Transponders - a cautionary tale...

[Chris Y]

I use a transponder, which was provided by MST about a year ago (1 year tomorrow, to be exact), and on Saturday, it failed..

Well, perhaps 'melted' would be a more accurate description.

It's an orange 'AMB clone', made by Dutch company Chronit Solutions BV. (http://www.chronit.com/products/ram-bat.html) These were widely sent out last year, when (I think) supplies of the AMB 290 were running low.

The case has bulged on the side, and a black sticky compound has oozed out and solidified. It really stinks of melted plastic, and unsuprisingly doesn't work anymore.

It was hooked into a feed from the dashboard, so only came on when the ignition was on, and it was mounted on the roll cage - no vibration, no heat.

This was its first meeting of the year, after not being used for about 6 months. It was working (well, the light was on) when I went out for practice, and I know some, if not all of my laps were counted. Trouble is, I was suffering from a misfire at high (near 6k) revs, and I put that down to HT leads.

After practice, and during the lunch break, I tried to start the car up. Initially, it started, sounded rough, and then died. It refused to start up again. We started diving into the engine bay and dashboard, looking for a wiring, HT or coil problem. The coil was getting power, but there was no spark from the HT. We tried 3 coils - no success there.

There was a burning smell inside the car, which we thought was coming from the dashboard, until Maisie noticed that the transponder was smoking! Realising what was going on, I disconnected the transponder, and the car fired into life. It seems that the transponder was sucking all the power from the coil, and preventing the car from starting!

Fortunately, we made the race, but if we hadn't tried to start the car in the lunch break, or if Maisie hadn't spotted the smoke, we might not have... In the race, the car did not misfire at 6k revs - that misfire was caused by the transponder...

Anyway, my point is - now that the new season is here (or approaches), check your transponders. Leave them on for a few minutes and make sure they don't smoke. Check your car for a misfire at high revs....

The happy ending is that MST are sending me a new one, and it will be a proper AMB red coloured version. Meanwhile, here's a piccie of the melted one. You can just about see the bulge in the case, near the top of the picture, and the black 'goo' that has oozed out..

[Bob Pearson]

To have these things forced on us as they were and then find them detracting from our track time is a very disturbing tale. If anyone from MST reads this site I would like to know why we, in this technically enlightened age we can't have battery operated transponders and so make them independant of our cars systems.

[JR Ewing]

You can have Bob, it's a straight choice - direct or battery powered

[Bob Pearson]

That's interesting JR,I wasn't given that choice last winter,I will take your word for this and try to swop ours for some battery powered items.

[PDL]

Bloody hell. Thanks for warning Chris, I've posted a link to this thread on my board.

I'm lucky enough to havew an AMB 290 (or is it 260?).

Phil

[Chris Y]

Yeah, as posted above, you can choose the battery powered one, although I think they're more expensive. They're not generally offered as an option, so you have to specifically ask for one.

I've never heard of any problems with the red coloured genuine AMB transponders..

[Lee Janotta]

Plastic cases, printed circuit boards and cheap components. If you're going to spend a lot of time and money prepping the car, it worth taking the transponder apart and putting it back together properly with military-grade components in a proper stamped steel enclosure.

[alfasud]

To cause that sort of drain on the electical system, it would need to be an almost direct short circuit, or at least quite a few amps curent draw.

It would be interesting to take apart and see if it was a broken wire (shorting out) or some component failure. I'm not sure if I'd worry about metal boxes and the like, but a visual inspection of the wiring every now and then wouldn't hurt. Don't see a problem with powering it off the car either, but next time I'd use a fuse or circuit breaker.

[PDL]

I've wired a 3 amp fuse direct into mine. Any I switch it on by plugging in the fuse :-)

I presume that the ignition cut off doesn't need to cut of transponder as well, right?

[Crash Test]

A bit off topic, but what they hey...

At the local track, they used to hire out transponders to sprint competitors, however they wound up selling a lot of the motorcyle ones, in a quasi sort of way. A few things to always remember:

1. 1 zip tie CANNOT hold a transponder on.
2. Do not mount your transponder on the exhaust pipe, IT WILL MELT

[Chris Y]

You can't take these transponders apart, they're sealed units in epoxy resin, to prevent vibration damage.

In any case, doing so would invalidate the guarantee, and besides, I've already sent it off, and the replacement has arrived - nice swift turnaround.

I believe it was component failure though - the black stuff oozing out looks like a capacitor failure to me.

PDL - ideally, the cutoff should isolate all electrical circuits - effectively disconnecting the battery. It's the safest way (and also preserves your battery)

[Flagman]

I presume that the ignition cut off doesn't need to cut of transponder as well, right?

I bet you would change your mind if you where trapped in the car, with a major fuel leak, and the transponder started smoking....

[JimW]

I presume that the ignition cut off doesn't need to cut of transponder as well, right?

Please may I have a little rant? I know that several marshalling colleagues have said the essentials so far but this so worries me that I feel that it is worth emphasising.

The master isolation switch is there for the driver's safety. It needs to be connected to anything which is electrical and has enough energy to spark off petrol fumes. I.e. anything which is not classed as "intrinsically safe" in an explosive atmosphere. (So your extinguisher operating system is OK).

Don't bypass it, don't wire the video camera separately (and No, I do not think you should be allowed to have these running off their own batteries), don't have the fuel pumps powered separately (just because you once knocked off the switch).

Don't do it, you chap. We really don't like fire fighting practice outside training days, never mind resuscitation training.

OK I feel better now and thank you for reading this.

Jim Whitaker

[PDL]

No worries - and its OK to have a rant. I'm new to this and was having a problem finding the wire going to the cut off. At the weekend, I re-wired it so the ignition switch cuts off everything.