On Sun, 12 Dec 2004 17:30:57 -0500, "tempus fugit"
put finger to keyboard and composed:
Thanks Frank.
What is a fusible resistor?
It's a safety resistor that is designed to fuse under fault
conditions.
The IC is an STK 4161 which I can;t find a data sheet on.
Is this the one?
http://www.satel.hu/file/document/El...K/STK4161V.pdf
This was one of my
first suspects, but now that I see that it is desoldered, I assume the
problem must be somewhere else.
You should test for shorts between the load side of each of the
fusible resistors and ground. You will always measure a short on the
winding side. If after desoldering the STK4161 IC there are no longer
any shorts on the load side, then the IC must have been the culprit.
Just to be sure, test for shorts between pins 10 & 11, 10 & 9, 13 &
14, and 13 & 11.
It's kind of tricky to test something that
you can't power up. I think my next step is to desolder the xformer and see
if the low resistance is still there to see if the problem in the xformer
(if the low resistance is a problem) or somewhere on the board (I'm assuming
that the resistance from the DC + to ground shouldn't be quite that low,
otherwise it'd need to source 50 - 75A, which seems unlikely).
Any other thoughts?
Thanks
The transformer is the last place I would look. In any case you will
always measure close to zero ohms on the secondary side.
"Franc Zabkar" wrote in message
.. .
On Sun, 12 Dec 2004 13:18:19 -0500, "tempus fugit"
put finger to keyboard and composed:
Sorry bout that - should've put that in m OP. It's a Sansui RZ-590.
There are a number of 1 ohm resistors (they are marked FR and have the
symbol of a fuse in series with a resistor?).
These are fusible resistors.
I know how to measure
voltages, but as I said in my OP, the unit is dead - it shuts down
immediately after power up, so there are no voltages to measure. There
are 3
secondaries - a pair of reds with a black, a pair of blues with a white,
and
a pair of browns. The one in question is the reds and black, which I
assume
is for the high(er) voltage supply to the output IC, as they are connects
to
50v electros.
Also, on further inspection, I found that the output IC, although mounted
well, doesn't have any of the pins actually soldered to the board. I
don't
know if this could cause the fault, and I don't know if they have been
desoldered for a reason.
This IC is probably a hybrid amp (STKxxxx ?). The previous tech
probably desoldered it to isolate the source of a short circuit. Be
prepared to replace it.
thanks
"Mark D. Zacharias" wrote in message
...
The low resistance you measure may be normal. Some Sansui receivers had
bad
1 ohm resistors in the power supply. There's lots of possibilities.
Model
number would help.
Mark Z.
"tempus fugit" wrote in message
...
Hey all;
I'm working on a Sansui receiver that shuts down as soon as I switch
it
on -
no lights or anything. I've taken it apart and inspected the power
supply
section, and found that there is a very low resistance in a couple of
the
transformer's output wires. If I measure between either of the reds
(there
are 2) and the black (which is connected close to the reds, so I'm
assuming
that these taps go together) the meter reads about 0.6 or 0.7 ohms.
Is
it
possible that this is the correct reading for this, or should I take
that
to
be a dead short? I get somewhat higher readings on the other taps -
more
like 2.5 or 3 ohms.
Also, has anyone had experience with a reciever with similar
symptoms?
Any
tips?
Thanks
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