Quad 306 Advice / Confirmation

[Pepperamip]

About a year ago I bought a Quad 306 from a guy who sold it as upgraded. In his listing he advised exactly what he undertaken and provided pics of the work completed.

Can any you quad experts tell by these pics if he's done a good job or if theres any more worthwhile tinkering to be done?



https://uploads.tapatalk-cdn.com/20190411/3ff581d77e6bc94485180474aa9325d6.jpghttps://uploads.tapatalk-cdn.com/20190411/7f4eaa3fb26c90f362d8dd451f7b4cdc.jpghttps://uploads.tapatalk-cdn.com/20190411/38e632da890ff7a1279064d0c3c88825.jpghttps://uploads.tapatalk-cdn.com/20190411/1047d76997d670a811df97b895122dcb.jpg

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[smangus]

Might help if you post up what he said he did to it.

[Pepperamip]

I can't remember and I don't think I can get to the original ad.

Can you see any good stuff in there? The blue caps are nichicon and the transformer was new but no idea on its provenance.

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[M6NTL]

Take a look at my Quad 306 Refresh and Upgrade thread here

https://r.tapatalk.com/shareLink?url=https%3A%2F%2Ftheartofsound%2Enet%2F forum%2Fshowthread%2Ephp%3Ft%3D62558&share_tid=62558&share_fid=4177&share_type=t

There are some fantastic tips and hints I was given in here!

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[Light Dependant Resistor]

About a year ago I bought a Quad 306 from a guy who sold it as upgraded. In his listing he advised exactly what he undertaken and provided pics of the work completed.

Can any you quad experts tell by these pics if he's done a good job or if theres any more worthwhile tinkering to be done?



https://uploads.tapatalk-cdn.com/20190411/3ff581d77e6bc94485180474aa9325d6.jpghttps://uploads.tapatalk-cdn.com/20190411/7f4eaa3fb26c90f362d8dd451f7b4cdc.jpghttps://uploads.tapatalk-cdn.com/20190411/38e632da890ff7a1279064d0c3c88825.jpghttps://uploads.tapatalk-cdn.com/20190411/1047d76997d670a811df97b895122dcb.jpg

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The work done is OK, but not the way I would do it. The resistors which are 1k is optional part 14a in the 306 schematic. The other work is reverse biased diodes and parallel capacitors - possibly adding current and noise to
ground planes which are at odds with other purposes, ie SK3 is the zobel network and therefore close to the current dumping bridge,

Although sometimes difficult amplifier boards usually try to abide by what is called star earthing ie a ground path for each needed ground return, so intersecting with diodes and capacitors
needs to be checked with a oscilloscope, that no added noise is being added. The electrolytic capacitors are across the zener diodes. Better is to replace the zeners with dedicated current sources
and voltage references. As I outlined in Mark's thread there are unnecessary excessive currents at the zener diodes placed simply so the zener will function, rather than considering what the
zener anode or cathode as the case may be attaches to.

The 560 ohm resistors sensibly raised above the board always are stressed and need to be replaced with 5 watt types - see Marks thread

[Pepperamip]

Thanks Mark, I skimmed your thread before but I'll go back over it again with a bit more attention.

Chris thanks for looking and your comments. Just had a feeling it might not be at its absolute best so glad I asked.

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[Light Dependant Resistor]

Thanks Mark, I skimmed your thread before but I'll go back over it again with a bit more attention.

Chris thanks for looking and your comments. Just had a feeling it might not be at its absolute best so glad I asked.

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Hi Paul
I will work on a definitive step by step for the 306, might take me a few months though- so you can see what is needed. I do have some spare 560 ohm 5 watts
so send me a PM and I will send you the 4 needed.

[Pepperamip]

Chris that's much appreciated (PM incoming) Thanks.

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