[TechAssist] Re: Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio Output I.C.?
- From: "Bruce Tiedeman" <btied@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Sat, 22 Jan 2005 22:29:01 -0500
Sorry Damon, the condition of the audio output is OK in the external output
condition. I can hook speakers up to the audio output terminals and drive
the speakers, works normal..
If I switch to internal audio the output blows and takes out a couple
diodes. This seems to happen on the Left channel , if I disable pin 10, LS
audio it will not blow. You may be right, if on internal DC is getting to
that Left side may be it. Will work on that and see if it can be confirmed.
My print does not show the switching (internal speakers to external) very
well, makes it a little harder..
thanks
Bruce.
----- Original Message -----
From: <damon101@xxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Saturday, January 22, 2005 9:02 PM
Subject: [TechAssist] Re: Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio
Output I.C.?
> Ok, if it still blows in external setting with no speakers and the diodes
> blow too with no load on it, then the reason it's blowing is because the
L/R
> inputs have DC on them, which means the previous stage is killing the
output
> amp....that's most likely, but any previous stage can ship DC to the final
> stage....you got your work cut out for you.....time for a schematic.
>
> Of course if this amp uses a plus/minus supply, one missing supply rail
will
> cause the same symptom too.....
>
> Damon Brunger
> Telrad Electronics
> Fort Wayne IN
> ----- Original Message -----
> From: "Bruce Tiedeman" <btied@xxxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Saturday, January 22, 2005 9:55 AM
> Subject: [TechAssist] Re: Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio
> Output I.C.?
>
>
> > Thanks Guys, I have double checked all my connectors to make sure they
are
> > in the proper socket and not backwards. I have found some bad solder
> > connections where the AV board plugs to the main chassis. On "my print',
> it
> > looks like the signal is switched from "internal to external only", at
the
> > switch. I can not see where the signal for audio goes through the AV
board
> > (PB1670-1). I have checked for a problem on the audio line to the switch
> in
> > both positions . Yes when the audio I.C blows it takes out the diodes as
> you
> > suggested. When they are replaced with a new audio I.C all is good with
> > audio switch in external position. I have left the switch in external
> after
> > the repair it does not matter still blows. I will solder board connects
at
> > AV board and take it from there, trying not to blow my last I.C.
> > thanks for your help,
> > Bruce.
> >
> >
> > ----- Original Message -----
> > From: "jonas miglinas" <miglinasj@xxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Friday, January 21, 2005 11:40 PM
> > Subject: [TechAssist] Re: Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio
> > Output I.C.?
> >
> >
> > > Ditto Tony,
> > >
> > > I remember having the same trouble some two years ago with a Toshiba
> > blowing
> > > the audio ic and diodes after having repaired a dead set symptom.
> > > I inadvertently put a plug in the wrong socket (these were not
labeled)
> > > either on the main board near the audio ic or on the video board where
> the
> > > speaker switch is located. Two of the sockets had the same number of
> pins
> > as
> > > the plug. Blew four ic's and a number of diodes before I got the
> schematic
> > > and found out what I had done.
> > > Been looking for that schematic, can't seem to find it. More than
likely
> > > loaned out and forgotten. If I find it, I'll let you know Bruce.
> > >
> > > Jonas Miglinas
> > > Miglinas TV
> > > Chicago
> > > ----- Original Message -----
> > > From: "Tony S" <tcselectronics@xxxxxxxxx>
> > > To: <techassist@xxxxxxxxxxxxx>
> > > Sent: Friday, January 21, 2005 9:52 PM
> > > Subject: [TechAssist] Re: Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio
> > > Output I.C.?
> > >
> > >
> > > > Bruce , not sure if this helps but I remember replacing several
1N4148
> > > > diodes under the heat sink of the audio output on several toshibas
> with
> > > > blown audio outputs. Usually happens if the customer tried to hook
> > stereo
> > > > into the output speaker terminals of the TV.
> > > >
> > > > Tony Saracco
> > > > TCS ELECTRONICS
> > > > 406 Andra Ct.
> > > > Gilberts, IL 60136
> > > > tcselectronics@xxxxxxxxx
> > > >
> > > > ----- Original Message -----
> > > > From: "Bruce Tiedeman" <btied@xxxxxxxxxxxx>
> > > > To: <techassist@xxxxxxxxxxxxx>
> > > > Sent: Friday, January 21, 2005 7:03 PM
> > > > Subject: [TechAssist] Fw: Re: Toshiba CF3566A (Tac9190)Blows Audio
> > Output
> > > > I.C.?
> > > >
> > > >
> > > > > Audio Output I.C shorting on internal audio setting only!
> > > > > I spoke to soon on this set. This chassis is difficult to work on
> > having
> > > 3
> > > > > separate boards that tie together. I removed the chassis and left
> the
> > > > > cabinet in customers home. The set has High Voltage and Audio now
> > ,after
> > > > > the
> > > > > audio and power supply repair.. If I put the audio switch on back
of
> > > > > chassis
> > > > > to internal setting it blows the Audio Output I.C immediately. "On
> > > > > external
> > > > > Audio it works good audio and all". Is it possible the "speakers
> have
> > to
> > > > > be
> > > > > hooked up" on this chassis to prevent this problem. I have gone
over
> > the
> > > > > circuit many times and all voltages check good. ( with external
> audio
> > on
> > > > > only). I am stuck with this problem? Have not seen any thing like
> this
> > > > > before, but don't work on many Toshiba sets with this type
chassis.
> I
> > > have
> > > > > a
> > > > > print and followed the audio from main chassis to AV board and
back
> to
> > > > > main
> > > > > chassis again, I can not find any part tied to this circuit that
> would
> > > > > cause
> > > > > this.. I have blown a few of these audio I.C's ,it is getting
> costly.
> > > > > any help on this appreciated,
> > > > > Bruce.
> > > > >
> > > > > B&T Electronics
> > > > > 139 Margaret St
> > > > > Sarnia Ontario
> > > > > Canada
> > > > > N7T 2Y3
> > > > > 519 344 1850
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > Subject: Re: [TechAssist] Re: Toshiba CF3566A (Tac9190) No Start
> Relay
> > > > > click
> > > > > only!
> > > > >
> > > > >
> > > > >> Fixed! Thanks for the help , found a bad cap (C651) at the audio
> > > > >> output I.C, it was leaking causing the output and diodes to short
> in
> > > that
> > > > >> section. .
> > > > >> I also repaired the power supply.
> > > > >> Bruce.
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > >
> >
>
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