Upgrading a Quad 405-2

[Argh!]

Hmmm. Just seen this. The answer is: "I don't know"!

The amp is in the loft at the moment - I'll have to dig it out at some point and have a look. It was a while ago, but I'm pretty sure I took all those photos...

Anyway, did you enjoy your rebuild?

EDIT: Three things...

1. I have the original photo taken on a Nikon Coolpix on 02/09/2011 @ 18:43 and resized for the web page (hence the "a" suffix)
   
2. The image on my page is considerably higher resolution than the one on Snook's
   
3. Look closely and the opamp is an OPA134, which Snook doesn't mention but I do all over my page... and that's what's in my amp.
   

Don't know what's happened, but you are right in that the images are seemingly identical (down to the smear of heat sink compound) apart from the date code! All very odd !

 

[Argh!]

While I was browsing the web for Quad 405 refurbs etc. I looked at Keith Snook's and Nick de Smith's web sites and interestingly the images of the 405 boards were identical apart from the date code on the output transistors. Its like spot the difference. The top one is from Keith Snook http://www.keith-snook.info/QUAD-405-2-Modification.html and the lower one from Nick de Smith https://www.desmith.com/NMdS/Electronics/QUAD_upgrades.html I found this a real puzzle. I wonder what the explanation is.

 

Well, I dug it out of the store...

Difficult photographing the TO3s in situ... but if you look closely you can see a date code of 8323. I rest my case!



All assembled, it's quite nice. I'm tempted to use it again... It's 10 years since I did this project. Time to put it to use!

 

[mikejt]

Hi, thanks for your reply, the similarity in the two images will remain one of life's mysteries.
The Quad rebuild is still outstanding. I'm not an electronics engineer, although I studied Power and Electronics many moons ago and remember struggling with trying to understand the transistor equivalent circuit. However I'm fairly adept at soldering and Halfords sell the multicore with lead and tin. So no excuse apart from memories of puffs of smoke and burnt loudspeaker speech coils which incidentally lead me to buy the 405, 33 and FM3 over forty years ago.