Quad 33 / 303 Noise on Start-up

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13-Jun-2016 11:35 AM

franco

franco

Posts: 16

Hi All,

I have a 33/303 combination that we use daily that has developed a fault. The 33 was revised around 2010 and unused until I got a 303 for revision. 303 was revised about 2-3 years ago.

Recently the combo has started making a "static" noise through the speakers for 1-2 seconds when I turn the dial on. after that it seems to work fine.

This is not just dirty pot crackle as it doesn't matter how far you turn it on, the noise is always the same.

I don't run this amp hard, it normally just has the dial on "3" with volume controlled on the Sonos box attached.

Any thoughts on what could cause this? I'm quite good at soldering, but pretty hopeless on diagnosing faulty components.

Thanks

Franco

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13-Jun-2016 11:55 AM

Stefaan

Stefaan

Posts: 621

The first thing to do is tot switch on the 303 with the speakers connected and without input (remove the interlink cable from the DIN-connector).

Is the noise still there? Then it comes from the 303. Otherwise the problem is in the 33.

If the noise comes from the 303 the first thing to check is the quiescent current and the voltages (like described in the Upgrade / Revision manual).

Is the noise in both channels? Then it can be due to a problem in the power supply. Otherwise there is probably a faulty component in the channel that has the problem.

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13-Jun-2016 12:25 PM

franco

franco

Posts: 16

Hi Stefaan,

Will try your suggestion later today. I think it is likely to e the 303. It is an ugly example, where as my 33 I used for years with a valve amp prior to revision is quite nice.

I also remember trying to set the quiescent current was a nighmare. The pot is so sensitive.

Thanks,

Franco

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13-Jun-2016 03:38 PM

franco

franco

Posts: 16

Hi Stefaan,

Quick check shows it is the 303. Guessing I need to haul it ut and play with the quiescent current.

Regards,

Franco

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14-Jun-2016 05:44 AM

EJP

EJP

Posts: 1677

I doubt that it has anything to do with the quiescent current. More likely C101 or one of the small transistors.
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14-Jun-2016 01:07 PM

franco

franco

Posts: 16

Thanks for the reply. I'll interrogate it this weekend.

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13-Aug-2019 02:45 PM

V0ltair3

V0ltair3

Posts: 6

Hi Stefan,


I am facing a similar problem... I have a 33 / 303 that I've upgraded with the DADA 33 / 303 kits respectively a couple years back. The issue seems to be linked to the pre-amp itself, but I am a bit lost on the troubleshooting part.


When I apply the kit, I've replaced the transistors as well, any direction pointers would be well appreciate it!


Thank you,

Ivo

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14-Aug-2019 04:05 AM

EJP

EJP

Posts: 1677

Please start your own thread and describe your symptoms and tests completely.
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