries 14.26v

 

The symptom is... rotate thermostat dial so as to call for heat.

Amber light flickers (warning Low Volts, but clearly not so)

Fan's start. Supply Voltage from EBL 99 drops to 8v ( !) and then recovers fluctuates between 9v & 12.4v.

After 7 seconds or so the gas valve vibrates, like a fizz but no "clonk"

Fans stop. red light comes on.

 

If I disconnect the Truma from the leisure supply and reconnect the separate accumulator (at 12.5v) I get a normal start up

Fans run for 23 secs,

Gas Valve opens (Clonk) then gas ignites (Wuumph )

a few more seconds then the second and third stage valves open. (Clicks)

 

I have taken out the blade fuse from the EBL (thinking it might be oxidised) but all seems well. The boiler is on EBL plug 4, which also powers the step, and that's working so methinks the connector is OK.

 

All a bit of a mystery really. Any thoughts anyone?

 

All voltages measured across the boiler connectors. Polarity also correct

 

 

2019069436_sepbattery12.5voltssml.jpg.d0e9881cf3dc072d86dc8b78a5d87ab6.jpg

2038222285_ViaEBL14.26beforeignitionsml.jpg.524950768cb128e8a790958cff843227.jpg

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201213392_DuringignitionviaEBL10.03vsml.jpg.b0ce474e715d32219320a03f917d5c0a.jpg

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I’m not an electrical engineer but it sounds to me like there’s insufficient current to maintain the voltage.

 

You mentioned that connecting the spare battery showed that the boiler could work correctly but I’m unsure where you connected it in the circuit.

 

So if you’ve not already done so I’d suggest disconnecting the existing leisure battery and connecting the spare battery in its place so that all the power is routed via the EBL 99 as normal. If the boiler still fails to work you’ll have ruled out a failing leisure battery.

 

If the above didn’t result in a positive result I think I’d start tracing the wiring first from from the leisure battery to the EBL99 to check for poor connectivity and then from the EBL99 to the boiler for the same reason.

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There is obviously a "high" resistance somewhere in the supply circuit, "high" being relative in this context, possibly only a fraction of an Ohm.

 

As suggested by BruceM, start with the habitation battery but just monitor the voltage across the terminal posts, instead of swapping out.

 

Possibly the best method to follow up with is, to connect your multimeter -ve to battery negative with a long trailing lead, and test at all accessible connections round the circuit.

 

Alan

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  • 3 weeks later...

Thanks for the useful suggestions. I've finally identified the problem(s) there were actually 2 and I think i may have caused the second.

 

Problem 1

The poor spark rate was simply oxidation on the mini spade connectors on the ignition transformer.

 

Problem 2

In the process of checking the supply lines I think I enlarged one pin of the molex socket on the EBL. It came to light only after I removed the EBL from under drivers seat. I took it out because I thought the fault might have been internal.

 

The general condition of the molex socket (just the one feeding heater and elec step) was pretty ropey and I couldn't have done all the damage. The EBL was actually a refurbed unit fitted by a dealer in Germany several years ago. I think the socket might have been a bit dodgy to start with. All the others are ok.

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  • 2 months later...
Hi all, new to the forum. I have a Truma C3402 heater and an trying to get it firing. while i was dismantling it i Noticed this red and black calbel with a connector on it. has anyone any idea what its to connect to?

InkedIMG_1670_LIve.jpg.e4f8faf50bc259839de290ec97a9a4e5.jpg

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Welcome to the Out&AboutLive forums Dave.

 

As the connector on the red/black cable is itself not connected to anything, it’s reasonable to assume the cable is for an ‘option’ for the heater. (My Herald motorhome had a Truma C3402, but I sold that vehicle 17 years ago.)

 

Does your heater have Truma’s usual electric safety/drain (with a red knob that needs lifting to close) or a manual drain valve? Alternatives might be for a ‘window open’ shut-off or, perhaps, for a remote room thermostat (that I fitted to my Herald but I think did not connect to cabling near the heater’s base).

 

If you don’t get an answer here, I suggest you contact Technical Support and send them a copy of your photo.

 

https://www.truma.com/uk/en/service/customer-service

 

This link might also be useful (though not for identifying the mysterious cable)

 

https://motor-roam.co.uk/truma-trumatic-c3402-boiler-inspection-troubleshooting

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