Autohelm 800 Power transistors

[winater]

Hi,
Our trusted Autohelm 800 started a mutiny, and after opening her up the problem appeard to be fried power transistors.

Two of the four transistors on the position TR4 and TR8 were fried beond recognition
the others were;
BDW 93B 8923 on position TR7
and
BDW 94B 8917 on position TR 6(?)

My question to the gathered wisdom here is; what were the typenumbers of the unrecognisable transistors?
Bonuspoints question ;-) whith which type of transistors could all four of them best be replaced?

 

[zambant]

They are a pair of Darlington transistors
Data sheet is here
www.farnell.com/datasheets/296701.pdf
Farnell stock them - cheap as chips
http://uk.farnell.com/multicomp/bdw...93b|match|p|plid|&CMP=KNC-GUK-FUK-GEN-SKU-MDC
Good luck
John

 

[LadyInBed]

Was one failing the cause or was it the effect from something else failing?

 

[Beyondhelp]

That's what I was going to say. This is probably/possibly set up as a H-Bridge motor driver something along the lines of this:



Check the motor is all ok, and does not have burnt coils. The other thing is if this is a H bridge and it was sent the wrong drive signals they will also self destruct, so that would need checking too.