Maker Pro
Maker Pro

fuse/ power supply question or problem on amplifier

I

ian nicoll

Jan 1, 1970
0
Our amplifier was on yesterday and suddenly stopped working, the T1A fuse on
the 240V side of the transformer had blown, for no apparent reason. I did an
250V insulation test on the 240V side of the t/f and it was clear, there
didn't appear to be a short circuit on the 240V side of the t/f or an
interwinding fault or a fault to earth on the LV side, the connector from
the LV side is connected to a rectifier board with, I presume, some current
limiting feature. As far as I could see there was no obvious fault component
in the amplifier.

I didn't have any T (antisurge) fuses so I used a F1A quick blow fuse. The
amplifier worked fine last night but today the fuse blew within a few
seconds (or less) or the amplifier being switched on (using the button on
the front which switches the 240V circuit).

The amplifier is a Marantz about 12 years old.

Is it possible that using a quickblow rather than an anti surge fuse has
caused the fuse to blow the second time. Is there likely to be some current
limiting device on the rectifier board? Any other pointers things or things
I should look for.

Thanks

Ian
 
A

Asimov

Jan 1, 1970
0
"ian nicoll" bravely wrote to "All" (09 Sep 03 15:33:44)
--- on the heady topic of "fuse/ power supply question or problem on amplifier"

in> From: "ian nicoll" <[email protected]>
in> The amplifier is a Marantz about 12 years old.

in> Is it possible that using a quickblow rather than an anti surge fuse
in> has caused the fuse to blow the second time. Is there likely to be some
in> current limiting device on the rectifier board? Any other pointers
in> things or things I should look for.

in> Thanks

in> Ian

Yes, a fast fuse will go... well... faster! What can happen with a fast
blow fuse in an application requiring a surge rating is that one might
switch the power at the instant the line voltage is at maximum and the
fast fuse goes pfffft... If the slo blow one goes again then worry...

Asimov
******

.... Power is obtained by current meeting resistance
 

uengin

Sep 21, 2009
4
Joined
Sep 21, 2009
Messages
4
I'm sorry I saw this post after I posted my question on a new thread, but my issue is also fuse related. I don't know what's the etiquette here, to put the link to the question or repost the question here....so I will just repost it here and save people going from page to page:


Hi,
Firstly, I hope I am not reposting a thread that already exists. I am a newbie, so please be nice to me :-[

Secondly I am an electronics engineering student in my third year for background information purposes.

Now, the problem I need help with is this; I have household/domestic amplifier which keeps blowing a fuse, obviously because the circuit is drawing too much current, but I need help to diagnose where and how it is drawing too much current so I can rectify the problem. This unit has a toroid transformer with various outputs. I have tested if the rated unloaded output is actually as rated on the toroid, affirmative. Because there are several outputs there are 3 fuses. The rest of the outputs are unfused.

The output voltages are 0-29V (unfused), 0-6V (unfused), 0-11V (single fused - it's fine doesn't blow), and 29-0-29V (dual fused). The one fuse that keeps blowing is the fuse that is on one out put of the 29-0-29V output. Now there are rectifier circuits following the fuses (as per any power circuit I guess). The fuse that keeps blowing is the centre fuse that is missing in the photo. I have also tried shorting over the fuse. What happens is the toroif transformer begins to warm up and the rectifier bridge warms up.

Any ideas and diagnosis procedures clearly outlined will be very much appreciated. Thank you in advance. Included are photos of the fuse section of the board. The track side photo has been flipped horizontally to correlate to the view from the component side.

i43.photobucket.com/albums/e399/uengin/RIMG0045.jpg
i43.photobucket.com/albums/e399/uengin/RIMG0044.jpg
 
Top