IC needed (out of SONY unit)

[Phil Allison]

"Rudolf Ladyzhenskii" <rudolfl@optusnet.com.au>

I do not have problems using substitute parts, although I prefer
originals,
but in this case we are talking about modifying the circuit.

** Any substitute of one part for another **is** a modification - so
ALL repairs where parts are changed involves modification. If the new
part is not up to performing the job, is of substandard manufacture or any
way is not as suitable as the original then an early failure can result.
This possibility is an inherent risk in doing repair work.

Equipment manufactures have ***exactly *** the same problem - they have
no idea what they are sending out he factory door is any damn good or not
since THEY did not themselves make the bloody components.

If you are nervous about making changes to something because you fear
mysterious, unforeseeable consequences - then by all means don't.

But please do not tell others with more technical insight that you they are
wrong to do so.





.............. Phil

 

[Ross Herbert]

On Thu, 6 May 2004 23:33:45 +1000, "Rudolf Ladyzhenskii"
<rudolfl@optusnet.com.au> wrote:

No, I do not know anyone who was sued, but I do not want to be first one
either.

No one will know until something happens (fire or person gets slectricuted,
etc.). Then investigation will show a modified unit, even if this mod is not
the cause. (I am probably being paranoid here).

Being an engineer, I know that when ANY part in the power supply of the unit
is changed, it must go through approval process. Unit was tested for
electrical compliance as well for EMI/EMC and any change can affct the
performance.

I do not have problems using substitute parts, although I prefer originals,
but in this case we are talking about modifying the circuit.

Rudolf

As I see it removing the blown STIL and replacing Ri with a NTC is all
that you need to do. It is not as though it requires hacking into the
board and making modifications at board level.

As far as electrical approval and EMI/RFI is concerned I doubt there
would be any problem since many other SMPS use exactly the type of
inrush limiter siggested by PA without any problems. Also we are
talking about a laptop PSU, hardly a high power device. The resistance
of the NTC is no more than 10 ohms cold and probably less than 1 ohm
when hot so it is not likely to result in any deleterious or hazardous
situation.

But, as you say, it is your decision whether you do the repair or not.
But if you don't fully explain the situation to the customer and give
him an opportunity to authorise the "mod" you may run the risk of him
blabbing to all his mates that you are incompetent and can't do a
simple repair.