DIYbanter - View Single Post - blown fuse on fairly new Yamaha HTR 5790 receiver

Jamie

wrote:

One of the two main fuses blows instantly as soon as power is applied
to receiver. I checked the main power supply caps 2@10,000uf and they
were ok. I also checked the bridge rectifier and it was ok. When I
remove the two power leads to the transformer it does not blow fuse.
The main windings of the transformer are 1.0 ohm. The output
transistors are each about 800 ohms at the speaker terminal (prior to
relay).

What else to check?????

Thanks!!

To save your self some fuses and hassles, find
your self a high wattage incandescent lamp rated
for the line voltage your using (120v 200W) for
example. Use that in place of the fuse until you can
removed the solid short.
WHen you say you removed the main windings? I can
only assume you're referring to the primary side of the
xformer?. If so, how about disconnecting the secondary
sides?
You may want to perform a short test to ground to see if you have
a shorted xformer. The preferred method is to use a megga meter.

Usual causes are arc's from lightning storms or over heating of the
enamel if you do find a short to ground.
--
If disconnecting the secondary from the bridge removes the short,
then try disconnecting the output supply that goes from the bridge and
caps into the amp.

Also, you may have a time delayed on or soft start circuit that may not
be soft starting.

P.S.
Because a CAP or bridge test ok at DMM voltage levels does not mean
they are good.

--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5