Whoops..... ESU magic smoke

I'm not very well versed in decoder operation so I have a problem with my perception of what may be a good idea. I understand the bit about feeding the motor output from the chip via a DPDT relay powered from a direction dependent lighting output. However when the relay energised direction is selected my guess is that the motor output would be directed via the defective output stage and therefore nil.
I think the relay would need to take power from a function that's independent of motor direction.
 
Hmmm. That's a good point Neil, yes the decoder would naturally try and reverse the motor output thru the duff output. Seems like you're correct, the relay needs to be driven by another function that's NOT directional.
 
Any idea what the chip is that's blown? Wouldn't surprise me if its a FET similar to the ones used on other decoders. I may still have a spare somewhere from when I repaired my Lenz Gold Maxi.
 
ntpntpntp said:
Hmmm. That's a good point Neil, yes the decoder would naturally try and reverse the motor output thru the duff output. Seems like you're correct, the relay needs to be driven by another function that's NOT directional.
Click to expand...
Humm...
Yes, we would need to use a separate function button to control the direction of movement.. This would also mean direction-dependent lighting would not be operative. - The motor only works going forwards..

A 'simple' fix becomes more problematic, as we work it through! ::)
 
Well lads I hope the two attached photo/diagrams help as to what has blown.

The diagram shows the XL V3.2 with twelve pins per side
The photo shows XL V3.5 with the screw terminal.... in essence, both are more or less constructed pretty much identically except for the pinouts.

The transistor (indicated with the arrow) glowed red and then spouted the smoke.

esu loksound xl diagram with arrow.jpg

esu decoder photo with arrow.jpg


Nick....
If you have a spare FET that matches the blown one ...could you possibly fix the board?
 
whats the number on the Fet, I might have some
 
Sparky
All the boards are locked away for tonight, but I will get the number tomorrow... many thanks to you for the input...and also to the rest of the lads........
 
Can't find the spare FET at the moment, I had a look through my store of ICs. :-[ Found some bridge rectifiers I was looking for a little while ago though, and I seem to have dozens of 1458 dual op-amps which I must have bought back in the early 1980s!
 
Sorry to be a bit late but have just spotted this.
How old is the decoder ?
If it is less than a year old and you have proof of purchase you can get it replaced.
I did it through SW Digital, the UK importers, and no charge was made, even though I had a "frying tonight" moment.
It did take about 2months to be returned, though....
 
TONYWARD50 said:
Sorry to be a bit late but have just spotted this.
How old is the decoder ?
If it is less than a year old and you have proof of purchase you can get it replaced.
Click to expand...

Unfortunately Tony , it is a V3.2 and I bought it used (it had been taken out of a Marklin loco) so it is well over the age of warranty cover....... :( :(
 
TONYWARD50 said:
Sorry to be a bit late but have just spotted this.

It did take about 2months to be returned, though....
Click to expand...
Ah, about half the time of Massoth then! >:( ::) ;) ;)
 
MMMM this magic smoke sounds expensive

I think King Edward cigars could be cheaper O0 O0 O0 O0 O0 O0
 
Rhinochugger said:
MMMM this magic smoke sounds expensive

........
Click to expand...

It sure is - I think the open market rate is around £165 per ml. when it's pressurised into its liquid form, but you need a special Government license to buy it like that.... ;)

It is made and sold by the same company that makes Long Weights, Left-Handed Screwdrivers and Tartan Paint. :o

Jon.
 
ntpntpntp said:
Can't find the spare FET at the moment, I had a look through my store of ICs. :-[ Found some bridge rectifiers I was looking for a little while ago though, and I seem to have dozens of 1458 dual op-amps which I must have bought back in the early 1980s!
Click to expand...

I for some reason have about 300 Bc108's
 
will look it's a huge box of components that was salvaged from radio club qth, when we cleared it out prior to demolition, there are tubes of Ics in there
 
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