DVD-Software.info

[Dave C]

Hello Sirs,

I (hi-fi newbie)just bought a rough end sony es home amp from a pawn
shop, m# tda-330es, that the protection circuitry comes on and stays
on once the unit is powered up, I can only guess some homer didnt use
proper pre-amplification/switching and/or cross phased the speaker
output leads when he or she hooked this up last and cooked one of the
final or main "stereo hybrid" op. amps, on diode/continuity test, this
one transistor, p/n 2SA2921 (sanken), is wide open, and the body of
the part looks like it got burned by an clutzy/overzealous "tech" with
not enough time and too much soldering iron, it has a melted dimple in
it, the solder leads for all four of these that go onto the final amp
pcb look ratty also as the "tech" didnt clean up the rosin left in
between the leads etc.

Q: Are these transistors still available ? nte's cross ref. shows
them both as obsolete and NLA, 2sa1215 and 2sa2921, HELP !!! Mouser
shows some older jap p/n's like this in an older catalog from around
1999, I went to there 'site and did a search and nada.

The unit is switchable between mono and stereo on the back panel,
which works, indicating to me the unit still has logic/smooth 5vdc, on
power up, the mono or stereo led lights up breifly but then goes back
to the protection led, and stays on.

Qv2.0: Are these sanken transistors origional equipment parts that
came in the unit ?? if so, sony used way too much heat sink grease on
these !! Also, should anything else be tested related to this besides
the complimentary transistors etc ???

Any other suggestions or comments would be much appreciated, and
forgive me if I have offended anyone in this group in any way by
placement of this post ..

Thanks in advance,

Dave Carper ..

[Mark D. Zacharias]

Sounds like the burned one is bad all right, time to get it to a shop for
repair. Even if you manage to get some transistors to replace them with, the
market has been flooded with substandard counterfeits. A knowledeable shop
would be able to get high-quality replacements, hopefully. The 2SA1215 and
2SC2921 have been discontinued by the manufacturer, so any new ones with
those numbers are fake.

Mark Z.
"Dave C" <pindoc2@yahoo.com> wrote in message
news:e36894e2.0412040759.77cc2542@posting.google.com...

[Jerry G.]

You should have an experienced shop service the amplifier for you. If any of
the outputs are blown, you can be sure that there are other faults that must
be serviced. Usually when there are blown outputs, the drivers, and other
support components are also damaged. If this is the case, the new outputs
will blow again as soon as the power is re-applied.

The best transistors are the original ones, or ones that are a very close
match to the original specs. It is also important that the transistors are
pair matched to make sure that the cross-over distortion is kept at a
minimum, and that the current balance is as accurate as possible.

--

Jerry G.
=====

"Dave C" <pindoc2@yahoo.com> wrote in message
news:e36894e2.0412040759.77cc2542@posting.google.com...
Hello Sirs,

I (hi-fi newbie)just bought a rough end sony es home amp from a pawn
shop, m# tda-330es, that the protection circuitry comes on and stays
on once the unit is powered up, I can only guess some homer didnt use
proper pre-amplification/switching and/or cross phased the speaker
output leads when he or she hooked this up last and cooked one of the
final or main "stereo hybrid" op. amps, on diode/continuity test, this
one transistor, p/n 2SA2921 (sanken), is wide open, and the body of
the part looks like it got burned by an clutzy/overzealous "tech" with
not enough time and too much soldering iron, it has a melted dimple in
it, the solder leads for all four of these that go onto the final amp
pcb look ratty also as the "tech" didnt clean up the rosin left in
between the leads etc.

Q: Are these transistors still available ? nte's cross ref. shows
them both as obsolete and NLA, 2sa1215 and 2sa2921, HELP !!! Mouser
shows some older jap p/n's like this in an older catalog from around
1999, I went to there 'site and did a search and nada.

The unit is switchable between mono and stereo on the back panel,
which works, indicating to me the unit still has logic/smooth 5vdc, on
power up, the mono or stereo led lights up breifly but then goes back
to the protection led, and stays on.

Qv2.0: Are these sanken transistors origional equipment parts that
came in the unit ?? if so, sony used way too much heat sink grease on
these !! Also, should anything else be tested related to this besides
the complimentary transistors etc ???

Any other suggestions or comments would be much appreciated, and
forgive me if I have offended anyone in this group in any way by
placement of this post ..

Thanks in advance,

Dave Carper ..