Where are the fuses on nad 7250pe

[Anna Maria]

My NAD 7250pe suddenly has no sound. I'd like to check the fuses but I don't know where they are. Can you help, please ? Thanks a million,
Anna Maria

 

[Guest]

I'm looking at my 7155 (cosmetically identical) and the AC fuse is immediately behind the power switch. There are what look like low voltage (DC) fuses on the big board to the right.

Before you start digging too deep, if the display is lit (which suggests the power fuse is okay, and probably the DC fuses are okay) do check that the speaker switch is in the correct position and that the Listen switch is on the correct selection.

 

[Anna Maria]

I'm looking at my 7155 (cosmetically identical) and the AC fuse is immediately behind the power switch. There are what look like low voltage (DC) fuses on the big board to the right.

Before you start digging too deep, if the display is lit (which suggests the power fuse is okay, and probably the DC fuses are okay) do check that the speaker switch is in the correct position and that the Listen switch is on the correct selection.

OK, I found two fuses: 250v Buss MDL 1/10 and 250v Buss MDL 3/8. The unit goes on with both of them in, however if I remove the 250v Buss MDL 3/8 the power is off. UHM..... If I remove the other it makes no difference. I wonder if the one that makes no difference controls the speakers?
I am rereading your message and I see you say the other fuse controls the DC power? I am really puzzled.
Thanks a million for taking the time to explain.

 

[Guest]

You may be on the correct course. Have you any way of checking the fuse that seems to make no difference -- sometimes if a fuse has blown it looks like it's smoked inside.

You could test it with small battery and a low voltage bulb or find a friend who owns a multimeter -- or find an electronics hobby store and take the fuse in and ask for a replacement.

I may be wrong about the DC part and remember that my receiver is not quite the same model as yours. If the fuse that doesn't seem to make a difference is really 250 volts it isn't DC.

If both fuses have identical lettering on the actual fuse body they may both be 250 volts as your observation suggests -- so you might try swapping them and see what happens.

You MUST remove the receiver's power lead from the wall socket before touching anything marked 250 volts (that incidentally is the maximum rating of the fuse -- in Europe the power is 220 or 230 volts and in the US 110).


Incidentally, there are other ways to diagnose faults on a receiver. Have you tried plugging a pair of headphones in to the headphone socket and see if there's any audio. If you can hook up another amplified system (say the speakers that come with a desktop computer) to the tape output of the receiver this may help narrow down the type of problem.

 

[JAYDEEJOHN]

Best answer selected by jaydeejohn.

 

[valle3452]

OK, I found two fuses: 250v Buss MDL 1/10 and 250v Buss MDL 3/8. The unit goes on with both of them in, however if I remove the 250v Buss MDL 3/8 the power is off. UHM..... If I remove the other it makes no difference. I wonder if the one that makes no difference controls the speakers?
I am rereading your message and I see you say the other fuse controls the DC power? I am really puzzled.
Thanks a million for taking the time to explain.

Hi. I just finished work on a 7250PE that had no sound but all fuses and output stages tested good. I found faulty potentiometers in the driving stages that would send everything else in the power stage off to massive DC offsets and the amp into protection. The speaker relay wouldn't kick in as a result. If you are unfamiliar with this area I can suggest you take your amp in for service somewhere.

E.