Quad 405-2 humming transformer

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13-Jan-2020 01:59 PM

J-O

J-O

Posts: 8

Hi, 

Since the transformer in my Quad 405-2 hums a lot (no hum through the speakers ) I have bought a toroidal transformer to replace it. But how to mount it in the amplifier? DaDa has a mounting plate in the shop but it has not been in stock for ages ... so what to do?

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13-Jan-2020 03:30 PM

Ton

Ton

Posts: 69

Perhaps an option if no mounting plate is available. 

Look at this post , someone used the plate of the old transformer. 

The link also shows a picture how it is done. 


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13-Jan-2020 06:22 PM

Stefaan

Stefaan

Posts: 631


The mounting-plates will be available again in the future but there is some delay because they have to be manufactured to measure.

You can also use a sheet of aluminium of 3 to 4 mm, cut it to the right size and bend it in L-shape.

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14-Jan-2020 07:41 AM

J-O

J-O

Posts: 8

Thanks for your tips! Stefaan, have you any idea how far in the future it will be before your mounting plates will be available again? 3 - 4 mm aluminium sheets seems hard to get here. Looks like I will have to go to China via eBay.

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16-Jan-2020 02:03 AM

EJP

EJP

Posts: 1742

I have a couple here if you can contemplate postage from Australia. Contact me off list if interested.

Esmond Pitt

Dada Electronics Australia

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22-Jan-2020 08:28 PM

chartz

chartz

Posts: 14

QUAD UK can still supply the original part, cheaply (less than 100 €). I bought one in May 2019.

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14-Mar-2020 10:19 PM

J-O

J-O

Posts: 8

Well, I have now installed the toroidal and what do I find ... the same hum as before - from the unit itself not through the speakers. Apart from that everything measures just fine so what to do now? 

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15-Mar-2020 07:31 PM

Ton

Ton

Posts: 69

Right before the hum started, did you make any modification to the 405 ? Could the hum be caused by a ground loop ?Did you change anything to the speaker inputs ?

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15-Mar-2020 08:32 PM

chartz

chartz

Posts: 14

Why didn't you buy the real transformer from Quad?


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16-Mar-2020 10:22 AM

EJP

EJP

Posts: 1742

The toroidal is (a) smaller (b) lighter (c) cheaper (d) better.
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16-Mar-2020 01:37 PM

Stefaan

Stefaan

Posts: 631

We also have some original second-hand 405 transformers in stock (they are not in the Webshop).

Send an e-mail if you are interested.

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16-Mar-2020 02:06 PM

chartz

chartz

Posts: 14

Hi,

Quad themselves charge less than € 100 for a brand new transformer!

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16-Mar-2020 04:49 PM

J-O

J-O

Posts: 8

As I bought the toroidal before I knew that Quad still supplied a replacement I am now stuck with the one I got. 

I think now that my post about the new transformer humming just like the old one is not really true. The sound now emitting from my amplifier is higher in frequency and do not make the casing vibrate as it did before. What I hear is more a kind of oscillation coming from the left amplifier board and as I said before no hum from the speakers, only music or no sound at all. 

A ground loop would I think be heard from the speakers. But what could oscillate on the amplifier board to give off this kind of hum???

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17-Mar-2020 01:05 AM

EJP

EJP

Posts: 1742

A toroidal transformer costs less than half of EU100.
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