Quad 44 - replacing CD4066BE switches with MAX4066CPD..with strange results..

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08-May-2019 12:03 PM

Jay

Jay

Posts: 41

Hi All,

Recently I bought 4 MAX4066CPD's for my 44 (ser. # > 23000).

Removed the older switches, then soldered 4 IC sockets on the motherboard;then inserted the new MAX4066CPD's (and yes: looked at correct placement - notch @ the right side of course) and...alas..no sound whatsoever.

Subsequently reinserted the old CD4066BE's and...result: clear sound!

What am I doing wrong? Any thoughts or comments?

Regards,

Jay

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08-May-2019 04:18 PM

Stefaan

Stefaan

Posts: 593


Hello, Jay,

We do not recommend the use of MAX- or other analog switches we haven't tested in the Quads for revision.

Obviously the pin lay-out of the MAX IC's you bought is different from the normal pin layout, you can check this on the datasheet.

Finally we don't recommend using IC-sockets for Opamps or switches in the Quads as they may cause HF oscillation.

Stefaan

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12-May-2019 08:38 AM

Joost Plugge

Joost Plugge

Posts: 965

Recently I discovered a remark in the Max4066 Datasheet, it stated NO negative powersuply, I did not have time to test the implications, but it is something weird, in a 44 you use plus and minus 7.5V.

Joost Plugge

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12-May-2019 03:02 PM

Joost Plugge

Joost Plugge

Posts: 965

Oops, I reread the datasheet, there should be no negative signal voltages with ground as reference: they even put in protection diodes to cope with this situation; but in a 34 and 44 the ground level of the 4066 switch is at -7.5V, so all the other voltages are positive compared to this level, so there should be no fundamental problems. Fine, but testing is the proof of the pudding, I opened a 34 series 1 and put in Ic sockets, sorry Stefaan, and a fresh set of MAX4066CPD, no problems at all.

So there should be something else that causes the troubles. Maybe fake chips?

Joost Plugge

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12-May-2019 06:29 PM

Jay

Jay

Posts: 41

Thanks for your answer, Joost. Farnell was my supplier for the MAX4066CPD's...

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13-May-2019 11:37 AM

EJP

EJP

Posts: 1589

Well I think you have to look at reverse insertion, bent legs, all the fun and games we've had over the years. They do work. My own 34 and 44 have had MAX4066s in them for twelve years. If there was some problem I think I would have noticed by now.
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