Marantz PM30SE amp problem

[nicoll]

The fuse has blown on our Marantz PM30SE amp. I replaced the fuse and all
was well for about 30 seconds when the fuse blew again.

The fuse is ok with the t/f disconnected from the circuit board. I noticed
two regulators/transistors? nos Q801/802 close to the bridge rectifier have
discoloured the back of the PCB. I can't see any other component which looks
stressed. I 'm thinking a component failed may have failed causing a high
current causing heating of the regulators/transistors.
I'm not sure what to look for next and I'd welcome any suggestions. I tried
emailing info@marantz.com to ask for a schematic but my email bounced.

Thanks

Ian

 

[Jerry G.]

Obviously something is drawing too much current, if you are using the
correct type of fuse.

Most of the common problems with many of these receivers are in the output
stages. You would have to take voltage and current measurements, and signal
level measurements to determine which devices are going defective. There can
be many types of parts and conditions that can cause this. You will have to
send the set to an experienced service tech, to properly service your unit,
unless you have the training, service information, and instruments to do the
work.

If you added more speakers, or changed them for new ones, the total load
impedance may be too low, thus forcing the output stage in the amp to pull
too much current. Also, playing your receiver excessively loud (over
driving the unit for its power rating) can cause it to pull too much
current, and blow the fuse.


--

Greetings,

Jerry Greenberg GLG Technologies GLG
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WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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"nicoll" <newsnicoll@btinternet.com> wrote in message
news:bqnkge$jue$1@titan.btinternet.com...

The fuse has blown on our Marantz PM30SE amp. I replaced the fuse and all
was well for about 30 seconds when the fuse blew again.

The fuse is ok with the t/f disconnected from the circuit board. I noticed
two regulators/transistors? nos Q801/802 close to the bridge rectifier have
discoloured the back of the PCB. I can't see any other component which looks
stressed. I 'm thinking a component failed may have failed causing a high
current causing heating of the regulators/transistors.
I'm not sure what to look for next and I'd welcome any suggestions. I tried
emailing info@marantz.com to ask for a schematic but my email bounced.

Thanks

Ian