Quad 405 Mk1 replacement PCB's

[Impman71]

Hi,

My old Quad 405 mk1 has developed an issue on one channel and I would like to change the boards whilst hopefully repairing it as they look very ropey and i burnt a couple of tracks a few years back on one of them whilst doing some mods
I was planning on checking everything as I swapped it across, but am struggling to find an exact replacement and my electronics knowledge is very lacking!
I have found these:

Class A dynamic biasing 80W amplifier PCB Quad 405 2pcs | eBay

which are the same size and look very similar, but there are a few things missing and most noticeably(to me) is the line in polarity is reversed.
My boards are M12368 iss9 - I am wondering if the ones above are MK11's and if i am likely to have any issues when swapping everything around. I have downloaded the 405 service manual which lists all the component values. I was hoping it was going to be like painting by numbers😀

Any info gratefully received!

Thanks,
Colin

 

[JonSnell Electronic]

For the asking price, you won't go too far wrong. The polarities are probably down to copyright issues.

 

[v12nut]

These might be a better bet
Higly sought Class A dynamic biasing 80W amplifier PCB Quad 405 MK2 1pc ! | eBay

I suspect they may be copies of a Dada board.
cheers

 

[AndrewT]

the fact that the first link claims ClassA tells you they know nothing about what they are selling.
What will their customer support be like?

The second link shows a PCB and sch and the sch seems to have been highlighted to show what is on board and what is off board. And still claim ClassA ! and can't spell highly.

I would go for the second, but don't expect any customer support from someone who has stolen QUAD's I.P.

I am working with a Jim's PCB and the pads, even the through hole plated, come off !!!!
The epoxy is not thick and not tough, but that makes alterations easier.

 

[Chris Daly]

Hi Colin
I think you may find the eBay after-market Quad 405 boards from China
are larger than an original board pair, and will not fit in an original casework for a 405.
There is however a specific Quad 405 case made for them available
which is black and a bit bigger.

From my experience the Net Audio Mk3 boards are a very good indeed.,

Cheers / Chris

 

[Impman71]

Hi,

Thanks for all the input; I have gone for the ones from Jim's Audio - they look very similar to a pic I found of the Dada board, just a few subtle differences.
I did like the look of the Net Audio boards, but I cannot justify spending that much(That and I fancy having a go myself).
Attached is a pic of the Dada board and also a completed board from the Ebay vendor.
Cheers,
Colin