what sort of blown transistor is this? can't identify to replace

[sbadger]

Hi,

My bathroom extractor fan has died, i opened it up and found that a
transistor has blown.

It's quite small and reads :-

20103
ST MA
A122

I believe that ST is the manuafacturer, but they have been no help so
far.
The fan is a Greenwood Airvac T100-T 240v, a new board is £38+vat+pnp,
i'd much rather pay 12p for a new transistor.

if anyone can help me find an equivilent I'd be most greatful.

thanks
Stewart

 

[Franc Zabkar]

My bathroom extractor fan has died, i opened it up and found that a
transistor has blown.

It's quite small and reads :-

20103
ST MA
A122

I believe that ST is the manuafacturer, but they have been no help so
far.
The fan is a Greenwood Airvac T100-T 240v, a new board is £38+vat+pnp,
i'd much rather pay 12p for a new transistor.

What makes you think the part is a transistor? Could it be a triac?
What else is on the PCB?


- Franc Zabkar

 

[Steve Kraus]

What does this control board do for you? Is it variable speed? I agree
that it sounds more like a triac. What else is there? A speed control
with a triac will be pretty much like a light dimmer with a potentiometer
(variable resistor control that you adjust), the triac, and possibly a
small disc capacitor and inductor (coil) to reduce emmission of radio
interference. I believe that this arrangement really only works properly
with a brush / commutator type motor, not the induction motor that drives
most fans. So the motor type might be a clue as to the electronics. Then
again maybe it's some sort of DC motor and completely different electronic
speed control. If it's the simple triac speed controller then that's good
because pretty much any with sufficient rating will work even if physically
not the same. You could even buy a light dimmer, remove the triac and
discard the rest. It does still need to be mounted to whatever heat sink
there was.

But perhaps I've made the wrong assumption about it being a speed
regulator. Maybe it's a noxious gas detector!

 

[sbadger]

Hi Guys,

Thanks for the replys, and sorry about laking details.

Your right that i am only assuming that it's a transistor, but
the pcb is marked as TR1, (which could mean triac too i guess).

I know that it's blown because it's physically damaged - the front of
it has cracked off.

The fan turns on when the light/power is turned on, and a pot sets
how long the fan will run after the light/power is turned off.

When I say it's 'quite small', i'm pretty sure package type is a TO92.