Joe Paulson wrote in a message to All:

JP> For $3 at Goodwill,I got a Sanyo Radio/CD/Tape/2 speakers that
JP> didn't work.Made in April.1955.It was a duplicate of one that I was
JP> using and I might get some usable spare parts.
JP>  
JP> When I plugged it in,nothing happened.
JP>   On opening it up,I saw a gray layer over part of the MB near the
JP> 110 V.A.C. plug that looked like something vaporized.
JP> My experience had been in tube circuit repair and I trying to learn
JP> about what the new parts are.
JP>   The 110 V. power socket ( symbol CN ) was unusual with 2 pins for
JP> the A.C. and 3 pins up to the MB (motherboard) where the center pin
JP> was partially  missing.It looked like that this pin had vaporized. 
JP>   The socket looked like the following:
JP>  
JP>                -------------
JP>                            I
JP>      110V.A.C. -----       I
JP>                            I-----I
JP>                ----              I \ 1    Pin 2 Partially missing  
JP>                                 I \ 2
JP>                ------------------I \ 3
JP>         -------------------------------------------                
JP>                                            MB
JP>  
JP> Checking with an ohmmeter,there's no connection between the A.C.
JP> and the 3 pins.The 3 pins terminate on the MB .What is this?

Without being able to see what you're working on I'm not sure how much I
can help,  but let me toss this out to consider.  A lot of that stuff is
made with wiring in that area to be shipped all over the world,  which
involves different power voltage levels,  different plugs,  and maybe some
other things being different as well.  You may see a transformer with two
primary windings in there which in the US (or Japan) model would be
connected in parallel,  in other markets they'd be in series,  or different
taps would be used,  or stuff like that.

JP> I started checking voltages.The 110 VAC goes to a transformer and 
JP> steps down to 12.1 VAC. with a fuse in one leg,(still good) and 
JP> goes to a circuit of 4 diodes and 4 Caps.Checking the diodes with 
JP> the ohmeter,I get values from 1.0  to 2.2 megs,and nothing with 
JP> the leads reversed.The Diodes are "D", the caps are "C" ,
JP> resistors are "R" as expected.I see that "L" are
coils,"CN" are 
JP> jacks.

JP> I noticed that there are wires running between tie points in the MB
JP> with the symbol of "J".What are these? 

Jumper wires?

JP> I thought the printed circuit took care of connections.

Not if it's a single-sided board,  which is pretty likely.

JP> One side of the 12 VAC is also the B+ leg.?

Maybe.  Some stuff tends to use a lot of different power supply voltages. 
Is +12 the only one you could find in there?

JP>  The radio has a connection for batteries (8 D cells= 12 volts). I
JP> figured that if the power supply was bad,it could run on 
JP> batteriesonly and would verify the internal circuits.
JP> When I connected the 12 V.D.C.,I started to see smoke and quickly
JP> diseconnected.I felt around for hot spots and found one hot area in
JP> the middle of the MB.

Any idea what part it was?

JP> I saw a L shaped metal separator,about 3 " long leg,3/4 " short 
JP> leg,about 5/8 " deep that was hot.Attached to it ,by a screw,was  a
JP> black piece,of several layers about 1 3/4 " by 3/4 " ,with the 
JP> symbolsToshiba TA 822?K with 14 pins going to the MB.
JP> On the other side of the metal separator,I see a 25 V, 2200 MFD 
JP> cap.

Sounds like it might be an audio power amp chip,  and that metal bit was a
heat sink.  The cap would be either power supply bypass or maybe output
coupling,  if the output of the device sits at half the power supply
voltage.

JP> What does the symbol TA mean and is there any table of descriptions 
JP> on the Web? A look at the DIGIKEY catalog wasn't helpful.

Digi-Key probably wouldn't carry that part.  Maybe you'd have better luck
with JDR or Jameco,  or one other outfit whose name I can't recall offhand
that I used to get lots of parts for consumer-type gear.  Digi-Key
specializes in a lot of digital parts,  not so much the consumer-type chips
and things you'd find in tv and stereo gear,  which is a whole 'nother
animal.  The TA is probably just the mfr's prefix for that part.

JP> If the B+ and one side of the 12 VAC are in the same leg,what 
JP> kindof a rectifier circuit is that with 4 diodes and caps?

Sounds like a bridge rectifier to me.

JP> I also see another strange piece;
JP>  
JP>             bolt hole
JP>              v
JP>            --  ------------I metal support
JP>            --  ------------I
JP>                 I          I \    The black item labeled "Q" was   
JP>                 I          I \    was held up by the 3 wires to the
JP>                  -----------I \    MB.
JP>             -----------------------------MB

That would be either a power transistor or a 3-terminal chip like maybe a
regulator?  What sort of numbers are on that one?

JP> Right now,my first inclination would be to replace the 25V,2200 MFD
JP> cap and repair the vaporized wire in the connector and see what 
JP> happens.I still can't figure out where the current came from to 
JP> vaporize the metal in the center wire.
JP> If nothing else,I could still use the parts as spares for the good
JP> unit that I have.

Something to fool around with,  anyhow.

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