There she blows...!

[RichardW]

So, after nearly 12 years and 140k the transistors threw in the towel on the Xantia's blower this morning. I'm thinking about earplugs for the way home There seem to be loads of replacement units on E-bay so going to get one of those as they are <£20 and the replacement trannies look hard to source, and not that much cheaper. I might see if I can get some in due course, and repair the board in the car, then I will have a spare, if the e-bay one turns out to be a light weight.

Seems like 140k might be the tipping point for things going wrong - we shall see....

Already onthe list for the crimbo holidays:

Xantia:
Handbrake cables
Pollen filter
Battery swap with C4
Rear wiper - first attempt not good enough, and it still has a short on it

C4
Rear pads
Oil change
Air filter change
Battery swap with Xantia

Hoping for some good weather!

[CitroJim]

The trannies are freely (as in easily, not free as in costs no money!) available from Farnell Richard...

I saw someone on ebay the other day was offering repair kits as well, comprising the trannies, heat-sink compound and replacement screws...

£20 for the whole shebang is not bad though... The only thing that worries me as they might be cheap copies and thus not very long-lasting or reliable...

Sounds like you have a busy Christmas in store

[Mandrake]

What type are the original transistors ? I assume they usually fail short circuit ?

Is it worth replacing them with something a bit higher rated ? Wouldn't be the first time that I've seen power transistors marginally rated for their intended purpose, sometimes a healthy amount of overspec'ing is worthwhile.

[CitroJim]

No, one normally fails open circuit in my experience Simon. That then causes the one remaining one to do all the work and after a while it throws its toys.

The circuit is badly designed in that there's no low-value emitter resistors to help with current sharing.

I always replace with a pair of MJ11015 with the same batch number to help with current sharing. Ones bearing the same batch number should be fairly well matched.

Never replace singly or with differing batch numbers or you'll find one runs a lot hotter than the other and the module will be unreliable.

In all the ones I've done to date I've only ever known one replacement pair of MJ11015s to fail.

One thing I do when replacing is to test the module with it hanging in free air and after a few seconds of operation feel both transistors to make sure they're both roughly at the same temperature. be careful as they can quickly get too hot to touch and you risk a burn!

[RichardW]

It's fixed itself for now....how does that work then

[CitroJim]

It's fixed itself for now....how does that work then

They've healed up Richard... It does happen occasionally but it may not be long-lasting.

Also, the one perhaps that was short-circuit has now gone open circuit leaving the other one to carry all the load. Sadly if this is the case it won't do it for long before going short-circuit...

You can tell if you remove the module and run it for a few moments in free air. If one is cold and the other hot that shows one has gone open-circuit...

[RichardW]

New board fitted. Was built with the correct MJ1015 transistors, and works OK. Came from seller autosense - arrived almost next day, and was <£20 delivered - not worth bothering with the soldering iron at that price! Aif flow much improved too with new pollen filter - can't remember when I last changed it, it was, er, manky! Brushes are OK for the time being, should last another few miles yet.

Of the original list, still got to do C4 oil change and rear pads, and Xantia stat and rear wiper - weather was rubbish, and looking after 2 small boys takes up most of free time!

[CitroJim]

That is good value Richard...

Did the old module continue working or did it fail again?