Pls Help, 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

 

[Walter Harley]

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

When you say "quite small", can you be more specific? Exactly what shape is
it and what are its dimensions?

What makes you believe it's a transistor, and that it's blown? What, if
any, measurements have you taken on it? Can you tell anything about its
intended function the circuit it's in? I'm not trying to be rude, just
trying to get some more details.

 

[[email protected]]

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

Based on almost no information, here's my SWAG:

Trace the circuit board to see if one wire from the fan
is connected to one leg of the component without any
intervening components. If there is continuity from
the bad component to the fan, the thing is a triac
(aka thyristor), not a transistor.

I strongly suspect it is a triac. They do go bad,
often without some other problem causing them to
die. If the component is a triac, try replacing
it with a BTA16-800B for about $1.50 from Mouser -
perhaps someone from the other side of the pond
will know of a supplier there.
Datasheet at:
http://www.st.com/stonline/books/pdf/docs/7471.pdf

It would be interesting to know what features your
fan has to require more than an on/off switch -
please tell us!

 

[Jim Adney]

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

It's possible that the full number is 2SA122.

-

 

[Walter Harley]

Hi,

My bathroom extractor fan has died[...]

It's possible that the full number is 2SA122.

I thought of that too, before giving my earlier answer to the OP... but a
2SA122 appears to be a germanium RF transistor, which seemed like an
unlikely device in an exhaust fan.

I'd still like to hear the OP's answers to the questions I posed earlier.

 

[Jim Adney]

Hi,

My bathroom extractor fan has died[...]

It's possible that the full number is 2SA122.

I thought of that too, before giving my earlier answer to the OP... but a
2SA122 appears to be a germanium RF transistor, which seemed like an
unlikely device in an exhaust fan.

I agree. Seems VERY unlikely. I didn't look it up.

I'd still like to hear the OP's answers to the questions I posed earlier.

Right.

-

 

[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).

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.

Thanks again
Stewart

 

[Walter Harley]

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).

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.

What causes you to believe that it's blown? Is there obvious physical
damage, or are you basing this on measurements of some sort (and if so,
what)? Are other components also damaged?

By the way, if you haven't already, you might try posting to
sci.electronics.repair; some of the folks there are pretty good at
identifying components in consumer electronics based on their markings.
Include the new information you've given us, of course.

A thyristor in a TO92 package would be a little unusual, I think. I wonder
if it could be a JFET or MOSFET, in a timing circuit?

 

[sbadger]

Hi,

yeah it's blown literally, the front is no longer attached to the main part.
I'm pretty miffed at ST, they should at least know what it is?

 

[[email protected]]

Hi,

yeah it's blown literally, the front is no longer attached to the main part.

Then it is not a TO 92 package. See:
http://www.kilowattclassroom.com/Archive/Transistor.pdf

A TO 92 doesn't have a "front" and "main" part. More
likely - if your description is accurate - it's a TO 220
package, which looks like transistor on the right on
the url above which they call a Power Tab Package.

Did you trace the circuit as I mentioned in my first reply
to you?