"EADGBE" wrote in message
...
Arfa:

Are you saying that I should suspect the DTC114 or the 2SA1270? Or
something else?

I'm betting on the DTC114 being the culprit.

Well, it may be the culprit, but you did say that it seemed to compare
favourably, with others of the same type. It should be easy to check if this
stage is working or not, with a couple of voltage measurements. Just check
at the base of the DTC114, to see if the voltage there ever changes when you
alter things i.e. open and close the drawer, hit the PLAY button, hit the
STOP button, go from standby to on etc. If the voltage does change, then
check at the collector or emitter, and see if there is a corresponding, or
inverse change there. If not, then the DTC may well be faulty. If there is
never any change at the base of the DTC, then this is likely not the stage
that's at fault, and it's probably just not being switched by the system
control micro, as a result of some other condition not having been
fulfilled. As I said previously, you can always 'force' the stage, and make
the 5v appear on that second link ...

Try to be logical with the fault location process. Try to understand how the
stage that you are troubleshooting works, and then formulate a set of tests
that will prove out the various sections of it. Only do one test at a time,
and analyse the result against what you were expecting. Use the result
gained to re-evaluate the next test you had planned, and see if it is still
valid, or could be altered to provide you with more information, based on
what you've just found out. Try to remember that fault finding is a dynamic
procedure, which produces 'branches' and deviations from a basic 'model'
that you work out for your tests, at the beginning.

Arfa