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General Discussions => The Lab => Topic started by: pw8888 on July 27, 2019, 04:03:49 PM

Title: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: pw8888 on July 27, 2019, 04:03:49 PM
Hi Guys
i hope i am posting in the right part of the forum.
Just bough one of those amazing unit . vintage. with output transformer :-)

"but" ... i am getting 50hz hum on both output // louder on channel one .
could that be an easy fix ? condenser in the power supply going bad ?
just want to say that has NOTHING to do with the compressor noise floor. It is really something that ADD to the signal.just wondering that could be the transformer ? or wiring. another info is that the machine is NOT grounded at the moment.
i really appreciate your help !!
thanks
P
Title: Re: hum problem on ADR COMPEX FX760X-RS
Post by: radardoug on July 27, 2019, 05:30:44 PM
If its not grounded through the mains cable, and it has transformers, it will probably hum. Why is it not grounded? Do you have a death wish?
Title: Re: hum problem on ADR COMPEX FX760X-RS
Post by: pw8888 on July 27, 2019, 05:34:58 PM
sorry i mean no EARTH in the outlet .

only 2 places in my home have earth.
now some of those ADR where NOT balanced in /out (no transformer)
i can check to go out of the unit unbalanced  bypassing  the transfomrer and check ?


Title: Re: hum problem on ADR COMPEX FX760X-RS
Post by: radardoug on July 27, 2019, 08:35:28 PM
If you want serious results with studio equipment, it all needs a mains earth, and all the earths connected together. That is the first thing I would look at. The power supply may need recapping, but make sure you have grounded everything properly first.
Title: Re: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: pw8888 on July 28, 2019, 08:39:56 AM
SOLVED !!
after many try... i just bypassed the INPUT AND OUTPUT transformer ... and i dont have ANY problem left...
strange...thanks !!

P
Title: Re: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: radardoug on July 28, 2019, 05:17:58 PM
Did you ground the unit?
Title: Re: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: pw8888 on July 28, 2019, 05:35:12 PM
Did you ground the unit?
I did ground it but that didn’t change nothing at all. Still had this 50hz hUm (around -50db). Without transformer the unit is COMPLETELY quiet . Strange
Title: Re: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: noulou on July 29, 2019, 09:22:16 AM
http://rane.com/note110.html (http://rane.com/note110.html)
Title: Re: hum problem on ADR COMPEX FX760X-RS SOLVED
Post by: pw8888 on July 29, 2019, 06:13:03 PM
http://rane.com/note110.html (http://rane.com/note110.html)
Thanks !
Great info !