Hiss with dispay dimmed on A32

adinica

Active Member
Hello to everybody! I own a FMJ A32 and recently I expected a small but strange problem. The amp is hissing with display dimmed (the problem doesn`t occur with display off or full :nono:) and this hum is coming out from the tweeter.
So, the question is... it`s really an issue or is normal (as I know dispays are quite noisy in general).
The second problem is: the ring that surrounds the 2 mains capacitors was broken, the sound became harder and fatiguing.
What shoud I do? Thank you in advance! :lease:
 
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ANDY_DUTTON

Active Member
To dim the display the A32 modulates the VFD. i.e it turns it on and off very quickly to achive the intermediate brightness levels. Its not unreasonable to expect a small amount of breakthrough into the audio circuit, but if it is very noticable it could mean one of the decoupling capacitors on the display is failing.

The rings round the capacitors are there to improve the sound characterisitc. You can replace them with a Nitrile Rubber O ring which you can get from hardware stores or electronics component distributors such as RS or Digikey. Measure the old one if you can, it needs to be fairly tight round the capacitors.

Regards,
Andrew


Regards,
Andrew
 

adinica

Active Member
Thank you Andrew, helps me a lot! Till then, I put on the caps the rubber pad from the preamplifier section... :rolleyes:
 

adinica

Active Member
I discovered something interesting! The rubber pad is "sounding" better than the ring!!
 
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